Subject: RE: Compact Crank or just the inner ring? Switching to a compact crank is easy. You can find directions online to do it yourself, but a bike shop will probably charge you only $25 and include grooming your derailleurs ... go ahead and replace your cables at same time. If you do it yourself - get a cheap crank wrench from Performance - You can use the same bottom bracket, but this is a good time to change out the BB. Be very careful threading the new BB into the frame. A BB is good for 5000 miles so you might not need to do this. If so, lube the threads of the BB with Phil grease or any high quality grease AND wrap a single pass of Plumber's Teflon Tape (the white tape) around the threads to prevent squeaking. - Lower the front Derailleur about 3-4 mm to account for the smaller diameter of the compact 34 (or 36) tooth versus the standard 39 tooth. - Whoops, don't forget the chain. You probably need to take two links from the chain. WHich means you should probably just replace the chain, since this is a good upgrade very 2000 miles or so. Most triathlon courses will accomodate a 39X27 gear ratio ... so it might be easier to switch your cassette. But if you ride your tri bike all the time, you will really enjoy a compact crank and a 12-27 cassette. THis is the set up I use on my roadie and it's nearly perfect for hilly central Maryland. Also, any Shimano 10-speed crank will work fine with a 9-speed set-up. (I don't think they make 9-speed compact cranks). Another more affordable alternative might be to get a Shimano or FSA brand 52 tooth (big ring) and 38 (small ring) 130 BCD chain rings. 52-38 rings X 12-27 cassette will handle almost any tri course except SavageMan ... and set you back only $35 per ring. But go ahead and replace your chain if you have not replaced in a while. THe length of your crank shaft (172.5 or 175 most likely) is stamped on the inside of each crank. Based on your questions ... I'd think about getting LBS help in this but it's something you can also handle on your own . Edited by jsselle 2011-03-31 1:53 PM
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