marnan

My winter commuter is a 1994 MTB with 7 speed STX/LX with slicks. The crank is beat. It is a compact 42/34/24 STX 58mm/94mm BCD. I have a used Sora road group that I could probably sell on Ebay for 40 or 50 bucks, but could I use the Sora road crank 52/42/30 on this bike with the 7 speed STX shifters. The BB is compatible. I am not sure about the STX rapid fire shifters, would they allow the chain to engage into the large ring on the front derailleur ? Would I be better off selling the Sora group and investing in chainrings, cassette (IG60), and a new chain to keep this old 7 speed going.

Psychic Pimp

Might work, but not very well.

You will run into chain length problems going from a 42 to a 52 big ring. Also, the mtb front derailleurs are made with a different radius and cage length than road pieces. MTB derailleurs are typically made to match a 44 or 46 max ring vs a road unit being made to match a 52 or sometimes bigger.

Shifters are not really an issue if it is all semi modern Shimano. road and mtb derailleurs are more the same than not as far as cable pull to travel.

You're better off selling the Sora group on ebay and getting new MTB stuff.

Your LBS should be able to get the stuff you need. If not, try biketoolsetc.com. Be careful buying this kind of stuff on ebay, people think it's more valuable than it is.

marnan

Thanks Psychic - this is what I needed. I wasn't aware that shimano mtb and road shifters have similar cable pull to travel. Anyway, I do have the Sora front derailleur I could use with the Sora Crank. However, I would need a new chain and it turns out the Sora front derailleur has a 31.8mm band and the the bike needs 28.6mm. So, I definitely agree I will sell the Sora group and use the money to buy new chainrings, cassette, and chain. I suspect that 7 speed parts will be harder to find as Shimano rolls out the newer stuff (10 speed) so I will buy now rather than later