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Mountain crankset with 46 or 48 tooth?(25 posts)

Mountain crankset with 46 or 48 tooth?sfrider
Aug 23, 2003 10:50 AM
I bought a Kelly cross frame and I'm probably going to use a mountain crankset because the guy who builds the bikes for the Kelly race team says that they've designed the frame for an mtb set-up and when you try using a road cranks, you have to mess around too much with finding the right spacing for the bottom bracket. He said it can also mess up the chainline. I am probably going to use an Ultegra cassette with it.

Where can I get an XT crankset with a 46t or 48t big ring (It comes stock with a 44t)? I don't want to buy a new crankset and then spend even more cash on a bigger big ring. Where can I get a good deal on a 46t or 48t chainring? Does it have to be a Shimano chainring? Does anyone sell the XT cranks without the rings?

Are there other brands that sell cranksets in the same price range with a bigger big ring or let you choose your rings? Do they have the same chainring design with shift ramps? I would rather go all Shimano drivetrain if it will shift better. Thanks
re: Mountain crankset with 46 or 48 tooth?The Walrus
Aug 23, 2003 11:36 AM
Don't get hung up on Shimano for the crankset. You can run 48/38 on 105 or Ultegra; as far as I can see on Shimano's website, there are no longer any MTB cranks that handle anything bigger than a 44t, and they no longer make any 5-arm MTB cranks, which might have taken aftermarket rings. Check out the thread below for some recent discussion of crank options.
Kelly recommends mtb crankssfrider
Aug 23, 2003 12:21 PM
I know I have the option to run different rings on road cranks but Kelly strongly recommends mtb triple cranksets for spacing, chainline, and clearance reasons. Otherwise I would go road cranks, no problem. I don't want to have a bike that doesn't shift smoothly.
You riding this as a 'cross bike?MShaw
Aug 23, 2003 9:55 PM
or a road bike? Either way, if you REALLY want a triple, I'd try and dig up some first gen. XTR cranks (or anything with the 110mm bolt circle). That way, you get the triple AND the big rings (46-50t) that you're looking for. Remember: a 50x12 is the same as a 53x13 when you're riding the road.

I'm running the Cook E-cranks with a 110mm adaptor. If you can find them, they work great.

Once you get the spacing issue correct, and you'll have to do it regardless of what crank you run 'cause you're trying to make a mtn triple work on a "road" bike... You'll have to get the front derailleur adjusted for your particlular setup. Once you do that, it should shift just fine.

I've found that an XTR front derailleur will shift the 50t big ring I run in the summer just fine. Come 'cross season, I'll switch back to either the 46 or 48.

That help?

