Crank size difference--will it really help?



C

caaron

Guest
I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
getting refitted to the bike to help with numbness in my hands and we ended
up moving the seat position and also raising the handlebars. After we did
that it was suggested that I should really be riding on 165mm cranks because
I have short legs. I'm seeking opinions re:

Will there be a noticeable difference in performance with shorter cranks?

How hard is it to change out Ultegra cranks--do I need special tools?

Do I change the cranks themselves or do I also have to change the gears (it
is a triple) with the cranks as a set?

Thanks in advance...

Chuck
 
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we
> ended up moving the seat position and also raising the handlebars. After
> we did that it was suggested that I should really be riding on 165mm
> cranks because I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?
>
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the gears
> (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck


Chuck: Hard to believe you'd fit a 5200 that came (stock) with 172.5mm
cranks and have legs short enough to justify 165mm. Rarely do I find someone
that would fit even a 50cm bike that would benefit greatly from 165mm
cranks... generally, that would be more likely for the length of leg seen on
a 48cm or smaller. Generally; your mileage may vary.

You can buy just crank arms, but I wouldn't, as a pair of crank arms cost as
much, or more, than a new set of cranks. Given that chainrings do wear out,
the new set would make more sense. But I wouldn't go to 165mm without trying
some first. Changing them out is no big thing; in fact, on Ultegra, all
you'll need is an allen key (8mm? Not at the shop right now, so I don't have
one to look at).

But we really need to know how tall you are, what your inseam is, and maybe
even the size of bike (just to get an idea how the whole package fits
together).

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
 
"caaron" <[email protected]> wrote in
news:[email protected]:

> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I
> was getting refitted to the bike to help with numbness in my hands and
> we ended up moving the seat position and also raising the handlebars.
> After we did that it was suggested that I should really be riding on
> 165mm cranks because I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter
> cranks?
>
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the
> gears (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck
>
>


I think Sheldon's a fan of 165s, at least for fixies.

From http://sheldonbrown.com/harris/cranks.html

"165 mm is Good!
We generally recommend 165 mm length cranks for road fixed-gear use.
This shorter length makes it easier to spin faster cadences, and also
reduces the risk of striking a pedal while cornering (with a fixed gear,
where you have to pedal through the corners, this can be an issue.)"

The 5200 was last made with the Ultegra 6503 crank, which was the last
of the 3-piece models. I'm assuming that's the model you have.

Depending on whether you have integrated pullers currently, it could be
as simple as using an 8mm allen wrench and 15mm pedal wrench to make the
switch. At worst, you'd also need an octalink-compatible puller,
probably $10-15.

You'd be best off buying the complete crankset and getting new rings.
The right arm alone is only $20 cheaper than the whole set.

This, of course, assumes you can find a place that still has the
6503/165 in stock, because I don't think QBP has them anymore.

I guess Airbomb claims to have them, $175.99

http://store.airbomb.com/ItemDesc.asp?IC=CR6340

Another option would be to get a Sugino XD600 and a Shimano UN-73 Bottom
bracket, for a little more than half the price of the Ultegra crank. It
has 46-36-26 rings, but some lower gears would be good with the shorter
crankarms.
 
caaron wrote:
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I
> was getting refitted to the bike to help with numbness in my hands
> and we ended up moving the seat position and also raising the
> handlebars. After we did that it was suggested that I should really
> be riding on 165mm cranks because I have short legs. I'm seeking
> opinions re:
> Will there be a noticeable difference in performance with shorter
> cranks?
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the
> gears (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck


We need more data. What is your inseam and height?

I'm 5'5", 29" inseam, ride a 48cm bike that came equipped with 165mm cranks
and it was surprising how much I struggled on the first ride to keep up with
the group. I switched them out for 172.5s and I was happy... happy as a...
hippo. Then again, I had been using 172.5s before and probably had some
muscle memory.

--
Phil, Squid-in-Training
 
On Sun, 25 Sep 2005 16:47:21 -0400, caaron wrote:

> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we ended
> up moving the seat position and also raising the handlebars. After we did
> that it was suggested that I should really be riding on 165mm cranks because
> I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?


Well, that is a big jump, so, yeah, you probably will notice the
difference. How short are your legs? Usually it does not matter all that
much what crank length you use; you will become accustomed to what you
have. But for really long or short legs, it might be worth dealing with.

