i have a new rigid tandem, mtb, w/ disc mounts f/r. i'd like to set it up w/ disc brakes for some serious road descents, but keep it low $$$. the 48 hole rhyno lite wide rims (i have a pair of 2.5" hookworm tires) look fine, and leave me the option of going back to rim brake if nec. are 14ga spokes better, or should i look @ the double butt 13/17/14's, or whatever they are? 3x or 4x? i'd like to avoid the big $$$ hugi et al hubs, can i just use the cheapie shimano rear tandem 145mm hub w/ a santana disc adaptor? (i heard they make a disc adaptor that threads onto the arai drum threads on the left side of non-disc hubs). are these kooky? if so, i'll spend the $$ nec. for the right hub, and realize the stouter ratchet engagement of these higher end hubs might be a necessity.
what about using an XT rear mtb hub w/ longer axle and spacers? since these are 36 hole max?, is that ever enough spokes? i plan on mostly road stuff, little fire trailing, maybe some singletrack, but in general my off road skills aren't sufficient to challenge most setup's integrity.
also, i've heard some stuff about tandems w/ front discs ripping out the axle or breaking off fork dropouts... is this mainly off-road? again, i'm not an air-person. mine won't take a 20mm through axle, but i'd sure be willing to pony up some $$$ for one (26", steel, rigid fork that's 20mm t-a capable), anyone know of who might build such an animal? i would also be willing to convert my f. hub to solid axle if nutting it would reduce chance of tear-out.
i want the absolutely burliest setup, couldn't care less about weight. i weigh close to 200, wife is 135, friends are similar to me, so not putting ridiculous loads on the bike. i do want it solid though, as i'm shooting to take it down monitor & ebbets passes in the sierras. if anyone has any experience with disc stuff on tandems and/or this type of dowhilling, i'd love to learn what you've learned. don't gotta be a rocket scientist to figure that this is an area where "learning the hard way" ain't gonna cut the mustard.
thanks for any help!
The BikeForums Team
-adv-
This is an archived thread, you can find the full version of this thread, with images, links and more content here.
Basically, if you avoid the 203mm rotor up front, your standard axle will be ok. Do a search in the Tandem threads if you want the whole explanation on why it's not a good idea with a standard quick release. We use an XT disc rear hub, as we specified standard 135mm spacing when we had our frame built. We're probably about the same weight, and abuse it off road, but high speed on road is a bit different. Do you want to stop the bike, or slow it down on steep hills? Discs are for stopping, drums are for allowing a controlled speed going down hill. Big difference. We have 203mm discs front and rear, and we can stop quickly, but the system would overheat if we tried to use the brakes to control our speed on a steep hill. How are those hookworms treating you? I want to try a set, but they're pretty pricey over here.
TandemGeek
i have a new rigid tandem, mtb, w/ disc mounts f/r. i'd like to set it up w/ disc brakes for some serious road descents, but keep it low $$$. ...i want the absolutely burliest setup, couldn't care less about weight.
Based on everything you've said (cost, weight, bomb-proof), I'd recommend that you install an Arai drum brake set up as a drag brake and operated using a thumb shifter. It's relatively cheap, removable, and bomb-proof. As for tandem wheels, always use double-butted spokes. Like all bicycle wheels, the larger the flange the stronger the wheel and the more spoking options you have available, e.g., you can 5x a 48h wheel with a large flange hub. You'd be hard pressed to do more than 3x on a low-flange 36h.
As for the discs...
You could do a disc set-up and, yes, a thread-on disc adapter manufactured by Dimension is available and works just fine. Of the hubs you've mentioned, the Shimano Tandem hub would most likely fit the requirments you've outlined (cheap & durable enough). However, you would need to discuss wheel compatibility / disc caliper mounting with someone like Mark Johnson of www.PrecisionTandems.com or one of the other tandem speciality dealers who is familiar with your brand of frame and disc brake installations to find out what, if any, special adapters might be necessary to ensure you have all the right bits for a 203mm Avid BB7 disc brake installation, noting that a 203mm rear brake kit is not a standard item sold off the shelf.
