How do I replace the crankset of my Trek 2100 road bike?

Question

Road bike question:
Do I need to adjust the chains and/or anything else when I replace my Bontrager Race 54/42/30 crankset with a smaller one, say, Bontrager Race Lite 52/42/30 crankset ??

Answer 1

Yes.

The chain should be fine but you will need to raise the front derailleur. After installing the crank follow these simple instructions:

1) Loosen the cable fixing bolt on the front derailleur and pull the cable free.

2) Loosen the derailleur clamp bolt just enough that the derailleur can be moved.

3) Raise the derailleur on the seat tube so when you actuate the derailleur the cage misses the large chainring by 1mm to 2mm, or 1/32" to 1/16". Retighten the clamp bolt carefully.

4) Make sure the shifter is in the "low" position, reattach the cable, and adjust.

Answer 2

Turn your bike over. Place the gears into the smallest cogs. Your derailier should be about horizontal, but the chain should not fall onto the jockey wheel.

Now change into your largest cogs and make sure that the chain is not being stretched too and that it can be managed easily.

Finally take a tape measure and measure the length of 12 links of chain. These should be 12". If it is less than 12 1/8 then you still have life in the chain, although anything over 12 1/16 should be changed. If it is 12 1/8 or over, change the rear cassett at the same time (This is a chain wear check by the way).

Luck

Answer 3

I would say no, base on the fact that it's only a small difference between the two cranksets. Once you have switched it over, take it for a ride and see how well it shifts. If it's not shifting too well, make some rear derailleur adjustments, then if that doesn't work, take it to the local bike shop and have them make the final adjustments.

Answer 4

Not the chain, with your small ring the same and you big ring just 2 teeth smaller it will be fine. (you really have a 54 chain ring??? that is very rare indeed!)

Ohiojeff is correct. If you are replacing the crank and not just the ring, your front derrailleur may (maybe not) need to be move sligtly closer to the big ring (same distance it is from your current one) cable re-adjusted and Hi - Low stops reset.

Answer 5

you may have to lower your front derailer to the smaller outer ring, and that would require readjusting the cable and perhaps the stops if the new crank rides a little closer or futher out on the taper. it really isnt a big thing though.