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Anyone got any old shimano cranks?
I am looking for a pair of used Shimano cranks XT XTR 175mm length (off a medium or large framed bike) for free or borrow.
The small frame bikes I ride come with 170mm cranks so I want to try the 175mm to see if the almost 3% gain in mechanical advantage does anything noticable on rides, think LONG rides.
I know it will reduce ground clearance but thats not really a problem and it wont matter for the experiment.
Many thanks
Craig
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I'm actually of thinking going the other way and going shorter. From what I have read you may not notice the difference as there are too many other factors involved. What I mean by this is you can change the length an go for a ride to compare but you may not have the same energy as you previous test so that could be the difference etc. To get true test results you need to at least use a power meter.
There is plenty on net regarding this. Here are a few links...
http://www.nettally.com/palmk/crankset.html
http://www.myra-simon.com/bike/cranks.html
http://www.peterwhitecycles.com/fitting.htm
http://www.myra-simon.com/bike/mtb-advice4.html
Cheers
Brian
(err, yep, insert joke here)... ...long cranks make it harder to negotiate trails, as you drag the crank arm over rocks and whatnot. Increasing your chances of crashing. I would suggest going for a shorter crank and put your normal cranks back on for a long ride or a race.
..Brian, I had originally thought that shorter was a better option until someone pointed out that its harder to pedal with a smaller circumference..... I know 165mm cranks are available. I am not so sure looking at all the top cyclist spinning smallish looking cranks. Mind you it could be the long legs...but that was the intital aim of the experiment. To achieve a better ratio to keep little legs in the power zone.
Ditty, not concerned with the clearance, I dont bash pedals now so 5mm cant make much difference. More air in the shocks could compensate for example.
So I am getting old and dont go out much so things like this take my interest these days....I'll try the experiement either way if anyone has some old bits I can try.
thanks for the interest
Longer cranks will give you more leverage and power I am running 180mm cranks and the difference from 175mm was quite noticable as for clerance it can be a problem on the smaller bikes but the 29er handles them just fine.
Longer crank arms also increase the time you spend in the 'dead spot', Not really worth worrying about... Crank lengths are quite dependant on leg length, so give it a go.
Yeah - this is very interesting indeed.
Pratiwi will need a new drivetrain at some point and I was considering if she could do with shorter cranks. On the showing from these articles the answer is for sure. Currently she's got 170mm, but these will be replaced with 165mm at least.
According to some of this though, something even shorter is called for (up to 10cm shorter still!), but then you're getting into exotic territory, if anything can be found at all.
..yep agree with that. I guess there is a "sweet spot" where you get all the best bits.
Longer is going to increase the dead spot but that may be outweighed by the gain in mechanical advantage. Alternatively, shorter cranks will lessen the dead spot but be harder to pedal, which may counteract?
Someone will no doubt come up with a scientific artical or something from a pro to shed light on the arguement as with the above post from Brian.
Will let you know what I find.
Craig
You'll find formulas; case studies; expert opinions; plenty of not-so-expert opinions, but in the end it comes down to what works for you.
Guidelines are purely that, what you are doing i.e. experimenting is ultimately the way to go...