Please Define 135 OLD?
I'm starting my first build using a kit from Bamboo Bike Studio. I'm setting up the jig now and after watching their video, they show how to set jib for 120 or 130 OLD. Where exactly does this dimension measure from? I actually need 135 OLD I believe for my Shimano Alfine 11-speed IGH (and my contact at BBS stated the build can do this OLD). I've got a question email out to the BBS...but thought I'd also ask here for the great collective wisdom.
In case anyone is interested, here is the relevant viddy showing the drop out jig setup:
OLD = Over Locknut Dimension. Your Alfine hub is OLD = 135mm. Measure it to check.
Translated into frame dimensions, it's the distance between the inner faces of the rear dropouts.
For a normal rear wheel each of the two faces should be 67.5 mm from the frame centre line
Last edited by Mark Kelly; 01-13-13 at 03:58 AM.
There is a BBS in Toronto where you could ask for build tips.
So the issue I have is the jig provides for 120 or 130 mm OLD using different configurations of the provided spaces. I can't just add another spacer to achieve 135 mm between the dropout inner bolting surfaces...as this would just raise the dropout furtherest from the mounting board another 5mm...the dropout closest to the board will remain at same distance from the board. All other jig mounts (head tube, BottomBracket, Seat Post) are also position a fixed height from the board (co-planer). So that would mean the dropouts would no longer be equal distance from centerline with the rest of the frame (albeit only by 2.5 mm).
To do this precisely, I think I need to shave off 2.5 mm from the dropout-to-board spacer (a solid block of Alu), effectively lowering the nearest dropout 2.5 mm. Then add a 5mm spacer between the two dropout, effectively raising the furthest droput 5mm from the other one (but only 2.5mm more from centerline)....giving a total of 135 mm between the two, keeping them equally distant from centerline.
Since I have no good way to shave off 2.5 mm from the Alu mounting block, should I consider adding 2.5 mm spacers between all the other jig mounts and the board? Might be doable with careful selections of washers etc.
Or, is this extra 5mm clearance possible by just forcing apart the 130mm OLD dropouts a little each time I place the wheel in between?
Thanks...yes I'm aware of them. I have emailed the BBS Studio address and I'm sure they will advise soon...but there's lots of knowledge here too that will be nice to learn from.
Originally Posted by Canaboo
Spreading the dropouts works ok with steel but at times can be a PITA. Don't know about bamboo. I really don't see a reason that the aluminum block couldn't be replaced with a hardwood block that has the the correct spacing. I'm assuming that you have some woodworking tools since you are working with bamboo. A good quality drill press and a table saw would get decent results I would think. Shimming the rest of the fixture will work as well. Just make sure the other fixture parts are well supported across their width so the can't "wobble".
Originally Posted by busdriver1959
Thanks. Actually, I am a bit compromised in my currect working environment. I'm in a condo and doing the build in a small solarium room with no real pwer tool accessibility. If needed, I could just take the alu block to work where I have contact in the machine shop that likes to do little jobs for me on the side ;-)
I'll consider shimming the other mounts if I can find some alu or steel plates of uniform 2.5mm thickness. I think trying it with a bunch of washers is a little sketchy.
OK, just got response from BBS. They recommend performing initial setup at 130mm, then after the first glass stabilization of the frame, when re-configuring the jig from horizontal to vertical prior to carbon layup, the rear stays are quite mobile and I can add the extra 5mm spacing then using supplied spacers. Should work, but a bit worried I'd lose equal spacing from centerline if one stay gives more than the other. am I worrying too much?
The other things you could do is to build it with the dropouts off centre by 2.5mm eg 65mm CL to NDS droput and 70mm CL to DS dropout, then reduce the dish on the wheel by 2.5mm to suit. With the Alfine hubs flange spacing being 25.5 : 31.8 this will give you very close to even tension both sides (28.0 : 29.3).
Of course you won't be able to swap wheels without re-dishing, but is that ever seriously a problem? On my touring bike I built in a 3mm offset so that I could run Campy 10 speed with a 0.7 to 1 tension ratio. It takes about 5 minutes to re-dish a wheel.
Please Define 135 OLD?
Definately get the jig right for your OLN before proceeding. Seems that means taking a jig bit to your machinist friend for a tuneup. That will give you a much better result Later you could have him make a few spacers for the other OLNs if you need them then. Having to be twiddling your wheels or mod'ing the frame afterwards to make up for not being jigged up correctly seems to be an exercise in futility and a poor precedence for going forward...(apologies in advance for slightly offending those posters who suggested such).
Originally Posted by TornadoCAN99