11-36 cassette on an Ultegra Cyclocross bike

[PTaylor73]

I just upgraded my 2012 Stevens Vapor disc (10-speed Ultegra) cyclocross bike (with dual-action shifters on drop bars) for easier cycling uphill with a Shimano Cass Deore Xt 10SPD M771 11-36, a Shimano XT RDM771SGS Rear Derailleur (9-speed MTB to work with the 10-speed Ultegra shifter), and a new KMC X10-SL 10 Speed Chain.

It works! the hardest bit: (not really, just squash it with pliers and it breaks off): removing the crimp off the end of the cable to fit the new derailleur (I super glued the end of the cable to prevent it fraying). I didn't shorten the new chain at all. I left the washer underneath the cassette in place.

I've also changed my front chainrings from 36 to 34, and from 46 to (52 I think).

Amazingly, I didn't have to adjust anything other than the in-line adjuster, to centre the chain to the cassette teeth (a quick one-off adjustment).

Edited by PTaylor73 on Friday 28th August 20:41

Edited by PTaylor73 on Friday 28th August 20:45

[Barchettaman]

PTaylor73 said:

I just upgraded my 2012 Stevens Vapor disc (10-speed Ultegra) cyclocross bike (with dual-action shifters on drop bars) for easier cycling uphill with a Shimano Cass Deore Xt 10SPD M771 11-36, a Shimano XT RDM771SGS Rear Derailleur (9-speed MTB to work with the 10-speed Ultegra shifter), and a new KMC X10-SL 10 Speed Chain.

It works! the hardest bit: (not really, just squash it with pliers and it breaks off): removing the crimp off the end of the cable to fit the new derailleur (I super glued the end of the cable to prevent it fraying). I didn't shorten the new chain at all. I left the washer underneath the cassette in place.

I've also changed my front chainrings from 36 to 34, and from 46 to (52 I think).

Amazingly, I didn't have to adjust anything other than the in-line adjuster, to centre the chain to the cassette teeth (a quick one-off adjustment).

Edited by PTaylor73 on Friday 28th August 20:41

Edited by PTaylor73 on Friday 28th August 20:45

The joys of cross-compatability between Road and MTB geoupsets! Nice job.

I would imagine you've got 50 as a big chain ring, I think 52/34 would be beyond anything other than a triple front mech, having said that, someone's probably made that work somewhere.

[PTaylor73]

I just looked, it is 52T, Stronglight 5-Arm/110PCD Chain Ring.

You've just got to keep your eyes open for potholes

MPH at 90 rpm:

[Barchettaman]

Beyond the 16t FD limit specified by Shimano but heck, if it works, it works.

Do the two smallest sprockets work when in the small front chainring, or does the chain rub either on the big ring or the bottom of the FD cage? I know small-small isn't an ideal chainline but it's nice to have.

[PTaylor73]

I see that the chain actually falls off the side of the bottom wheel of the derailleur when on the 34T front and the four smallest cassette teeth, maybe because the chain is too slack. I dislike cross chaining, so I hadn't tried this until now, for me it won't be a problem. The chain starts to rub very slightly on the 52T chainring when in the 5th smallest cassette ring.

I cycled up a hill last night that I'd of always walked up before, albeit with a short stop near the top.

[PTaylor73]

52 to 36 does work, but with rubbing on the front derailleur when on the two largest cassette rings.

[PTaylor73]

[PTaylor73]

Just saw the Hope Expander Sprocket.
https://www.google.co.uk/search?q=Hope+T-Rex+Expan...

It will give 11-40 instead of 11-36. The 17t in the cassette is removed, so you get both 36t and 40t.

Will also change the front 52t back to 46t -- it may be that I can shorten the chain a little as well.

Pics when I do it...

[astroarcadia]

https://www.youtube.com/watch?v=DzUunm4suo0

A friend has just has an Enigma Ti build finished with a 105 CX group-set and a 40t rear cassette.

All you need is a Roadlink.

[PTaylor73]

Thanks, will see if I need the RoadLink on this 10-speed?

It appears you get a new B screw included for if it needs adjusting too far (saw its wise to nutlock this screw to avoid it moving position)

Watched the vid, knees are something I also think about. One of those little hidden motors would help as well :-)

[pembo]

Where do you live that a 34-40 ever needs to come into play? Surely by that point walking is the better option?

Good effort getting it to work though, I think I might go to an MTB rear mech the next time I break mine, especially if it's a simple swap. MTB mechs are clutched right, so better for 1x?

