Disc brakes for Tandems

[barriecartledge]

Despite Thorns refusal to fit Disc brakes on Tandems and their advice not to do so, I still went ahead and ordered a Bob Jackson Tandem with Hope Hydraulic Disc brakes.

After 2 years and 4 Summer Tours I can report that the brakes have behaved impeccably and that my rims are in mint condition, I have not had any trouble with them and can highly recommend them to anyone considering fitting them.

Perhaps Thorn dont want superb all weather braking with no rim wear, I do!

Barrie Cartledge

[TimCPike]

Do you have a road fork?

I can see how they could do a good job on the back wheel, but the momentum of a tandem and a nice bendy road fork with all the breaking power happening at the end of it could be disastrous. It was that thought that meant we have canti's.

If you stuck a rigid mtb fork in that should take the strain, but then you've lost most of the vibration damping. You pays your money you takes your choices...

[barriecartledge]

No, the front fork is a very powerful mtb fork and the tandem has 26inch wheels and living in the Yorkshire Dales, we have very steep hills and no one descends faster than us.

The braking and damping are superb so no problems whatsoever, I am also a racing cyclist of many years and have lots of experience of bike handling both on and off road, indeed my wife and I organise cycling holidays based on our self catering cottages, so the tandem gets used a lot.

I can highly recommend to anyone hydraulic disc brakes for a tandem with 26 inch wheels and built with mtb forks and the very best headset available (The latter should be used on any tandem, regardless of types of brakes)

quote:Originally posted by TimCPike

Do you have a road fork?

I can see how they could do a good job on the back wheel, but the momentum of a tandem and a nice bendy road fork with all the breaking power happening at the end of it could be disastrous. It was that thought that meant we have canti's.

If you stuck a rigid mtb fork in that should take the strain, but then you've lost most of the vibration damping. You pays your money you takes your choices...

[TimCPike]

Disc brakes were tempting, but the eventual decision of a road fork, 700c wheel... forced us to abandon the idea.
Having decided on those components we needed a suitable rim-braking system. No problems so far and the Suntour SE canti's let us out-break most other bikes.

[Chris Land]

I have been talking about this recently with respect to a tandem trike we were thinking of getting.  The main issue seems to be that a disc has a much smaller circumference than a rim and they can overheat quite easily, giving the potential for the disc to warp and lock on.  I can't remember who it was, but a few years back a tandem manufacturer went bankrupt after being sued when someone went off an alpine pass when this happened.  Perhaps this is one of the reasons folk at Thorn (and other places) are reluctant to use discs on theirs?

[barriecartledge]

Dont be fooled, rims can heat up quicker than disc brakes and when they do they usually go with a very loud bang and can land you in deep trouble.

Modern hydraulic brakes are fantastic and here in the Yorkshire dales with gradients of 1 in 3 we have had no problems at all.

Personally I think that reluctance to use them is purely based on hearsay rather than experience, ask Robin Thorn if he has ever used disc brakes for any length of time, if he had, then he would have no problem recommending them.

For my style of fast riding, I would chooes nothing else.

quote:Originally posted by Chris Land

I have been talking about this recently with respect to a tandem trike we were thinking of getting.  The main issue seems to be that a disc has a much smaller circumference than a rim and they can overheat quite easily, giving the potential for the disc to warp and lock on.  I can't remember who it was, but a few years back a tandem manufacturer went bankrupt after being sued when someone went off an alpine pass when this happened.  Perhaps this is one of the reasons folk at Thorn (and other places) are reluctant to use discs on theirs?

[barriecartledge]

Of course everyone has their own opinion, i am just sticking up for disc brakes when everyone else seems to be putting them down.

By the way Robin Thorn does not recommend 700c wheels also!!!

quote:Originally posted by TimCPike

Disc brakes were tempting, but the eventual decision of a road fork, 700c wheel... forced us to abandon the idea.
Having decided on those components we needed a suitable rim-braking system. No problems so far and the Suntour SE canti's let us out-break most other bikes.

[reaganjj]

I have been using an Avid mechanical (regular mountain bike) disc brake on my mountain frame (road bar/lever) tandem for 1 year with no problems.  Before that, I had several violent tire blowouts due to rim heating when using just V-brakes.  Even without blowouts, I would find melted tubes that where glued to the tire walls.

