Well the title should pretty much say it all, but here is a little background: After running my Maxi for a while with the stock drums and dealing with pretty crappy braking capabilities, I decided it was time to upgrade to a disc brake.
Well, everyone upgrades to a hydraulic disc, at least that I have seen, which seems like way overkill. A brake made to stop a 400lb bike going 70+ mph is not necessary on a 150lb bike going 70+ mph with a much shorter wheelbase. In fact, I thought it would be a bit dangerous, and a few people I spoke to (who have ridden hydro-disc peds) agreed.
I have ridden a few mountain bikes with manual discs, and they stop scary fast. So I figured if I took something that stopped a 25lb bike scary fast would be perfect on a 150lb bike. So I turned to Ted, who has a lot of experience in mountain biking, and asked his advice. We decided that it would be a great idea, and we would go halfsies on a set of Avid BB7′s with 203mm rotors, per Ted’s expert opinion.
Since I am running a spoked rim, it was going to be a little bit harder to get everything to work, compared with the mag rims, which you can just drill a few holes, slap it together, and bam! Done. I had a couple ideas on how to do things. Some better than others…
Ted is still working on getting his Gabbiano up and running after a sick frame redesign (keep your eyes peeled for his update when it’s done). But his will also be equipped with an Avid BB7 setup. Oh yeah, we are both running K10 hydraulic forks
Anyways, enough boring shit. PICTURE TIME!!!!
The hub was pretty nasty when I took everything apart, so the first thing I did was chuck the hub in the three jaw lathe and turn down the OD of that ugly flange in the center, as that was where I was going to press fit my disc brake adapter.
That is a picture of adapter V1.0. It is a 0.0015″ press fit on the flange, and I cut the chamfer in it so that there would be room to drop some welds. I figured with a few tack welds in there and the press fit, the thing would hold up nicely.
Took it to Starlite welding in Redford, MI (my usual spot for TIG welding) and had the guy drop a few tack welds in that chamfer.
Then I put it back in the mill, and faced it, drilled it, and tapped it to accept an M5 0.8 bolt. I had to face it on the mill so it was nice and flat, that way it could fit the spacer I was going to make.
I had to make a spacer so that the disc sat off of the hub a little bit. I had to do this so that there was room for the caliper to sit without hitting the spokes. A disadvantage compared to mags, but I love the look of spoked wheels.
Then I powder coated it gloss black. I know there is some dust and shit on it in the picture. And I didn’t really spend too much time prepping it because I just wanted to get the bitch done. It’s not really noticeable in person anyways. I kept the adapter raw so it remained flat.
Then I powder coated the spokes flat black.
Hanging them up each individually was a bitch, so I just put down a six-pack and did it. It made it more enjoyable, and they came out pretty decent.
Since the rim was chrome, I reverse plated it using a car battery, some hydrochloric acid, solid copper wire, and a car battery. Once the chrome was stripped, the Nickel and Copper came off in the sandblaster nice and easy. The acid also took of the rust.
Then I powder coated it flat black.
I left the nipples chrome and then reassembled the wheel. You can see my tapeline here. I left a little extra untaped for aesthetics, and to make sure the nipple didn’t run into the powder coat.
After Deadly Tedly gave me a quick truing job, it was ready to go back on the Maxi.
I’ve got my spacer sitting in place here. You can see the 12mm axle I got from Treats since I converted it to sealed bearing to work with K10 forks.
Put the disc on with some blue loctite, and the wheel was done.
With tire, mounted loosely.
You can see my spacer there. The spacer is just drilled with clearance holes, the M5 bolts have about 15mm of engagement on the spacer I made which is plenty. You can also see the little nub leftover that used to be the tab for securing the brake plate when using the drums. I had to grind it down to fit everything.
Now I just needed to make and weld a mount for the caliper.
Very very rough shape of the bracket as I figured things out.
Bracket cleaned up and welded on, unpainted. To weld it: I took the fork tube off the triple tree and drained the oil. Then I did about two 1/4″ long welds at a time on either end of the bracket. Letting it cool naturally in between each two welds. No quenching. This worked great with no warping of the fork tube until the very end, when I decided to lay down about 1.5″ of weld all at once. Because I was being impatient. Like an idiot.
I warped it just a tiny tiny bit at the very end of the tube, so there is a little bit of resistance. I’m not too worried, as I’m sure it will wear over time and also if everything is working right, it shouldn’t get to that very end part if there is enough oil. I can tell you though that this method works. Ted did it on his forks without warping. Ted is much more patient than me when it comes to welding, but I am learning.
So now it was all done, forks refilled with oil and time to test!
About the third time I squeezed the brakes I noticed nothing was really happening. I thought maybe the pads were glazed from the previous owner since Ted picked them up used on eBay. I rolled the bike back inside and held the brake while pushing the bike by hand. The rotor wasn’t moving, but the bike sure fucking was. Yep. Snapped all six tack welds and shredded the press fit.
That sucks. Back to the drawing board for V2.0.
I took some cues from the mag guys and blended those up with my own initial theory and came up with the following:
Yes, another adapter. This one is 1″ deep with a step cut half way through. The smaller diameter will press fit where the old adapter was press fit (after I cleaned it up on the lathe) and the bigger diameter was put in there to clear the little bracing ribs inside those spoked hubs if you’ve ever looked down in one without the brake plate on. The overall OD of this was also a very mild press fit into the ID of the hub itself. I made it 1″ deep so it would clear the weird taper on the center of the hub and I could drill into it like the mag dudes do.
There it is pressed in. You can see it is sitting a little proud, but that’s fine. I need to put it in the mill to get my bolt circle drilled, so I’ll face it while it is in there. But first to drill and tap the sides perpendicular to the face to hold it down.
So then I swiss cheese my hub like a fucking asshole. Head in the damn clouds. Ugh. Whatever. It is ugly, but I powder coated it so you can’t see the holes as easily, and I’m not worried about the structural integrity. It should still be really tough. The hole in the top left is where it is supposed to be. There are three of them around the hub and my adapter is tapped to match and fit M5 0.8 bolts.
So now onto V2.5 with the right goddamn holes drilled and tapped.
So now to break, I would have to overcome the shear strength of three M5 bolts with about 15 threads of engagement. Pretty much not happening. So then I faced it, drilled and tapped it to work with the spacer I made, put it all back together, had Ted true it again, blah blah blah, and put it back on the bike.
Pleas excuse my lack of headlight and fairing, the bike is a bit naked in this picture. But there it is all remounted. Time to go out for testing again.
Didn’t even make it out of the shop. V3.0 now has a METAL brake lever instead of PLASTIC. Man, I’m a jerk sometimes.
Stops like mad. If I lean back hard enough I can skid the front tire. It is plenty strong. In fact it makes me wonder how people with hydro discs don’t go ass over tea kettle more often? I couldn’t imagine how much those things grab. I’ll have to check someones out a rally this season. I feel VERY confident with this setup. We will see if I experience any brake fade on longer city rides when it gets warm enough out to have longer city rides.
Ted picked up the front and rear calipers and both rotors for I think, like, $50 used on ebay? And they are in great shape. We are gonna replace the pads though, because they are a bit worn, and inexpensive to replace.
Overall, I’m very pleased with the performance and price and look. Thanks for reading.