Magura brake installation and adjustment instructions for HS22 and HS33 brakes.
Couple of you asked so this is what I wrote up for installing Magura rim brakes on unicycles. see below and the attached word file.
Magura HS33 and HS22 rim brake installation and adjustment
Unicycles
March 2011
Installation:Magura rim brakes take more time to install and adjust than other types of rim brakes and this can be a frustrating process for first-timers. Plan on spending 20-30 minutes to get them adjusted where you want them. Once they are all dialed in, they should be close to maintenance free.
- Unicycle manufacturers are notorious for poor quality control on the wheel builds and you may find that even a brand new wheel may need some work before you can install brakes. Start by making sure that your wheel is true, centered in the frame, there are no broken or bent spokes and the spoke tension has been brought up a little higher than the average bike wheel. This may be a good time to get your local bike shop to true it for you or download Sheldon Brown’s wheel building/truing advice at: http://www.sheldonbrown.com/tooltips/truing.html
- Check to make sure that your rim’s brake track is free of burrs and deep scratches that could tear up your brake pads. If your rim’s brake track is powder-coated, this will rob much of the performance from your rim brake. Anodizing is fine, but powder coating may need to be sanded off of the brake track if you find that it keeps the brake from working properly.
- Clean all the dirt out of the brake mounting holes on the frame with q-tips and rubbing alcohol. If you find that brake mount bolts won’t thread into the holes easily by hand, the threads are likely clogged with powder-coating/paint (very common). Don’t force the bolts into powder coating clogged mounting holes. Though it is a TOTAL pain in the ass - and you can curse your unicycle frame manufacturer all the way to the hardware store, the holes need to be carefully cleaned out with a metric tap (use cutting oil too) and the dried powder coating debris cleaned out with q-tips/alcohol.
- Lightly grease the four bolts.
- Install the pads on the slave cylinders. They snap on and off easily without tools.
- Install the mounts and slaves on the frame with the four bolts, leaving the bolts finger tight. You will want to move the black plastic resin rings around on the slave cylinders to adjust the distance between the pads and the rim. New resin rings will slide in or out easily over the ribbed surface of the slave cylinder, but the used rings will take a “Set” from these ribs and won’t want to slide over the ribs as easily. In order to slide/move used resin rings, you may need to remove the slave cylinder from the mounts, move the ring with your fingers and then reinstall the slave cylinder in the mounts.
• To avoid nuisance brake pad rubbing from wheel and frame flex, I have found that it is best to set the slaves/pads as far from the rim as you can, while still allowing the lever blade to have the braking effect you want.
• If you have a habit of idling on one side, you might set the low pedal side slave/pad further from the rim than the high pedal side. - Most riders want the brake pads to hit the rim square, without any toe in or out and the slave cylinder piston at about a 90 degree angle to the rim brake track. Test ride to see if the brakes squawk or chatter. Readjust the mounts/slave cylinders if needed and make sure the mounting bolts are tight enough when you are done to keep the slave cylinders from moving around.
Making your Magura rim brake last forever:1. For under saddle mounting of the HS33 and HS22 levers, you may want to position the lever body as far back toward the seat post as possible to keep the lever from getting damaged in hard UPDs. Also remember to wrap the brake line one or more times around the frame neck/seat-post before you install the lever. You may also want to adjust the small 2mm Allen sets crew on the lever blade so the lever blade sticks out less and rests closer to the underside of the saddle.
2. For the HS33 levers, you might want to try to ride with the Red Turbo Pad Adjuster (TPA) wound up “into” the lever blade as much as possible (this leaves the brake pads out as far as possible from the rim). The TPA is a nifty device that is designed to give you some on-the-fly adjustability of how close the pads are to the rim, but if you ride with the TPA wound “out” (this drives the brake pads toward the rim) from the lever blade more than a full turn or two, the TPA has a small threaded rod that is more likely to break or strip in a hard UPD/crash. The real bummer is that that little TPA threaded rod used int he 2004 style HS33 levers has an unusual fork shaped end on it and isn’t made anymore by Magura. I only have a few replacement TPA rods here in my parts bin in Portland.
The two reasons that you’d be tempted to wind the TPA “out” are when you have a slow fluid leak or the brake pads are getting worn down. Find and fix the fluid leak and re-bleed the brake and get into the habit of adjusting the slave cylinders in the four bolt clamps when your pads are getting worn, which for unicycles shouldn’t be a frequent need.
Other helpful tips:
• Pads that are worn/dirty/oily can be cleaned with rubbing alcohol and the faces can be sanded with sandpaper if the previous wear is uneven. Black and red pads perform the best for most unicycle rims. The Green and grey pads are too hard and yellow/clear trials pads usually grab too hard.
• You don’t need to worry about using a brake Booster (that metal horse-shoe shaped thing that bikers use when they install rim brakes) for unicycle frames. They are usually overkill for the relatively small braking forces involved in unicycle braking. Also, the mounts for v-brake posts are not suitable for unicycle frames (unless your frame is a late model Coker and comes with v-brake posts). You will need the Magura four bolt mounting brackets that Unicycle.com sells.
• The mounts sold by Unicycle.com sometimes come with bolts that are maddenly too short to thread into your frame brake mount bosses (Nimbus frames seem to have this problem more than others). You may need to buy longer (5mm) metric Allen head stainless steel bolts to replace these. Interestingly, if you need these 5mm longer bolts for the Nimbus 36 frame, the small tubing diameter used in that particular frame makes it necessary to shorten/cut down these bolts about 1/16” or they will bottom out on the frame tubing under the brake boss. You will see what I mean if you watch the ends of the bolts as you tighten them down.
• Crossover tube length: If the crossover is too short there will not be enough room between the tire and the crossover, and the crossover is likely to get wiped out by tire debris. I cut the plastic tube part of the crossover to different lengths for different frame/tire combinations:
*KH24, KH26, KH36, Nimbus 36, all Nimbus MUNI, all Hunter frames: 10” crossover tube
*Surly Conundrum and Nimbus 36” frames: 12.5” crossover tube
*If you do need to replace a broken crossover tube, use heat/flame to soften the tubing. DON’T use a knife to remove the broken tube ends form the barbed fittings (the fitting will leak due to knife cuts). I have new crossover tubes/fittings for sale. I also sell Magura bleed kits, olives, fittings and tubing.
Contact me if you have questions,
Brycer1968
uniflasher@hotmail.com