[E65Ross]

pembo said:

Where do you live that a 34-40 ever needs to come into play? Surely by that point walking is the better option?

Good effort getting it to work though, I think I might go to an MTB rear mech the next time I break mine, especially if it's a simple swap. MTB mechs are clutched right, so better for 1x?

Surely depends on how comfortable you are riding low cadences. I typically like 90+ rpm and don't like going below 85rpm if I can avoid it... I can do it, but I just prefer not to. I regularly ride up some hills which reach 17% and, running a 50/34 and 12-30T it's not possible. I'd like a 32T or even 34T.... But that'd compromise lower down the cassette so I don't bother....but can totally understand why you might want a bigger cassette

Most of my training rides ař fairly hilly. My favourite 51 mile loop I do has 3800ft of climb in it, and the 1st 5 miles and last 3 miles are almost dead flat....

[richardxjr]

10sp+ Shadow Plus are clutch, yes, but the 9sp XT mech you'll need to work with 10sp STi's aren't.

BUT a narrow wide chainring does most of the chain retention work, so if your chain is nice and short it'll work fine.

I run 40T 11-36, will change to 38T for very hilly loaded touring (same gear as 34-32) and it's absolutely brilliant. Even the gaps are fine on road. Do get the crisper lighter XT cassette over the slightly cheaper SLX one.

Narrow wide 110bcd chainrings are £20 at Superstar after their 25% off everything in May code MADMAY25FB

[pembo]

Cheers for the code Richard, I've been on the lookout for a 36T narrow-wide for my cross bike, ran a standard one this season and had 2 chain drops so not too bad but would rather have none.

[pembo]

E65Ross said:

Surely depends on how comfortable you are riding low cadences. I typically like 90+ rpm and don't like going below 85rpm if I can avoid it... I can do it, but I just prefer not to. I regularly ride up some hills which reach 17% and, running a 50/34 and 12-30T it's not possible. I'd like a 32T or even 34T.... But that'd compromise lower down the cassette so I don't bother....but can totally understand why you might want a bigger cassette

Most of my training rides a? fairly hilly. My favourite 51 mile loop I do has 3800ft of climb in it, and the 1st 5 miles and last 3 miles are almost dead flat....

I'm looking at it in really simple terms here but if you have a bigger cog at the front than the back the input will be higher than the output. For example, if one rotation of the 34T cog at the front produced 1m of forward travel, the resultant forward travel at the rear 40T cog (and therefore, wheel) would be 0.85m. Surely this would be less efficient so it would be better walking or have I got something wrong?

[E65Ross]

pembo said:

E65Ross said:

Surely depends on how comfortable you are riding low cadences. I typically like 90+ rpm and don't like going below 85rpm if I can avoid it... I can do it, but I just prefer not to. I regularly ride up some hills which reach 17% and, running a 50/34 and 12-30T it's not possible. I'd like a 32T or even 34T.... But that'd compromise lower down the cassette so I don't bother....but can totally understand why you might want a bigger cassette

Most of my training rides a? fairly hilly. My favourite 51 mile loop I do has 3800ft of climb in it, and the 1st 5 miles and last 3 miles are almost dead flat....

I'm looking at it in really simple terms here but if you have a bigger cog at the front than the back the input will be higher than the output. For example, if one rotation of the 34T cog at the front produced 1m of forward travel, the resultant forward travel at the rear 40T cog (and therefore, wheel) would be 0.85m. Surely this would be less efficient so it would be better walking or have I got something wrong?

Maybe some people don't want to get off the bike? Plus, pushing a bike up a hill can be a pain in the backside. I think you're looking at it too simply, it's also to do with energy expenditure, which your "easier walking" thing doesn't account for. The cranks may be going round faster but you'd be putting in less power per rotation. It's quite complex but if it makes it easier to actually stay on the bike and continue pedaling, then I don't see a harm in that

[idiotgap]

Liking this thread!

[mon the fish]

I was struggling up the 20% hills near me (the Lecht ski centre etc) with a 34-25, changing to a 30T rear sprocket has made a massive difference, bloody brilliant going up hills now

[richardxjr]

Not surprised Mon. That bit by the snow gates is a bit ouchy! Last July, 6 degrees it was, horizontal stair rods.

[PTaylor73]

I visit the coast a lot, so you get some hills like

https://www.google.co.uk/maps/@50.3500625,-3.58119...

But I'm rubbish at climbing hills tbh