Bicycle Mechanics - Upgrading from 6spd to 8/9spd

A friend of mine is hoping to upgrade her suntour 6 spd set up to 8 or 9 spd shifters/cassete/wheel/chain and derailluer.

I told her that there's no way that 9 spd chain is going to work with her old cranks, but I'm not sure about the 8 spd chain.

Is there an easy way to test?

Thanks,

Barton

Is the frame worth putting a new drivetrain on? Unless it is something really special, a new bike might make more sense.

Yeah, its a rather well-maintain touring bike with a double butted Tange steel frame. We found it in a dumpster.

Especially given that a new 8 spd drive train can be assembled from Nashbar for $250

An 8s chain will work, however, if you are going with a new drivetrain, you should probably change the chainrings along with everything else. So, you are looking for shifters, fd, rd, cassette, rings, chain, cables & housing plus a rear wheel. Then you will need to spread the rear of the frame to fit the wider axle spacing of the new stuff.

the crank is a funky design. not sure of the hole spacing but i think it would be difficult to locate rings and a new Sora crank is only $50.

A friend of mine is hoping to upgrade her suntour 6 spd set up to 8 or 9 spd shifters/cassete/wheel/chain and derailluer.

I told her that there's no way that 9 spd chain is going to work with her old cranks, but I'm not sure about the 8 spd chain.

Is there an easy way to test?

Thanks,

Barton

It(Shimano 9 Speed Chain - Cassette) worked for me on a 1981 Peugeot with a Stronglight Crank. I use Simplex friction down tube shifters. Dura Ace rear Derailleur. Peugeot Simplex front derailleur - Smooth. . .

Thanks that definitely helps. My eyeball estimation says that it will work. The teeth are considerably narrower than the chain.

The bike is a Holdsworth Panache and it is a Renoylds 531 not Tange. I don't know what I was thinking.

I would still swap out the rings. Putting all new stuff on a bike and leaving worn rings will wear out the new stuff faster. The 9s stuff wears faster than 8s, and so on, since everything is a wee bit narrower as you go up in the number of cogs.

Converting a frame designed for 6 speed to the later 8/9 speed will pose some geometry problems.

Spacing on the back side is narrower for 6-7 speed bikes than 8/9/10 speed bikes. Narrower frames will require expanding the back end to fit the wider axles/cassettes of the later groupsets. The later groups can create chain angles that are far more extreme than was possible with 6 speed gearsets. I've seen the retrofits done successfully with 6/7 speed frames with only front derailleur rubbing in the extreme gears. But I've also seen attempts on 6/7 speed frames that had chain alignment and fitment problems that could not be fixed.

I don't think the effort is worth it when there are aluminum road frames available online and in catalogs for under $300

But aluminum is NOT the same as a Holdsworth made from 531. This is a touring bike, so it has a relatively long whelbase, so the angles shouldn't be a problem.

Converting a frame designed for 6 speed to the later 8/9 speed will pose some geometry problems.

Spacing on the back side is narrower for 6-7 speed bikes than 8/9/10 speed bikes. Narrower frames will require expanding the back end to fit the wider axles/cassettes of the later groupsets. The later groups can create chain angles that are far more extreme than was possible with 6 speed gearsets. I've seen the retrofits done successfully with 6/7 speed frames with only front derailleur rubbing in the extreme gears. But I've also seen attempts on 6/7 speed frames that had chain alignment and fitment problems that could not be fixed.

I don't think the effort is worth it when there are aluminum road frames available online and in catalogs for under $300

Because everybody knows a generic low end aluminum frame is better than a hand built high end steel frame. If it's newer it must be better!

Consider using 8 cogs with 9-speed spacing, which should fit within a standard 6-speed bike's 126 to 128mm rear overlock dimension. If you do not object to nonindexed shifters, they will save you alot of money and hassle. I would use the old chainrings, assuming they are aluminum. A worn/elongated chain will wear out cogs and rings rapidly, but worn aluminum rings probably will not greatly shorten the life of your chain.

But aluminum is NOT the same as a Holdsworth made from 531. This is a touring bike, so it has a relatively long whelbase, so the angles shouldn't be a problem.

Absolutely agree. My 1976 frame was converted to 9 speed, and I have less problems with it than with my new frame which was designed for 8-speed, but which has shorter chainstays.