slow 'n' steady
Join Date: Mar 2009
Location: on the onion river
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bottom bracket size help?
i recently had my LBS install a bunch of stuff including a sugino xd2 500 triple crankset and new ird bottom bracket on my surly crosscheck.
now according to VO's site, sugino recommends a 113mm bb for a road bike to a 115mm for a bike designed for larger tires. riv says a 107 to 110 for a road bike, and 113 for a bike with bowed chainstays such as most mtn bikes. sheldon's chart shows 113 to 118 with as small as 107 fitting certain road bikes.
when i got the bike back i noticed that there is quite a bit of space between the crankarms and the chainstays. maybe an inch give or take, i haven't measured it yet. there is also quite a bit of space between the small chainring up front and the chainstay. i asked what size they installed and was told a 118mm. i mentioned that i had heard 113 to 115 and was told that 118 is the minimum for a decent chainline, and to not have the chain rubbing adjacent cogs on the cassette when in cross-up gears.
i measured from the middle chainring the to the center of the down tube, and i get definitely more than 45 which is what shimano specs for a road triple according to sheldon's chart on bb size. as accurate as i can measure it looks like 48-49. i shifted to the middle chainring in the back (12-25 9spd) and the chainline definitely flares out slightly at the crank.
am i correct in assuming that i need the 113 considering that 48-49 is 3-4 more per side, and 6-8 overall. 118 minus that 6-8 would leave me at 112 -110. as i mentioned the mechanic (who has been very helpful and seems very knowledgeable) said that a 113 wouldn't fit.
anyone who has installed a triple on a crosscheck, what size bb did you use and how is the chainline?
should i take it somewhere else? can the spindle alone be swapped ($15) or do i have to buy a new bottom bracket ($50).