Chainline Question

[Rada]

I recently picked up a Stevenson Custom Cyclo-Cross frame that I am figuring was built around 2000. It is similar to the old Kelly Knobby X with the flared chain stays. The bottom bracket is a Ritchey 68mm and has 132.5mm rear spacing. The stays are 43cm. From doing some searching it would seem I need a mountain crank that uses an octalink or taper bb and a compatible road bb. I'd appreciate anyone out there with some experience with this to chime in. Thanks.

[pinkshogun]

very patriotic nipples

[thirdgenbird]

very patriotic nipples

The 14 year old in me came out when I read that.

[markie]

Cool frame! can we see the rest of it? Are you going for gears or single speed?

[Peter P.]

Due to its 'cross heritage, that frame's driveside chainstay clearances may only be for a typical pairing of cyclocross chainrings such as a 36x48, vs. a mountain bike triple. Do you have anything from an existing bike you can install temporarily to check for clearances? That would be what I recommend.

[foon]

My rock lobster cross also has fairly wide chain stays. I need to use mtb cranks on the thing. Chainline is a bit further out comparing to road cranks. It is not ideal but it's not a big problem either.

Your two main concerns would be crank clearance and chainring size. I had to play with bottom bracket length/spacers/ chainring sizes quite a bit before I found the combo I liked.

Without knowing your intended gearing, I would recommend square taper mountain cranks for the many different spindle lengths available, and a 135mm wheel for straighter chainline.

[Rada]

I've tried a road triple with 48/38/26 gears and the drive side was fine. Oddly enough the non drive side has a problem with the crank arm.

Thanks Markie. Plan is to make it a geared all rounder. It has some pretty interesting braze ons. A few bad pics with some components on just to see how it sets.

[Rada]

Would like to run with 48 or 46/34 in the front and 12/30 in the rear. I was wondering if it would be better to use 135mm hub in the back. Thanks for the info.

My rock lobster cross also has fairly wide chain stays. I need to use mtb cranks on the thing. Chainline is a bit further out comparing to road cranks. It is not ideal but it's not a big problem either.

Your two main concerns would be crank clearance and chainring size. I had to play with bottom bracket length/spacers/ chainring sizes quite a bit before I found the combo I liked.

Without knowing your intended gearing, I would recommend square taper mountain cranks for the many different spindle lengths available, and a 135mm wheel for straighter chainline.

[foon]

Are you going to leave the granny ring off the triple cranks? Even though you have no clearance issues, chainline would pretty fairly far out comparing to a compact double setup.

If you're keeping the triple, I would probably try to find a different nds crankarm that clears the stay, providing what you have right now is barely not clearing.

If you're getting new cranks, the inexpensive suginos are nice, with square taper you can just try a few different lengths until both sides clear. For newer external bb cranks, here's some measurements at the bottom that may be useful:
http://www.blackmtncycles.com/2011/04/cross-frame-crank-compatibility.html?m=1

As for the 135 wheel, it may not be necessary at all if you have clearance with road doublev cranks with your smaller than 50 big rings.

[rwsaunders]

It looks like the frame builder is active...perhaps reach out to them with your question as well.

http://stevensoncustombikes.com

[Rada]

Thanks for the link foon. I agree about Sugino cranks. I had an older GP, but unfortuanatly I sold it.

I'll probably contact Bill Stephenson soon, thoight it rude to contact him around the holidays.

[Rada]

Quick check and it does not look like any of those compact cranks will work.

[markie]

What a cool frame. I have an older IF Planet X. It took me ages to work out that it needed a mountain double for a decent chainline. Road cranks and Isis bottom brackets did not give me enough crank clearance at the chain stays. Ymmv, but that is where I would start.

[ais99spoke]

Looks a little more "tour"-ey than "cross"-ey judging by the spoke carrier, mounts for fenders and racks, and pump peg. Not likely to be tons of other differences, but the BB might be a bit low for aggressive cx riding, if that's your intention - especially with longer cranks. Should be fine with either 130/135 OLD hub

[Rada]

Good eye. It does have a low BB, but it should come up some. The tires in the pic a half flat 25's and I am going to use some 35s. It also has a really long wheelbase at 106cm. Quite a bit longer than my 78 Trek TX700. I agree it is more in vein of a tourer. I don't race, but like to do centuries.

[Mark McM]

Looking at the photo in your second post, it looks like the fork has way too much offset. It's tough to be sure by eyeball, but it looks like the front end geometry as near zero trail, or maybe even a negative trail. With that much fork offset, this will not be a very stable bike at all.