So, I have a touring bike with a compact double, and the gearing doesn’t go low enough for loaded tours in the Alps.
The bike is a Merida cyclocross frame with slicks, a Shimano R600 compact double with 50/34 in the front and a 10-speed 12-28 ultegra cassette in the back with a 105 RD. 105 right hand brifter and some cheapo left hand brifter. Hub is 105 if that matters.
I was going to replace the double with a triple, but I realized that it would cost a metric fuckton. New crank, new left brifter, new FD, possibly a new (longer cage) RD as well. And triples seem to have a 30T granny ring by default, which is just about 10% lower than what I’ve got now. Not that much lower for all that money.
So, I’m thinking about just getting a cassette with a bigger big cog and a long cage RD. a 12-32 would get me a slightly lower low gear than a triple crank with the current cassette, and 12-36 would be lower than 1:1 which is more than low enough I’m sure. People seem to suggest sram apex for this purpose, altho I can also see big rival cassettes on sram’s site as well.
So, is this a good plan? Would a long cage road RD be sufficient if I don’t crosschain like crazy, or do I need to buy an MTB (Deore/LX/XT) RD?
What is the difference between road and MTB cassettes? E.g. sram lists both Rival (road) and X9 (MTB) cassettes on its website as PG 1070, with mostly the same cog counts. Are they the exact same thing? If there is generally no difference between road and MTB cassettes, why don’t people just use Shimano MTB cassettes for their touring frankenbikes? I’m sure shimano makes a bunch of MTB shit in the 12-32/12-36 range, yet people seem to have welcomed big apex cassettes like the messiah, as if there was no alternative. I’m so confused.
people welcomed apex because it is easy to understand. running MTB RD’s and cassettes with 9/10 shimano shakes was always an option, it’s just not written on the box.
is a 34x34 or 36 even low enough for loaded touring in the alps? determining the lowest gear you need is step 1.
there are lots of triples with sub-30 rings. consider square taper. look for something with a 110/74 bcd.
go to a friction bar end for front shifting. or even a falcon thumb shifter, if price is really a concern.
you’ll need a 9 or 10sp shimano MTB rd to take up the extra slack. and a new longer chain. use your current cassette.
Sugino OX801D gets you a 30t double, but they’re spendy.
I run a 50/34 front with Shimano 9s shakes, an LX rear mech from Wiggle and a 12-34t SRAM cassette. You could probably do the same with a 10s setup. Rear mech is here:
You could get a triple crankset, then stick 28/42 chainrings (plus a bashguard if cosmetics are important) on it to make an alpine double. That would give you a 1:1 dump gear and enough high end to spin up to 20 mph or so.
Yeah, 34x36 would be enough I’m sure. We don’t usually do really big climbs. I climbed all but one of the hills on previous tours on 34/28. On that one I walked 150 yards and got back on when my heart rate settled down. My gearing was too high (had to mash really hard in some spots) but not by a crazy amount. I usually felt like one more gear would be just about enough.
This year we want to give Stelvio a shot (without the luggage) and there’s no way I’m doing Stelvio on 34/28.
I don’t want to go back to bar end shifters or square taper. I want to keep the drivetrain reasonably modern and decent quality, so I wouldn’t want to go lower than 105 level. I’m sure modern road triples can take smaller rings than 30 but that would mean throwing away the stock granny ring and buying a smaller one, so even more expense. It seems simpler to just replace the cassette with a 12-36. Cassettes are cheaper than cranks and I could keep the current shifters. My hardcore cred is out the window anyway so I might as well embrace the beard factor with a massive cassette and an MTB RD that sticks out like a sore thumb. The obvious downside is the wider spacing between the gears but I’m not too worried about that.
I guess the idea is that I wouldn’t need new shifters or a new RD if I don’t use the big ring. Interesting. If I were to do this I would probably want 28/44 or even 28/46. I’d just leave the big ring on. It looks better than a bare spider or a bashguard and I’d get one with the crank anyway.
I might still have to replace the FD, though. I’m not sure it will work with a 28T granny.
[quote=halbritt]Sugino OX801D gets you a 30t double, but they’re spendy.