>
> How hard is it to change out Ultegra cranks--do I need special tools?


A couple. You need a crank puller. This is a small tool that is quite
inexpensive. Much less expensive than the cranks themselves. You have to
know what sort of crank you have (year, not just model), to get the right
one.

>
> Do I change the cranks themselves or do I also have to change the gears
> (it is a triple) with the cranks as a set?


You may be able to find just the arms, but you will have to search for
them. More commonly they come with rings. How old are the current ones?
How much wear do they have? Maybe it would be worthwhile to change them.
Worst case scenario is that you would have extra rings for when the
current ones wear out, if you can't find bare cranks.


--

David L. Johnson

__o | "It doesn't get any easier, you just go faster." --Greg LeMond
_`\(,_ |
(_)/ (_) |
 
I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9" tall
and have a long torso and short legs. My inseam is 30" and the distance
from the top of my femur to the floor is 89cm. Based on Peter White's
18.5% calculation guideline, 165mm cranks would be just right. Similar
calculations from Ergobike (edward ZImmermann's bicycle sizing site) also
come out at 165mm.

Previously I had a 58cm Trek 5200, which I found too big to ride
comfortably, so I got the 54cm Trek a few years ago and it seems to be a
better fit. At age 60 I find I need the handlebars higher for comfort and
I'm a recreational rider, not a racer, so my rides average about 15mph.
I've always had trouble spinning fast, and although I can get up into the
high 90's I find my average cadence is in the low to mid-eighties on most of
my road rides. So I was wondering if changing over to the 165mm cranks
would make enough of a difference in comfort and cadence to make it
worthwhile to do the change and what downside there might be, if any...

Thanks for the replies

Chuck


"caaron" <[email protected]> wrote in message
news:[email protected]...
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we
> ended up moving the seat position and also raising the handlebars. After
> we did that it was suggested that I should really be riding on 165mm
> cranks because I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?
>
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the gears
> (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck
>
 
"caaron" <[email protected]> wrote in message
news:[email protected]...
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we
> ended up moving the seat position and also raising the handlebars. After
> we did that it was suggested that I should really be riding on 165mm
> cranks because I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?
>
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the gears
> (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck
>

When I got my new bike, I begin to worry whether I had the correct crankarm
length. I considered spending hundreds of dollars to replace my brand new
excellent crankset. I read lots of different ideas about what is the
correct crankarm length based on lots different inputs - your size, style of
riding, etc.

Then I realized that the "experts" can't even agree what is the right size.
Also, I noted this fact:

The difference between 172.5 and 165 is 7.5 mm - or about 4%. I wondered
whether I could even feel a 4% difference in crankarm length in a blinded
test. I decided that for me, a few percentage points difference in crankarm
length could not possibly be worth hundreds of dollars for a new crankset.

Just my 2 cents. Your mileage may vary.

BobT
 
caaron wrote:
> So I was wondering if changing over to the 165mm cranks
> would make enough of a difference in comfort and cadence to make it
> worthwhile to do the change and what downside there might be, if any...


You have to try them and see; there are lots of personal history
stories inre crank length-- short folks happy on 175's, tall ones happy
on 165's, and so on. I went to 165's for "everything" because I was
living near a track and wanted to use the same length all the time
("every little bit helps"). Surprisingly, my knees stopped having a
certain soreness that occurred regularly after hard rides when I used
172.5's. Not an expected result, and FWIW the knees, which have been
iffy for a good long time, have been doing better with 165's for about
five years now. "Works for me".

Park Tool has a "help" section inre bike maintainance. You'll note that
cranks have to be torqued pretty substantially. Sears has inexpensive
torque wrenches, I've seen your crank in 165 length go v. reasonably
priced on ebay, etc etc.; likely nothing you can't do yourself. And
then sell the ones you don't want <g>.

