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Single ring set-up parts question!(8 posts)

Single ring set-up parts question!skip work to ride
Sep 23, 2003 7:57 AM
Does anyone know the Shimano part number for the shims that are suggested to space out your bb to accomadate the inside chain guide for a dual chain guide set-up?

Anyone thoughts on running 42T versus 44T (Pro's common set-up).
re: Single ring set-up parts question!eurochien
Sep 23, 2003 9:06 AM
I don't know if there are shims that can work out for that (I'm a Campy guy). A triple bottom bracket (XT - XTR) may be better for optimal chainline. As for 42 vs. 44: flat course: 44. Hilly course: 42. Also depends on your own comfort level spinning or pushing big gears of course.
42 or 44? what's in the back also mattersclimbo
Sep 23, 2003 10:08 AM
gearing can be so different depending on the combination of gears, not just your front ring, it's really about what you are comfortable in pushing. A lot of "pros" and many, many A racers run 42's anyway so I don't know that one is more common than the other.
Don't need no steenkin' part numbers...triangleforge
Sep 23, 2003 10:53 AM
Your LBS should have a big bag of them, as they come in handy for all sorts of other things like spacing cassettes & freewheels or adjusting the chainline on fixies & singlespeeds.

And they should be almost nearly free, so pick up a few.

Generic Partskip work to ride
Sep 23, 2003 7:30 PM
You are right, these are made by Wheels Inc and others and are cassette spacers. XTR bb come with them two. I guess they come in 1MM and 2MM thickness.

Thanks for the heads up. I would ruined my week looking for them...
Can't be done, need to adjust spindle width.ChrisA
Sep 24, 2003 11:14 AM
If your intent is to adjust where the front chainring is in relation to the rear cassette, shims won't work. You will need to buy the BB with the correct spindle width. The width of the spindle determines how far out the chainring ends up and how much clearance you have for the chain guides. Shims will only help fit a BB to different width BB shells.
I do it all the timetriangleforge
Sep 25, 2003 8:05 AM
You're right that you've got to get the right spindle length, but that just gets you in the ballpark; there's a lot of improvement you can make in chainline using 1-2 mm of shims on one end or the other of the drivetrain. And it's as common as dirt. How else do you think singlespeeds & fixed gears do it? Even better, look closely at brand-new bikes on the show room floor sometime and you'll be amazed at how many of them have the BB shimmed on the drive side.

Single ring, use a triple BB.pp_mcgee
Sep 27, 2003 7:43 PM
I run a single dura ace crankset with a 42t chainring, and a spot chainring guard, on a dura ace triple BB to even the chainline, with a 12-25 in the back.

That works well for me. I'm a smaller rider and tend to push smaller gears, however. I'm not a pro, either, but I've used this set-up to place top 10 in a couple UCI elite races last year. It works well.