Adding a disc brake was safer for me at least in the last year.  I now see companies like DaVinci using Avid Disc brakes.  They use 203mm rotors.  Mine are just 165mm.  I would guess that 203 mm rotors can tolerate more heat before failure (everything fails at some point).  Does anyone have any experiece with these brakes?  If so, do you know where to buy them?

I use only a rear disc brake and continue to pump heat into the rims to share the braking heat load.  I am always worried about rim failure due to wear.  Only one season of moderate use shows visable rim wear.   I am going to invest is a micrometer to help me keep track of wear.  Having a rim split open will likely cause a terrible crash. I worry because I use 100-lb 1-inch slick mountains tires on the road.

I have heard of even single bikes that tour with saddle bags have had tire blowouts on long steep hills.  Probably all bikes will have disc brakes someday when the technology is proven and cheaper.

I use 48 spokes on the back to reduce the stress on the spokes caused by the disc brake.  There are extra forces that a disc brake causes that transmit the stopping force through the spokes.  Maybe 48 spokes are overkill, but I feel safer with them.  I would not go less than 40 spokes in any case.

I bought an adapter that coverts a drum hub into a disc hub.  It works great.  It just threads onto the drum threads and mounts a 6 hole disc.

Cheers,

John  

[reaganjj]

I did find the 203mm rotors.  They are downhill rotors and Avid sells an adapter to fit a 165mm caliper to a 203mm rotor. The downhill rotors come with more vanes (spokes) to increase strength and the extra diameter should help with heat dissipation.  If the 165mm worked with the punishment I gave it, the 203mm should be even better.  I am also going to try the Avid road brake caliper.  The 203mm rotor may not work with the 160mm designed road caliper.  I will let you know how things work out.

I found all this stuff at:

http://www.aebike.com

http://aebike.com/site/page.cfm?PageID=30&SKU=BR6959

http://aebike.com/site/page.cfm?PageID=30&SKU=BR6907

Chow,

John

quote:Originally posted by reaganjj

I have been using an Avid mechanical (regular mountain bike) disc brake on my mountain frame (road bar/lever) tandem for 1 year with no problems.  Before that, I had several violent tire blowouts due to rim heating when using just V-brakes.  Even without blowouts, I would find melted tubes that where glued to the tire walls.

Adding a disc brake was safer for me at least in the last year.  I now see companies like DaVinci using Avid Disc brakes.  They use 203mm rotors.  Mine are just 165mm.  I would guess that 203 mm rotors can tolerate more heat before failure (everything fails at some point).  Does anyone have any experiece with these brakes?  If so, do you know where to buy them?

I use only a rear disc brake and continue to pump heat into the rims to share the braking heat load.  I am always worried about rim failure due to wear.  Only one season of moderate use shows visable rim wear.   I am going to invest is a micrometer to help me keep track of wear.  Having a rim split open will likely cause a terrible crash.

I have heard of even single bikes that tour with saddle bags have had tire blowouts on long steep hills.  Probably all bikes will have disc brakes someday when the technology is proven and cheaper.

I use 48 spokes on the back to reduce the stress on the spokes caused by the disc brake.  There are extra forces that a disc brake causes that transmit the stopping force through the spokes.  Maybe 48 spokes are overkill, but I feel safer with them.  I would not go less than 40 spokes in any case.

I bought an adapter that coverts a drum hub into a disc hub.  It works great.  It just threads onto the drum threads and mounts a 6 hole disc.

Cheers,

John  

[reaganjj]

I would like to give my impression of the warpping rotor crash given above:

My 165mm rotor gets very hot - probably red hot.  It does warp slightly.  All that is needed is a slight push back to get it into condition again.  A rotor warps as it cools.  It seems unlikely that a rotor would warp suddenly and stall the wheel.  I could picture other failures like a rotor vane breaking and cause a failure or caliper parts melting and causing a lock-up, but not a suddenly warped rotor.  A red hot rotor would tend to re-find its center while spinning IMO.  All this is just my imagination working here.  I have no first-hand knowlege, but am very nervous of bike part failures.  It makes me more nerviuos knowing that I am not the only one that will get hurt if a failure occurs.  I encoruage everyone here to share any hazard information - heresay or not.