IMHO, don't let concerns about cadence take away from your riding
enjoyment. Work with it if you want, "spin-ups", telephone pole spins,
etc., but NBD except to make it easier to cope with speed variations in
racing or fast group rides. --D-y
 
>I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9" tall
>and have a long torso and short legs. My inseam is 30" and the distance
>from the top of my femur to the floor is 89cm. Based on Peter White's
>18.5% calculation guideline, 165mm cranks would be just right. Similar
>calculations from Ergobike (edward ZImmermann's bicycle sizing site) also
>come out at 165mm.
>
> Previously I had a 58cm Trek 5200, which I found too big to ride
> comfortably, so I got the 54cm Trek a few years ago and it seems to be a
> better fit. At age 60 I find I need the handlebars higher for comfort and
> I'm a recreational rider, not a racer, so my rides average about 15mph.
> I've always had trouble spinning fast, and although I can get up into the
> high 90's I find my average cadence is in the low to mid-eighties on most
> of my road rides. So I was wondering if changing over to the 165mm cranks
> would make enough of a difference in comfort and cadence to make it
> worthwhile to do the change and what downside there might be, if any...
>
> Thanks for the replies
>
> Chuck


What are you using for saddle height (measured from center of crank to top
of saddle)? Traditional wisdom would be around 66cm if I'm figuring
correctly, which, on a 54cm Trek, would place the top of the saddle 13-14cm
above the top tube (or 12cm above the seat collar, which extends above the
top tube a bit and represents the measuring point for frame size on a 5200).

Those all sound like pretty normal measurements (if they're reasonably close
to what's on your bike). If so, I find nothing there to indicate that
there's any "need", based on leg length, for a shorter crank. You might wish
to try one for the heck of it, but I'm not sure what symptoms need to be
addressed, particularly in light of your stated RPMs which are *not* at the
low end. Low-to-mid-80s are perfectly acceptable for most people; not
everyone does well spinning like Lance.

I'm also somewhat concerned by what sounds like a hit-and-miss approach to
fit. How did you end up initially with a 58cm frame? When I mock that one
up, it looks like the saddle would be almost sitting on top of the top tube.
You're potentially over-compensating and swinging from one extreme to the
other, when someplace in the middle might be just about right.

But getting down to the effects of shorter cranks- generally, you'll be able
to spin a bit more (because the crank is traveling through a smaller circle,
so your feet aren't actually moving as far/fast per revolution), but you'll
also be losing some leverage, which could be an issue climbing. In general
there's a trend toward longer cranks these days, seemingly with little
downside (we're not seeing more knee injuries today than back-in-the-day,
even though there are more people serious mile now than back then).

Good luck, and let us know how the experiment turns out-

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
 
I doubt that it would make much difference to you. I have three bikes
that I switch between regularly. The tandem has 165 mm cranks, the
folding travel bike has 170 mm, and my usual road bike has 175 mm. If
I pay attention it seems to me that I spin a bit faster with the 165s,
but the difference is minimal and I can't say I notice any clear
benefit of one length vs. the others.
If you had any specific knee problems with the longer cranks then I
could see the rationale for switching to shorter ones. But I wouldn't
bother if you don't have any particular issues that you can attribute
to the longer cranks.
 
caaron wrote:
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we ended
> up moving the seat position and also raising the handlebars. After we did
> that it was suggested that I should really be riding on 165mm cranks because
> I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?


Probably not.


> How hard is it to change out Ultegra cranks


Not very.

--do I need special tools?

Yes

>
> Do I change the cranks themselves or do I also have to change the gears (it
> is a triple) with the cranks as a set?


Yes.
 
Well, my seat is higher than that--74cm above the bottom bracket to the top
of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and more
power.

Chuck

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
> >I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
> >tall and have a long torso and short legs. My inseam is 30" and the
> >distance from the top of my femur to the floor is 89cm. Based on Peter
> >White's 18.5% calculation guideline, 165mm cranks would be just right.
> >Similar calculations from Ergobike (edward ZImmermann's bicycle sizing
> >site) also come out at 165mm.
>>
>> Previously I had a 58cm Trek 5200, which I found too big to ride
>> comfortably, so I got the 54cm Trek a few years ago and it seems to be a
>> better fit. At age 60 I find I need the handlebars higher for comfort
>> and I'm a recreational rider, not a racer, so my rides average about
>> 15mph. I've always had trouble spinning fast, and although I can get up
>> into the high 90's I find my average cadence is in the low to
>> mid-eighties on most of my road rides. So I was wondering if changing
>> over to the 165mm cranks would make enough of a difference in comfort and
>> cadence to make it worthwhile to do the change and what downside there
>> might be, if any...
>>
>> Thanks for the replies
>>
>> Chuck

