Cranks

[wilmar13]

180mm for me.

This is an interesting thread. I'll have to comment later.

I too ride 180's... when I switched from 172.5's I dropped 20 sec from a weekly 10mile TT and began climbing mountains much better... also over short hills a noticable difference in being able to "diesel" over. I would like to try longer, but as it is you hit your pedals on hard turns with a std frame

I find it funny that so many components have such large range of sizes and cranks do not, yet the smallest difference (even going from 170 to 180 is only 6%) is a polarizing topic to everyone.

 

[crashnigley]

I am 5'9" with a 29.5" inseam. Originally My LBS set me up with 172.5's. I rode these for almost two years and they always felt just a bit too long. I had a nasty dead spot at the top of the peddle stroke and my knees were really feeling it - especially when riding in the drops. I finally switched over to 170's and much to my surprise it made a HUGE difference. No more dead spot, no more pain and a much smoother spin at high cadence.

Not that everyone should expect this kind of result - I believe that I was that unusaul case where I was in between sizes and a minute adjustment (5mm total in leg extension) actually made a noticable difference. I suppose it makes sense that such minor adjustments would have a greater impact on a smaller rider - you know, percentages and all that.

The point is that we're all different and you really have to experiment to find what works best for you.

Oh, by the way, while I was at it I went from DA10 to FSA k-force since I had to shell out the cash either way.

 

[53-11]

I too ride 180's... when I switched from 172.5's I dropped 20 sec from a weekly 10mile TT and began climbing mountains much better... also over short hills a noticable difference in being able to "diesel" over. I would like to try longer, but as it is you hit your pedals on hard turns with a std frame

I find it funny that so many components have such large range of sizes and cranks do not, yet the smallest difference (even going from 170 to 180 is only 6%) is a polarizing topic to everyone.

It's amazing to me that cyclists with sub 30" inseams actually ride 172.5, etc (even a 170mm seems big honestly)

My theory is that geometry on these smaller frames lends well to the adaption of shorter legs to longer cranks. The steeper seat tube angle found on smaller frames decreases distance to the pedals and the proportionall longer top tube lets them rotate them selves forward about the BB. (This is sort of an exaggeration of what I did when I went from 170s gradually to 180's). I have a 36" inseam so the 180mm isn't out of the ordinary for me.

 

[Achilles180]

I am 6'0" (183 cm) with a 36" (91.3cm) inseam and have been using 180 mm for a couple of years now, with a set of 185 mm TA Carminas on my fixed gear bike. At a half-century age I use a triple crankset pretty much exclusively, as grades exceeding 15% are far from rare in California. That limits me to TA, DuraAce triple or Campy Record with a TA tripleizer middle chainring. I found going to a longer length suddenly causes Achilles tendon strain, but the fixed gear keeps me from going too hard too soon, and gets my legs ready for the hills. I started the fixed gear training with 175s and a 38-16, then switched to 177.5 and had to go to a 42-16. I could spin as fast on downhills AND climb uphill grades more easily. When I changed to the 180s I ultimately ended up with a 42-15 and spinning a hair faster than with the shorter cranks. So if I get more power (higher road speed) at the same crank speed, why on earth would I want to go shorter? Once I put the 185s on the geared bicycle I might find I lose a few rpm, but it will probably be worth it. And I find lengthening cranks 5mm requires me to raise the saddle 5mm, as well as slide it forward an equivalent amount. My knees hit my chest if I don't raise it, and it is already "too high" according to the various wacky formulas people use to set saddle height.

Some observations:

My first bicycle came with 170mm cranks in 1974. I was a lousy climber and sprinter until I switched to 177.5. I finally found some value in getting out of the saddle. If getting out of the saddle only keeps you from losing speed, your cranks may be too short.

With 175s I want to shift up one tooth. They are too short.

With 177.5s I have to shift up two teeth when I get out of the saddle to keep from spinning uselessly. They are a little short for me.

With 180s I have to shift up at least two teeth before I get out of the saddle, and often shift up again. They feel pretty good.

With the 185s I was shifting up a couple of cogs, but the tendon strain forced me to switch back to 180s. That was not the climbing and sprinting torture of everything shorter, but I immediately missed them.

I'm sorry I can't tell you what it feels like to ride cranks which are 10mm too long, but I have not found them yet. I have found the chart in Bernard Hinault's book to be pretty good. It is more conservative than the proportional theories, but it explains why Merckx switched to 177.5 for the Alps. My 177.5s are going on my track bike.

Pete

 

[531Aussie]

I have found the chart in Bernard Hinault's book to be pretty good. It is more conservative than the proportional theories,

I don't have time to look through all of this thread, so, what does Hinault's chart say about crank length?


thanks

 

[53-11]

\I have found the chart in Bernard Hinault's book to be pretty good. It is more conservative than the proportional theories, but it explains why Merckx switched to 177.5 for the Alps. My 177.5s are going on my track bike.

