# Bicycle Mechanics - compact crank, gear compatability (noob)

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hopsing08
08-13-09, 05:26 PM
My question is I got a Rival comapact crank; 50/34T and a Shimano Ultegra 12-25T cassette. (as i have heard many times that shimano cassettes are a little more quiet.) Is this setup good? did i lose too much top end or with my gearing did i completely negate my compact? i researched to compact part but i guess i just trusted the guy at the bikeshop to know what cassette would go well with it.
i do climb alot though and i want to make sure that my cassette compliments my Compact crank. thank you for your time and patience.

idcruiserman
08-13-09, 07:10 PM
No way to answer that question. Put it on your bike and try it out. I use 11-23 with my compact crank.

hopsing08
08-13-09, 07:21 PM
No way to answer that question. Put it on your bike and try it out. I use 11-23 with my compact crank.

11-23 is the one i see most commonly. i just wanted to make sure that my 12-25 is good. i know there are some gear heads out there.

Al1943
08-13-09, 07:26 PM
You probably made the best choice.

Al

DaveSSS
08-14-09, 07:42 AM
This takes some simple math to analyze. Your 50/12 is a bit higher gear than a 53/13, so you've lost most of the top gear that a lot of bikes have. The lowest gear is just abit higher than a 39/29, so you've got more low gear than a typical 39/27.

12/50 x 53 = 12.7

25/34 x 39 = 28.7

Using a 50/34 with an 11-23 doesn't do a thing for the gearing range, compared to a 53/39 with a 12-27, but it does reduce the big cog jumps at 21-24-27.

hopsing08
08-14-09, 11:24 AM
So essentially with the setup that I have, I lost a little top end speed but I did gain a little extra for climbing. Since I wont be sprinting for stage wins I'm sure I wont miss the top end.

Thanks DaveSSS and Al1943 for your input.

urbanknight
08-14-09, 12:18 PM
^ Correct.

Should you feel the need to change anything in the future, this is a great resource.

http://www.sheldonbrown.com/gears/