>
> What are you using for saddle height (measured from center of crank to top
> of saddle)? Traditional wisdom would be around 66cm if I'm figuring
> correctly, which, on a 54cm Trek, would place the top of the saddle
> 13-14cm above the top tube (or 12cm above the seat collar, which extends
> above the top tube a bit and represents the measuring point for frame size
> on a 5200).
>
> Those all sound like pretty normal measurements (if they're reasonably
> close to what's on your bike). If so, I find nothing there to indicate
> that there's any "need", based on leg length, for a shorter crank. You
> might wish to try one for the heck of it, but I'm not sure what symptoms
> need to be addressed, particularly in light of your stated RPMs which are
> *not* at the low end. Low-to-mid-80s are perfectly acceptable for most
> people; not everyone does well spinning like Lance.
>
> I'm also somewhat concerned by what sounds like a hit-and-miss approach to
> fit. How did you end up initially with a 58cm frame? When I mock that one
> up, it looks like the saddle would be almost sitting on top of the top
> tube. You're potentially over-compensating and swinging from one extreme
> to the other, when someplace in the middle might be just about right.
>
> But getting down to the effects of shorter cranks- generally, you'll be
> able to spin a bit more (because the crank is traveling through a smaller
> circle, so your feet aren't actually moving as far/fast per revolution),
> but you'll also be losing some leverage, which could be an issue climbing.
> In general there's a trend toward longer cranks these days, seemingly with
> little downside (we're not seeing more knee injuries today than
> back-in-the-day, even though there are more people serious mile now than
> back then).
>
> Good luck, and let us know how the experiment turns out-
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
 
165 may be right for you if you have shorter than average legs. i ride
a 54" frame and 170 cranks. i can feel the difference between 175 and
170. i haven't tried any other size. and i definitely prefer the 170.
 
> Well, my seat is higher than that--74cm above the bottom bracket to the
> top of the seat and 23cm above the top tube. I had it lower but it felt
> cramped and when I raised it to this height I got better spinning and more
> power.
>
> Chuck


Chuck: Have you had a fitting done by somebody who does more than have you
stand over the top tube? By that I mean measurements (arm, torso, inseam,
shoulders etc), turn that into a mock fit and then observe the results?
Self-fit doesn't always work too well; measurements can be off, and there's
nobody to observe the results and notice things like rocking hips, toes-down
pedaling, arched (curved) back etc.

A really good fitting person isn't useful just for high-speed
performance-oriented riding. Indeed, if you get someone who starts talking
about getting you into a lower position for "efficiency", you've got the
wrong person.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"caaron" <[email protected]> wrote in message
news:p[email protected]...
> Well, my seat is higher than that--74cm above the bottom bracket to the
> top of the seat and 23cm above the top tube. I had it lower but it felt
> cramped and when I raised it to this height I got better spinning and more
> power.
>
> Chuck
>
> "Mike Jacoubowsky" <[email protected]> wrote in message
> news:[email protected]...
>> >I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
>> >tall and have a long torso and short legs. My inseam is 30" and the
>> >distance from the top of my femur to the floor is 89cm. Based on Peter
>> >White's 18.5% calculation guideline, 165mm cranks would be just right.
>> >Similar calculations from Ergobike (edward ZImmermann's bicycle sizing
>> >site) also come out at 165mm.
>>>
>>> Previously I had a 58cm Trek 5200, which I found too big to ride
>>> comfortably, so I got the 54cm Trek a few years ago and it seems to be a
>>> better fit. At age 60 I find I need the handlebars higher for comfort
>>> and I'm a recreational rider, not a racer, so my rides average about
>>> 15mph. I've always had trouble spinning fast, and although I can get up
>>> into the high 90's I find my average cadence is in the low to
>>> mid-eighties on most of my road rides. So I was wondering if changing
>>> over to the 165mm cranks would make enough of a difference in comfort
>>> and cadence to make it worthwhile to do the change and what downside
>>> there might be, if any...
>>>
>>> Thanks for the replies
>>>
>>> Chuck

