I have a Nightrider 36er, and I was planning to put a v-brake on it based on ideas in this thread.
The brake which I ordered, an Avid SD-3, arrived today, but it doesn’t fit as well as I had hoped. There are two problems:
It only has 102mm arms, so doesn't clear the top of the tyre by as much as I'd like. This is an easy fix, just find a brake with longer arms (some are listed as 107mm).
It seems like the rim is too wide (42mm) for this particular brake when it's mounted on the bottom holes of the Magura mounts. The sections where the pads mount aren't parallel by the time the pads are hard up against the rim, and the tops of the arms are sticking way out. It's even worse when the brake is in the "off" position.
Does anyone who’s done this before know of brakes which fit a 42mm rim? I’d prefer one which curves inward towards the top to follow the frame profile. I realised today that other unis which can take v-brakes stock (Coker and QuAx) use narrower rims which probably makes this less of a problem.
Another thing that occurred to me is that I’d need to remove both brake arms when removing the wheel. Unhooking the cable won’t allow the brake to open enough to clear the tyre because the pads get caught on the frame. A bit of a hassle, but it is what it is.
I’m close to throwing in the towel and just ordering a set of Maguras. I already have a mounting kit which came with the uni ready to go. I’d go with an external disk but it’s extra expense for a new set of cranks and I’m not sure that I want the extra Q factor.
I used a Shimano Acera v brake on my nightrider. I chose it because of the long arms.
As for the spacing problem, i can only take a stab at it since there weren’t any 42mm 36er rims when I did it. If brake arms don’t open wide enough taking air out of your tire is more common than removing a brake arm. If you’re having this problem with V’s it is almost certain to be a problem with Maggies.
Did you use the small washer stack on the rim side of the pad mounting slots? The brakes come with a large stack, and a small stack so that you have some adjustment for rim, and frame discrepancies. The small stack next to the rim will allow the caliper to run more vertical.
FWIW, i hated maggies on my Nightrider. The frame was so flexy that when i would push hard going up hills the pads would rub the rim. V’s work much better, and to be honest a BMX caliper would be a better option to the Maggies.
Thanks for the reply. I was copying your arrangement but couldn’t figure out why there was so little room for movement. If your rim was narrower than 42mm then that could explain it.
I have the pads setup with the smallest washer stack. I can’t see how to move the pads outward any further unless I remove the washers altogether and lose adjustability or locate some thinner pads, if such a things exist. Is the horizontal distance between the pivot and pad surface the same for all v-brakes? I suspect that it’s part of the spec, in which case maybe they will never fit this particular rim.
I’ve tried to locate the Aceras previously but they’re getting hard to find (over here). I have one more place to try which I’ll follow up with if I can sort out the rim/pad spacing.
Well, you could try to mount them with all of the washers on the outside of the mounting slot. They don’t need to hit perfectly square to the rim, and in fact normally are adjusted to have a bit of “toe-in” to reduce noise. If they do run a bit more square to the rim they will be a bit more effective, and louder. Unless your stud is threaded all the way you will need to use the included orbital washers as spacers or you will run out of threads.
Yeah, it was losing the toe-in adjustability that made me reluctant to remove all the washers. I think I’m going to have to do it though to make it fit.
I’m going to keep slowly accumulating bits and pieces to make this work but I’m starting to feel less inspired about the whole thing now. It doesn’t help that the hills didn’t seem to bother me at all on today’s ride for whatever reason…
If the hills aren’t bothering you i think the brake is more trouble than its worth. If your goal is to use it as a drag brake to help manage descents i think the toe in isnt that important. It just doesn’t take much braking on a 36" rim to make a big difference.
In the end I made a disk brake bracket that bolted to my Nightrider, and I used a crank mounted rotor. That was really smooth, and much better modulation. I think rim brakes on the 36 tend to be a bit grabby. If you really want toe-in to help with detuning the grabbiness you could file the pads, or put a thin piece of shim on the back edge of the pad where it mounts.
Well, at the moment I’m running 138mm cranks but I have some 125mm spare which I want to try out sometime. I was originally planning on putting the brake on before the shorter cranks just in case any hills catch me out, but I’ll probably just try the cranks brakeless now that the brakes are proving a hassle. I’m not really in a hurry to downsize the cranks, I’m just curious.
About the brakes themselves, since I’ve only been riding the 36 for not-quite-two months I’ve enforced some patience on myself by ordering the remaining bolts and spacers from the cheapest possible source, which happens to be in Hong Kong. So I have about a month to wait. When they get here I’ll source some Acera or Alivio brakes (they seem to be the same as far as I can see) with 107mm arms and have another crack at it. If I lose interest before then it will probably just stay brakeless.
One day, most likely a few hundred miles into the future, I might look at disc brakes again once I have a bit more experience and a better idea of exactly what I want.
I do really enjoy riding by the way, not just endlessly debating the merits of different gear with myself. But if I didn’t play tricks on myself then I would never have even bought my first unicycle :p.
Here’s my setup. Used the Onza adapters that fit on the magura brake bosses, allowing you to run the V-brakes. They have plenty of braking power, are a fraction of the cost of Maggies ($19.95 for Shimano V-brake!) and set up and adjustment is FAR easier and faster than dealing with hydraulics.
No bleeding, no leaks, and customizing or changing cable length is a piece of cake. Also MUCH easier and faster to remove wheel by simply disengaging brake cable. You can also run the brake pads farther from the rim than maggies, and not lose any stopping power. This also prevents the pads from rubbing on the rim if it’s less than true.
No knee clearance issue. And I got these because I didn’t have any extra maggies to use on the 36er. But these V-brakes are so much easier and practical than maggies in every respect, not the least of which is the ability to adjust the pads in/out/up/down and any angle for optimum performance. And because they don’t need to be so close to the rim like maggies, any wheel/frame flex will not cause unintended pad contact with the rim. Oh, and at just $19.95, they are much, MUCH less $$ than maggies rim/disc brakes!
That’s been my thinking with a V-brake setup with Terry’s. I’ve had my eye on those adaptors for a while. I don’t need a brake even on the 36er, but I’d like to try one. V’s are easy to maintain too which suits me as a daily uni commuter.
I’m willing to take the chance. Seems other folks have had positive experiences with a v-brake over the long haul. Given that it’s such a simple and inexpensive option, I hardly have anything to lose for trying.
I’m currently running a U-Brake on my 32. It mounts on the same studs for V-Brakes on a 36 inch frame.
The disc is nice because it is very progressive in the way it grabs, a rim brake can be a bit too much; however, it has a lot of tuning/detuning that discs don’t have. Maggies are the only brake that I have which I don’t really like. They are either on or off, and not much room for detuning (without mismatching levers/calipers).