Gearing down a compact chainset

[gaw1962]

I have a 50/34 chainset and want to lower my gears. Is changing to 46/30 chainrings a sensible option? I think this will avoid having to change the cassette and rear mech.
I think I can get 46 outer/30 inner for a double from Spa cycles. Could I go lower? 44/28 or perhaps 44/26, and if so where would I get the chainrings?
The bike is a Trek Lexa with a Shimano 12-28 cassette.

[Valbrona]

The smallest inner ring you can fit on a compact 110 BCD double crankset is what you have now - 34t.

If you want smaller chainrings on a double that would mean fitting an MTB crankset,and that might not work because of altered chainline. You also have the choice of fitting a triple, but then you would need a minimum of a new LH shifter.

[freeflow]

It might be simpler to change your cassette and possibly your rear mech. Have a play on Sheldon Browns gear calculator too see what gives you the best bang for your buck.

[mattsccm]

I am going to take a guess and assume that you have a through axle BB. You may be able to fit a MTB double chainset. I bet you will need to play with the little spacers as you will probably be swapping from a 68mm width BB to a 73mm one but that's no big deal. Modern 10 speed doubles are often 28/42 chainrings. I use such a set up on my cyclocross bike that is really my road bike. With a 12 t smallest sprocket its fine apart from long gentle down hills where I spin out at about 30mph. No problems with that. Swapping the outer ring for somethinga touch larger would be easy but you may come up against the range of the front mech being an issue.

[ANTONISH]

The old Stronglight 80 would allow a 28 small ring. I don't know if they are still available (or even if you would want one).

[Tiberius]

I have just been through all of this with a Specialized Sirrus Comp.......

I trawled the forums, hummed and hahhed, faffed with thoughts of medium V long cage mechs....I did my own head in !!!...

Eventually.....11/32 cassette, Deore MTB mech, new chain.....Didn't cost that much, was easy to do, AND works perfectly....

I SUSPECT that you will eventually come to the same (ish) conclusion.....Good Luck !!.....

[Keezx]

I think I can get 46 outer/30 inner for a double from Spa cycles. Could I go lower? 44/28 or perhaps 44/26, and if so where would I get the chainrings?
.

Buy the touring triple from Spa and you can fit a 44 on the inside and a 24 to 30 inner ring.
Outer ring isn't necessary.

[Brucey]

I have a 50/34 chainset and want to lower my gears. Could I go lower? ........The bike is a Trek Lexa with a Shimano 12-28 cassette.

You don't say which Lexa model you have but IIRC some versions are fitted with 8s Claris gears.

If you don't have one already, you can buy a larger capacity Claris RD-2400-GS rear mech (for as little as £12) and this will allow you to run a larger rear sprocket down to 32T. Sprockets (cassettes) and chains are consumables; you may find that they get worn (to the point of needing replacement, ideally) in as little as 2000 miles.

If you have a different Lexa model it could have sora, tiagra or 105 equipment, but the same logic applies; it isn't difficult or expensive to fit a new cassette + chain, and a rear mech if needs be too.

If (say) a 32T (or perhaps 36T) rear sprocket gives a low enough gear, then that is what I'd suggest you do. The advantage to a different chainset would be that you can perhaps (if you fit a 24T inner chainring) eventually go to an even lower gear if needs be.

cheers

[pwa]

I had a similar problem with a bike my wife has and got what I needed from Spa Cycles. I bought a pair of "triple" cranks (a bargain at about £20) and a compatible Shimano bottom bracket. I only wanted 2 chainrings, so I bought a black "chain guard" to put where the outer ring would usually go, then put a 40 and a 28 on. Because the difference between 40 and 28 was the same as the difference between the original 46/34, just sliding the existing mech down to the right height got everything working nicely. 46 is a big enough ring to allow for reasonable speed, and do we really care if we have to freewheel on fast descents? If you decide to go down this route but don't know exactly what you want, I suggest you pick up the phone and call Spa. Try to pick one of their less busy days.

[gaw1962]

Thanks all! I think I'll go for a cassette change to up to 34, with a long cage mech. If lower needed I'll look at the other options.
Graham