open topic, for anything cycling related.
I went from 175 on the commuter to 172.5 thinking it'd help me knees. Tiny adjustment to saddle height and I forgot all about it until I saw this thread. Can't say I've noticed any change but then again, I don't have a wind tunnel and a quiver of sensors hanging off me bike.
...whatever the road rules, self-preservation is the absolute priority for a cyclist when mixing it with motorised traffic.
London Boy 29/12/2011
Hard to see a change from just 2.5mm. I think you need at least 5mm to see if it makes any difference to anything. I took 10mm out of my crank length and it made a difference to me. But so did wedges, lowering my saddle, changing my cadence and doing some other exercises. They are all just small steps than can add up.
I mark my seatpost position with a bit of electrical tape.
One of my bikes felt like the saddle was a touch low, so I raised it slightly. It feels much better now. The electrical tape is now about 2.5mm above the clamp.
2.5mm is definitely noticeable.
2.5mm at the bottom of the pedal stroke + 2.5mm at the top of the pedal stroke would be even more so. Or, if the saddle position is adjusted to suit, 0 at the bottom and 5mm at the top.
OK Tim, then to rephrase:
In the context of whether knee problems can be helped noticeably by shorter cranks, bigger steps are better.
I actually think that 167.5mm would be my ideal crank length as I occasionally ride 170s to find they are too long, but the 165s feel a bit short out of the saddle and sometimes in it even though I ride them regularly. However the rarity of 167.5 means they are expensive and so far I can only find them (from mainstream manufacturers) in Japan.
I'm on my old bike at the moment because the new one is creaking like a malaka
The seat is a touch higher on it and it is easier on the legs as a result. Both 175mm cranks.
What I'm taking out of that is run your seat as high as you can without over extending your leg or rocking the hips. Those shorter blokes must have done so to save their knees I'm assuming.
I went from 2.5 mm longer on my new bike and haven't noticed any large difference on strava segments, they are short though. I am slightly faster but I'm riding more so slightly fitter Then again I'm slightly older
I went to 177.5 on my tt bike when I actually got to use it and went faster over all the same courses than I did on the 175s.
Luckily Dr_Mutley has been very patient and thoroughly explained to me, with pictures , how to fix it. Just waiting for the bits. He's also given me a link to the cervelo forum where the problem has presented itself several times.
Is there a serious suggestion that crank length has some bearing on gearing here? Gearing stays the same, but leverage changes. That's it. So someone with longer cranks pushing the same 53/11 finds it easier than someone on 170's.
Why he pros use longer cranks would be interesting to hear. Can you break the list into sprinters and climbers? That would be interesting
For me, my strength lies in climbing. I am short and run 170's. I ran a set of SRAM red 172.5 for a month or two and found it hard to cadence as naturally as with the slk 170's. I also lost a little av speed. Changing back to 170's fixed it straight away. And yes I adjusted saddle.
I recently bought a cx for commuting which had 172.5 and I changed it to 170 after I found my cadence to be a little lumpy over 110rpm. Now it is much better. Anyone want a set of 172.5 cx gossamer pro cranks?
I might be overly sensitive to change, but I think it's fair to say it is noticeable to some people and not to others.
My guess,given they are racing, is they tend to run longer cranks as they find them faster or more comfortable to maintain a high average speed.
Pantani 170mm -180mm in the mountains
If you are short then 170 is probably right for you.
However I am a never was and really have NFI apart from what works for me anyway
Yes, there is relationship between crank length and gearing, as the length of the cranks affects foot velocity, so a different gear will give the same foot velocity with different crank lengths.
I did the maths a long time ago and in simple terms, about 5mm of crank length is equal a tooth on the big ring.
165/50 is approx 175/52
A helmet saved my life
Thanks for all of the helpful replies everyone! It's overwhelming the help and insight here
I've currently got 170mm and I'm 6'2 with long legs so I think I shall go 175mm when I upgrade.
If only they made a 10T
Not worse than the guys on France Television during Tour de France. I just can't understand they keep them... I much prefer Eurosport, Virenque is a laugh, despite his poor command of French (much better now actually), Jacky Durand and JF Bernard are very good.
you can get bigger chain rings... I am a big fan of my 55 on my 180's. I will run a 56 on my TT bike next year... Although it is more about having a good chain line than actually using a 56 / 11 all the time .
What are you running?
The biggest option I can find is 53/39T 175mm for Ultegra. Can I swap chainrings for a 55?
I run DuraAce 180mm cranks ( only DuraAce runs longer than 175 in road cranks ) ... but XT runs 175,177.5 & 180mm in mtb cranks.
I run 55 chain rings... probably a 54 is closer to standard on the longer cranks... it isn't about spinning more, it's about having a better chain line and the option of slightly bigger gearing if needed. I don't want to spin, I don't like to spin... I am quite happy at 88-90 rpm average.
Apparently they do exist in other brands. Probably just harder to find.
http://www.campagnolo.com/jsp/en/groups ... tid_12.jsp
http://www.wiggle.com.au/sram-rival-dou ... pQodHWMArg
http://www.amazon.com/Crankset-180mm-Wh ... B005DUCQ68
Being able to use a bigger cog on the back with the bigger chainring is probably more efficient too.
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