Shifting to nine-speed

rflynnr

The chain on my commuter/tourer is knackered and I was about to buy a replacement chain and 8-speed cassette when I recalled Sheldon's advice that Shimano 8- and 9-speed cassettes are interchangeable. I've priced a 9-speed Tiagra chain, cassette and shifters and can live with the expense (approx €100). My question is this, however: do I also absolutely have to change the front derailleur (also Shimano Tiagra) which bears a sticker describing itself as an 8-speed ? If so I'll probably replace the chain-rings as well but would like any advice on whether I could survive with the existing front derailleur/chain-ring setup for a couple of months.

(BTW - I know that for "a few hundred" more I could probably buy an entirely new bike but I've just lashed out on a cargobike and the limits of my purchasing power have already been well and truly breached.)

Muller_1

You should be fine keeping the existing front mech and chainset. I'm currently riding 9 speed cassette with 7 speed shifters and old chainset from 7 speed tiagra on my commuter. Only have use of 7 cogs on the back but works fine.

rflynnr

Hmmm: thing is, I'm planning to use all 9 speeds at the back and I'm wondering whether the 8 speed front derailleur provides sufficient tolerance for that range of shifting both across the three rings as a group and for rear-cassette shifts on individual front rings.

seamus

Front mech shouldn't make a difference with a switch from 8 to 9-speed. The width of the cassette is identical. You also won't need new chainrings, or a new rear mech, if your current one is a long cage. All you really need is a new shifter (though they might come in pairs), a new chain and a new cassette.

You shouldn't really be using the full range of gearing, to be fair. You should as much as you can, try to keep you chain in a straight line to minimise wear. So for the small front ring, you should try to limit yourself to the largest 5 rear cogs, for the middle ring, try to stick within cogs 2 - 8 at the back, and on the largest ring you should stick with cogs 4-9 at the back.

Having large crossings (such as big ring -> big cog or small ring -> small cog) will increase wear on your chain.

xz

I switched from 8 - 9 speed recently, chain ,cassette and most importantly to use ALL the gears, I changed the shifters too. To compensate for the cost of this, I trawled E-bay, adverts.ie etc until I got the shifters second hand, and while I was at it, I got a barely used 105 hollowtech chainset for €50.

The front derailleur did not need to be changed

Wez

Yeh, I'd say the front derailer will be fine, only thing I'd see as a hurdle would be the shifters.

I've read about the compatability of the 8-9 speed cassette's but if you can use an old analogue shifter where you increase tension on the derailer (to change gear) progresivley (e.g. off an old racer) then you shouldn't have any problems selecting gears. Seeing as alot of new racers click into gear (and I'm guessing you have one), you more than likely wanna keep it original, and not have seperate shifters..

Just thought I'd mention it as a budget idea. Anyone know if this would work?

And I'd definitely second the Ebay idea, look around and you'll be able to cheap find parts no problem!

blorg

Wez wrote: »

Just thought I'd mention it as a budget idea. Anyone know if this would work?

I think friction will work with any speed as long as it covers the whole range of the derailleur.