As for the front fork, so long as your frame manufacturer has indicated that the fork sold with your tandem IS rated for use with disc brakes (don't assume, always verify... noting that some of the C'dale Moto FR Tandem forks that have disc brake tabs AREN'T suitable for disc brake use), a 203mm disc brake kit could probably be used with a QR skewer so long as the fork dropouts were oriented down and/or down and forward, has an axle retention system, e.g., lawyer tabs or recessed nut flats, and a beefy steel QR skewer like an Shimano XT model was used. However, you would need to be very diligent about checking your QR tension before and after any ride to make sure it was super tight when you start your ride and did not "shift" or loosen in the drop-out during your ride. The latter is indicative of a potential problem where brake torque is trying to pull your front wheel loose. Replacing the front QR axle with a threaded/bolt-on axle would certainly be an option; however, you'd still need to verify proper tension before & after each ride and I'd recommend putting some alignment marks (paint) on each nut and the drop-outs so you could "see" any evidence of axle shifting.
Edited: Substituted Arai for Avid
simsi
TandemGeek
I assume you mean an Arai drum brake? As far as I'm aware Avid don't make one, but I may be wrong.
Ian
TandemGeek
I assume you mean an Arai drum brake? As far as I'm aware Avid don't make one, but I may be wrong.
Yes; sorry about that... Not the first time I've fubar'd that one.
stapfam
also, i've heard some stuff about tandems w/ front discs ripping out the axle or breaking off fork dropouts... is this mainly off-road? again, i'm not an air-person. mine won't take a 20mm through axle, but i'd sure be willing to pony up some $$$ for one (26", steel, rigid fork that's 20mm t-a capable), anyone know of who might build such an animal? i would also be willing to convert my f. hub to solid axle if nutting it would reduce chance of tear-out.
i want the absolutely burliest setup, couldn't care less about weight. i weigh close to 200, wife is 135, friends are similar to me, so not putting ridiculous loads on the bike. i do want it solid though, as i'm shooting to take it down monitor & ebbets passes in the sierras. if anyone has any experience with disc stuff on tandems and/or this type of dowhilling, i'd love to learn what you've learned. don't gotta be a rocket scientist to figure that this is an area where "learning the hard way" ain't gonna cut the mustard.
thanks for any help!
I run Disc brakes on a Mountain Tandem and I have the 200mm disc on what is a very effective disc brake system. (Hope mono M4's) When I initially fitted this system, I was using Quick Release and I was worried about the contortions the forks were going through under braking. The Flex they were taking was horrendous, so I changed to 20mm axle, which gave me peace of mind, but these were on a far stronger triple crown fork that also stopped the flex. If I had gone to a more conventional 180mm disc, I may not have had the problem, But I wanted and got one of the most effective brake systems it is possible for a Tandem. The fork manufacturers were not worried about the QR on 180mm discs but deferred judgement with the 200mm.
Braking with disc brakes involves a different technique. You build up speed to your maximum, and brake hard. Bring the speed down and release the brakes. when the speed builds up again, then repeat the process. They are not a drag brake. Continual application will create a lot of heat, wear out the pads, overheat the disc and then the pads, and even overheat the brake system causing fluid to boil(At the extreme) or create a weak spot in the hydraulic piping. (At the even more extreme, particularly when couple with a possible damaged pipe).
Cable disc brakes will eliminate the fluid problem, but I am afraid that they have to be a quality unit to come up to grade for a Tandem, so no cheap special offers or end of line will be suitable. If a cable brake is any good it will be in demand and will not be sold cheap.
There is not a cheap way of Changing to disc brakes. It will include the units themselves, and probably new wheels. If more effective braking is required then look at the Magura hydraulic Rim brakes. Very effective units that may cost new ceramic rims to save wearing out rims, but very effective for road use, and will allow a rear hub brake to be fitted for a safety margin. They will also not affect the forks either.
If you still want to go disc brake, then Email or PM me and I will sent you the details of my conversion on the Dale MT that was done last year
Brian
Cable disc brakes will eliminate the fluid problem, but I am afraid that they have to be a quality unit to come up to grade for a Tandem, so no cheap special offers or end of line will be suitable. If a cable brake is any good it will be in demand and will not be sold cheap.
Avid mechanicals. The only tandem rated mechanical as far as I know. We use them with 203mm XT rotors, and they do the job quite well. They also make breaking down/assembling a coupled frame that much easier.
bikertemaster
rhino lites would be great because they are HEAVY duty rims.HUGI makes some good tandem hubs but expect to put out some$$$$$$$ for them.as per spokes 14 gauge would do fine if you don`t plan on intense riding-IE mega big drops and rocks/people that you might run over. :eek:
arboc!
there not that expensive... look @ DeeMaxs, $650 for a pair!