Bicycle Mechanics - Do I need a new derailleur?

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CPW
08-03-05, 08:11 AM
I've got a Jamis Quest road bike w/ a 12-23 rear cassette and I want to replace it w/ an 11-32. It's got a Shimano 105 RD. Will I have to replace the drailleur? I'm getting different answers depending who I ask as well as a "Lets try it. It may work." I expect to buy a new chain either way.
If I have to buy a new RD, I apparently have two options:
AT @ around $90 or LX @ around $60.
I would have thought it was pretty cut and dry as to whether the 105 will handle the new cassette or not. If I need a new RD, which do your reccomend?
Thx,
CPW

sydney
08-03-05, 08:15 AM
I've got a Jamis Quest road bike w/ a 12-23 rear cassette and I want to replace it w/ an 11-32. It's got a Shimano 105 RD. Will I have to replace the drailleur? I'm getting different answers depending who I ask as well as a "Lets try it. It may work." I expect to buy a new chain either way.
If I have to buy a new RD I apparently have two options:
AT @ around $90 or LX @ around $60.
I would have thought it was pretty cut and dry as to whether the 105 will handle the new cassette or not. If a need a new RD, which do your reccomend?
Thx,
CPWYou get different answers, because 'it depends'. Big cog spec for that deraielr is 27.They usually handle a 30 and sometimes a 32 depending on hanger length. Ya got nothing to loose by trying it and adjusting the B screw to the limit. Otherwise get an LX and be done with it.
CRUM
08-03-05, 09:31 AM
If the Quest came with a triple crankset, then the chain wrap is most likely 37 if it is a 105 derailleur GS. That is assuming Jamis spec-ed the right derailleur Shimano advises for use with a triple. If it is a GS(mid cage) derailleur, the jump to 32 teeth may be attainable with just a chain swap. As sydney says , it's worth a shot just changing the chain first and seeing what happens.

CPW
08-03-05, 04:36 PM
I went w/ 11-32 cassette.
Unfortunately, it required cassette, derailleur and
chain. I just hope I didn't go so extreme that I'll
be sorry. I kept all the original parts in case I
want to go back. I've now got the same gearing as
Jamis's touring bike so it should be workable. I've
lost alot of fine tuning (big jumps between gears now) but hopefully not too much on
the tall end. I went w/ the XT stuff as that was what
they had in stock and they gave me a deal on it. It
would have cost me more that the difference between AT
and LX to go back to the shop (1 hr round trip-but the
place I like to do business).
I'll see how it goes. Thanks for the replies.
CPW