8 to 9 speed cassette.. Any problems?

[Pedaldog.]

For various reasons, mostly lack of cash, I was intending to do some swapping of tyres on different bikes so that I could get one out on a trial run. Then I wondered about just swapping thw whole wheel.
It has an 8 speed cassette on it at the moment so would there be anything to worry about if I just put the 9 speed cassette on the 8 speed wheel?  I assume they're the same OLN and I don't expect any dishing differences. Am I missing anything?

[Biggsy]

No problem if it's a Shimano hub.  I think no problem too if it's Shimano-compatible other make.

It is a problem if it's Campag.  Let us know, anyone, if you want details for Campag.

[andrew_s]

8 to 9 is just a cassette swap.

You may have to swap chains as well if the state of chain wear and new cassette wear isn't compatible.
It depends whether you swap chains at the 0.75% point or just carry on using the chain until it gives problems, then replace both chain and cassette.

[Polar Bear]

8 speed shifters shift more cable using lthe same rear mech geometry.   Also, an 8 speed chain is liable to rub on larger cogs next to teh chain as well as more so on the front mech side plates.

[Pedaldog.]

Thanks for the help. No worry about the chain and sprockets as they are all new and unused for the Bike the wheel is going on to. I only want it as a temporary measure for a few weeks and then I'll get things all swapped back. Too cold to go out and do it for a few days looking at the forecasts but maybe at the end of the week.

[Biggsy]

8 speed shifters shift more cable using lthe same rear mech geometry.   Also, an 8 speed chain is liable to rub on larger cogs next to teh chain as well as more so on the front mech side plates.

I was assuming the bike the alternative wheel is going on already has a 9-speed shifter and mech, hence the desire to use a 9-speed cassette.  Otherwise, Pedaldog, stick with 8-speed cassettes if you want to want to carry on with an 8-speed indexed shifter.

[Pedaldog.]

Yes, 9 speed equipped on the new frame and forks. It's only the fact that I can't finance a pair of decent new tyres before the new year that makes me think of this idea. Might not do it as I am in no rush.

[Polar Bear]

OK, I see what you mean.  I interpreted it as you putting a 9 speed cassette onto a bike with 8 speed transmission.   The 9 speed cassette should just slide onto and 8 speed freehub no probs - unless you've got some weird dura Ace / XTR kit 

[Pedaldog.]

Nah!  I let the last motorbike go a month or so back and bought a Thorn Sherpa frame and forks. Most bits are new Deore, bars and shifters are some that I kept from a "Special" bike. Only thing I am short of to get it in a basic rolling state are tyres. I was going to do a complicated swapping of tyres from one bike to another, the tyres I have are too fat for the mudguards, and then decided just to swap the cassette and wheels so it's only a quick job and easy to put back again.

[Biggsy]

The 9 speed cassette should just slide onto and 8 speed freehub no probs - unless you've got some weird dura Ace / XTR kit 

It'll be good if anyone can post details of Shimano or Shimano-compatible exceptions - in case it helps anyone else reading this, now or in future.


Campagnolo

Campag's 8-speed splines are different from the Campag 9/10/11-speed ones.  Campag 9-speed sprockets can be modified to fit an 8-speed freehub, but you'd need to be very keen to bother, and there won't be room to get nine sprockets on properly.

Regarding the other way around: Campag 8-speed sprockets fit Campag 9/10/11-speed hubs, but the short tabs designed for steel freehubs badly chew up the aluminium freehubs of 9/10/11-speed.  Conversion kits have been available to Convert a 9-speed Mirage/Veloce cassette to 8-speed spacing.  Note. 8-speed sprockets are thicker than 9/10/11-speed's.  Find the numbers via Sheldon Brown's "k7" page.

Also consider Marchisio and other independent-make custom cassettes.