October 25th, 2011
For a while now I’ve felt that there just HAS to be a better solution for single speed disk dropouts. In the past I’ve typically used sliding disk tabs.
These are pretty finicky to install, though. It involves not just getting the tab in the right place as you would with any disk tab, but also making sure that the slots end up parallel to the slot in the frame end/dropout (I’ll let you decide what you want to call it). Simple as it might look, this is a process that usually ends up taking me about an hour! It occurred to me at some point that if the tab was just PART of the dropout it would make things much easier. It’s location would just be right from GO! This solution is common place, after all, for vertical disk dropouts.
Then there’s the issue of fender/rack attachment working around a disk caliper. Not really an issue for your typical mountain bike, but increasingly it seems fenders and racks matter to the crowd that is buying custom steel. The folks at Paragon Machine Works made a “lowmount” disk dropout some years ago that seemed like a pretty brilliant solution to me.. I bought some. I never ended up using them, though, because so often I’m building single speed (or internally geared hub) bikes. A single speed version seems like a logical enough thing to make, but I’m not aware of anyone offering such a thing. For single speed, the “lowmount” option has the added benefit of not being in the way when you need to slide your wheel out the back to fix a flat.
Over the last couple of years I had played around with various designs but never really came up with something that I liked enough to have made. A few weeks ago, I found myself awake at 5 in the morning and decided to give it another crack. I felt that the nose bike deserved its owny own dropout, and decided that the time it would save me in production would be well worth the effort. I think I like these ones. I had a small run of them low taper waterjet cut.
If there are any builders out there that read this blog, I’m happy to send you a pair at cost (around $40 I think), if you feel like testing them out. They’re made of 3/16″ 4130, and I can supply them with SS faces if you want them (keeping in mind that if you use faces on the inside of the dropout you’ll have to pad out the caliper with a similar thickness washer to keep it in plane.. Of course a lot of disk calipers at this point have that much adjustment built in to the mount! so maybe not!) They’re made for 12.5mm SS tips, and CS tips of around 15mm (which is roughly where you end up if you shorten bent stays enough to keep the bend the right distance from the axle, if you follow me.. The dropout is pretty long on the CS end). The fender/rack tabs are 4.2mm blank holes.. the right size to run a 5mm tap through. They are beyond the plane of the back of the dropout, so if you don’t plan to use them, they’ll come off in about 30 seconds on the belt sander.
I haven’t tried them out yet. They just arrived yesterday. I’ll get back to you on whether or not they work.. whether or not I made some sort of bone headed mistake somewhere.
In other news, the bloody sciatica has been pretty bad lately. Bad enough that I tracked down a physical therapist and made an appointment. He determined that it was radiculitis and not, in fact, sciatica (“ridiculous” seems pretty apt to me!) a distinction that is determined by just how far down the leg the symptoms exist. He gave me some exercises to do. It has gotten significantly worse. In fact, by definition I’d have to say that now it IS sciatica! (beyond ridiculous, in other words).
I’ve been in discomfort now, in one way or another, for about three years. There’s a part of me that has just accepted it. Lately though, it’s occurring to me to be a little pissed off about it! I got pissed off about it enough to get proactive last week, and now I feel worse. GAH!! I went back to the PT yesterday to report. He seemed pretty stumped. I suggested amputation. He said that there were a couple of things he’d like to try first. We’ll see what happens.