single speed ratio for gravel/CX?

anyone running their CX bike or gravel bike SS? if so what’s a good starting ratio for short steep off road interspersed with tarmac sections as the terrain is by me?
bike is a steel 26er with 29x42mm rim/tyre combo.
used to run 34×19 on my SS 29er mtb which was just about bearable on road with not too much spinnyness but obvs less rolling resistance on a narrower less aggressive tread tyre will change this.
so, any advice?

I can confirm that 39×20 for the Dirty Reiver is hard work! 😧 This was last year. Wasn’t too bad for the first 140km or so but was getting tired going up over the Forest Drive to FP3.

I find it’s not so much steepness, though I do avoid roads with double chevrons on the map, but sustained climbs that are the problem as you don’t have chance to recover.

34×19 or 34×20 sounds like a good starting point. Just looking at what some of the SSers who ride things like the HT550 and BB200/300 use and 32×20 or 34×20 seems to be the rough ballpark.

42:16 off and on road works for me, but I have 35mm tyres and my neighbourhood isn’t steep at all. I would go for something around 2,5 ratio as a starting point.

36:18 when I had my Koga with 2.1 29er rubber was good.
48:16 on my IRO steel sscx great for couple of hour blasts and short steep stuff (evil on long drags)
32:20 on my 29+ dropbar monster at the dirty reiver this year, have used 34:20 and 32:18 the past couple of years there. As whitestone says its the long 6-9% climbs that are a knobend as there is nowhere to recover.

as with all singlespeed ratio choices its a always a compromise somewhere and very much down to you personally, do you prefer to hold a high cadence and spin to win, or are you happier churning a bigger gear inch at a slow rpm

I used to run 34/17 for racing CX, but I like to spin

I’ve got 45×19 on my Pompino, fixed though. It gives a nice cruising cadence at around 26-28 km/h with the 32 mm tyres that it currently has. I do have a 22-teeth freewheel for the times I’m going to be mostly riding in the woods with, and I’m okay with spinning it on the roads in between too.

It’ obviously heavily dependent on fitness, of which I severely lack, but if any steep ups are involved, I’d definitely be starting closer to a ratio of 2 than 2,5.

I run 34×17 at present – low enough to cope with 6hr+ rides in the Surrey Hills and South Downs – bit under-geared for the roads. I rode 36×20 for the Southdowns Way and cleaned every climb, including the scrabbly stuff after Amberley.

My SSCX (700c) is 39/18. By chance because that was the spare second hand chainring the bike shop had lying around at the time. I find it a little stiff on steeper climbs with difficult traction, but broadly very rideable.

I also have a SS hardtail (26″) with 32/16, which works well for me in almost all situations.

38 X 18

2:1 on 26″ for my SS mtb. I’d proibably o 2:1 on 700C or possibly 2.25. On road I ride 2.75:1 or even 3:1 when proper race fit, which is a nice gear for 20 mph cruising, but to big for gravel.

42:16 is standard fayre for road SS off the peg bikes. I think you will struggle with that off road cor CX/gravel – hence 2-2.25:1 woul dbe a better choice.

38×17 was a good compromise for riding in and around Bristol. I originally ran a 38×19 but it was too low on the roads. I was running 700×35 tyres. I would gear it down for super hilly rides, may try a 18t sprocket when I get my SS rebuilt.

If anyone happens to have a Sram right hand hydralic brake/shifter Force or Rival they don’t need then let me know! Shifter mechanism can be knackered as I won’t be using it.

43 x 18 for me but I ride fixed rather than single speed so any lower becomes a spinning chore of slowness on fast flat sections but wouldn’t want it any higher for the gravel hills. I also have to consider skid patches which is why 43 ring is great.
Probably best for people to give gearing in inches as difficult to compare all the different fronts/rear combos added to different tyre sizes.

63 inches

38×20 here,700cc 35c.

Could probably do with being a bit bigger on my commute. Plenty of off road slow speed sections.

🙂 as expected a massive range of options, cheers everyone. better experiment

I’m running 42/19 with 2.0″ tyres on my 29er Scandal – which gives a 64″ gear.

That’s a bit high for me on the lumpy offroad bits, but barely enough for the road for a decent cruising speed.

Trial and error required I guess. If climbs are often steep, you’re off road and you’re not some kind of monster then I’d be starting at only a shade longer than 2:1 on 26″ wheels, but that would be very slow for what most call a “gravel” bike. I have towards both ends of the range with 33:16 on a 26″ mtb (which is ok in hilly devon and I’m not very fit) and 42:18 on a 700×38 gravel bike in flat country (anything I’d call a “climb” on that would kill me but it’s a good balance between feeling just right off-road and maintaining a reasonable road speed).

IME road plus steep off-road is something you’ll never find a good gear for.

I used to run 36×16 (61″) on my Cross Check, which was ok… just about bearable on the road, but only just, and usable for a lot of off-road; but it did count me out of some of the steeper off-road climbs near me and after a while I decided to put gears on.

For context I use about 70″ on a road bike and about 52″ on an MTB, and they’re fine. If it was a case of “ride out on the road, ride off-road, ride back on the road” I’d use a cassette hub and dinglespeed it, but for completely mixed rides I’d probably be thinking about a hub gear.

I have a Singular Peregrine with 45c tyres, i ride 38/16 when loaded with bikepacking bags or 40/16 rest of the time, we only have short sharpish climbs where i am, 40/16 means that i can still spin at 18-19mph on the road but still good off road unless there is a drag of a climb.

32-14 (29×2.1 tyres ) was my gear for SSUK, surprisingly not shit up the hills, I wasn’t pushing any more pushing than anyone else and it was a good gear for the 100mile ride there from reading!

My commuter now has the same gear except it’s 42-18 iirc with 700×38.

So about a 65-66″ gear.

That’s about right on the flat for me when I’m in a bit of hurry, and just about manageable up moderately steep hills which suits my commute (the standard 52″ gear adds about 20minutes!). I’m thinking of dropping to a 39t chainring to give more options, I.e. 39-16/17/18/19 depending on fitness.