>>
>> What are you using for saddle height (measured from center of crank to
>> top of saddle)? Traditional wisdom would be around 66cm if I'm figuring
>> correctly, which, on a 54cm Trek, would place the top of the saddle
>> 13-14cm above the top tube (or 12cm above the seat collar, which extends
>> above the top tube a bit and represents the measuring point for frame
>> size on a 5200).
>>
>> Those all sound like pretty normal measurements (if they're reasonably
>> close to what's on your bike). If so, I find nothing there to indicate
>> that there's any "need", based on leg length, for a shorter crank. You
>> might wish to try one for the heck of it, but I'm not sure what symptoms
>> need to be addressed, particularly in light of your stated RPMs which are
>> *not* at the low end. Low-to-mid-80s are perfectly acceptable for most
>> people; not everyone does well spinning like Lance.
>>
>> I'm also somewhat concerned by what sounds like a hit-and-miss approach
>> to fit. How did you end up initially with a 58cm frame? When I mock that
>> one up, it looks like the saddle would be almost sitting on top of the
>> top tube. You're potentially over-compensating and swinging from one
>> extreme to the other, when someplace in the middle might be just about
>> right.
>>
>> But getting down to the effects of shorter cranks- generally, you'll be
>> able to spin a bit more (because the crank is traveling through a smaller
>> circle, so your feet aren't actually moving as far/fast per revolution),
>> but you'll also be losing some leverage, which could be an issue
>> climbing. In general there's a trend toward longer cranks these days,
>> seemingly with little downside (we're not seeing more knee injuries today
>> than back-in-the-day, even though there are more people serious mile now
>> than back then).
>>
>> Good luck, and let us know how the experiment turns out-
>>
>> --Mike-- Chain Reaction Bicycles
>> www.ChainReactionBicycles.com
>>

>
>
 
Yes, I actually was fitted by a good, independent bike shop and it was there
that we moved the seat back and up, so that was definitely an improvement.
They asked me about my riding style and physical problems (back, neck &
shoulder pain) and made adjustments to the bike. Then I rode it on the bike
stand while they observed and they fine tuned from there. The conclusion
was that the adjustments to this bike were a good compromise but that I'd
never really find a bike that fit my body size ideally without having a
custom frame made. They did pick up my toes-down pedaling style but I think
that's improved since we moved the seat back. The problem I've had with fit
is that every shop where I've asked advice has a different idea as to what
proper fit really is. Some don't consider the comfort needs of the older
rider and others (many of whom seem like they really do understand fit) tend
to depend more on their visual evaluation of me on the bike than the "fit
kit" or other fitting aids. Afterwards I find myself taking their advice,
but still fine-tuning the fit based on my own comfort and ride experiences.
Prior to that I had my wife take accurate measurements and tried the formula
route with various on-line fitting guides. The problem there is that again,
many are designed for optimum racing fit for a 24 year old rider, which I'm
not. And there were also variations for frame types, seat back angles, etc.
Even then, the results came out anywhere between a 54 and 58cm bike, which
is a big difference. But when I looked back on my calculations last night,
most of them agreed that I should be using 165mm cranks...

My question about the crank lengths really came from a recent visit to my
Orthopedic doctor, who is a cycler himself. In fact, he shared with me that
about 20 some years ago he bought a frame from Eddie Merckx and welded it
himself and still has the bike he built from it today. Anyway I had been
reading Peter White's bike fitting article (which makes good sense) and
mentioned the 18.5% crank length formula to my Dr, and he was kind enough to
measure my leg length while I was there. So that is why I asked the
question about crank length, since the guidelines call for 165mm and I'm
riding on 172.5mm. I don't mind spending the money for a new crankset, but
was curious as to how much the 7.5mm difference might make and how difficult
it would be to make the change myself. Sounds like an easy mechanical
change and after reading many of the replies here, I'm inclined to spend the
money to buy a shorter crank set.

