Functional bikes. Not Porn not Anti

I take it there's more to it than just parting off some tubing? Ie, there isn't a stock tubing size that works is there?

The first batch were done from some tube which had the right ID, which we then turned down to the correct OD and parted off. That's the right way around, as you get the machined finish on the visible part and the less attractive mill finish where nobody can see it. The latest batch were turned from solid, since it's actually easier to get the ID and OD concentric that way, doing it from tube you're relying on the mill extrusion being concentric or you have to indicate on the ID in a 4-jaw. On a CNC, once the programming is done the actual spindle time to add a boring operation is negligible, so we get better and more consistent parts with no set-up, just sling the bar in the feeder and all faces of the finished part are true to the spindle axis regardless of the quality of the stock.

If you have a lathe and time on your hands, they would be very easy to make, you just couldn't do them for the price on a manual machine if you expected to get paid minimum wage.