mylo

HI all!.
I just picked up a used CX bike that I will be using for gravel and winter riding, it is all SRAM and is 2x10. It currently has a 52/36 and 11/26 on it, not ideal for gravel.

The crank/chainrings are 110bcd. I would like to go 48/32 or even 46/32, and 12/30 or 32 on the back.

I am looking to keep things as budget friendly as possible as its not a fancy bike and I don't want to sink a lot of money into it. The areas that I ride are very flat, very little climbing.

Can I get away with just swapping the rings and adjusting the front derailleur and throwing a new cassette on? I think the rear derailleur says it will accomodate 28t but I hear these can go higher.

Thanks!

Kapusta

When you say the RD will accommodate 28t are you talking about chain wrap capacity or max cog size?

HillRider

That 110mm bcd will accept a 33T chainring as the smallest and 34T rings are far more common. A 32 isn't possible.

For a rear derailleur with a listed 28T maximum cog you might get away with a 30T by tightening the "B-screw" a bit. A 32T cog isn't likely to work.

mylo

It says the max cog size is 28t so I guess I'll do that and maybe try a 30.
Can I keep my existing crank and just swap the rings and adjust the front derailleur?

HillRider

Did you read what I posted above? A 110 mm bcd crank cannot accept a 32T chainring. If you want a smaller small chainring you need a different crank. You could change that large ring for a 48 or 46 but you can't go usefully smaller for the inner chainring.

tyrion

I'd get a 46-30 crankset first (around $130 retail), and if that doesn't get you low enough then get an 11-30 or 11-32 cassette. I wouldn't get a cassette with 12t small cog - you're giving up 9% of your range for no good reason, IMO.

Moisture

You can make that work on gravel unless we're talking about steep climbing.

36/52 will work out great on gravel. Swap out the rear cassette for a 11/34 and you're good to go.

FWIW, my vintage road bike is 40/52t front and 14/34 rear. 2x5.

It may sound down on gears, but it's quite pleasing to have such a robust range of gears where you find yourself using each and every single one during every ride. I'd say its just enough of a ratio spread for gravel use.. at least for my needs.

In the future, if given the option I would go for 36/52 and 11/34.

I actually got a spare biopace crank laying around with 3 ratios (28/38/48) incidentally, i think this would work perfect for gravel.

mylo

I meant get a 33 or 34t chainring and leave the crank alone.

Russ Roth

Depends on the crank. 4 bolt asymmetric FSA cranks will fit a 32t though from experience it is a little hard to find, I bought mine from the UK; their omega and gossamer cranks use them and have been common on cross bikes for the last 6 or 7 years. 5 bolt you're correct though I've never seen a 33t outside of BMX, 34 is the effective minimum.

TGT1

52-36 is kinda odd for a CX bike. 46/36 is the normal CX setup.

I'm running a SRAM 2X10 medium cage with a 48/34 FSA front and a 34 -11 Shimano MTB cassette. You'll need to shorten the chain a few links for the correct wrap.

Works great, 1-1 bailout gear and good road speed coverage. Have it tuned so that only the large/large is noisy.

The 48's may be hard to find though. When I found them I bought all of them that were available on line (only 3), and that was a while back.

The 1-1 will get you as steep as CX geometry will allow on dirt fire roads without major traction loss. Any lower gearing would not gain anything.

HillRider

A 48T chainring with a 12T cog gives 108 gear-inch high and a 46x12 gives a 103 gear-inch high. Do you really need more than either for gravel riding?

What you gain from a 12T smallest cog is a more useful interior gear that the 11T cog displaces.

tyrion

If I never rode downhill on a paved road, it would be enough. But a lot of people use gravel bikes on paved roads.

Given 10 cogs going up to 32t, I'd much rather have the wider range than the tighter spacing. It's just personal preference.