changing chainsets

Is it really worth replacing the whole crankset to get 53T? I'd suggest only if your bike rides are downhill in both directions.

Note that if your rear cassette has a 12T as smallest cog, then changing it to a 11T gets you a larger gear with a 52T front, than a 53T would with the 12T. I.e. 53/12 is *less* than 52/11.

I got a Sram force double crankset for £78 on eBay , is your compact worn out?

Or if you want to Pardy go and get some Q rings...

Or just go for a 52 big ring for virtually no difference.

You will also need to move your front derailleur up to accommodate the extra height of the chain rings.

Don't forget to think about chain length. Going from a compact to a double, you might not have enough slack in the chain so a new one might be required.

It's fairly straight-forward. 5 minute job once you have the right tools.

a) Purchase new chain-rings - make sure they are the right "Bolt Circle Diameter" (BCD) for your crankset's spider. If you have a 50/34, your crankset almost certainly is the "compact" 110mm BCD (as opposed to the 130mm "double" standard).

b) Purchase spare chain-bolt rings. You always seem to break at least one when you change rings. I'd recommend steel, the aly are just to soft & fragile.

c) You need a good length ratcheting socket wrench, with the right size allen bolt head. You need either a flat screw-driver, or another allen wrench, to hold the other side of the chain-ring-bolt.

Process is easy, unscrew the bolts, slide the chain-rings off over the crank, slide on the new ones, torque up the chain-ring-bolts :). Then you need to adjust the height of your front dérailleur - loosen the actuating wire, loosen the FD clamp bolt, raise the FD, tighten the clamp & wire, adjust FD as needed.

Note, you might not find 110mm 53/39 rings - those tend to available only for 130mm BCD. But you can get 52/38 and maybe 36.