Chuck


"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
>> Well, my seat is higher than that--74cm above the bottom bracket to the
>> top of the seat and 23cm above the top tube. I had it lower but it felt
>> cramped and when I raised it to this height I got better spinning and
>> more power.
>>
>> Chuck

>
> Chuck: Have you had a fitting done by somebody who does more than have you
> stand over the top tube? By that I mean measurements (arm, torso, inseam,
> shoulders etc), turn that into a mock fit and then observe the results?
> Self-fit doesn't always work too well; measurements can be off, and
> there's nobody to observe the results and notice things like rocking hips,
> toes-down pedaling, arched (curved) back etc.
>
> A really good fitting person isn't useful just for high-speed
> performance-oriented riding. Indeed, if you get someone who starts talking
> about getting you into a lower position for "efficiency", you've got the
> wrong person.
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
>
> "caaron" <[email protected]> wrote in message
> news:p[email protected]...
>> Well, my seat is higher than that--74cm above the bottom bracket to the
>> top of the seat and 23cm above the top tube. I had it lower but it felt
>> cramped and when I raised it to this height I got better spinning and
>> more power.
>>
>> Chuck
>>
>> "Mike Jacoubowsky" <[email protected]> wrote in message
>> news:[email protected]...
>>> >I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
>>> >tall and have a long torso and short legs. My inseam is 30" and the
>>> >distance from the top of my femur to the floor is 89cm. Based on
>>> >Peter White's 18.5% calculation guideline, 165mm cranks would be just
>>> >right. Similar calculations from Ergobike (edward ZImmermann's bicycle
>>> >sizing site) also come out at 165mm.
>>>>
>>>> Previously I had a 58cm Trek 5200, which I found too big to ride
>>>> comfortably, so I got the 54cm Trek a few years ago and it seems to be
>>>> a better fit. At age 60 I find I need the handlebars higher for
>>>> comfort and I'm a recreational rider, not a racer, so my rides average
>>>> about 15mph. I've always had trouble spinning fast, and although I can
>>>> get up into the high 90's I find my average cadence is in the low to
>>>> mid-eighties on most of my road rides. So I was wondering if changing
>>>> over to the 165mm cranks would make enough of a difference in comfort
>>>> and cadence to make it worthwhile to do the change and what downside
>>>> there might be, if any...
>>>>
>>>> Thanks for the replies
>>>>
>>>> Chuck
>>>
>>> What are you using for saddle height (measured from center of crank to
>>> top of saddle)? Traditional wisdom would be around 66cm if I'm figuring
>>> correctly, which, on a 54cm Trek, would place the top of the saddle
>>> 13-14cm above the top tube (or 12cm above the seat collar, which extends
>>> above the top tube a bit and represents the measuring point for frame
>>> size on a 5200).
>>>
>>> Those all sound like pretty normal measurements (if they're reasonably
>>> close to what's on your bike). If so, I find nothing there to indicate
>>> that there's any "need", based on leg length, for a shorter crank. You
>>> might wish to try one for the heck of it, but I'm not sure what symptoms
>>> need to be addressed, particularly in light of your stated RPMs which
>>> are *not* at the low end. Low-to-mid-80s are perfectly acceptable for
>>> most people; not everyone does well spinning like Lance.
>>>
>>> I'm also somewhat concerned by what sounds like a hit-and-miss approach
>>> to fit. How did you end up initially with a 58cm frame? When I mock that
>>> one up, it looks like the saddle would be almost sitting on top of the
>>> top tube. You're potentially over-compensating and swinging from one
>>> extreme to the other, when someplace in the middle might be just about
>>> right.
>>>
>>> But getting down to the effects of shorter cranks- generally, you'll be
>>> able to spin a bit more (because the crank is traveling through a
>>> smaller circle, so your feet aren't actually moving as far/fast per
>>> revolution), but you'll also be losing some leverage, which could be an
>>> issue climbing. In general there's a trend toward longer cranks these
>>> days, seemingly with little downside (we're not seeing more knee
>>> injuries today than back-in-the-day, even though there are more people
>>> serious mile now than back then).
>>>
>>> Good luck, and let us know how the experiment turns out-
>>>
>>> --Mike-- Chain Reaction Bicycles
>>> www.ChainReactionBicycles.com
>>>

>>
>>

>
>
 
Hi... my advice?... get a set of 170 cranks... 165 are too short.... u'll
get more power and more consistency using 170. !72.5 is way too long for u
specially if u r kind'a short person u know... thats the reason because u
have pain on your knees (not new), ALthoug i can use 172.5 i might suffer
some pain in my knees because of that little difference.

