[Closed] Another roadie question: what 10-speed cassette ratio to go for??

depends on what your going to be riding ... if its generally flatter stuff and gentle hills, then the smaller cogs may be better ( 11-21 ). this would also have a benefit of closer ratio gaps between gears, so you can jump between gears to get that optimal cadence (if your into that sort of thing ... I aint )

if youre needing a higher gearing cause its more hilly, then the larger one may be better ... in terms of chainset, its the length of the rear mech arm that decides how wide a ratio you can go for ( doubles have short arms, triples have long arms to take up the wider range of chain length )

I couln'ttell you off the top of my head what would fit ... there are plenty of forum threads via google which will have already discussed the merits of them all.

how strong and where do you ride. With a 53 on the front don't bother with anything starting with an 11, it is pointless, best guess would be 12-25/12-27, try it and see is the answer though

11/23 Is fine for most things 11/25 or 11/27 if its hilly
But it depends on your legs.

I live where you live and therefore would assume to ride in similar places ❓ - I run a 53-39 with a 12-25 (9spd) rear mech.
Only times I've felt overgeared is riding a couple of hills in Peaks/ Yorkshire which isn't very often.
To be honest, 90% of the time I only ever use the 53 and 3 of the cassette gears as it's so flat round here.
Being overgeared will do one of two things - make you fitter, or break your legs.
(wouldn't consider myself in any way an expert though - I ride the road bike more than any other of my bikes, but I'm not a roadie 8) )

On a double, I'd go with a 12T.

I have a 12-26 with a 53-39 on my Trek and whilst normally Ok for shortish rides,it was woefully inadequate on the 60 mile Chilterns sportive I did last week where there were long 20% gradients to climb.

I`d go for the 12-27 at least ,if unless you are a superemely fit,race whippet. 😀

Definitley going for a compact chainset next time!

Depends on you, but 53/39 with 12-25 is a common choice. I run that but always keep the 25 in reserve or screwed out so it can't be used.
Deffo okay for anywhere south of the big hills i.e Chilterns and down.

That said I'll be wussing out next year and going compact with a smaller tighter block, you won't even notice the hills then.

cool, thanks for the tips guys, appreciated. I'll give a Dura-ace 12-27 a go - doing OK through Merlin, 25% off RRP to start with, then another 10% off for VIP, 10% off in their Shimano sale and a further 5% cashback through Quidco = £130 delivered next day including a Dura-ace chain, bargain 🙂