Due to lack of space and money I’ve sold the bouncy bike (which I’ll miss very much) and gone the “one bike for everything” route with an entry level Urban/CX bike that comes with a decent Sora group (for now). I will be commuting and riding singletrack and long XC rides on this bike, and maybe enter the odd cyclocross race. I don’t care much for road riding.

I am not stripping down the bike and building it up with “nicer” components in a hurry. This is all just theoretical at this point until I see how I get on with the stock setup, but I’ve thought about the possibility of switching the drivetrain to 1x by using the following:

– Cheap 130 BCD chainset (like SRAM Apex?) converted to 1x with a RaceFace NW 42T.
– SRAM Apex 10 speed brifters with a SRAM X9/X0 med cage MTB rear mech.
– SRAM 11-36 MTB cassette
– 42T cassette expander (from Wolftooth or the hopefully soon to be released Superstar equivalent)

To me the above sounds like it should work fine (at least according to this), but I have a feeling that – as Murphy’s Law would have it – something won’t play nice with something else.

Before someone says SRAM CX1: I can’t afford it and I plan on hunting down second hand parts to build a cheaper alternative (if all that is technically feasible)

What am I missing?

Road shifter wont work with mtb rear mech.

It is my understanding that SRAM 10spd road shifters have the same cable actuation as SRAM 10spd mountain bike shifters, and thus could be paired with SRAM MTB mechs. See link in my post. My question is about the potential of adding the expander, really, as I can’t seem to find info on someone attempting this setup.

Hmmm… I was planning on Shimano10spdSTi and 9spd mtb rear… that link suggested the practise isn’t as good as the theory.

Oh, CX1 cranks with ring are cheap at Chain Reaction at the moment.

I’m running a Shimano 9 spd road shifter (tiagra) and 9 spd XT rear mech – works perfectly with a single 40t chainring.

Sram road shifters work fine with sram mtb rear megs, they have the same cable pull ratio.

It’s Shimano road and mtb 10 speed which aren’t compatible.

I don’t know how well sram mechs work with expander sprockets.

10spd 105sti is fine with 9spd rear mech.

I’ve got a Sora crank with stronglight dural 36/46 rings. The Sora crank is fine. I did have a full 3500 group less brakes until I got some bargain 5600 105. Still see no reason to swap crank.

Not sure about sram mountain mech with Road sti’s. If they are the same pull there’s no reason it shouldn’t work.

Wouldn’t you be better off with a 110 compact crank? Only other obvious pitfall I see is the crank-ring interface. Are the NW rings available 5 hole 110 or 130 bcd?

Kelvin – I’m using 10 speed Shimano road shifters with 9 speed mtb rear needs on two bikes and it works fine, plus have set up my mates to do the same thing.

For 1×10 though there isn’t a clutch so don’t know how they’d work in that scenario. I have heard of people taking the mech apart and increasing the cage spring tension. Don’t know if that’s doable on more modern mechs though.

Sram mountain mech and expander should be easier than shimano iirc…

http://raceface.com/components/rings/rings/single-ring-narrow-wide/

Seems to suggest that 5hole Road mount isn’t available.

I believe so long as you use a mountain bb not a road one you can fit mountain cranks on a 68/73 cx bb shell though? Just the road bb is spaced differently?

@vincienup I’ve been riding 1x for years on my mtb and love the simplicity. CRC has RF NW rings in 130BCD in 40T, 42T and 44T.

Another reason is that I would like to potentially use the LH shifter to actuate a dropper post.

Five-bolt RF NW 130BCD rings do exist.

As above, you won’t find a nw chainring in 130 or at least not easily. You’ll want a road compact which is 110bcd

10 speed sram road and mtb is interchangeable and you’d want a clutch rear mech for 1x.

@nemesis I see no reason why this wouldn’t work, but I could always get an FSA Gossamer 110 BCD crankset.

