8 speed cassette with 7 speed indexer?
 

I need to replace my rear wheel and right now I have an old freewheel cassette(Shimano). When I replace the wheel I want to upgrade to the cassette set up. My bike has the old style index/friction shift lever on the downtube (which I don't want to change). All the wheels I see are 8/9/10 speed compatible. If I use an 8 speed cassette and just limit the rear derailler to eliminate the low gear, can I still use my existing shifter? Thanks in advance.

Hi, with friction shifters u can put anything u want in the rear end of the bike. Put 8/9 or even 10. The only problem u might have is the RD, probalby a 7 speed one wont be able to reach the 9th and 10th cog (probalby it will), always u can get a 105 - 10 speed shimano rd for less than 30 bucks at ebay for example and problem solved.

I'm not an expert in new shimano but I believe u can put a 10 speed cassette in a 8 speed wheel no problems, but the lockring needs to be a 10 speed one because the threads are longer (10 speed casstees have them included usually). Just in case i have done it in my commuter, but if you want to be sure check sheldon web site, it will tell you better than me about the cassettes compatibility (im a campy person)

Correction...If I use the 7speed shifter with an 8 speed cassette It would automatically eliminate the low gear if the indexing (cable tension) is set correctly?

NO corrections here, I said "WITH FRICTION SHIFTERS" aka "if you use FRICTION MODE"

I NEVER said anything about using INDEX MODE. Hudge difference between one mode and the other one. Probably u havent use friction mode ever? Many people dont even know friction, thing i really miss, because with friction u can put any combination of component brands. Old stuff with new stuff etc.

Cheers :)

Hey thanks for the advice ultra. I wasn't clear with my question...sorry. I know I can switch my shift lever for the rear derailler to friction mode and the 8 speed will work fine. But if I want to use the index mode, I'm not sure if I can do that... If I can index 7 out of 8 gears (eliminating the lowest, which I never use anyway)? Actually you were very clear in your advice...thanks again!

Shimano 8s is 4.8mm cog spacing. 7s is 5.0mm spacing. Some have made this work, others not so lucky. YMMV. For the least amount of indexing "error", you'll need to set the cog/derailleur alignment on the 4th cog. this will result in a 0.6mm cumulative error in both 1st and 7th positions.

That's actually an interesting question.

7-speed and 8-speed cassette spacing are a hair's width different. Some people say that you can get 8-speed cassettes to index using 7-speed shifters. Personally, I've gotten them to work - sorta - but never to my satisfaction. If you want to try, the best set up is to get a cog in the middle of the cassette to align perfectly with the derailleur pulleys. That way, your out-of-adjustmentness will be split in each of the two directions.

Another alternative is to install a spacer behind a conventional 7-speed cassette.

The simplest solution is to use friction shifters. That's what I do with my retro grouch bike.

Incidentally, what's the distance between your rear dropouts? If it's 130mm, that's good. If it's 126mm, you might have some more decisions to make.

Don't eliminate any gears. Shift past the last click until the chain shifts to the largest cog and adjust the stop screw. You don't need a click for the largest cog for index shifting any more than you do for friction shifting. Cable tension stops the shifter at the correct place. A lot of 7 speed shifters have a "ghost" extra click anyway. I've been using 8 speed shifters with a 7 speed cassette for years and it works flawlessly. The spacing difference isn't enough to cause problems for modern Shimano derailers. The same should hold true for 7 speed shifters and 8 speed cassettes. When 8 speed first came out, a lot of people discovered that they could use their old shifters when they upgraded their rear wheel.

Every time this comes up Retro Grouch says it won't work and I say it will. Maybe I should ship my wife's Fuji to him so he can try it for himself.

Hey thanks guys...now it makes sense. I think I'll try the 8 speed cassette with indexing (If it isn't right I can switch to friction for now). Hey Retro Grouch my dropouts measure 130mm...why is this better?

Thanks Dirtdrop, I will try that for sure.

I have been running 8S with a 7S shifter since 1989 on my mountain bikes. It really doesn't matter which spacers you use, the 3.0 8S or the 3.1 7S, except that the space from second largest to third largest can be a bit strange. Just a couple weeks ago I opted to become really fussy about it and actually used a 6S spacer in that position to give it that final taste of perfection.

Now, this is with a Deore XT 7S thumbshifter--YMMV with downtube shifters. IIRC, they don't have the 'extra click' that the thumbshifters have.

Your rear derailleur will handle 8S, 9S or 10S just fine, so long as the inner cage clears the spokes in low gear.

That's not what I said at all. Read my post and you will find that I was very careful to not to say that it didn't work. Matter of fact, I even said how to make it work.

I said that I've never gotten it to work to my satisfaction. I've played with a bunch of different mix and match variations over the years. I've just never been satisfied with any of them over a very long period of time.

I'm entitled to my personal observation just as you are entitled to yours. The OP is entitled hear to both points of view so he can form his own opinion.

130mm is better because you can, for sure, fit an 8-speed road hub without having to make any other changes.

There are some Shimano wheels that will take 8/9 but not 10 but others that take any of 8/9/10.

Er. Example?

I think that this might be the other way around. There are some that take 10 only but not 8 or 9. The Ultegra SL 6600 set is one such example.

Mostly if they will take 8 or 9 then they will also take 10 (sometimes with a spacer)