Crank length opinion please

Quoted message said:

Dear All,

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

How long are your legs? If you're male and of average height (or
shorter) 170mm will quite possibly be better for you - I believe
there are more people on cranks that are too long than too short.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

Quoted message said:

Dear All,

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

Whenever this subject comes up on a cycling forum, about half of those
responding say they don't notice, or aren't bothered by, a 5mm difference.
(I'm one of the other half).

170 should be OK if your leg length is about average. Your saddle should be
lowered by 5mm if you do get these.

But if you're happy with the way pedalling feels with your current cranks
then then it'd be wise to play safe and go to some trouble to get 175 again.

~PB

Quoted message said:

Dear All,

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

Thanks for your help!

Nick

Some people have claimed that they can feel longer/shorter cranks, and
reset their saddle height etc. to suit.

I went in the other direction, 170 -> 175mm.

I didn't notice any difference, didn't have to change anything else to
match.

hth,

bookieb

I said:

Your saddle
should be lowered by 5mm if you do get these [170mm]

Sorry, wrong way round. Raise by 5mm.

~PB

bookieb said:

Some people have claimed that they can feel longer/shorter cranks, and
reset their saddle height etc. to suit.

I went in the other direction, 170 -> 175mm.

I didn't notice any difference, didn't have to change anything else to
match.

Whether you notice it or not, your are extending your leg further on the
downstroke. The pedal is simply 5mm further away.

~PB

IIRC I've got 1x165, 3x170, 1x172.5 and 1x175[1] in the fleet and /I/ can't
tell the difference

1 - the MTB came with 175s, but I can't remember whether I stayed at 175
when I put a new chainset on...

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
The entire population of Uxbridge has no idea that it doesn't
actually exist.

Thanks everyone for your speedy replies!

I am 5' 8" so perhaps 170s would be better. I've never measured my leg
length before!

The general opinion seems to be I won't notice.

All I've got to do now is decide!

Thanks again!

Nick

[email hidden] <[email hidden]> typed:

Quoted message said:

Dear All,

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

Depends on how much you notice small changes.

In my experience, bearing in mind I'm a short-[censored] at 5'4", I noticed a
large difference between 175 and 170's (I went from 175 to 170) mostly
for the better. Being of a stout build (Short _and_ fat) I felt better
when really pushing on the pedals with the slightly shorter stroke and
really felt like I could keep a smoother cadence when it mattered, on
the muddy stuff, with the smaller diameter pedal stroke.

So, it may be only psychological, but yes, overall and IME and IMHO,
it's noticeable.

Like you, I didn't change them specifically for the difference in
length, but the crankset needed replacing and this was readily available
at a silly bargain price (Decathlon, Nottingham) so it would have been
churlish to refuse. 😉

--
Paul - [censored]

Quoted message said:

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

Lots of people say they can't notice a difference, but I ended up with some
170s on a hack bike because wiggle had them really really cheap, and I
thought I too wouldn't be able to notice. However, it felt weird enough
that I ended up salvaging some 175s to replace them, so evidently YMMV
(probably also worth mentioning that I am quite tall).

Anthony

Pete Biggs said:

bookieb said:

Some people have claimed that they can feel longer/shorter cranks, and
reset their saddle height etc. to suit.

Quoted message said:

I went in the other direction, 170 -> 175mm.

Quoted message said:

I didn't notice any difference, didn't have to change anything else to
match.

Whether you notice it or not, your are extending your leg further on the
downstroke. The pedal is simply 5mm further away.

~PB

Absolutely. I'm not sure whether my saddle was a bit low to begin
with, or the 5mm extra down to the peadal was too small for me to
notice.

It does seem strange though - I wonder if I'd notice a 5mm change in
saddle height either?

I'd guess that there's a fair degree of "placebo" effect in there as
well - if someone told me that they'd move'd my saddle up/down by 5mm,
I might be able to feel it, regardless of whether they'd actually done
it or not. Maybe I'm just suggestible...

Well, only one way to find out, but I CBA to try it, so, for me, it'll
remain one of life's mysteries.

bookieb

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Dear All,

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

My current cranks are 175mm long.

Am I likely to notice any difference between the two?

I have 170s on my road bike and 175s on my ATB - I don't notice any
difference, but shorter cranks are better for twiddling and longer
better for stomping so if they were the other way round I might notice.
If you fit 170s to your ATB you might want to raise the saddle 5mm, you
will have an extra 5mm ground clearance for the pedals, and your bottom
gear will effectively be 3% higher (that's the same as having a 31 tooth
rather than 32 tooth largest sprocket).

Quoted message said:

If you fit 170s to your ATB you might want to raise the saddle 5mm, you
will have an extra 5mm ground clearance for the pedals, and your bottom
gear will effectively be 3% higher (that's the same as having a 31 tooth
rather than 32 tooth largest sprocket).

When you put it in sprocket size terms, I think sticking with 175
length is sounding favourable as I'm happy with my current ratios.

I just hope it's not another month wait for the 175s to come in!

Thanks everyone,

Nick

Pete Biggs said:

Quoted message said:

Dear All,

Quoted message said:

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.

Quoted message said:

My current cranks are 175mm long.

Quoted message said:

Am I likely to notice any difference between the two?

Whenever this subject comes up on a cycling forum, about half of those
responding say they don't notice, or aren't bothered by, a 5mm difference.
(I'm one of the other half).

170 should be OK if your leg length is about average. Your saddle should be
lowered by 5mm if you do get these.

But if you're happy with the way pedalling feels with your current cranks
then then it'd be wise to play safe and go to some trouble to get 175 again.

~PB

Doesn't it also have an effect on the gear inches/ratios? Probably
not much, I think it's all explained on Sheldon Brown's site...

Regards,

Duncan.

Duncan Smith said:

Doesn't it also have an effect on the gear inches/ratios? Probably
not much, I think it's all explained on Sheldon Brown's site...

Yes, another poster mentioned the percentage.

I thought it wasn't enough to mention, and also it'd be a poor reason to opt
for a particular crank length.

~PB

Quoting <[email hidden]>:

Quoted message said:

I need some new cranks for my mountain bike and the shop only has
170mm length ones in stock.
My current cranks are 175mm long.
Am I likely to notice any difference between the two?

Some people are more sensitive than others. However, if your saddle is
currently correctly adjusted, you _will_ notice if you forget to put it up
5mm. :-)
--
David Damerell <[email hidden]> Kill the tomato!
Today is Tuesday, March.