I’m converting a Trek Cronus CX bike to participate in my first ever season of gravel riding. The current drive train set up is Sram Force with 46/38 up front and 11-28 (10 speed) cassette, which I don’t feel will give me a wide enough range of gears. Would replacing the small chainring with a 34t and putting a 12-36 cassette in the rear give me more appropriate gearing? Doing local grinders around Central Texas and maybe a road trip to Steamboat Springs this summer. Just got a set of Hunt 4 Season Aero wheels w/ 38mm Gravel Kings (don’t think the fork will accommodate anything larger). Thanks
2 Likes
I would suggest, as a starting point, 46/36 up front with 11-32 in back. Check your rear derailleur to find out how large a cassette it can handle before you go larger. Gearing will also depend on fitness, and whether you really think you need that 1:1 (or lower) ratio. Personally my inclination would be a tighter rear cassette if you have a 2x up front for smaller jumps between gears. Also, great choice on the tires. Set them up tubeless, play with how low you can comfortably run the pressure, and enjoy that buttery smooth ride. 38mm is plenty. 
As an aside, hell yeah! Welcome to gravel! So many of these races and rides go astoundingly beautiful places, and the community is awesome. I hope you have a great season!
1 Like
46/38 is probably 130bcd, meaning 38t is the smallest you will fit on those cranks. Could be wrong but its pretty likely.
Totally depends on your fitness and climbs you want to do. I run 46/36 w 11-32 for gravel. Would probably go 46/34 if I could be bothered changing it
I’m a Campy guy, so I know zip about Sram (not really digging it on the CX bike to be honest). was looking at this, wondering if compatible
1 Like
If you’ll face hills of any consequence, I’d consider gearing that gets you at least 1:1 ratio.
3 Likes
No one ever says man I wish I didn’t have that gear to spin up that hill. I love my 32 on the rear and wish I had a 34 sometimes.
2 Likes
I have a 34T small ring and 11-40 cassette. I usually use the biggest cassette cog only when I’m trying to keep a training ride easy. If I was building a gravel bike up, I’d go with an 11-36 cassette, and probably 50-34. Course, the right gearing also depends on how strong a rider you are, and the kind of terrain you ride.
1 Like
You were one “p” away from making that brilliant… 
4 Likes
I’m a small guy (5’6, 120#). FTP was about 215 last summer, but is probably about half that now as I’m 5 weeks post extensive knee surgery. that was my concern about gearing - I think I’m going to be “sit and spin” til early summer. Thanks for the info!!
1 Like
It’s worth noting, that with 10 speed sram, you can directly swap out your rear derailleur with an mtb version, which are very cheap right now, and can allow for bigger cassettes. Like others have said, your fitness will guide the gearing, but I’ve found you want 1:1 for longer rides. Maybe go for a spin on your local gravel roads and see how it feels with what you have, and iterate from there.
1 Like
This is a good point, you might find its cheaper to get a new long cage rear clutch mech to go with say an 11-36* sram rear cassette that gives your more all round ability plus chain retention over the rough stuff*
*quick and dirty response, you’d need to check one the ability to handle the chain growth with that combo
I’m riding a different option that works for our gravel in the northern states that does have a fair bit of climbing. One by with a 38 up front and 11-46 cassette. The down side is top end speed for me is about 33 mph spun out on cadence. I’ve needed the 46 on a couple races including a climb at SBT GRVL. I’m betting on upgraded bike fitness this year via TR and hope to change the 38 to 40.
So for me one by is the way to go, less weight and one less thing to break.
Get a cassette with a larger range. I don’t know if you need to change your chainrings.
A 38t small ring should be pretty great unless you are over 200lbs and are going to be doing a very climb dependent event.
For my personal planning I like to use the following to get my expected speed after I do some reaserach on the course. (For instance I look up the significant climbs or very steep sections and figure out how fast I’ll be going.)
Then I take my speed estimation and use a gearing calculator to determine if I’ll be able to get by with that setup.
https://www.bikecalc.com/speed_at_cadence
It’s worked out pretty well. This does take the ‘what do you think’ out of the equation and lets you figure out really what cadence you should expect to be putting out on the hills.
I don’t know about Steamboat Springs but in TX your gearing may or may not be correct. If you’re going to be doing Tx Chainring Massacre or Tx Gravel Champs, your stock gearing is just fine. If you’re going to race up Kinder Mountain, Flatrock Mountain, Windmill Hill, Flyin’ J Hill, or anywhere in the hill country you’ll want a 1:1 gear.
1 Like
definitely some Hill Country events
so from CJ and Jonyboy’s suggestion, would this be suitable (long cage I would assume):
paired with:
Another vote here for having a 1:1 option. I ran 40/11-40 this weekend and when I needed the 40/40… I REALLY needed the 40/40.
1 Like
I live in NorCal and we have tons of climbs. I climb all the time and love it. I just purchased a gravel bike with the new GRX with a 48/31 in the front and 11-34 in the rear. Wow that is not enough gearing especially around here. Per GravelCyclist.com’s recommendation I just put an 11-40 cassette on and it feels sooo much better. The gearing feels looser, like there’s more room to breathe. Did a 20mile 4,000’ ride yesterday with dirt climbs over 20% and being able to spin a bit more than grind helped so much. I don’t subscribe to the idea that having bigger gearing makes you not as “cool”. Give me even more gearing so I can do more climbing!!
My Shimano rear derailleur technically is only spec’d for max a 34t cog but tighten the b tension screw allows the derailleur to shift smoothly and quietly into the 40t.
Did you mean to go for an 11-23??? Wrong link perhaps?
12-36t