I have a Specialized Allez with a 12-27, I think, 9 speed cassette on the rear, with a compact double up front, 50/34. The LBS reckons I will shortly need to change the cassette and chain so for once am planning ahead. I don’t know whether to just stick with 9 speed and get a new cassette and chain possibly upgrading to Ultegra (?) from Sora or whether it is worth looking at 10 speed? My worry about that is if doing so would mean having to change the RD which is Tiagra as well as the shifter and chain which I need to renew anyway, then it starts looking expensive. Would my existing Sora shifter work OK with an upgraded 9 speed cassette? I am tempted to upgrade but am put off by the cost. Second hand kit might alleviate that though.

As you say if you go 10 speed ,you need shifters,mech,cassette and chain so it will be costly.

Ultrgra or even 105 cassette might shed 50g or so.No reason you can`t use either with your Sora kit assuming you go for 9 speed.

just buy a new 9 spd shimano cassette and a chain, if you buy a new bike or break a shifter then maybe look at 10spd/11spd.

I’ve been thinking about upgrading my cross bike from 9 speed Sora/Tiagra/105 mix to 10 speed, and i reckon the most economical way to do it is to just buy a new Tiagra 10 speed group set, you can pick it up for about £300. 10 speed STI’s would probably cost you close to £100 alone.

you could get a 9spd Ultegra cassette and KMC X9 chain (£43+12ish)

or, like you say, 10spd STI + cassette + chain

Your rear mech will be fine with either setup.

All depends on how much you want to throw at it, and no one can tell you the answer to that one.

Personally I run my commuter 9spd and my best bike 10, but that’s just a historical accident more than anything else.

if you get on with your sora shifters then what mrmo said

Your rear mech will be fine with either setup.

Correct.

Yep, rootes and reggie are right, 9/10 speed road stuff is interchangeable, only on MTB 10 speed stuff they changed the cable pull ratio.

Thanks guys. The wallet is saying stick with the 9 speed but the heart says upgrade. I think the wallet will win in the end.

9speed is fine and it is cheap as it is ‘defunct’ 😆

Personally I would stick with 9 speed as there are other implications that will make it expensive.

Have a look at upgrading to a 9 speed ultegra casette but I don’t think there is much in it. My cross bike runs tiagra as it is virtually the same weight. Get a decent chain.

Weightweenies may help you get weight information.

As said above, the cheapest way to do it may be to buy a whole groupset that is 10speed but as then you’d also get the latest and better shifters.

Save your money, 10speed won’t revolutionize your riding.