curttard

I have this 2006 Stumpjumper. I keep it in my car at work and ride on my lunch break. I'm always in different locations, so sometimes it's a trail ride and sometimes a road ride. I have some spare wheels from other bikes; I keep the spare front wheel with a road tire on it, and would like to do the same with the spare rear wheel, so I don't have to change the rear tire all the time depending on if I'm doing road or trail that day, but the spare is an 8-speed XT from 1993 and the Stumpjumper has a 9-speed.

Is all I have to do is get a 9-speed cassette and swap it on the spare and I'm good to go? Jenson has 9-speed 11-32 XT for $40.

10 Wheels

Try the 8 SPD Cassette.

You may be surprised.

Presently running with 9 SPD Shifters

With an 8 Spd Cassette

on a 7 SPD Hub.

Runs good.

HillRider

Yes you will need to install a 9-speed cassette on the spare wheel to get any kind of decent shifting. However a different rear wheel, even with the same cog count cassette, may require some minor rear derailleur adjustments to the limit screws and/or cable tension.

Also, if the chain is worn, it may skip on the new cassette so you might want to buy a dedicated chain for the spare wheel and switch both together. A chain with a master link (KMC, Wipperman, etc.) will make this easy.

fietsbob

have to match the shift lever, (unless you use friction shifting)

8 front and back or 9 for lever and cog count..

nfmisso

I would get two new 9 speed cassettes and one new 9 speed chain, unless your current 9 speed cassette has less than 1K miles on it.

curttard

The really surprising thing is I've never tried it! Will do.

Hmm. Well, switching chains sounds like kind of a pain, and messy. I changed the tire today in 5 minutes or less (including pumping to 100psi) so it's not a huge deal, so I'll just stick with that if I can't get a totally painless wheel-switch going.

I'll give the 8-speed a try just to see what happens.

That's a good idea. I'm assuming it's got more than that, I bought the bike used.

DiabloScott

Might also run into brake problems if the rims aren't about the same width. And if they are, then I'd put give them all a good truing and dishing to make sure they all match. Then, one new 9-speed on the wheel with the road tire and you should be fine.

Chain wear and cassette wear isn't something you have to worry about for lunch time rides until you start to have skipping problems or something.

Bill Kapaun

IF you have a 7 speed hub, it means you are using 8 of 9 cogs with 9 speed spacing.
You DON'T have a conventionally spaced 8 speed, so your advice is wrong.

10 Wheels

I ride with a mechanic and often surprise him with things I try.

Bill Kapaun

I suggest you have them post instead of leading the OP into a can of worms.

DMF 

You don't say what the cassette range is on the two rear wheels. I recommend one high range for road (smaller sprockets) and one low range for trails (larger sprockets). Quick wheel swap and you're ready for your ride. Your current sets may be sufficiently different to do this. Or not. Now on the cassette vs. chain issue, chains and cassettes wear together. For good shifting you need to change to a cassette with somewhere near the same amount of wear. Obviously "new chain / new cassette" is the baseline, thus the posts above. If you use a different cassette and your shifting is crappy, then you need to look at the wear issue. Good luck!

hueyhoolihan

i think i'd seriously consider finding a compromise tire width/weight that will work for both situations. would really, really simplify things.

you're already half way there with that extra front wheel as is.

u235

I swap between a wheel with a 7 speed Shimano megarange 13-34 freewheel and an 8 speed SRAM 850 11-32 cassette. A minor tweak of tension on DER and maybe the vbrake pads but not every time. Takes maybe 3-5 minutes total for the swap and I do it relatively often depending on where I am going and conditions. That is time where I might be cleaning the chain, adjusting pads, spinning my wheels and feeling, checking and looking things over anyway. I dont swap chains (currently an SRAM 850). I've never had a problem with it and both shift clean and accurate. The DER is a Deore M591 and the shifter is a SRAM gripshift if that matters. A 9 shifter may be a little more sensitive.

curttard

Definitely, but riding on the road with the 1.25" 100psi slicks is just so much nicer than the 2" knobbies, and I'm not sure what tire compromise would be good enough for often muddy singletrack that usually includes creek crossings, while still not feeling like a chore on the road.