Totally get the 1x thing, I was meaning more the 110 compact might offer more choices of non Road ring. I had a feeling you were a bit knackered if you wanted anything much smaller than 48 or so on the outer… I keep my cx as a double simply out of habit. I rarely bail to granny on it but that’s more the use the bike sees. I found the gear spacing worked better for me with roadie cassette than big old mtb one, but that’s all personal taste. I run sram on my mtbs but do like shimano Road stuff. If I could make a shimano clutch mech work properly I’d probably be heading the route you’re describing.

If RF have started offering nw in 130 spacing of course, that’s probably crank debate over. 🙂

Interesting dropper idea. I got to the point Christmas before last of wanting a dropper on my cx for trail but never quite did it. I was thinking more along the lines of Lev with button probably just below the hood inside though where I could reach it with index finger… Shifter operated dropper is something I’ve heard of but never seen done. No reason it shouldn’t work unless pull is wildly off… 🙂

Hadn’t seen rf f doing nw 130s but I’d still be going compact for the versatility.

Gear shifter operated droppers are brilliant or at least my mtb one was. Must admit, I’ve been considering 1x on my cx for a while too. Only thing stopping me is losing a couple of the higher gears which may be a little limiting when I use it on the road.

@vincienup Yes, this would make sense if I intend to do a lot of road riding, but I don’t, so I have a feeling I won’t be using the big ring much. Most of my riding will be on the local mountain bike trails, and while I am aware that climbing on a CX bike will be easier compared to a full suspension mountain bike despite the different gearing (due to less weight, more efficient power transfer, etc), there are some climbs around that I wouldn’t want to do with anything taller than 1:1 (I ran 34T-36T with an 11-36 on my mountain bike).

Re dropper: It’s been done with Shimano STI LH shifter. Not sure about SRAM double tap shifters though. Edit: That’s actually a SRAM shifter in the video 😳

I can also confirm sram 10 speed road / mtb gear can be mixed with no issues. I have cx bike with 11-36T cassette using a x7 type 2 clutch mech and force shifters. I added an in line barrel adjuster though as there is no trim on the force shifters like mtb triggers / road mechs have.

Guess that’s you sorted then!

Mine almost never makes it onto Road, I just lazily went for ‘classic cx double’. It came with standard compact and 11-32 but the 50 was too big for what I wanted and the 11-32 didn’t give sensible spacing with the 36/46 rings I changed to. Expanders weren’t really on the scene at the time or I might have persisted.

Interesting RF have gone 130 not 110, possibly reusing some of the tooling they had from the Cadence stuff that didn’t really sell? It’s certainly going to set a fire under the ‘compact’ doctrine…

No real reason this lot shouldn’t work for you I don’t think then. It is fun seeing people’s reactions to a CX bike on singletrack even though it really shouldn’t be a surprise by now!

I’ve run 1×9 on N/W chain rings with non clutch mechs on road and Mtb bikes with no issue. One chai drop in 3000 km. due, I think to a knavkered chain

Thanks everyone. Sounds like the only way to see if a cassette expander will work is to try it out! It’ll take me a while to hunt down cheap second hand bits, but I’ll report back here on how it works out, including the dropper mod if I ever do it.

I’ve got 1×10 with a RF ring on the front and 105 mech and cassette. Chain doesn’t fall off.

I also run 29er mtb wheels because CX wheels seem to to heavy road wheels, rather than light and strong disc wheels.

If you’re looking for thick/thin CX chainrings, try Absolute Black, they do them in 110 and 130bcd.

I used a 110bcd Absolute Black ring along with X0 Type 2 rear mech, Rival shifters and an 11/36 cassette for the past year or so with no problems.

I converted my Giant TCX in the winter for cross racing.
Used Shimano 105 10speed with Absolute Black ring and the tension modification on their website on the 105 10 speed rear mech.
Worked a treat,no dropped chains!
So anyone going down the Shimano route it is worth a try!
Thanks,
Max