Suntour to Shimano Alivio chainring out of alignment

KSpeedy

Hi,

Hope someone can help.
I have a Trek 4300 2009 which had a Suntour chainring which I swapped out for a Shimano Alivio square taper.
Once all back together the Alivio chainring is further out the by quite a bit.
To resolve this would I need a new bottom bracket to align the mid ring with the mid of the rear cassette.
If so what is there a specific bottom bracket that would be the right size or do I need to carry out some measurements to work out what I need.

Thanks

jimothy78

Yes, you're likely to need a different BB (assuming you actuallly mean you've changed the crankset, not just a chainring)- give us the model number of the crankset (printed on the inside of the crank arms, probably staring FC-M... ) and we can look up what size you'll need.

KSpeedy

Sorry, I meant changed the crankset.

The existing crank, according to the Trek site was:
SR Suntour XCC-T102 42/34/24

The new crank is:
Shimano Alivio FC-M410

Much appreciated.

jimothy78

Ok, great.
the shimano techdoc for that shows that you need a square taper BB with a spindle length of 113mm. The other dimension to get right when purchasing it is the BB shell width (determined by the frame) and which will be either 68mm or 73mm. You can find this out by simply measuring the BB shell directly (from one edge of the frame to the other), or by taking out the old BB, which will more-than-likely have the size printed on it in the form A x Y (where A is the shell width and B is the spindle length).

then you just need to source a new BB with the dimensions A x 113. You'll also need to check it's described as "english thread" - which is the way it screws into the frame.

this one comes in both the possible sizes you might need, and is cheap as chips:
http://www.chainreactioncycles.com/shim ... -prod34652

KSpeedy

Thanks for all your help.
Was 73mm so obviously bought the 113 x 73.
Also bought the tool to extract.
Much appreciated. Pint owed

jimothy78

Good luck.