or Connect
Cycling Forums › Forums › Bikes › Cycling Equipment › ? 175 vs. 172.5 crank arm length
New Posts  All Forums:Forum Nav:

? 175 vs. 172.5 crank arm length  

post #1 of 7
Thread Starter 
What is the significance to my training/general riding of pedaling two different bikes one with 175
and the other with 172.5 length crank arms?
post #2 of 7

Re: ? 175 vs. 172.5 crank arm length

> What is the significance to my training/general riding of pedaling two different bikes one with
> 175 and the other with 172.5 length crank arms?

None at all.

But you will get other opinions. Ignore them, for I am right.

--
Ted Bennett Portland OR
post #3 of 7

Re: ? 175 vs. 172.5 crank arm length

On Tue, 11 Mar 2003, MMCS wrote:
> What is the significance to my training/general riding of pedaling two different bikes one with
> 175 and the other with 172.5 length crank arms?

No difference, provided your knees bend equally well.

Then, here is my own story about crank lengths. I have always used 170mm cranks and I was very upset
to find out that the, still beautiful, used Record pair I had picked up at a shop were 170 and
172.5, respectively. After going back to the shop the seller acknowledged the mismatch and quite
honestly said: 'That's not right. I'll do my best to try to find a good mating pair for you'
(not been able, thus far). Let me add that he is the MOST experienced mechanic, racer himself
upon a time, you can imagine.

Recently I had considered getting those cranks back and install them, differring lengths
notwithstanding. After all, my left knee is much better that the other one and I know it can bend
more and better. I consulted a good friend of mine, an experienced cyclist too, and he said: 'I
wholeheartedly advice you not to'.

Funny how different people would behave differently and suggest so different approches!

Who has got two 170mm cranks for me, anyhow? I would be satisfied with just the spiders, of course.

Sergio Pisa
post #4 of 7

Re: ? 175 vs. 172.5 crank arm length

"Jay Beattie" <jbeattie@lindsayhart.com> wrote in message news:v6sdftcq6q53a8@corp.supernews.com...

> I know we always trade the same links (with the same equivocal studies) when this issue comes up,
> but is there really no good science on crank length?

I don't know of anything equivocal about the studies of Martin et al. - and those are essentially
the only true scientific studies of the topic that I am aware of (in part because I never got my
senior honor's thesis published).

Andy Coggan
post #5 of 7

Re: ? 175 vs. 172.5 crank arm length

"Jay Beattie" <jbeattie@lindsayhart.com> wrote in message news:v6vbqvepfh9veb@corp.supernews.com...
>
> "Andy Coggan" <acoggan@earthlink.net> wrote in message
> news:sSwba.16125$gF3.1424268@newsrea....earthlink.net...
> > "Jay Beattie" <jbeattie@lindsayhart.com> wrote in message
> > news:v6sdftcq6q53a8@corp.supernews.com...
> >
> > > I know we always trade the same links (with the same equivocal
> studies)
> > > when this issue comes up, but is there really no good science on
> crank
> > > length?
> >
> > I don't know of anything equivocal about the studies of Martin et
> al. - and
> > those are essentially the only true scientific studies of the topic
> that I
> > am aware of (in part because I never got my senior honor's thesis published).
>
> Do you have a link (if there is one). -- Jay Beattie.

http://www.ncbi.nlm.nih.gov/entrez/q...PubMed&list_ui
ds=12183473&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/q...PubMed&list_ui
ds=11990729&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/q...PubMed&list_ui
ds=11417428&dopt=Abstract

http://www.ncbi.nlm.nih.gov/entrez/q...PubMed&list_ui
ds=10828327&dopt=Abstract

Bottom line: alterations in crank length within (and even beyond) the normal range used by
cyclists has no significant effect on either maximal power or submaximal efficiency. Factors other
than performance (e.g., ground clearance, comfort) should therefore take precedence when selecting
crank length.

Andy Coggan
post #6 of 7

Re: ? 175 vs. 172.5 crank arm length

MMCS <econorama@attbi.com> wrote"

> What is the significance to my training/general riding of pedaling two different bikes one with
> 175 and the other with 172.5 length crank arms?

Almost nil. 1.4% difference in the pedaling circle diameter. It boggles my mind that parts
manufacturers will offer 170mm, 172.5mm, and 175mm cranks, but no 160mm or 190mm cranks.

Maybe they save costs by making them all the same size and just stamping them with different
dimensions-- I am sure no rider could distinguish the difference in a blind test. I'd lay
money on it.

Chalo Colina
post #7 of 7

Re: ? 175 vs. 172.5 crank arm length

> > What is the significance to my training/general riding of pedaling two different bikes one with
> > 175 and the other with 172.5 length crank arms?
>
> Almost nil. 1.4% difference in the pedaling circle diameter. It boggles my mind that parts
> manufacturers will offer 170mm, 172.5mm, and 175mm cranks, but no 160mm or 190mm cranks.
>
> Maybe they save costs by making them all the same size and just stamping them with different
> dimensions-- I am sure no rider could distinguish the difference in a blind test. I'd lay
> money on it.
>
> Chalo Colina

You are a cynical man, Chalo. But you are likely right in this case.

However (ah, I love that word), you can get short cranks from the cute little world of kids' bikes,
and long cranks have been made by Bullseye, if memory serves.

There is an exception to the idea that crank length doesn't matter and is not noticeable: for fixed
gear bikes, where 5mm can make a significant difference in how far you can lean in a turn before you
suffer a pedal strike. And suffer is the right word here.

--
Ted Bennett Portland OR
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Cycling Equipment
This thread is locked  
Cycling Forums › Forums › Bikes › Cycling Equipment › ? 175 vs. 172.5 crank arm length