Your CX ratios

[composite]

So I recently bought a Kite rolling chassis from Ian. I'm trying to decide how to build up the drive chain. It's the "chain set/do I buy a double or triple shifter" that I'm not really sure where to go with. Now bare with me a bit on this, I will try to keep it under control but the ramble may get to BB200 rambling proportions.

I want to use this bike for a number of things:
Commuting, road rides, off road rides - gravel/fire roads and more than likely a mixture of the 2. The bike may be packed up with full bikepacking gear... it may not. dare I say it I might even do a bit of CX racing but I don't really want that to influence the build.

I'm going to go 9 speed to keep cost down; initial out lay and maintenance.
Going to go for 9 speed Sora STIs for brakes/shifting. Will go with a mtb cassette (11-34ish) with XT rear mech.

So initially I will be putting on a Tiagra crank with something like 38-50ish. I'm getting this for nothing from my Dad as he has it laying around.

So I think that will give me a huge range of gears suitable for all purposes. 38-34 would be low enough for off road shouldn't it?

I had thought though eventually I might put something like the FC-M590 Deore 9-Speed 48/36/26T Triple, just to make sure I have the sort of range I'm used to with the MTB. Of course I could ride it for a bit and see how I get on with the 38-50 but I need to decide if I'm going to get a double or triple shifter. Currently all my doubles on my MTB are actually triple shifters/converted triple cranks so I could just get the triple shifter and use it as a double right?

What sort or ratios are people running on their CX bikes any way?

[Dan_K]

50/34, 11-32. Has been fine for most things...

[composite]

The other thing I could do is buy this group set from Ribble. http://www.ribblecycles.co.uk/gsd/road- ... SHR&bike=1

Go with the 34-50 double front, sell the rear mech and cassette.

EDIT: I guess if the Tiagra crank from my dad is going OK then I could sell the sora crank as well maybe.

[Bearbonesnorm]

I had a 50/34 ... can't recall I ever used the big ring. Swapped it for a 26/36 and the bike is much more user friendly. It can get a bit spinny on road but I don't use 'em much.

[atk]

I went for a similar "do-all" gearing when I wore out my last groupset. I'm running 42/32 paired with 13-26 or 11-28 (8speed). The small tooth difference at the front means nice smooth shifting and has been great for a mix of audax and some cross-style riding in the Peaks and Pennines as well as everyday use. It has a similar range to a compact-double (50/34 11-32) but without as much top-end, I'd rather coast down hills and have better shifting and smaller gaps in the cassette.

[ianfitz]

29/42 FSA chain rings and 11-34 10 speed cassette.

sometimes miss the high gears on road but very rarely.

[Mike]

Neil I'm running a MTB cassette 11-32 n a triple MTB up front on my cross check but changed the big ring to a 48 as I like using it on the rd with slicks also so I'm not spinning out.
On stu's advise I went for bar end shifters over my stu gears. They work really well off road as u can go straight through the gearing with ease n speed! I find the MTB gearing works well especially if u wanna use it in wales. I love mine and will do more bikepacking trips on it next yr.

[ScotRoutes]

XT cassette and road triple on my Amazon

[Ben98]

My current CX ratios are 50-34 with an 11-32 cassette, and that gets me up just about everything tbh
The plan is to get campag 10 speed shifters (much cheaper than any of the shimano ones) to use with a shimano 9 speed mtb rear mech (similar enough pull ratio with a certain cable routing) using the same ratios

[mountainbaker]

I use 34/50 compact chainset and 11-28 cassette, gets me up everything around here, but I have to get out of the saddle on the steeper stuff. I thought about going 11-32, but I'm too lazy to sort it out (and skint).

[Blah]

38 x 11-32 on the commuter cross bike, 38 x 11-34 on the cross racer here. Has been fine for everything from long days audax style on the commuter, to 3 peaks cx on the race bike.

[Pickers]

34/46 and 12-28 cassette here, just about low enough for me to wheeze my way up the local stuff. The bike came with a 34/50 compact chainset so I just swapped the outer ring down to make it more usable. It also came with an 11-32 cassette which was just too gappy for the mixed use I was putting it to so that went when it was worn out. I wanted something different to the MTBs I had, not trying to build another one.

[Zippy]

FYI, I run an 11-32 9 speed cassette on a long cage 10 speed shimano 105 rear mech on my cross bike commuter. I did the maths and it works (tis 1x9 though). You'll have to double check if that works with a double setup. 34T wouldn't have fitted.

[psling]

As others above, all I can really add is what I run. Used primarily for commute on road & fireroad plus touring on road I'm running 53 / 42 / 30 triple with 11-28 cassette. This gives a good range for hilly pootles and touring for my aging legs. When I used to ride a CX off road on singletrack and the like I ran 40 or 42 front with a 16 rear; made choosing levers a bit simpler

[Dainiusd]

Previous year done BB200 with 46-36 x 11-28 (was a bit too hard actually ) , this year enjoying 38 x 11-34

[slowupslowdown-under]

34 / 48 with a 11 - 28t

Fine for peaks riding with conditioned legs!!

[composite]

I'm beginning to think that 50-39 (had it confirmed from my dad) might be a bit hopeful. I guess it will get me going for now though. I'm leaning towards going for a double long term now though as most people don't seem to be running a granny and even on the mtb I don't use the granny a huge amount any more.

[jameso]

38-34 would be low enough for off road shouldn't it?

All very variable dep on how you pedal, fwiw I have a 38T single ring on my CX-packer and an 11-32 at the rear, with 710mm OD 40C tyres. I'll put an 11-34 on when I get a mo as the 32 is a bit low for a loaded hilly day even on some of the steeper roads here, but it's ok, would do. A 34 would get me up most if not anything that I can handle the bike on, for me if it gets tricky as well as steep a CX bike struggles where the MTB doesn't. 38-36 feels really low locally so would be ok for 'proper hills' I think.

For my road-going tourer I have a 34-48 with 12-28, that works well with a light load. 32-48 would be ideal I think. The 50T of a normal compact is just too high especially if you have bigger tyres effectively upping the gearing. I have 665-670mm OD 650B wheels that match a 700x23C, for comparison.

[mountainbaker]

I think it really depends what riding you're gonna be doing. I ride my bike on the road a lot, and do bits of offroad here and there. A lot of my riding is on shitty local lanes (basically off-road), but when I do hit a nice fast B road, I want to be able to get some real speed on the downhill. 34-50 works well, but like I said, could do with 11-32 instead of 12-28, just to have more range and make the big ring more useful on anything steeper than ~5%.

[Dan_K]

Same as mountainbaker - I use my CX bike as a winter road bike/cross bike/easy trails/tourer. 50/34 works for the road sections. It's pretty flat here but the 11-32 gives enough for the Surrey Hills.
It's rare that I'm flat out in the big ring but it's good having a similar ratio to my road bike.