Probably u'll feel some performance difference with 165, why? because the
torque is a lot less than with a 172.5 especially in higher gears (hope ur
not one of those riders). If i was u i would get a set of 170 set of
cranks... 165 are too short even for u.(if u are using the same bike ull
feel the difference, maybe with another frame u wont, it depends not all
the bikes are the same set ups)

As experience, books always say something. formulas for this and this and
people from the LBS giving u advice about what is ok and what is not ok.
(some LBS people havent riden even in a tricycle but they had read a lot).
The problem is that rules arent always the same, rules and formulas depends
of many factor and usually they take only an average person.

Fausto coppy style was awefull but the guy was god damm fast... good
example right?

AN extreme case i remember, over here in xxxx a triatlhete woman. She had
the best bike in the market, the guys from the store were trying t get the
best position for her (she wanted the same) blah blah... I saw her last
custom made bicycle... was something hmmm... weird... she was pettite too..
well that day this woman went there to try that new frame (the 4th one), I
saw her on hte parking lot riding and I notice that no matter what frame
they built for her, her style will continue being crappy. I have no idea if
she is still trying to get a position as Greg Lemond but I bet that the
store people didnt say that the problem was her and her shortness to this
poor woman, there was nothing else to do. besides taking her money... or
maybe teach her how to really ride a bike and improve her style (no store
will teach u that)

As a general rule, usually short people have problems with their position
over the bike specially if the style and tecnnique is bad. Dunno if this is
your case... but usually thats what happens.


I saw in nashbar i think a set of cranks quite cheap and they look cool
too...

Cya...



PS: numbness in my hands <--- the seat is pointing to the ground, set the
seat level with the ground thats all u have to do, btw maybe you ride
putting all your weight over the front of the bike, and if thats the
case... i thnk we found the source of all your problems.






Peter Cole <[email protected]> wrote in
news:[email protected]:

> caaron wrote:
>> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I
>> was getting refitted to the bike to help with numbness in my hands
>> and we ended up moving the seat position and also raising the
>> handlebars. After we did that it was suggested that I should really
>> be riding on 165mm cranks because I have short legs. I'm seeking
>> opinions re:
>>
>> Will there be a noticeable difference in performance with shorter
>> cranks?

>
> Probably not.
>
>
>> How hard is it to change out Ultegra cranks

>
> Not very.
>
> --do I need special tools?
>
> Yes
>
>>
>> Do I change the cranks themselves or do I also have to change the
>> gears (it is a triple) with the cranks as a set?

>
> Yes.
>
 
On Tue, 27 Sep 2005 07:06:34 -0500, noname <[email protected]> wrote:

>Hi... my advice?... get a set of 170 cranks... 165 are too short.... u'll
>get more power and more consistency using 170. !72.5 is way too long for u
>specially if u r kind'a short person u know... thats the reason because u
>have pain on your knees (not new), ALthoug i can use 172.5 i might suffer
>some pain in my knees because of that little difference.

"172.5 is way too long for u", so, " get a set of 170 cranks". Do
you really think that 2.5mm is "way too long"? If the OP is having
knee pain, it is more likely due to the cleat alignment, and/or saddle
position[height, kops]. Here see what Sheldon has to say:
http://www.sheldonbrown.com/pain.html#knees

Pain and cycling, in general: http://www.sheldonbrown.com/pain.html

I have to believe that for all but a true professional bike racer,
changing out cranks for 2.5mm is a waste of time and money. Sure, if
you are replacing your wornout crankset, or building a new bike, then
go to the 170, but don't do it just to change size.

>
>Probably u'll feel some performance difference with 165, why? because the
>torque is a lot less than with a 172.5 especially in higher gears (hope ur
>not one of those riders). If i was u i would get a set of 170 set of
>cranks... 165 are too short even for u.(if u are using the same bike ull
>feel the difference, maybe with another frame u wont, it depends not all
>the bikes are the same set ups)
>
>As experience, books always say something. formulas for this and this and
>people from the LBS giving u advice about what is ok and what is not ok.
>(some LBS people havent riden even in a tricycle but they had read a lot).
>The problem is that rules arent always the same, rules and formulas depends
>of many factor and usually they take only an average person.
>
>Fausto coppy style was awefull but the guy was god damm fast... good
>example right?
>
>AN extreme case i remember, over here in xxxx a triatlhete woman. She had
>the best bike in the market, the guys from the store were trying t get the
>best position for her (she wanted the same) blah blah... I saw her last
>custom made bicycle... was something hmmm... weird... she was pettite too..
>well that day this woman went there to try that new frame (the 4th one), I
>saw her on hte parking lot riding and I notice that no matter what frame
>they built for her, her style will continue being crappy. I have no idea if
>she is still trying to get a position as Greg Lemond but I bet that the
>store people didnt say that the problem was her and her shortness to this
>poor woman, there was nothing else to do. besides taking her money... or
>maybe teach her how to really ride a bike and improve her style (no store
>will teach u that)


