Cross gearing semi-dilemma

[Wayne77]

Through a trade here I've managed to procure some parts to re-outfit my cross bike. Since it was a trade for a full group I wasn't too picky. Currently in my hands I have a 130 BCD SRAM Red crank with 40/38 rings & 11-28 cassette. I'm coming from a 110 BCD crank with a 34t inner ring that used to be on my x-bike...for cross that 34t ring isn't really needed, but I do take this bike on the single track from time to time where I appreciate the 34t small ring for the steeper climbs.

So I can either trade my 130 bcd crank for a compact crank, or maybe just buy one of those WiFli derailuers and stick a 32 tooth cassette on the rear. Looks like a 38 ring x 32 cassette is about the same gearing as a 34x28. Swapping out the rear der is probably less hassle than swapping out the crank... Any downsides to running a 42/38 up front with a 12-32 rear cassette? Or would it just be better to swap out the crank for a Compact and then buy some cross rings (maybe something like a 34/42)?

I haven't ridden a 42/38 crank before so not sure how well that tight of spacing up front shifts in the first place...

Or maybe I just gut it out and live with a 38 ring x 28 cassette lowest gear...

[Pastashop]

...I say, if the Q factor suits you, don't mess with it and just get a larger cog for the back (and derailer) – in my limited experience, it's easier to dial in the shifting in the back with new cogs and rd than in the front with a new crank and chainwheels, particularly if you're using smaller rings than before. (The curvature of the front derailer doesn't work as well anymore with smaller diameter rings, so you have to futz to get the height just right, or replace the fd...)

oh, and academically speaking, the pedaling load will be distributed over more teeth, so cogset and chainwheels may last longer. unless GAS (gear acquisition syndrome) strikes sooner. (guilty as charged!)

[sparky33]

Try the 12-32 with the derailleur you have. Turn the B screw in a bunch to clear the large cogs. This often works if you have a small chainring differential since the chain wrap demand is low.

Wifli units are mostly about wrapping up more chain for wide cassettes that are paired with normal (not cx) chainring combos. I think arm geometry is more forgiving too, but short cage units have surprising capacity in many cases.

[oldpotatoe]

Through a trade here I've managed to procure some parts to re-outfit my cross bike. Since it was a trade for a full group I wasn't too picky. Currently in my hands I have a 130 BCD SRAM Red crank with 40/38 rings & 11-28 cassette. I'm coming from a 110 BCD crank with a 34t inner ring that used to be on my x-bike...for cross that 34t ring isn't really needed, but I do take this bike on the single track from time to time where I appreciate the 34t small ring for the steeper climbs.

So I can either trade my 130 bcd crank for a compact crank, or maybe just buy one of those WiFli derailuers and stick a 32 tooth cassette on the rear. Looks like a 38 ring x 32 cassette is about the same gearing as a 34x28. Swapping out the rear der is probably less hassle than swapping out the crank... Any downsides to running a 42/38 up front with a 12-32 rear cassette? Or would it just be better to swap out the crank for a Compact and then buy some cross rings (maybe something like a 34/42)?

I haven't ridden a 42/38 crank before so not sure how well that tight of spacing up front shifts in the first place...

Or maybe I just gut it out and live with a 38 ring x 28 cassette lowest gear...

Biggest 'downside' is the lost gears, useful gears, in the middle of the cogset when you go up to a 32t in the rear.

[11.4]

I wouldn't think hardware but would focus on whether the gears work for you.

So many people get something like a 36-46 ring combo and frankly are overgeared in the 46. Stybar and Nys ride a 46. Most of us shouldn't. On the other end, with a typical spread-ratio cassette for cross, the bottom gears with a 34 are so low that you may not really be racing that effectively in them. So I often recommend a chainring combo like a 36-42 or 39-42. The advantages? First, it's an easy shift on the front -- less likely to throw a chain. Second, if your rear end clogs and isn't shifting smoothly, or if you just need to tweak a gear, this gives you a tweaking option. Third, close-ratio chainrings mean you can really tighten up your chain to reduce slap and also derailments. The ultimate argument for this is to go all the way to single-ring, but the extra ring gives you some protection and an ability to fine-tune your gear, which is something that all the people going single-ring are losing out on. A single ring can be OK if you are very consistent, but if you have better or worse days, you can choose the 40 or 42 (or swap the 40 out for a 38 or 39) to give you a gear you're really comfortable with. So many people try to race into a gear rather than gear properly for your race. You're on the way to gearing properly.

