What the F diffrence !!!

[thenoodle]

Hagar, if you ever find yourself in the position where you have to decide wheather you need 172mm or 175mm cranks......no matter what decision you make, you can always be sure that you made the right decision about the rugby team you support.

GO SHARKS!!!!!!!!!!!!!!!!!!!!!!!!! 

[HeartCoppi]

Please note that the diff between 172,5 and 175 is 2,5mm so on both cranks thats 5mm. Likewise from 170 to 175 is 10mm. I think thats a quite a big diff especially expressed as a % circumference increase

IMO its like walking up the stairs. The taller you are the more annoying and unnatural it is to climb one stair at a time. You might switch to taking stepping two steps at a time. The short guy wouldn't be bothered and continue to take one at a time.

Now imagine running up the stairs!

[downhilldemon]

The guys with longer cranks have to ride 3mm further per leg rotation. So lets say you ride 10km in 30 minutes @ 100rpm with 175mm cranks. You will on average ride 9 metres further than someone with 172mm cranks. Now there is enough bullsh*t to fertilize your spring gardens! 

 

not too sure of this - i dont think it matters if your crank is 10cm long or 1m long - its all connected to the same gears. so at 100rpm you gonna go the same distance - there is no effect on where the chain sits.

 

100rpm = 100rpm

[skaduwee]

I rode on 170mm crank for about 6 years, recently upgraded to 172.5mm.. wow big difference. Climbing is much easier, my cadence is even higher now that im fitter and i can push bigger gear.

 

 

 

Sprinters normally go for the 170 / 172.5mm cranks and climbers more for the 172.5 / 175mm.

[Speed Devil]

Check out what Sheldon Brown has to say. It's quite interesting

 

http://www.sheldonbrown.com/cranks.html

 

 

BTW, what is the length of an MTB crank?

Speed Devil2009-09-11 01:02:24

[skaduwee]

My mtb crank is 175mm.

[thenoodle]

The guys with longer cranks have to ride 3mm further per leg rotation. So lets say you ride 10km in 30 minutes @ 100rpm with 175mm cranks. You will on average ride 9 metres further than someone with 172mm cranks. Now there is enough bullsh*t to fertilize your spring gardens! 

 

not too sure of this - i dont think it matters if your crank is 10cm long or 1m long - its all connected to the same gears. so at 100rpm you gonna go the same distance - there is no effect on where the chain sits.

 

100rpm = 100rpm

DHKing' date=' you are 100% correct! Well done. I knew someone would fall for it. The last line should clear your confusion...................."Now there is enough bullsh*t to fertilize your spring gardens!" [/quote']

[cat-i]

 

The way I see it' date=' the weaker your legs then use a shorter crank to get more power from the revs. But if you have strong leg power I can see the benefit of using longer cranks.

It all depends on how high your cadence is. Im no expert but thats my opinion.

[/quote']

 

<confused> how will shorter pedals help weaker legs?

 

[Aquatic]

It comes down to leverage,but then like sheldon says,you got gears to compensate..The people who ask for shorter cranks generally have a smaller inseam or have knee problems.other people say they dont feel the difference.Wouldnt shorter cranks be slightly easier to pedal?

 

 

 

 

 

 

[cat-i]

i thought longer cranks would have more leverage?

 

if you try to open a bottle and you can't, and you put one of those bottle-opener-thingies around it, you can open it cos you've got a longer 'crank'? no?

cat-i2009-09-11 14:55:20

[EigerSA]

  the difference in  crank lengths will do nothing except change the fit of your bike. Putting a longer crank on will automatically mean you would have to raise the height of your seat so that you get proper leg extension during the pedal stroke.

 

The 'leverage' and 'cadence' discussion is completely irrelevant simply because you got gears! This type of discussion should be in the fixie thread since they would benefit more from experimenting with crank lengths.

 

 

 

[Johan Bornman]

I rode on 170mm crank for about 6 years' date=' recently upgraded to 172.5mm.. wow big difference. Climbing is much easier, my cadence is even higher now that im fitter and i can push bigger gear.

Sprinters normally go for the 170 / 172.5mm cranks and climbers more for the 172.5 / 175mm.[/quote']

 

You give two reasons for your higher cadence: your new-found fitness and your longer crank. Which one will it be?

 

 

[Guest Big H]

Ignorance is bliss....... or maybe this thread dispells THAT myth!!!!!!!!! ......or maybe some scientist can use it to analize the thought processes of cyclists!!!!!!!Big H2009-09-11 23:48:49

[Aquatic]

So if 2 guys with similar power outputs are riding the same combo, 50t front and12t rear,at the same cadence,under the same conditions ,even though they riding different crank lengths,the speed should be the same rite..But,will the guy with the bigger crank arms be using a little more energy to ride at the same cadence or is the difference over short distances not noticable?

 

 

 

 

[Minion]

 

So if 2 guys with similar power outputs are riding the same combo' date=' 50t front and12t rear,at the same cadence,under the same conditions ,even though they riding different crank lengths,the speed should be the same rite..But,will the guy with the bigger crank arms be using a little more energy to ride at the same cadence or is the difference over short distances not noticable?

 

 

 

[/quote']

In an ideal mechanical system, the two riders in the same gear ratio, with the same cadence and power output will be going at the same speed and producing the same amount of work.

The difference is that the rider with the longer cranks will use less force, but he has to move his pedals over a larger distance (larger circumference).

 

[Aquatic]

Interesting..so will there be a difference in fatigue levels?