Pete

To me proportional theory works if you are riding a "proportional frame" which isn't happening in the bicycle industry at all. Seating position is totally different as you move up the size range.

 

[Achilles180]

I'm guessing that a 531 vintage Aussie is over 40. So I will not suggest anything so extreme that it may injure you, the way I hurt myself. Hinault takes an entire chapter going over measurements, so until you can make the time to wade through all of the varying opinions in this thread, I will have to interpret the chart for you. His recommendations are based on the distance from the bottom of the pelvis to the floor. Find a book 9/16" (15mm) thick, stick a piece of paper to a wall, stand barefoot with your feet six inches apart and heels touching the wall and pull the spine of the book up into your crotch until it hits the bone. Mark that height on the paper and use that as your measurement. You should be able to get that measurement to within a couple of mm or 1/8". Do not round it off or I won't have any confidence that I'm not going to make you hurt your knees or tendons

I'll get back to you after I spend a day trying to ride 200 hilly kilometers, when it has been thirty years since I rode 100 miles with a inoperative pancreas (insulin-dependent diabetes). I'll find out if modern technology can compensate for advanced age

 

[wilmar13]

I too ride 180's... when I switched from 172.5's I dropped 20 sec from a weekly 10mile TT and began climbing mountains much better... also over short hills a noticable difference in being able to "diesel" over..

I forgot to add the disclaimer that I truely believed at the time that the longer cranks would make me faster and therefore somewhere between 0 and 100% of the gains were psychological.

 

[531Aussie]

I'm guessing that a 531 vintage Aussie is over 40. So I will not suggest anything so extreme that it may injure you, the way I hurt myself.

still in my 30s

thanks for the info

 

[lefeur]

I ride 200mm cranks from Lennard Zinn. I love them!

 

[wilmar13]

I ride 200mm cranks from Lennard Zinn. I love them!

Do you ride a standard frame, and if so do you have any clearance problems in corners... I mean obviously it would not be good for a crit, but I mean in everyday riding do you ever have problems?

What is your inseam?

 

[lefeur]

Do you ride a standard frame, and if so do you have any clearance problems in corners... I mean obviously it would not be good for a crit, but I mean in everyday riding do you ever have problems?

What is your inseam?

I do ride a standard frame and I only do general purpose riding and TT's. As far as bottoming out in the corners, I have had no problems with these types of riding. It's close, though. I had these cranks on my touring bike for a while. It has 2-sided SPD pedals which are thicker and wider than the single sided ones on the bike the cranks are on now, and I would occasionally bottom out on a tight corner. So I would say they definately would not work for crits. There is one other very minor problem. When making a sharp turn, like in the middle of the street, the front of my shoe hits the rear of the front wheel more so than it used to. Very minor problem, though.

My inseam is about 36". Lennard has two crank length formulas on his sight. When I did the calculations, one formula suggested I use 210mm cranks and the other suggested 200mm. I went with the 200's because I was worried about bottoming out.

I am definately faster with these new cranks. Especially when climbing. I have a 300 foot hill that I occasionally climb for a self-test. Now, I've never done a side by side comparison on the same day, but in previous years I've only managed about 375 watts. This year with the new cranks I can muster around 430 watts.

 

[531Aussie]

Well, believe it or not, I've read this whole thread, and there are some interesting annecdotes and testimonials.

I'd like to say that it's disappointing that J-MAT (is he still around?) didn't respond to this link which was posted ages ago -- http://www.bsn.com/Cycling/cranks.html -- because I think it provides the most balanced discussion on the topic. And, depite J-MAT's claims, some riders do switch back to 175s after trying 180s. There's a former Olympian down here named Rob Crowe who did that, and he's 6ft 3"!!


I have an 89.5cm inseam, and I'm 182cm tall.

I was on 170mm cranks for a few years after I believed a sudden switch from 170s to 175 caused some suprapatellar bursitis (I'm still not sure if the cranks were the cause). At the start of this year I worked up the courage to try some 175s, which I did for a few months, then, after reading everything I could find on proportional crank length theories, I now have 180mm cranks.

I'm still not sure what is the correct length for me.

These are a couple of my perceptions of the cranks so far:

I've had the 180s now for about 4 months, and I'm still not sure if I'm faster on flat roads. I'm positive that climbing out of the saddle with longer cranks provides me with the extra leverage of the longer arms, because I'm not restricted by being in the fixed, seated position.

When I had the 175s, I was already in a pretty high and forward postion, so when I got the 180s, I basically had to drop the seat 5mm. I'm not sure if this lowering of the saddle has countered the benefits of the extra leverage.

I believe that the "you can't spin a longer crank" argument is a bogus if we're talking about a difference of only 5mm to 10mm, because we have gears!! Simple. Man, some of the stuff I read made me think I'd be riding a windmill. Very long cranks (over 200mm) and track sprinting are different stories, but grinding around in a club race with an extra 5mm is not gunna kill your spin.