[Lewis Moon]

Through a trade here I've managed to procure some parts to re-outfit my cross bike. Since it was a trade for a full group I wasn't too picky. Currently in my hands I have a 130 BCD SRAM Red crank with 40/38 rings & 11-28 cassette. I'm coming from a 110 BCD crank with a 34t inner ring that used to be on my x-bike...for cross that 34t ring isn't really needed, but I do take this bike on the single track from time to time where I appreciate the 34t small ring for the steeper climbs.

So I can either trade my 130 bcd crank for a compact crank, or maybe just buy one of those WiFli derailuers and stick a 32 tooth cassette on the rear. Looks like a 38 ring x 32 cassette is about the same gearing as a 34x28. Swapping out the rear der is probably less hassle than swapping out the crank... Any downsides to running a 42/38 up front with a 12-32 rear cassette? Or would it just be better to swap out the crank for a Compact and then buy some cross rings (maybe something like a 34/42)?

I haven't ridden a 42/38 crank before so not sure how well that tight of spacing up front shifts in the first place...

Or maybe I just gut it out and live with a 38 ring x 28 cassette lowest gear...

These are the reasons I have a couple of sets of wheels and like to have cross compatibility between (most of) my bikes. One day I'll be hammering on the road and need a 48, the next I'll be riding 19% hills and want the 34, the next I'll be 'crossing and want a 46/36, the next SSCX and......
I like to be able to swap chainrings/cranks/wheels/cassettes among all my bikes.

[Wayne77]

Thanks guys - this is all very helpful information. For now I'll stick with the 42/38 up front w an 11-28 in the back. Maybe I'll keep an 11-32 handy for the random single track ride...

[Pastashop]

I wouldn't think hardware but would focus on whether the gears work for you.

So many people get something like a 36-46 ring combo and frankly are overgeared in the 46. Stybar and Nys ride a 46. Most of us shouldn't. On the other end, with a typical spread-ratio cassette for cross, the bottom gears with a 34 are so low that you may not really be racing that effectively in them. So I often recommend a chainring combo like a 36-42 or 39-42. The advantages? First, it's an easy shift on the front -- less likely to throw a chain. Second, if your rear end clogs and isn't shifting smoothly, or if you just need to tweak a gear, this gives you a tweaking option. Third, close-ratio chainrings mean you can really tighten up your chain to reduce slap and also derailments. The ultimate argument for this is to go all the way to single-ring, but the extra ring gives you some protection and an ability to fine-tune your gear, which is something that all the people going single-ring are losing out on. A single ring can be OK if you are very consistent, but if you have better or worse days, you can choose the 40 or 42 (or swap the 40 out for a 38 or 39) to give you a gear you're really comfortable with. So many people try to race into a gear rather than gear properly for your race. You're on the way to gearing properly.

That's really good advice!

[nooneline]

So many people get something like a 36-46 ring combo and frankly are overgeared in the 46. Stybar and Nys ride a 46. Most of us shouldn't.

Totally agree - with this and everything else. Stock bikes spec'ed with 46/36 are my pet peeve. 42/36 or 44/38-39 would work so much better for so many more people.

[BSUdude]

Totally agree - with this and everything else. Stock bikes spec'ed with 46/36 are my pet peeve. 42/36 or 44/38-39 would work so much better for so many more people.

Probably done that way because it works better for the majority of people that buy them but only do 1 or 2 CX races and spend the rest of the time on bike paths or winter training or "gravel grinding"...

IMO, a bike optimally setup for CX RACING won't work great for much else.

OEM specs on even high-end CX bikes are kind of a joke...until 1x11 is spec'd (which will probably only be on top tier bikes), you kinda need to change the gearing up front, as others have said. For the most part the stock wheels are laughable. But they work for beginners until you race enough to realize how bad some of the stuff is.