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new crankset, old derailleur?

 
   
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iron_mike

Mar 14, 12 11:45

Post #1 of 4 (386 views)
new crankset, old derailleur? Quote | Reply
just installed a new crankset on my old MTB (new alivio). same old BB (square taper, ancient), and same old front derailleur (late 90's XT). did i cock up by not measuring chainline? am i going to be able to adjust the front der., or do i need to replace it (or the BB)?

thoughts?

-mike
____________________________________
http://utoronto.academia.edu/MikeCallaghan

http://howtobeswiss.blogspot.ch/


jeremyb

Mar 14, 12 13:57

Post #2 of 4 (359 views)
Re: new crankset, old derailleur? [iron_mike] [In reply to] Quote | Reply
Typically, the crank determines the BB axle width. The new crank should tell you what width axle to use ---- then measure your current axle width.

The FD doesnt care ---- though you may have to adjust it to fit the new chainline if it's different than before.


+1lap: Lightweight Cyclocross Bikes
It's not how fast you go fast, it's how fast you go slow


OneGoodLeg

Mar 14, 12 14:46

Post #3 of 4 (349 views)
Re: new crankset, old derailleur? [iron_mike] [In reply to] Quote | Reply
realistically, I don't think you're mixing apples and oranges too severely, so they should all work OK together. Trying to frankenstein mismatched shifters, RD, and cassette is usually prone to more trouble than up front. Might take some tuning of the FD (both max/min screws and cable tension) but it should be within the range of adjustment capability.


iron_mike

Mar 14, 12 23:00

Post #4 of 4 (320 views)
Re: new crankset, old derailleur? [iron_mike] [In reply to] Quote | Reply
thanks, guys -

as i say, we're talking about a 90's vintage steel frame, with 8spd around back and a triple up front. the derailleurs are actually XT/XTR level, but the BB is an ancient (original spec!) square taper and the new crankset is a pretty basic $50 alivio number. i'm hoping they all play well together, but just recently got so swamped with work that i decided to take it in to the shop and let them worry about it!

it's an ancient old rig but i sort of love her, and need one more tour out of her this april. then i'll leave her on a mountain top to return to nature.

-mike
____________________________________
http://utoronto.academia.edu/MikeCallaghan

http://howtobeswiss.blogspot.ch/