I'm going to get the cassette and see what happens, and go from there. I'm still on the hunt for a road bike, so once that happens my problem will switch to "how do I fit both bikes in the back of my CRV".

70sSanO

You have been given a lot of different opinions, but if it were me I would probably compromise with a single tire for both, but if not I'd do the following...

Take a spare rear wheel, without a cassette, and see how well the brakes line up. If they work then you can move on to adding a cassette.

Remove your existing cassette and mount it on the spare wheel. Run through the gears, if the shifts are close enough you are golden. If they are off noticeably you will need to put a skinny spacer on one of the wheels behind the cassette, or play with the hub spacers so the the cassette cogs line up the same on both wheels.

If you can get both wheels lined up the same, get a couple of cassettes and a new chain and you should be fine.

Note: having 2 indentical rear wheels would go a long way to make this easier.

John

HillRider

Bill is correct. Your advice is misleading because you aren't using a 9-speed shifter with a real 8-speed cassette. You are using it with a truncated 9-speed cassette and that's why it shifts properly. The OP should ignore your claim that a 9-speed shifter will shift well on an 8-speed cassette. It won't.

dksix

Merlin has 9 speed cassettes from $14-$20 and 9 speed chains for about $11, they also offer free shipping somewhere around $65 (about $7 shipping on orders under the free ship minimum). I order from them somewhat often, shipping to me in TN is 5-8 business days.

https://www.merlincycles.com/cassett...sort=price-min
https://www.merlincycles.com/kmc-x9-...ain-44763.html

MarcusT

I've read numerous posts about 9 sp vs 8 sp and how they are not switchable. Well, I had an 8 sp cassette laying around and decided to do the same thing for an extra wheel.....and it works fine, no problems, do not even need adjusting. Deore set up from around the same time period. Maybe I got lucky, maybe it will fail on a miserable uphill, but for now it works

dabac

9 and 8 will both physically fit on the same f/h body.
8-speed overall width is 35.4 mm, 9-speed is 36.5 mm. This will usually be within the range of the locknut reach.
So from an assembly POV, it'll work.


As for shifting, yes/no/maybe.

Personal opinion on what's good enough, degree of wear and tune, riding style etc pretty much makes a single defined answer impossible.
And the more speeds you have, the closer the spacing becomes.

curttard

Well, this is hugely irritating -- I just looked and all 3 of my spare wheels are fronts. Damn it! I don't know why I would have gotten rid of the rears but that's what seems to have happened.

Tire changing for me!

Thanks for all the responses.

dabac

Personal opinion on what's good enough, degree of wear and tune, riding style etc pretty much makes a single defined answer impossible.
And the more speeds you have, the closer the spacing becomes.


Reports about "half" upgrades and rideable mismatches have been around since 7-8 speed mixes became possible.


So I'm not surprised about someone finding 8-9 speed mixes rideable.


Never heard anyone claiming to successfully have mixed 6-7 speed though.





I really don't think you do.


A regular 8-speed cassette won't be possible to fasten on a 7-speed f/h body.
Total width of a 7-speed cassette is 31.9 mm, and an 8-speed is 35.4 mm.
The length of the bodies are matched accordingly.
Generally, the locknut simply won't engage the f/h threads.
It's not long enough to cope with a 3.5 mm gap.


If, by chance, you manage to ge the locknut to take thread, both thread and spline engagement of the smallest sprocket will be marginal.


I'd be surprised over the parts going together, and even more surprised if it held up for riding.


There are some workarounds, 8-of-9 will fit on a 7-speed body. Some cassettes can be pulled apart and the inner sprocket dished to overhang the body flange.


Either your identification of parts are wrong, or you've got some seriously unusual hardware.
Maybe a locknut made extra long.
Or some weird intermediate f/h body design.
But your combo can't be assembled from regular, stock parts.

Camilo

Nah. Two wheels with 9 speed cassettes will most likely swap easily and quickly. Not complicated at all. He rides enough to justify different tires.