re: Mountain crankset with 46 or 48 tooth?Eric Marshall
Aug 23, 2003 5:14 PM
I'd just stick with the 44. I run a 46, and rarely use it during races, and when I do it's always on pavement. You can always compensate for the smaller chainring with a smaller cassette.
Will use the bike on the road a lotsfrider
Aug 23, 2003 9:42 PM
I will be using the bike for little bit of commuting and some god miles getting to the dirt.
Triple 74/110 BCD crankhaimish
Aug 24, 2003 10:22 AM
If you're in SF, and are still looking for a mtb 74/110 BCD crankset, I have an older Shimano LX (M550, I think)26/36/46, 175mm crankset I'm about to pull off a bike and replace with some 170s. If you're interested, send me an e-mail at haimishathotmaildotcom.
which cassette?sfrider
Aug 25, 2003 4:38 PM
Which cassette? It seems like there isn't much difference in the small gears on road versus mtb cassettes. It looks like the Ultegra and XT both have 11 or 12 as the smallest gear.
forget shimano...jimmygroove590
Aug 25, 2003 12:53 AM
First off, you didn't say what kind of shifters you are going to use. If they're semi-indexed, like barcons, it won't matter as much than if you used full STI. Yeah, I can honestly say that chainrings with shift ramps work better, however, it is not a complete necessity. Right now I'm running on a retro mtb a crankset with no shift ramps and it works perfectly fine, due in part to a quality front mech. But anyhow, if you want my opinion, I say go with old square taper cranks, namely suntour xc pro non-micro drive cranks. Cold forged for durability and in the standard 110/74mm. Look around ebay, usually you can find this kind of stuff and square taper bottom brackets are super cheap too. Also, in this BCD you can find all sorts of outer ring sizes (I know cause I was looking up this exact same thing a few months ago). Just go to cambria or something like that and you'll find a wide selection in this size with shift ramps to boot.
Aug 25, 2003 1:40 PM
he's got it. Also there are bazillions old retro XC cranksets with 48/38 or 46/36 chainrings sitting in my parts box and in old bike shop bins. Not 9 speed compatible tho!
I'm running 9 speed downtube shifters on Kelly take-offssfrider
Aug 25, 2003 4:43 PM
Am I going to have issues running 9 speed with older style cranks?
What is "BCD"?
Also what measurements do the 110 and 74mm represent?
hey sfrider...jimmygroove590
Aug 25, 2003 6:06 PM
I'm not sure if you are being serious or kidding around, that bit about Nitrious Oxide was pretty funny either way, but I'll give the benefit of the doubt. BCD stands for Bolt Circle Diameter and that is what the numbers 110/74mm stand for. Basically they indicate what kind of chainrings are compatible. Shimano stuff uses some funky standards, like 104/58mm or something like that, so rings from a RaceFace crank will probably not work on a newer Shimano crank, especially since Shimano recently switched to a four bolt standard. NOS is more of an Ebay term, referring to condition of the item being sold. It stands for New Old Stock which means that it is new, but old or older at least so it should not have any wear and tear on it. Q-factor is something that I will vaguely explain as how far the cranks stick outward. Roadie cranks usually already have a low Q-factor, which is supposed to be conducive for spinning the cranks and for turning I believe. This is not true for MTB cranks which require more clearance or something like that, so the factor is higher. The Ritcheys I recommended have a very low Q-factor for an MTB crank, which is why they would be good for a cross bike I think, the best of both worlds kind of thing. As to your other question of whether older cranks will work with a 9 speed drive train, well I can't give any response. Personally I favour 8 speed.
NItrous - kidding of course, I'm not that dumb! nmsfrider
Aug 27, 2003 6:45 AM
oh, and I forgot...jimmygroove590
Aug 25, 2003 1:06 AM
Right now, actually, cambria is selling a bunch of old Ritchey comp mtb cranks, almost as good as the Suntour's I mentioned. Cold forged just the same, actually both by Sugino, though the BCD is in 94/58mm so the selection of outer rings is less, the largest I seen is 46. But, still, for the price that your paying it's pretty wicked for NOS cranks that have a very low q-factor which is supposed to give more of a roadie feel.
Jimmy's groovy lingo? 9 -speedsfrider
Aug 25, 2003 4:46 PM
Dude, you lost me - what is "NOS" and what is q-factor? I guess I'm getting old or something. Are you talking about adding nitrous to a cross bike? I'll check out Cambria, is 9-speed an issue?
no Ritchey cranks w/ more than a 44t at Cambria....sfrider
Aug 25, 2003 5:17 PM
Checked out their site, didn't see any. looked under "hot deals" too.
I think you were looking in the right place...jimmygroove590
Aug 25, 2003 6:19 PM
But, you were looking for the wrong thing. In my post I recommended CRANKS not a crankset. At Cambria, they are selling some old skool crank arms, in the 94/58mm standard. In that Bolt Circle Diameter you can find rings up to a 46 tooth that I have seen. I suggested to ones at Cambria cause they're super cheap for what your getting ($59 not including s/h). If you really got money to burn then go to rivendell and pick up this same crank in a BCD of 110/74mm and then buy a 50 tooth ring if 46 is not enough.
Aug 25, 2003 6:56 PM
sells the AC's in 2 forms last I checked. Splined BB, Cheap reasonably stiff, 110 74 BCD. have a set and can't feel the diff between it and my XTR Cranks. Vuelta and Salsa make fitting chainrings. Have a 48/36 right now but am switching down to a 46 or 44 as this bike is cx only and a 48x 11 is rarely needed. I'll go with a tighter chainline by closer ring spacing instead.
Q-Factor is the cranks relationship of pedal to BB spline on the horizontal axis. good Q-Factor for a rider puts their ankle, knee and hip joint in-line. Narrower cranks have tighter q's and if you have a wider a$$ will most likely put these joints at angles which hurts pedaling efficiency and your joints. Put your bike on a trainer in front of a full length mirror and check how you leg is aligned. There was a guy yesterday with forefoot varus (angle at the ankle joint) and his toes pointed in, heels out, knees out and then i to the hip. was ugly and most likely will do some long term damage to his joints.
Some thoughts...Chicago_Steve
Aug 25, 2003 6:58 AM
1) If your looking at the new splined shimano stuff the Ultegra BB won't work with the XT crank. You should be looking at an ES70 or ES71 BB to mate with your splined XT crank (if it is an older square taper XT crank this disregard this advice).