So, you are saying, because she is short, they can't build a bike to
fit her? That is the whole idea of going custom, to be able to cut the
tubes to nonstandard sizes. If they can't size the bike properly, it
is either their incompetence or her requesting/demanding incorrect
lengths.
>
>As a general rule, usually short people have problems with their position
>over the bike specially if the style and tecnnique is bad. Dunno if this is
>your case... but usually thats what happens.

As a general rule, really tall people have problems with their
position over the bike especially if the style and technique is bad.
This statement is as absurd as yours. If your style and technique is
bad, your height isn't the issue.
>
>
>I saw in nashbar i think a set of cranks quite cheap and they look cool
>too...
>
>Cya...
>
>
>
>PS: numbness in my hands <--- the seat is pointing to the ground, set the
>seat level with the ground thats all u have to do, btw maybe you ride
>putting all your weight over the front of the bike, and if thats the
>case... i thnk we found the source of all your problems.
>

There are way too many people giving advice, as absolutes. If I have
learned nothing else on these newsgroups, it is that when it comes to
bicyle fit and sizing, there are few absolutes.


Life is Good!
Jeff
 
Thanks for all of the responses to my question. I actually did buy and
install the Ultegra 165's and the results were dramatic--much easier riding
with less effort, and an increase in cadence by close to 10rpm along with an
average speed increase of about .7mph (seven tenths).

My bike finally feels comfortable to ride--hard to believe that such a
seemingly minor change of 7.5mm could make such a dramatic difference in
performance. And the cranks were ridiculously easy to install, so it is a
trivial mechanical procedure.

Thanks again.

Chuck


"caaron" <[email protected]> wrote in message
news:[email protected]...
> I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
> getting refitted to the bike to help with numbness in my hands and we
> ended up moving the seat position and also raising the handlebars. After
> we did that it was suggested that I should really be riding on 165mm
> cranks because I have short legs. I'm seeking opinions re:
>
> Will there be a noticeable difference in performance with shorter cranks?
>
> How hard is it to change out Ultegra cranks--do I need special tools?
>
> Do I change the cranks themselves or do I also have to change the gears
> (it is a triple) with the cranks as a set?
>
> Thanks in advance...
>
> Chuck
>
 
"caaron" <[email protected]> wrote:

> Thanks for all of the responses to my question. I actually did buy and
> install the Ultegra 165's and the results were dramatic--much easier riding
> with less effort, and an increase in cadence by close to 10rpm along with an
> average speed increase of about .7mph (seven tenths).
>
> My bike finally feels comfortable to ride--hard to believe that such a
> seemingly minor change of 7.5mm could make such a dramatic difference in
> performance. And the cranks were ridiculously easy to install, so it is a
> trivial mechanical procedure.


Did you use a torque wrench?

--
Ted Bennett
 
No, do I need to? If so, do you know the correct torque?

Chuck


"Ted Bennett" <[email protected]> wrote in message
news:[email protected]...
> "caaron" <[email protected]> wrote:
>
>> Thanks for all of the responses to my question. I actually did buy and
>> install the Ultegra 165's and the results were dramatic--much easier
>> riding
>> with less effort, and an increase in cadence by close to 10rpm along with
>> an
>> average speed increase of about .7mph (seven tenths).
>>
>> My bike finally feels comfortable to ride--hard to believe that such a
>> seemingly minor change of 7.5mm could make such a dramatic difference in
>> performance. And the cranks were ridiculously easy to install, so it is
>> a
>> trivial mechanical procedure.

>
> Did you use a torque wrench?
>
> --
> Ted Bennett