Wednesday, March 9, 2011

Making the Catrike wheels fit

Bad news. I went to two bike shops and both of them shot me down. Neither of them can make the new 16" Catrike wheels fit my KMX by swapping out bearings. They shared the following challenges:

- The bearings are difficult to remove b/c of the spacer that's inside.
- The bearings are difficult to measure while installed on the hub. To get an exact measurement, they suspect the bearings will have to be first removed. They don't know how to remove them. Apparently they're having trouble b/c there is no lip on it to provide leverage with the tools they would use. They know what tool would work, but they don't have it.

Sounds like bad news which it is, but one guy from Nomad Cyclery made an ingenious suggestion! He called it a step-up axle. Keep the stock bearings on the Catrike wheel and fabricate a custom axle. The axle will be the same 1/2" diameter as the stock KMX axle. Since that's too thin to fit in the Catrike hub, the axle will step-up to 20mm thick in the middle. Hmmm, very good idea.

Works in theory, but there's some major logistics that might slow me down. Where to get a custom axle?

Looking through the web, I found nothing on custom axles. Looking further I did find a few companies that can make custom bolts. I suppose an axle technically is no different than a bolt. They're both just threaded metal rods. Bingo!

I called up one of these shops and am in correspondence with them to fabricate the custom axle. I need to confirm the inside dimension of the Catrike bearings. I'll have to contact Catrike tomorrow since they're closed now.

Most bike shops already don't want to touch recumbents, let alone a trike version that takes up even more space. Luckily for me, the problem I'm having with compatibility has only to do with the wheel. The problem of trying to make a small diameter axle fit into a hub designed for a larger sized one is difficult.

After calling up 21 (Yes, 21!) bike shops with my intro,

"Good morning. Is your shop willing or does it have the resources to work on a one-off custom project involving a recumbent tricycle?"

Based on their responses, I narrowed down my list to 3 shops that would be worth my visit. My first stop was to City Cycles. Great guys there. John whom I spoke to on the phone was busy so I discussed my project with Ian who was awesome too. He inspected the parts and took the hub apart to access the sealed bearings.

Bad news.

Swapping out bearings with an outside diameter that matches the new Catrike wheel and an inside diameter that matches the KMX won't work. It will work for the outside, but not the inside of the wheel. The bearing unfortunately wraps around the spacer or sleeve. It's the sleeve that governs and limits the inside diameter of the bearing to the stock Catrike wheel.

Since this won't work, I have two other options:

1. Buy the KMX wheels for $120 a pop or hope that they'll be cool enough to support my ride and sponsor me or at least offer some sort of discount.

2. Have custom step-up axles made by a machine shop. My understanding of machine shops though is that they cost a lot to setup and if I'm only making two units, it'll cost a bundle. I'll have to check and get more exact numbers to see which route would be more economical.


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