Due to the decrease in the price of splined hubs and the high price of quality cotterless crank arms, I was thinking of finally upgrading my hub/crank assembly on my SHaKH NaS Muni. Now here’s the problem.
Part 1: The setup I have now uses the 99r12 Profile bearings (19mm x 41mm)
Part 2: The absolutely beautiful custom machined bearing holders are shaft collars, which means that they fit exactly with no room to change any dimensions of the bearings.
Part 3: I’d like to be in the $100 to $200 range for the crank/hub combo, which means that the Profile set is out.
So here’s the question: Is there any way to fit the KH Isis or the Qu-Ax with 42 mm OD bearings into my 41 mm bearing holders? The only thing I can think of is find some smaller outer diameter bearings with the correct inner diameter, or even 40 mm ID bearings and then use some sort of shim. Or would it be possible/advisable to try and shave 1 mm off the outer diameter of the bearings or off the bearing holders?
I know very little about bearings (I’ve never even replaced any before), so I don’t know if any of this is possible. I haven’t even checked the flange to flange width yet, so this may be a moot point, but I wouldn’t mind getting any feedback on this.
You have a Steve Howard frame, yes?
Can you post a picture of the bearing holder design on your frame? Does it have a lip on one side?
One option would be to get the bearing holders machined to fit the 42mm bearing size. That’s likely doable by any competent machinist if it’s a typical SH frame. The details would depend on the design of your particular bearing holder.
Here’t the pictures of the construction process. aaa is the bearing holders. I hadn’t thought of getting them professionally machined. Would that be expensive? Would it even be possible considering they’re parallel to each other? They do have a lip on the outside.
edit: I guess it’s not until aab that you can see the lip, once he started boring it.
Ah, you’ve got the welded SS SH frame.
The aluminum frames with the bolt on forks would have been much easier to get re-machined.
It might still be possible with the welded SS frame. It would depend on clearance issues for the tooling. Will the machinist be able to get the tool in there. I don’t know how that would work.
You’d have to get some advice from a machinist. If the task is reasonably possible the price should be within your price range. Shop around if you get a quote that is too high. Some machinists charge more than others.
So will all ISIS bearings have an outer diameter of 31mm? That’s a good idea, ZFreak. Does anyone have an idea of what I could use for a shim? That seems like a large step up (11 mm, or 5.5 mm per side), but it sounds like Kris tried it originally.
If the machining thing doesn’t pan out, I might try the bearing + shim, but it does seem like it may end up being a trouble spot while riding, and losing a bearing while riding probably wouldn’t be very much fun.
How hard would it be to grind down a couple bearings with a Dremel? The actual diameter I’d need to get the bearings to is 41.275 mm (the original is 1 5/8 inches). From my calculations, I’d only need to take off about a third of a millimeter all around. If Steve Howard didn’t make things to such precise specs, they might fit already.
hey, the 40 mm bearings will fit well if you get the plastic spacer thingys that come w/ the Torker unicycles. they are just thin plastic peices that sit in the bearing caps. Rubber works nicely for this as well. get something like that to fill the gap. probably don’t even worry about the metal spacers you can get from UDC
That’s great! Thanks a lot for finding these. It sounds like a lot less work than trying to modify something.
Now here’s another question. Are all bearings the same if they have the same number? I’m trying to look up R12 bearings to determine the thickness, and on another website, I found the dimensions of 1.625 X .313 X .750 in inches, which translates to 41.27mm x 7.95mm x 19mm. Or does R12 mean something else?
I’d forgotten how much fun it is to tinker and pick the brains of more experienced unicycle builders. Thanks, guys.
Okay, I’ve almost got it figured out, but I have one more question. Then I’ll stop writing this stuff.
How much does bearing width affect the hub/frame connection? I’m still waiting for a reply from JensonUSA, but I’ve discovered that my Profile bearings that I currently have (99R12) are 12mm wide. If the new bearings are thinner, as it sounds like most are, will that work? The bearing holders that are on my unicycle only have a lip on the outside, so a narrower or wider bearing would fit in the spot, but I don’t know if they will function correctly. Can anyone shed some light on this?