Shimano Front Chainwheel FC-MC19 Replacement? I have Shimano FC-MC19 22/32/42 175mm crankset on my MTB for 17 years and it's time to replace it but I find it difficult to figure out what new crankset will fit my bicycle.



Two years ago I replaced the original bottom bracket (it was 110mm) for Shimano BB-UN26 110mm and everything worked perfect. 

Now, I am wondering if I purchase Shimano Acera FC-M361 22/32/42 175mm crankset will it fit on my 110mm bottom bracket??? The specs of the Acera crankset that I am considering to purchase are literally the same as of the old crankset I am replacing but the new Acera crankset says that recomended bottom bracket is 123mm.



I don't see why the new Acera crankset wouldn't work on 110mm bottom bracket as the old crankset did for 17 years!? Also, I measured the distance from the bottom of the old crankset crank arm (where the pedals are attached to the crank) to the bicycle frame (where the crank arm is the closest to hit the frame) and there is 1cm of space on both sides, so no touching should occur between crank arm and the frame even if the new crankset is mounted on current 110mm bottom bracket in my opinion.

What do you think? Should I add spacers and how many??? Would that help? I really don't want to purchase new bottom bracket if everything would work well with the current one of 110mm spindle length.
The problem is not clearance between the crank arms and frame. You need to look at the clearance between the chainrings and frame, which is likely to be much tighter.

You also need to consider chainline - how for the nominal centers of the chainrings and sprocket cluster are from the centerline of the frame. You will be moving your cranks 6.5mm inboard, that's significant. I checked the specs of both cranks [here and here] and they both have a nominal chainline of 50mm, so you need the correct spindle length to get the correct chainline. 

I think you'll probably get chainring - frame interference with the shorter axle, and I'd get a new bottom bracket with the correct axle length  to avoid chainline problems anyway. A 17 year old bracket probably needs replacing in any case.