Cycling Mob: Road Cycling, Mountain Biking and More - View Single Post - Front shifter fails after replacing crankset

07-12-2004, 04:42 AM

Hi Sheldon,

Thanks loads for your reply.

I'm not sure if I have a "fat seat tube". My bike is a 2002 Trek 4300 - the
specs claim the bike has an 'oversized Alpha aluminium' frame with
'oversized powertubes'. The full specs are here:
http://www.trekbikes.com/bikes/2002/mountain/4300.html#

Also, I'm a little worried about getting a smaller BB because the left crank
is only a mm or so away from the BB housing on my 121mm BB. If I swap my
121mm BB for a 118 mm BB, will those 3mm be lost from both sides of the axel
(i.e. bringing both the left and right cranks 1.5mm closer to the BB) or
just from the right side of the axel (i.e. the left crank position will be
exactly the same on both the 121 and 118mm BBs but the right crank will be
3mm closer)?

Thanks,
Jack

"Sheldon Brown" <captbike@sheldonbrown.com> wrote in message
news:40F172F9.8090905@sheldonbrown.com...
> Daniel Kelly (AKA Jack) wrote:
> >
> > I've just upgraded my crankset and bottom bracket. And now I can't
> change
> > gears on the front derailleur. I've tried moving and adjusting the
front
> > derailleur.
> [snip]
> > 2) Before buying the BB and crankset, I read that the crankset needs
the
> > longest available BB axel, so I got 121mm BB.
>
> Bingo, there's your problem!
>
> > But perhaps this is a little
> > too long, resulting in the front chainwheels being pushed too far
> away from
> > the frame?
>
> Right.
>
> > My new BB is the Shimano LX Splined ES51 and the Crankset is the LX
> Splined
> > 9sp M571 170mm 22.32.44
>
> See: http://sheldonbrown.com/bbsize.html#deore
>
> Your cranks _should_ have a 113 mm spindle, if the bike has a
> normal-sized seat tube, 118 only if it has a fat seat tube. (Fat seat
> tubes place the front derailer mechanism farther outboard.)
>
> Sheldon "Chainline" Brown
> +---------------------------------------------------+
> | Time shouldn't just pass; things should happen. |
> | --Harry Turtledove |
> +---------------------------------------------------+
> Harris Cyclery, West Newton, Massachusetts
> Phone 617-244-9772 FAX 617-244-1041
> http://harriscyclery.com
> Hard-to-find parts shipped Worldwide
> http://captainbike.com http://sheldonbrown.com
>

07-12-2004, 04:42 AM	#13 (permalink)
Daniel Kelly \(AKA Jack\) Posts: n/a	Re: Front shifter fails after replacing crankset Hi Sheldon, Thanks loads for your reply. I'm not sure if I have a "fat seat tube". My bike is a 2002 Trek 4300 - the specs claim the bike has an 'oversized Alpha aluminium' frame with 'oversized powertubes'. The full specs are here: http://www.trekbikes.com/bikes/2002/mountain/4300.html# Also, I'm a little worried about getting a smaller BB because the left crank is only a mm or so away from the BB housing on my 121mm BB. If I swap my 121mm BB for a 118 mm BB, will those 3mm be lost from both sides of the axel (i.e. bringing both the left and right cranks 1.5mm closer to the BB) or just from the right side of the axel (i.e. the left crank position will be exactly the same on both the 121 and 118mm BBs but the right crank will be 3mm closer)? Thanks, Jack "Sheldon Brown" <captbike@sheldonbrown.com> wrote in message news:40F172F9.8090905@sheldonbrown.com... > Daniel Kelly (AKA Jack) wrote: > > > > I've just upgraded my crankset and bottom bracket. And now I can't > change > > gears on the front derailleur. I've tried moving and adjusting the front > > derailleur. > [snip] > > 2) Before buying the BB and crankset, I read that the crankset needs the > > longest available BB axel, so I got 121mm BB. > > Bingo, there's your problem! > > > But perhaps this is a little > > too long, resulting in the front chainwheels being pushed too far > away from > > the frame? > > Right. > > > My new BB is the Shimano LX Splined ES51 and the Crankset is the LX > Splined > > 9sp M571 170mm 22.32.44 > > See: http://sheldonbrown.com/bbsize.html#deore > > Your cranks _should_ have a 113 mm spindle, if the bike has a > normal-sized seat tube, 118 only if it has a fat seat tube. (Fat seat > tubes place the front derailer mechanism farther outboard.) > > Sheldon "Chainline" Brown > +---------------------------------------------------+ > \| Time shouldn't just pass; things should happen. \| > \| --Harry Turtledove \| > +---------------------------------------------------+ > Harris Cyclery, West Newton, Massachusetts > Phone 617-244-9772 FAX 617-244-1041 > http://harriscyclery.com > Hard-to-find parts shipped Worldwide > http://captainbike.com http://sheldonbrown.com >