Bicycle Mechanics - Upgrading my 1993 MTB (mix 7-sp and 9-sp stuff)

Hello,

I would like to make some changes to my 1993 Diamondback Topanga MTB. It still has all the original components (Shimano Altus 7 sp set; rapid-fire 7-sp shifters; 12-28 cassette, 28-38-48 crank, cantilever brakes).

I would like to keep the rapidfire shifters, the cantilever brakes and front derail. but put in other new parts, mainly to put in lower gear.

Is it ok to make changes such that it will end up
-Altus 7-sp rapid fire shifters (Original)
-Altus front derail. (Original)
-LX Crank (9-sp; 22-32-44) (New)
-14-32 cassetter (New)
-Deore or LX rear derail (9-sp) (New)
-cantilever brakes (Original)

Do you see any problems as it is or anything else needs to be changed?

The cost of all the replacements will definitely be more than what the bike is worth now: I just like the bike so would rather keep it than get a newer model, but do you think it's worth the cost doing this?

Thank you.

You can get a good used bike on eBay for the price you will pay for those parts. However, I don't think you will go above $180 if you get good prices on the new parts. Don't forget the new chain that will go with the new cassette and chainrings.

If you get a new rear derailler make sure it will fit your old style frame :beer:

I can see that if you are going to use a 9 speed crank that a 7 speed chain does not work that well on 9 speed rings. Also if you are changing your cassette you will need to change your chain as well. You can however use a 8 speed chain and chainrings with a 7 speed rear cassette easily, however 9 speed chainrings with a 9 speed chain on a 7 speed cassette does not work that well (for example).

A 7 spd shifter with a 9spd cassette? If you compare the 7spd
cassette side by side with the 9spd you will note the cog spacings on the cassettes differ. The 7 spd shifter will over shift the 9spd and at some point it will shift between two cogs and hunt back and forth between them not sure which way to go. Second problem is the 7spd shifter has -*7*- positions so you will have to decide whether to give up on the 27-32 cogs or the 14-15 cogs. The shifter can't cover the full cassette. So you won't gain and in fact may lose by changing to 9spd cassette. Leave it alone, it is a waste of money and effort. Steve

sch i think he's swapping out for another 7-speed cassette.

Yes, I am changing to another 7-sp cassette.

I would keep everything 7-sp and avoid mixing in 9-sp stuff except it just seems like it's easier to find 9-sp now.

My current 7-sp Altus rear derail. can go up to 28T I think so I am forced to change that one (b/c I am going up to 32T) and I haven't had luck finding 7-sp crank w/ 22-32-44, so thought I just get what's easier to get, a 9-sp. r.d and a 9-sp crank.

Thank you for all the response.

:)

You might be able to find a cheapo STX-RC crank ... those might be 7-speed compatible.

LX takes a splined BB unit, unless you can find an older model. I like the splined ones, but its one more thing to buy.

chi is right about that stx stuff. Most of i is 7 speed and very good quality. Look up stx on ebay and see what you can find.