Originally Posted by
repechage
You have a 12 t difference up front, a bit large, but not unprecedented.
Very close out back.
My guess assuming that the rear derailleur mount is aligned… is that you could remove some length of chain, the goal to get the upper jockey wheel closer to the cogs while still allowing the 48-17 and 36-12 to have reasonable capacity. I would gamble and take out three links of chain.
I think that's more or less right. You'd probably be happier with the wider gearing range you'd get from a 14-28 freewheel, which I believe that derailleur and chainring combination should handle. Whatever you use for a freewheel, make sure that the chain is long enough to work in the big-big combination (48-28 if you switch to a bigger freewheel, or 48-17 in your current setup). That's not a gearing combination you'd ordinarily use, but you will sometimes shift into it accidentally. If the chain is too short for that shift to happen, it will break something and possibly cause a crash