MTB single speed help
I ride my bike to work everyday
I have a Seven Sola SS MTB that I am trying to get up and running again
I bought a 48T SRAM Courier crank
Universal Cycles -- SRAM Courier PowerSpline Crankset 2012 - Black
This is compatible with the truvativ powerspline BB, I purchased the 68/113 mm version
Universal Cycles -- Truvativ Powerspline Spline Bottom Bracket
Of course this combination doesn't work on my bike - the drive-side crank can't be installed because the chainring hits the drive-side rear chainstay
What are my options? I prefer to use the SRAM courier crank if possible as the price is right and it is 172.5
Do I need a new BB? Spacers? I can adjust my chainline at some level as I have a Chris King SS rear hub
Thanks in advance for any help
Longer bottom bracket for the win. With a longer axle you'll probably need to adjust the chainline of your rear hub. Chances are good you'll be able to do that if it is necessary. It will involved dishing the wheel and moving/adding spacers to the hub. Dishing is pretty easy, especially if you spent the couple bucks necessary to buy a decent spoke wrench. Sheldon Brown has a lot of good information about this process, as well as pretty much everything else bike and single speed related. Before you undergo this process, first check something:
Is your bottom bracket symmetric? Many aren't. It seems like it'd be obvious. Still worth double checking as it could save you a lot of work.
I'm curious about the notation in the product description "113mm/118mm" for the bottom bracket. There's a little more digging around here to figure out what you need to do. What we need to know is what chainline your frame is capable of handling with your chosen chainring. Measure your seat tube's diameter (either circumference divided by pi or directly measure diameter with calipers), then divide by two. Then measure the distance from the edge of your seat tube to the closest chainring placement that works with your frame. Add the two numbers together to get the chainline your frame will accept. With that information we can quickly suss out what needs to happen at the rear hub to make this build work.
If you only ride in nice weather you're missing a lot of fun.
Originally Posted by Tig
dood...what are you doing?
the simple answer is that you are trying to put a set-up for a road ss/track/fixster bike with a 120mm rear spacing onto a mtb frame that has a 135mm old. your chainstays are much wider/flared than that bb is meant to handle, not to mention they (& ss mtbs in general) were never built to fit a 48t ring like came with that crankset.
the easiest fix may be to just get a much smaller chainring...
but the best solution would be to get the right parts to work with your frame, there are many inexpensive ss mtb cranks & bbs available so you might want to check into exchanging what you have there for something more suitable & less problematic.
if you have not already done so, get over to the ss forum on mountainbikereview for better advice on how to build a mountain bike than you will get here.
have fun & good luck...
Last edited by markaitch; 12-07-2012 at 04:53 AM.
You're going to have to space the chainline out quite a bit in order to make that set-up work. SS mountain bike frames are usually designed to fit a ~34t chainring or so, so they're not going to have the clearance to fit a 48t ring, as you've already seen.
Easiest fix is to use a smaller chainring and cog to get an equivalent gear ratio to the one that you're using with the 48t ring.
Man up, dumb down, and do one gear.
Return your crankset, if you can.
Raceface make several Crankset/BB combos that are ~100 bucks. You could get a 32/34T in the front and use a large cog in the back. The wider space in the rear will not allow for a large chainring in the front.
The smallest chainring you can get for the BCD on your crankset is a 38T, AFAIK.
Amazon.com: FSA Pro Road 9/10S 38T 130mm Black Chainring: Sports & Outdoors
Use parts made for your bike!
Thanks for all of the replies
I re-evaluated today - there is no way that it will work - even with a different BB and spacers
I am going to try to return the crankset - I don't think it will be a problem - I still have the original packaging and you can't tell that an attempt was made to install
Any thoughts about using the Shimano Zee crankset? I have installed quite a few hollowtech BBs so I have that aspect taken care of - Thanks!
If you really want to run a DH-specific crankset.
Originally Posted by WEG
Something like a Deore crankset would work perfectly well, especially for something like a commuter. I have one on my fixed gear and it was cheap and it works great.
You're overthinking this.
Man up, dumb down, and do one gear.