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Crank Arm Length for long legs: 180 vs 175 mm?(6 posts)

Crank Arm Length for long legs: 180 vs 175 mm?Treetop
Aug 3, 2001 9:09 AM
Hey Folks,
My local bike shop is custom building me a bike on a 66cm Cannondale
frame. I'm 6'9" and have a 38" inseam. The bike is running my $1500 and I'm not real excited about spending a lot more. I got a call from the shop that the only cranks made in 180mm length are Dura Ace, and they will run an extra 100 clams. Will this make a difference in anyone's opinion as to comfort/efficiency? I'm new to road bikes and am wondering if this hundred dollars would be better spent on a set of aero bars and just go w/ the Shimano 105 175mm cranks. Any thoughts for a newbie? Thanks,
Go with the 180'sCima Coppi
Aug 3, 2001 9:15 AM
With an inseam as long as yours, you'd really be better off with the 180mm cranks. I ride 180's, and my inseam is only 34". Remember, its not the 5mm of crank length that makes the difference, but the 31.4mm gained in the circumference of your pedal revolution that will help the fluidity of your pedal stroke.

Good Luck!!

Go with 180mm only if...Bruno S
Aug 3, 2001 9:58 AM
they will reimburse you the cost of the 105. If not you better save that money because you will have extra expenses that you are not aware off. Trust me on this one.

Regarding the cranks, I'm 6'3" and use 180. When I went from 175 to 180 my performance improved so I do recommend them to tall riders like yourself. I had to dish out $220 for them since they are only available in Dura-Ace but did this after one year of using the 175.

Aerobars? No way. Unless you are a triathlete.
180 vs 175 mm? Less than 3% differenceJamm
Aug 4, 2001 5:47 PM
Think about this: the 180mm cranks are less than 3% longer than 175mm.
I'll bet few could ever tell the difference without previous knowledge.

(The Dura Ace looks a lot better than the 105 though)
some knees can tell, but look at 5mm on a ruler first!nm
Aug 6, 2001 5:00 AM
it's a very small difference
Its a fine tune adjustment..Bruno S
Aug 6, 2001 10:41 AM
For the money it will give you little and should only be done when you are refining your ride. But never the less, even if you cannot tell the difference right away if you are tall its an improvement.