I'm fixing up my old 90's mountain bike and I got the same crankset from shimano. Everything about the cogs are exactly matching but the piece that mounts to the bike is inset where on the old set it sits slightly further off the bike frame. (I added photos, hopefully this makes sense).
The problem was when I put it on, the derailleur couldn't switch to the smallest cog because it is too close to the bike frame.
What is my best plan of action with this one?
by bigfriendmusic
9 Comments
Look up the spec on the new crankset and see what length bottom bracket spindle it calls for. Compare that length to the spindle that’s in your bike.
get a crank with the right offset, get a different bb, or get a different fd. i would opt for the first
Time to learn how to setup a front derailleur. Search Park Tool on YouTube.
Bb is the least expensive option to get the right chainline. You already have the cranks.
Check the sishimano website. You should find the specs for your new chainset rhere. Find out which BB you need. Order and install.
You’ll need a slightly longer bottom bracket for the new crankset. Even then it’s likely you’ll have to adjust the front derailleur to the new chainring location.
The new cranks all need a 123mm axle also known as a 122.5 and depending on your shell width either 68 or 73 mm shell
122,5
You may not need a new BB. Just adjust the front derailleur and see how that works. I recommend the Park tool website or YouTube channel if you’re not familiar with setting the limit screws.
Also make sure the big chainring isn’t too close to the chain stay, since the new cranks are sitting more inboard.