2) You can get larger chainrings to mount on your XT cranks BUT they are going to be aftermarket (Blackspire and Salsa make replacements). Look for 104mm bolt circle rings.

3) Instead of going to a larger chainring how about a smaller cassette in the rear. With an Ultegra cassette and the XT triple ring setup in the front you should be able to climb about anything within the limits of your cross bike while still having a pretty good top gear for the road. You might spin-out a little on downhills but the gearing should be fine for commuting.

4) I'm using an Ultegra Triple BB (118mm) with a Shimano 105 crankset and have been happy with the performance. The shifting and chainline seem to be no worse then my old setup (XT crank and 113mm ES70 BB).
re: Mountain crankset with 46 or 48 tooth?CurtSD
Aug 25, 2003 7:24 AM
Here's what I did:
I got a set of AC crank arms and a 110/74 spider from The crank arms work with a shimano XTR splined bottom bracket. Then I got XTR 5-arm chainrings (48/36/26) from They're ramped and pinned.

May not be the cheapest route, but I'm very happy with the setup.
re: Mountain crankset with 46 or 48 tooth?MShaw
Aug 25, 2003 10:37 AM
Those look similar in design to my E-cranks. How do you like them?

re: Mountain crankset with 46 or 48 tooth?CurtSD
Aug 25, 2003 11:33 AM
I like them, though I'm not much of a gear masher so I've never noticed flex with any of my cranksets.
Race FaceTWD
Aug 25, 2003 10:59 AM
They aren't exactly cheap, but you can get Race Face Turbine LP or Next LP cranks in Standard 74/110 BCD. As of last year they were available in both square taper and ISIS models. Race face makes rings for these cranks in 24,26,34,36,46, and 48 tooth.

Seems like they are either sold as crankarms only or with 24/34/46 ring set. I'm running the Next LPs with 24/34/46, but will switch to 36/48 on the middle and big ring when I wear the rings out. The 46 just isn't big enough on the road. The race face rings have shifted very well for me.

On a side note, I wouldn't recommend running MTB cranks as a double ring setup, unless you run something like a Third Eye chain watcher. I got tired of having to unjam my chain from where the granny ring was supposed to be. I figured if I was going to bolt something extra to my drivetrain, it might as well be a third ring. It's a nice bail out gear, and lets you climb super steep stuff that a double and skinny tires won't handle.
re: front derailleur optionsrichpierce
Aug 25, 2003 1:46 PM
Front derailleur cages are made for particular size ranges on the front chainrings. They have different arcs depending on the size chainrings they are designed for. Given the rise of compact design, most new MTB front derailleurs cannot handle big shainrings well. If you go with new skool front derailleurs designed for 44t max, you will not get smooth shifting on a 48t chainring. You will be better fof with an old skool deore XT, Suntour Xc pro or XTR front derailleur or even a road derailleur for big chainrings.
re: front derailleur optionsCurtSD
Aug 25, 2003 2:48 PM
They can be modified though. I used a bench grinder to modify the curve of the cage of an Ultegra front derailleur to fit a 48t chainring. Works well.