Classic & Vintage - Replacing a 6-speed cassette with a 7-speed?

The cassette on my 1982 Lotus Legend finally needs replacing. It has a 6-speed cassette; the LBS says a 7-speed cassette will work fine, since I'm using friction shifters. What do you think?

I have switched a few bikes around, 5 to 7, 6 to 7, 7to 5, ect. I havent had any problems as long as the derailer has the reach you just adjust the high and low stops. Most of the friction shifters I've seen have plenty of extra reach . I now have a 14 speed 1975 schwinn continental.

I have switched a few bikes around, 5 to 7, 6 to 7, 7to 5, ect. I havent had any problems as long as the derailer has the reach you just adjust the high and low stops. Most of the friction shifters I've seen have plenty of extra reach . I now have a 14 speed 1975 schwinn continental.

1. OP: are you sure it's a cassette, and not a freewheel? Cassettes slide onto the hub body, then are locked down, either by the smallest cog, or by a lockring. Freewheels thread onto the hub body. The only real concern you will have to do this is the hub spacing--you should measure the distance between the dropouts (probably 126mm), then make sure that your cassette won't add any extra. Even if it does, not a big deal, but I think it's possible your wheel might need a slight re-dishing. You'll probably have to adjust the derailer stops so the RD can move the extra range, but with friction shifters, this won't cause any other problems.

2. Tolfan, when switching from 5 to 7, did you have to re-dish your wheel at all?

Peripatetic:
I realize that the era would indicate a freewheel, and most mechanics assume so. But upon even a superficial examination, they all say, "Oh, nope. It's a cassette." Can you tell just by looking?

Bklyn: Generally, you can tell if you give the cluster a quick spin backwards. On a freewheel, you can see the body and freewheel puller splines remaining stationary as the cogs spin around them. On a cassette freehub, the entire visible assembly will spin.

Replacing a 6-speed cassette is a lot trickier than replacing a freewheel. The best thing to do is to replace the 6-speed freehub body (which is a Uniglide body) with a 7-speed Hyperglide freehub body. Your LBS should be able to order a replacement body and do the necessary work, or hand you the parts and let you do it. It's a pretty simple operation, really, one you can easily do with the right size Allen wrench.

Yeah, the whole assembly spins as one unit.
But ...gah. Sounding complicated. Can I ask how much a cassette should cost in the LBS? The mechanic quoted me $40 off the top of his head. That sounds high, but once you figure in shipping and the wait to get it from Nashbar, it's not more than $10 extra.... But would that include the body as well?

I'm not Peripatetic or tolfan, but I'll stick in my two cents worth.
1) I can't tell from your picture whether you have a freewheel or cassette, but I COULD tell from a good close-up.
2) I've done a bunch of 5-6 to 7 conversions over the past six months. Some have required a re-space, some have required a re-dish as well, and a lucky few have required nothing other than unscrewing the old freewheel and screwing on the new one, then adjusting the stops.
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A very useful source of info on compatibility, etc. of older bike parts is Sheldon Brown's pages at Harris Cyclery - a link to some of his articles related to gearing is pasted here: http://www.sheldonbrown.com/gearing/index.html

In the free-wheel world, there is a a fair amount of interchangeability, although you have to worry a little bit about hub spacing. Basic 5-speed free-wheels are 120mm, regular 6-speeds are 126mm. But Suntour also made "Ultra" 6-speeds that fit into the normal 5-speed spacing of 120mm. Similarly, they made a 7-speed Ultra that fit into the normal 6-speed spacing of 126mm. You might need to have your hub-spacing widened a bit, to go from a ultra-6 to a 7, but to go from a normal 6 to an ultra-7, it would drop right in. Everything is typically fine from the derailleur perspective, assuming friction shifters. But, the narrower Ultra cog spacing requires a narrower chain.

Just ran down to the bike room to take a picture (and get my hands all greasy). It's a Shimano cassette. You can see where the teeth are broken in one picture.

alright... CLEAN YOUR F'N FREEWHEEL!!!

wait no... that's a cassette... weird.

It looks like the early freehub design from shimano... the unit is held on by the axel assembly and there is a spline on the hub which it is fitted too. You may be able to remove the cogs like on a uniglide cassette and replace with a uniglide 6-speed cassette if you can find one. I am not on my computer so can't easily find catalogues etc.. with this stuff in it.

But, the narrower Ultra cog spacing requires a narrower chain.

True, if you have an OLD chain, like a classic Regina, anything from Sedisport forward shuld be no problem, with exceptions such as Shimano Uniglide, with the bulged out plates.

Modern Sram chains (7-8 speed type) are no problem and readily avail.

With the Ultra freewheels, sometimes, due to chainstay to dropout attachment style extra spacing is needed, 122 with the ultra6 and 127 with the ultra7 often cure the ills. Suntour Ultra freewheels are starting to become less common, the $15. ebay deals are long gone unless you are an ebay hawk and lucky.

cyclotoine pins the tail on the donkey.
An early Shimano freehub, and it's a cassette with the small cog screwing on as a lockring. Suffice to say, my LBS doesn't have the exact parts to replace the cassette. There's also no way to remove the freehub. They're building me a new wheel (using the already replaced rim) around a Shimano 105 hub with a 7-speed cassette. I guess I'll need a new chain also. Approaching $150, I think. Much money to spend on myself FIVE DAYS before my wife's birthday....!

Thanks for everybody's help.

I use simplex friction shifters on a 9 speed Campy chorus RD without problems


The cassette on my 1982 Lotus Legend finally needs replacing. It has a 6-speed cassette; the LBS says a 7-speed cassette will work fine, since I'm using friction shifters. What do you think?

Shoot, sorry I've spaced on this thread, Bklyn. I've got a pair of 27" wheels with a newer, hg-compatible freehub (no cassette). I have no need for this, so haven't gone looking for a $30-$40 cassette. Anyway, if for some reason you decide against the bike shop wheel, or you want a decent backup that's not as obsolete, PM me; this thing's actually about to go into storage for the winter, I've tried trading it away on a couple of occasions. As I said, I really don't need it.

cyclotoine pins the tail on the donkey.
An early Shimano freehub, and it's a cassette with the small cog screwing on as a lockring. Suffice to say, my LBS doesn't have the exact parts to replace the cassette. There's also no way to remove the freehub. They're building me a new wheel (using the already replaced rim) around a Shimano 105 hub with a 7-speed cassette. I guess I'll need a new chain also. Approaching $150, I think. Much money to spend on myself FIVE DAYS before my wife's birthday....!

Thanks for everybody's help.

You should be able to remove the freehub by taking the axle out, not that that would have helped you any because that hub needs that freehub body.

Periptatetic, thanks so much, but alas, I've already got a new gear cluster. This should last forever, but if not, I'll know who to call.