I’ve been picking up my bicycle repair hobby again recently (more so than just what I’m forced to when my bike breaks down), and find myself needing to purchase replacement parts for various components; to some extent they can be considered “consumables”. Chains “stretch” (i.e. the pins wear down); rubber grips break down; bearings wear down. My standard response to this has been just to pay a visit to the local bike shop and use their offerings, but sometimes this is not entirely satisfactory. For example, when a flange on my rear hub broke, I essentially needed to get a replacement wheel. But to match with my 30-year-old Dawes frame, I needed a 27″ rim with 126mm dropout spacing, and threaded to take a freewheel (instead of the more modern cassette of rear sprockets). I was actually slightly surprised that they had anything in stock that met those qualifications, but I ended up waiting a while to actually buy it, since I was also slightly tempted to buy parts and assemble the new wheel myself. Unfortunately, the offerings of the internet were not so great, either, and I didn’t find a way to assemble something I would be happy with (for a reasonable price) among the usual suspects of nashbar, harris cyclery, and the like. I may still investigate building my own wheel (and hopefully take advantage of sales), but not while I’m on a deadline to return a borrowed spare wheel.
The current component I’m considering are the ball bearings that are used in the four main parts of the bicycle that need to rotate freely. The local bike shop will only sell them to me in increments of 25, which is not a terribly useful number (some applications take nine, ten, or eleven balls per side). The leftovers are not really worth saving, since mixing different batches of bearings is a bad idea — all the batches are supposed to have the same diameter and tolerance, but within the same batch, the deviations will be much smaller than between batches. If the balls are (even slightly) different sizes, the load will concentrate on the larger ones, increasing the failure rate. There are loads of places on the internet that will sell me ball bearings (even Amazon!), but most of the bike-specific ones don’t list the tolerance on them, which seems really silly. I am rather inclined to put high-quality bearings into my bicycle, especially as the components themselves are quite inexpensive. So, I came to realize that the supply giant McMaster-Carr could help me out, as highly spherical steel balls are pretty much a commodity. And so they are, with 100 balls of the highest grade (25, i.e. sphericity tolerance of 0.000025″) running just a few dollars. This gets me to thinking, what else for my bicycle (or even just around the home) might I want to get from McMaster-Carr that I hadn’t previously thought of? They seem to be pretty good at documenting their inventory (unlike these random bike shops), so as long as I have dimensioning for what I need, I can be confident that it will work.
I look forward to reading comments about what fun or useful things people might get from the giant supply warehouses.