 

[wilmar13]

Well, believe it or not, I've read this whole thread, and there are some interesting annecdotes and testimonials.
I'd like to say that it's disappointing that J-MAT (is he still around?) didn't respond to this link which was posted ages ago -- http://www.bsn.com/Cycling/cranks.html -- because I think it provides the most balanced discussion on the topic. And, depite J-MAT's claims, some riders do switch back to 175s after trying 180s. There's a former Olympian down here named Rob Crowe who did that, and he's 6ft 3"!

Yes this is an excellent summary, but one thing that bugs me is that other places I have seen written that Indurain always used 180's but for TT and for his hour attempt he used 190's. I think it is really interesting to take into account foot size, as most other formulas do not do this. It makes sense. I am still going to stick with my 180's though.

 

[wilmar13]

I've had the 180s now for about 4 months, and I'm still not sure if I'm faster on flat roads. I'm positive that climbing out of the saddle with longer cranks provides me with the extra leverage of the longer arms, because I'm not restricted by being in the fixed, seated position.When I had the 175s, I was already in a pretty high and forward postion, so when I got the 180s, I basically had to drop the seat 5mm. I'm not sure if this lowering of the saddle has countered the benefits of the extra leverage.

You do realize that this "extra leverage" is really just lower effective gearing though right? Wait isn't it... oh god I am confusing myself again!

 

[531Aussie]

You do realize that this "extra leverage" is really just lower effective gearing though right? Wait isn't it... oh god I am confusing myself again!

my bike rides are just 2hrs of confusion

 

[531Aussie]

but wait, there's more.

I'm only just realizing the impact of having to lower the saddle when going to longer cranks.

As I said above, when I was on 175s, I was very high, and pretty far forward, so I had to drop the saddle 5mm when I got the 180s. With the extra 5mm at the top of the pedal stroke, my saddle is effectively a whopping 10mm lower, relative to my knee, when my knee is toward the top of the stroke. Does that make sense? ;p

To me, a 10mm drop in saddle height = less power

Hmmmmmm..........

 

[patttto]

I have 175's on my mountain bike, which is on my trainer, and 172.5's on my road bike.
In the winter, when I spent most time on the trainer, and then went out on the road bike, my hams would really tighten up. Position ect is slightly different, but seat high is exactly the same.
I thought it was the cranks, So I finally got a pair of 175's for the road bike.
2.5mm difference. My finger nails are not even that long, but Wow! what a difference.
Most noticable is maintaining higher speed. You know, that gear where you are / want to be cumfortable going ## MPH, With the 175's I can maintain it and feel cumfortable.
I don't care what the text book says, I like the additional leverage so much, I might just go straight to 180's. Somewhere in this thread someone said, if you are going to change just go straight to 180's. Well, I think they may have been right.

Here is another thought. I do Triathlons, and the first mile is a killer. I am thinking the longer cranks, because they require more bend, will have me looser for the run. Imagine spinning like a 150, and then trying to run with a long stride....Ouch, I can already fathom the tightness.
So, I guess I will be looking for a good deal on a pair of 180's.

Patttto

 

[wilmar13]

I'm only just realizing the impact of having to lower the saddle when going to longer cranks.

As I said above, when I was on 175s, I was very high, and pretty far forward, so I had to drop the saddle 5mm when I got the 180s. With the extra 5mm at the top of the pedal stroke, my saddle is effectively a whopping 10mm lower, relative to my knee, when my knee is toward the top of the stroke. Does that make sense? ;p

To me, a 10mm drop in saddle height = less power

Hmmmmmm..........

Nah, you are optimizing the wrong thing with this logic... Your knee is going to come up 10mm higher relative to your chest for sure, but your saddle to bottom of the pedal stroke is the same (if you dropped your saddle by the same amount of crank increase). By the logic that you are using, would you think that a set of 100mm cranks which would allow you to raise your seat height another 70-80mm would give you more power???

If your knees are hitting your chest that is something else... If I get real low my knees do hit my chest, but I have a 5" drop to my bars, and that only happens when I am in a descending tuck... If I went to 190's or so, I would have to go to a larger frame and stem as some of this comes from my extreme rear-ward position on the bike.

 

[wilmar13]

Here is another thought. I do Triathlons, and the first mile is a killer. I am thinking the longer cranks, because they require more bend, will have me looser for the run. Imagine spinning like a 150, and then trying to run with a long stride....Ouch, I can already fathom the tightness.
So, I guess I will be looking for a good deal on a pair of 180's.
Patttto

This is anecdotal but it seems that more often than not 180mm and longer cranks I see for sale used are from Tri-guys. Also I now that many Pros switch to longer cranks for TT so there could be some advantage from both running (in Tri) and having longer cranks with the more forward position of TT and Tri bikes.