I run a 50/34 front with Shimano 9s shakes, an LX rear mech from Wiggle and a 12-34t SRAM cassette. You could probably do the same with a 10s setup. [/quote]
That’s what I’m gravitating towards. What’s the 12-34 cassette? I only saw 32 and 36 so far.
I’ve heard about the 33T front chainring but that’s such a small difference from 34T that it doesn’t seem worth bothering with. If I could get a 30 on there I would do it and call it a day but that’s obviously not happening.
BTW the LX RD you linked is listed as a “trekking” part. I guess LX is now a trekking group. Is there any meaningful difference between “trekking” and “MTB” RDs?
It says max 32t, but it shifts 34t just fine, maybe it gets a little chainsuck.
[/quote]
yeah, my T661 handles 34t fine(Shimano datasheet claims max 32t) on the Rodriguez, I think some people at Riv were claiming up to 36t on the website.
Also, I have a photoset if you wanna compare the M591 Deore, the primary difference is overall tooth capacity: RD-T661 vs RD-M591
more photos in my flickr stream
It says max 32t, but it shifts 34t just fine, maybe it gets a little chainsuck.
[/quote]
yeah, my T661 handles 34t fine on the Rodriguez, I think some people at Riv were claiming up to 36t on the website.
Also, I have a photoset if you wanna compare the M591 Deore, the primary difference is overall tooth capacity: RD-T661 vs RD-M591
more photos in my flickr stream[/quote]
I’m sure I’ll come back with a “which MTB RD do I buy” thread if I decide to go down this route but it’s too much for me now. This compatibility shit makes my head hurt.
Is long cage only. One can also get an M772 GS (medium cage top normal) XT mech that even Shimano claims will shift a 36t. The medium cage might make it less prone to chain suck.
Someone correct me, but I believe the 10s Shimano MTB bits have a different pull ratio and won’t work with road shifters, no?
For SRAM they’re really all road cassettes except for the 36t ones, which is why the PG-1070 12-32t cassette is fucking heaven on earth
Shimano started making a 12-30t cassette last year that isn’t bad, but otherwise every big cassette they make is fucking awful for road use[/quote]
But what is the actual difference? Different cog/ramp profile that makes them louder/shift worse or something? I’d want more than 30T and probably more than 32T as well. Leaning towards 36T and trying to figure out whether to go sram or shimano if I do it. Maybe the 34T sram if it exists and is somehow better than the 36T (edit: I see it only exists for 9 speed).
Yeah, you can run a shimano 9spd mtb rear mech with an otherwise 10spd setup no problem but you can’t use a 10spd dyna-sys one in the same set up since the pull ratio was changed.
Yeah, my one is for 9s only. Hopefully Fred can correct me, but I believe your options are these:
[list]
[]10s 105 shakes
[]long(ish) cage 9s mech (that shifts 10s just fine) like the T661 or the M772
[*]Any 10s MTB or road cassette up to 36t from either SRAM or Shimano
[/list]
I run the crabon version of this on my FF for stupid hill climbs with a 11s 12/29 cassette and a Campy road dangler. Shifts ok with the campy front pusher after putting two BB spacers on the NDS (one on the DS)
You are correct heath, for shimano bits the 10spd shakes only play nicely with 9spd mtn danglers. I have a 46/30 double to an 11-36 running a deore xt double FD and an x7 rd shifted by Sram shakes which also works well. You can climb walls towing a trailer with like a thousand babies inside with that thing.
For SRAM they’re really all road cassettes except for the 36t ones, which is why the PG-1070 12-32t cassette is fucking heaven on earth
Shimano started making a 12-30t cassette last year that isn’t bad, but otherwise every big cassette they make is fucking awful for road use[/quote]
But what is the actual difference? Different cog/ramp profile that makes them louder/shift worse or something? I’d want more than 30T and probably more than 32T as well. Leaning towards 36T and trying to figure out whether to go sram or shimano if I do it. Maybe the 34T sram if it exists and is somehow better than the 36T (edit: I see it only exists for 9 speed).[/quote]
the gear choice on the big Shimano options are pretty bad for road use, you get stuck with a stupid 11t cog
and all the jumps are gigantic at the fast end, though they do sometimes give you one closer shift in the upper-middle vs SRAM