John

[Paul]

Its interesting reading your discussion folks (sorry to join the party late).
To add more momentum to the argument....I have a tandem that runs two v-brackes and last spring whilst coming down a rather steep hill in fine damp British weather we experienced a major blow out on the front wheel. I say major as the front tyre blew off and wrapped itself around the front fork. The resulting sudden jam threw my stoker off and she suffered a fractured eye socket and concusion etc. The failure as I understand it was caused by rim wear (minor), overheating of the rim as we were braking continuously for about 2 minutes (not a great deal if you ask me), tyres that were inflated with a hand pump and possibly old tubes (2 years old). No definative answer there, but perhaps some clues??? I believe it to be related to the rim wear and possible tyre inflation (done with a hand pump only).
The problem with rim wear as I see it in this country is it probably happens very quickly and could therefore happen again. Ever since then I have been actively looking at tandems with disc brakes and I find it quite annoying that very few will fit disc brakes front and rear.

I have read about a number of the issues as to why people like Thorn won't fit disc brakes and I have simple can not understand it. My stoker would certainly get a lot more confidence when riding if she knew the rims were unlikely to heat up and cause further facial injuries.

One question for you if I may. I notice your post came from the states. I have spoken to Santana (USA) recently and they are of the view that the optimum brake setup for a tandem is one v at the front and one disc at the back. The more I look into it, over here in the UK, most manufactures recommend two main brakes and one additional drag brake at the rear, probably as a result of our damper environment. It would also appear that it is only the smaller companies who will fit discs to custom builds. Please correct me if I am wrong.

Anyone know of any manufacturers that fit disc brakes to a road tandem at the outset?

[TimCPike]

Roberts in the UK will fit disc front and back, on a steel road fork. Cannondale do as well, though they use a rigid fork.

I'd opt for a disc brake if you use a rigid/mtb fork. The thought of all that stopping power being applied to the end of a flexible steel fork doesn't fill me with confidence though.

[John]

We live in the Pyrenees and race a 700C tandem in cyclosportives over Tour de France cols - Neither disc nor rim brakes are up to the job on their own as both overheat with equally disasterous consequences. Use both and deep profile rims which dissipate heat better especially if they're black. The simplest solution which works is rim brakes with a Shimano Nexave roller drum brake at the rear. Use the Nexave to slow down and the rim brakes in the tight bends. The Nexave gets very hot but still works and the stoker can tell you when the escaping boiling gease indicates you're overdoing in. My well trained stoker sprays water on the thing.

Even used in conjuction with rim brakes a Hope disc warped and rubbed thereafter.

An ex-pro mate clocked 105km/hr down the Tourmalet. Two rim brakes and a hope disc for stoppers were only just up to the job - His Michelin tyre was unglued at the bead but had stayed on.

[John]

I've tried a couple of disc brakes over the summer both on mountain tandems.

A Hayes Hfx9 dh 203 mm on my KHS which works well but consumes pads at about 40km intervals in wet and muddy conditions. It works well hot or cold and is the best disc brake I've used to date. I run a Dirt Jumper fork so there are no V-brake mounts.

A Magura Julie 170mm on a Cannondale. Frankly not a tandem brake Cannondale. Not even a solo brake in my opinion given its viscious nature cold and fade when hot.
The grabbing could have been caliper allignement but I think not.

[Si Davies]

I've been thinking about a disc for our Burley when it comes out of hibernation again.  Don't want a front one because of the cost: braze a mount on + new wheel.  But the back shouldn't be too bad as I've seen an interface to fit a disc rotor to the existing drag mount on our rear wheel, plus there are several clampon mounting brackets for the caliper.

If this was a solo I wouldn't bother because the rear wheel adds very little to the overall stoppage of the bike.  But on a tandem - where the weight stays further back under braking - I think this oughta be of benefit.  

Does anyone share this view or do you think that a rear disc would have little advantage over the current Vs?

Bear in mind that we don't need the new brake for slowing down on big hills, but rather for more control in mad Brummie traffic...