Crank Gearing Question
 

Hey guys I have a question on switching gears on my crank. This spring I built up a 2004 Trek 520 frameset. I knew that I would not be doing any touring until summer of 2010 so I used some parts I already had to get it on the road. My set up is an Ultegra triple 6503 crank and BB, XT FD-M771, Ultegra RD 6600GS, Ultegra 12-25 casette, DA 9 speed chain, and a set of DA Bar End shifters. I have already purchased a XT RD-M771SGS, XT 11-34 cassette, and was about to purchase a XT Crank when I saw that there are some crank gears available from Salsa that I could put on. The gears are 48/38/24. These are not quite the same as the XT's 44/32/22, but close enough for me and much cheaper. Will these gears from Salsa work or, as the noob I am, is there something not right here?

with the 48/38/24 crankset and a cassette with 11-34t you should have low enough gearing to do anything you want. That 24 X 34t is a really low gear...probably only used on incredibly steep hills with gear.

You should be fine. For unloaded riding you'll probably spend most of your time on the 38 chainring and the middle of your cassette....at least I do anyway.

Your Ultegra crank has 130/74 mm bolt circle diameters so be sure the Salsa chainrings match them.

Sorry Hillrider, I forgot to mention bolt circle diameters. Yes they are the same. Outer two for the Salsa are 130 and the inner is 74. Thanks.

The ring spacing might not be perfect since ring thickness varies all over the place, but it should be good enough. The only way to tell for sure is try it.

It will work well with the bar end shifters. You might consider a chain guide with the 14-tooth jump. Or perhaps you could stick with a 26 instead of a 24 for better shifting if a 26-34 combination is low enough for you.

I would go with the 26 tooth inner ring if I was you - it will make front shifting a little smoother and reduce the chance of dropping the chain (although still use a chain retention device like Third Eye or N-Gear), and your lowest gear will be plenty low enough. Are you aware of how widely-spaced the gears are on the 11-34 cassette? I would want something with tighter spacing for road riding. Even 11-32 is a bit better.

My Trek 520 now has 26-42 chainrings up front and a BBB 12-28 10-speed cassette out back, which I find to be ideal for touring - lots of closely-spaced gears, a good range for touring, and minimal shifting with the front derailleur.

The 24 will work fine. With a touring bike you want as low a gear as you can get.

Correction: You want as low a gear as you're likely to need (which is probably not the same as the lowest you can get). Unless you're hitting extended sections of >20% gradients (which I seriously doubt), then I cannot see the point of having a 24-34 gear, even on a touring bike.

Which in no way contradicts what Chris_W said, so no correction needed.




You're projecting again.