Originally Posted by
Frankfast
My bike is not set up for the hills where I live. I built the bike with a 53/34 crank and a 11/23 cassette. I'm thinking of changing to a 50/39 compact crank or a 12/29 cassette or both. Obviously if one or the other does the trick it would be cheaper but am willing to change both if necessary. Any opinions?
Assuming you've got a 53/39 and are thinking of a 50/34, that would certainly give you lower gearing.
Swapping out your cassette would also give you lower gearing and assuming your RD could cope with the wider range would be quicker and easier - you'd need a few extra chainlinks (or maybe just get a new chain and not faff around with it). If your RD can cope with it you could go to something like 11-32 or 11-34 - you'll get some much lower gearing but the price you'll pay is bigger steps between gears.
If you need much lower gearing you could go all-out and put MTB gearing on it - maybe a 42/27 or 36/24 at the front paired with 11-34 at the back. Going from a 39/23 granny gear to 24/34 would make a huge difference, although you'd trade your 53-12 top gear for 36-11 which would mean you'd have to really thrash the pedals to get up to speed.
You can get an idea of the relative gains by simply dividing the chainring size by the sprocket size.
At present your granny gear is 39/23 = 1.696
A 50/34 would give you a low of 34/23 = 1.478
A 12-29 cassette would give you 39/29 = 1.345
Replacing both would give you 34/29 = 1.172
The silly MTB extreme would give 24/34 = 0.706
The lower the number, the easier it will be to pedal if everything else is equal.