8 & 9 speed compatibility

pliptrot

I have XT 8-speed on the bike, and need a new rear mech. I've been offered an XTR (9 speed) rear mech and am wondering if it is compatible with an 8-speed cassette and shifters. I'd like to upgrade the entire groupset, bit-by-bit, and hopefully before everything goes 10-speed (rumours about which are circulating). Which, IMHO, is insanity (although the road set have no problems with changing cassettes and chains more frequently than tyres).

Andy B

a 9spd mech will work on an 8spd set up.

nicklouse

also not chains are either 8 or 9 spd.

ride_whenever

not really possible, you can sort of go 9->8 bit by bit, but not the other way.

Won't go 10 speed because it isn't really mud-proof enough.

supersonic

It can be quite complicated, but I'll have a bash at all the combos:

- Shifters MUST match the cassette for speeds
- Chain MUST match the cassette for 9spd, but 9sp chain is acceptable on 8spd cassettes
- 8 and 9spd chains work on 9spd cranks. However 9spd chains do not like a genuine 8spd crank (many 8spd bikes you see today actually have 9spd chainrings and often a 9spd mech!)
- 9 spd rear mechs have slightly thinner jockey wheels, however they work fine on 8spd
- 8spd rear mechs work on 9spd (as my Zaskar)
- 9 spd front mechs are slightly narrower. However they do work fine on either: just a little more tinkering maybe required.
- SRAM numbered shifters ONLY work on SRAM numbered rear mechs
- SRAM named shifters work with Shimano rear mechs
- 7 and 8 speed chains are the same

Now, I have bound to have c0cked that up somewhere, and its not set in stone. Some quirly combos out there!

Mettan

supersonic wrote:

It can be quite complicated, but I'll have a bash at all the combos:

- Shifters MUST match the cassette for speeds
- Chain MUST match the cassette for 9spd, but 9sp chain is acceptable on 8spd cassettes
- 8 and 9spd chains work on 9spd cranks. However 9spd chains do not like a genuine 8spd crank (many 8spd bikes you see today actually have 9spd chainrings and often a 9spd mech!)
- 9 spd rear mechs have slightly thinner jockey wheels, however they work fine on 8spd
- 8spd rear mechs work on 9spd (as my Zaskar)
- 9 spd front mechs are slightly narrower. However they do work fine on either: just a little more tinkering maybe required.
- SRAM numbered shifters ONLY work on SRAM numbered rear mechs
- SRAM named shifters work with Shimano rear mechs
- 7 and 8 speed chains are the same

Now, I have bound to have c0cked that up somewhere, and its not set in stone. Some quirly combos out there!

Hi Supersonic - any help would be appreciated - I've currently got an 8 speed Road bike with 8 speed Shimano shifters, 8 speed crankset, 8 speed KMC chain and 8 speed Shimano cassette - now, I've ordered a 9 speed Tiagra 50/34 Hollowtech 2 crankset (need Compact for hills/Sportives) - what I'm wondering is, I'll need to order a 9 speed chain to go with the 9 speed HT 2 cranset, but will the 9 speed chain work with my current 8 speed Shimano cassette ???? - I'm very unsure about this - the alternative would be to get a 9 speed cassette aswell to make sure everything maries up "ideally" - so I'm just unsure about what works and what would be the ideal situation. Can I just stick with the 9 speed chain on the 8 speed cassette or should I idealy go for a 9 speed cassette aswell?

Thanks - any clarification/advice appreciated.

nicklouse

use the same chain as matches the cassette.

supersonic

As Nick says, best to match the chain and cassette, though it can work in some circumstances. A new chain should always be used with new cranks, unless the chain is very new, or it will wear the soft alu rings quickly. 8spd chains have absolutely no probs on 9spd chainrings.

Mettan

supersonic wrote:

8spd chains have absolutely no probs on 9spd chainrings.

Thanks guys - just to pick up on this last point - so basically I can keep my current 8 speed KMC chain and put it onto a 9 speed HT 2 chainset/chainrings ?? if thats the case I might buy a new 8 speed chain to go onto the new 9 speed HT 2 chainset/chainrings just to keep any "wear" issues down to a minimum. I'm quite happy with my current 8 speed casette so this might be a bettwer way of doing it that getting a 9 speed chain and 9 speed cassette.

supersonic

If its not too old - less than 100 miles ideally. Otherwise it will kill your chainrings.

Mettan

Thanks mate - so basically, ideally I could go for a New 8 speed chain to go with my existing 8 speed cassette - and both of those will marry up with my new 9 speed crankset ??? - does that ok ? I'm just trying to get the detail sorted before ordering the chain.

nicklouse

correct.

supersonic

Should work! Just may need to tweak the front mech more than normal, or get slight rubbing in extreme combos.

Mettan

Thanks guys - the scenario behind all this is that I've got a Sportive coming up soon and haven't been able to find a decent 8 speed Roadie 50/34 Compact crankset (I've currently got a 53/39 Double) - I've therefor had to order a 9 speed one (the HollowTech 2 Tiagra 4550) to fit to my current 8 speed Road bike - bit messy, so have just been trying to fill in the rest of the blanks, as it were.

Thanks for the help though, I'll get it sorted now 8)

Mettan

Actually, after a bit of reflection I'm thinking of going completely 9 speed just to keep everything straightforward - I've already got the 9 speed HT 2 4550 chainset (arrived this morning), and am thinking of getting a 9 speed cassette and 9 speed chain.

Has anyone used the Shimano Deore 9 Speed HG50 cassette (11-32) ?? - I'm thinking of pairing it with a KMC X9L chain - so, am just wondering, has anyone used either of these - are they pretty solid/reliable etc ??

(This is all for hilly Sportives etc on my Roadie this year)

Thanks

supersonic

Yes, I have this deore cassette. Heavty, but hard wearing. I'd spend the extra on an XT.

Mettan

Thanks SS - I've currently got a KMC 8 speed Z series chain on a Shimano HG40 cassette - been a reliable workhorse - thinking about chains though, would you have any preference or reccomendation on whether to go for an SRAM chain or KMC one to match up with the HG50 Deore 9 speed cassette?? I'like the idea of the Powerlink/Missing link thing so it's going to be either SRAM or KMC matched to the Shimano block.

supersonic

I use a SRAM PC971 - seems very good for the money!