How important is having a drag break?
 

Ok, I'm relatively new to tandeming, even though I've owned two (a Cannondale RT-2000 with V breaks and my current daVinci with disc). I ran into a friend of mine the other day on a ride out here in the East Bay and he and his lovely stoker were riding their new Pinarello tandem. Yup, that's what I said, a Pinarello! Here's a link http://www.precisiontandems.com/cat_files/pinarello.htm

I digress. He had disc breaks and a DuraAce road break and asked what was up with that. He said it's a drag break like I should've known. OK, I'll admit it, I don't know of the concept. I imagine it's to use as a back up. Also, the stoker had bar-ends to control the drag break.

What am I missing here and is this something I should add onto my daVinci??

What, no brakes?

Their Pinarello has two disc brakes and a single rim brake? And the rim brake is the drag brake?
I've not heard of using a rim brake as a drag brake; applying a little bit of drag for an extended time could cause the rim to heat up, couldn't it?

Here's Sheldon Brown's (rip) discussion of bicycle brakes and their uses:
http://www.sheldonbrown.com/tandem-brakes.html#hub

As for "should you add a drag brake", that's up to you. Are you constantly riding your main brakes on long, mountain downhills? Then yes, you need a drag brake. It's an overheating issue.

On that Pinarello, the caliper MUST have been the regular brake and the disc set up as the drag brake. Many will say that ONLY a drum brake is suitable for a drag, but (some? many?) do use a disc for it. Lots of factors ... length and pitch of downhills, weight of team, ability of the pilot, fearlessness of stoker, etc.

The hub on our KHS is threaded for a drag brake but we've never felt the need to add one; have done no loaded touring or mountain riding on this tandem. V-brakes have proven adequate on Southern Indiana hills.

Is a drag/3rd brake a necessity? Depends on your comfort level/ability/terrain/riding style.
Huge majority of drag brakes are drum brakes.
Having said that there are many ways to activate/control braking for 3-brake set-ups; from dual pull brake levers controlled by pilot, to a 3rd brake controlled by pilot via a 3rd lever or barcon shifter for drag b rake. Most often stoker will have a brake lever or a barcon shifter to activate drag brake.
Disc are not recommended as drag brakes, but if you have double calipers/V-brakes etal as main brakes, then a disc could be used for intermittent extra braking on long or wet descents; any 3rd brake could be just extra brake power.
Personally we get along fine with calipers, V-brakes, U-brake, or old style canilevers. Have used combinations of that without a 3rd brake and we're still here to write about after 35 years of riding in tandem. Yes, have done some hellatious descents at 50+ mph in the mountains. Have done 11 mile 6% curvy mountain descent with old Mafac cantilevers front and rear. We were told we coulds not do that by an 'expert.'
Again depends on the team's ability/comfort level.
Just our experience.
Pedal on TWOgether!
Rudy and Kay/zonatandem

Being a neophyte when it comes to drag brakes, why is a disc not recommended as a drag brake?

We have been riding about a year and there are several 40mph hills around here for a single bike. It was an eye-opener to me the first time we took the bike out for a ride, as the speed quickly zoomed up coming down a hill close to home where I usually hit 30+ on my single.

I installed a drum brake on our tandem after a couple of hundred miles. We went to the Smokey mountains last summer for our first big outing. As new riders, I'm glad to have the drag brake to supplement our V-brakes. The extra two pounds is no big deal to us for the type of riding we do. It's also real handy for a parking brake. If had a set of disc brakes, I might not feel the need for a drag brake.

If you have rim brakes and do long descents, especially if touring loaded, the a drum brake would be a good idea. However, dual disk brakes should be perfectly capable of handling the same load. One other reason for a third brake controlled by your stoker would be for her to slow the bike down!

If you do long descent with rim brakes, you can explode the tube/tire. Here is the physics lesson: V1xP1/T1=V2xP2/T2. Where V=volume, P=pressure, T=temperature. All you need to know. Heat up a gas (air) and it either takes more volume or increases pressure, or both. Brake on a long mountain descent, and you blow the tires off the rims. Not a pretty picture. Our drag brake is a rear disc. Controlled by SWMBO with a bar end. We have heated the caliper body to the point that the decals melted off, so imagine what our rims/tires would have been doing! The disc has the "blue" look of heated metal. However, we take the whole thing off unless we are in mountains. Local rollers don't count. Needed only for sustained descents. Multiple miles. Since this team lives in the midwest, we only put it on for trips to Europe or Mountain West/Northwest. Using discs as main brakes is just fine I guess, but anyway, having a drag on those big descents is very useful. Empowers stoker, a good thing over all. With drag engaged, speed under control, captain feathers the main brakes to get the speed just right. Our tandem builder recommended the disc as a drag, so don't fully understand comments about not being recommended, smoking caliper body not withstanding.

I used to covet a drag brake. Now I know if I had one, and used it, I might cause the tandem to crash. I trust cgallagh to control the bike; with a disk brake on the rear we have plenty of braking power. Ergo I think having one is unimportant.

The main reason for a drag brake in addition to rim brakes is to dump energy without overheating the rim. A drum brake has substantial thermal mass and cooling fins, and relatively heat-insensitive shoe(s). A disk, on the other hand, succeeds in not overheating the rim, but risks overheating the disk itself, as well as the caliper mechanism. The results of overheating a disk brake, depending on manufacture, include a warped rotor and molten plastic parts, to the point of no longer functioning as a brake (even after cooling).

As has been pointed out, with due care, it can be used as a supplemental brake, but is not appropriate as a drag brake where it is constantly on enough to slow but not stop the bike for minutes on end.

To the original question, Kay and Rudy, who've ridden without one for 35 years, are a light team. I've never used one either, but I do own one, and plan to use it for loaded touring in mountains. We had one descent this summer where I'd have just as soon had it mounted. No curves, just several hundred feet of drop at double digit percent grade, with a stop sign at the bottom. Did not blow any tires, but sizzling hot rims at the stop sign.

We're a mid-weight team, so I would only use a drag brake with a load, as kinetic energy (and hence heat to dissipate) is proportional to mass. And gravitational potential energy, which gets converted to kinetic as you descend is proportional to distance to descend. Which is why it depends on the type of riding and team weight. The other piece - stoker comfort level - has to do with what happens when you hit a curve at substantial speed since you couldn't dump enough kinetic energy without overheating as you approach.

Bob, you have to understand that, in the tandem community, any questions about such things as drag brakes, wheel building, cornering, or even changing a single component can (and usually will!), bring out the "pocket protector people"! (It must be rubbing off, though ... I actually understood what he said!)

Hey, if you have a handle that starts with "professor" you're leaving yourself wide open to this sort of abuse.

hehe! True that! :thumb:

Does the bike stop when you want it to? You've got disc brakes front and back. I doubt you need any more stopping power.

The only reason you'd want to add a rim brake to your setup is if you're putting so much load on the disc brakes that they are heating up to the point that they are fading and your not able to stop.

Unless you're doing loaded touring in mountainous terrain, or you really ride the brakes, I would doubt that your disc brakes are not sufficient.

Thanks to all. Since we don't tour but do a lot of climbing with descents, I think we'll be OK.

We are a heavy team doing a lot of steep riding with and without bags. Love our old Arai drag brake. Can't imagine life without one.

Pinarello Tandem - Braking Combo
 

Dan,

I apologize if my answer seemed as though you "should've known." That was not my intent. Perhaps from being near deaf from 22+ years of flying jets caused me to not hear your question correctly.

For the others reading this.... I am the Captain and 1/2 of the owners of the above mentioned Pinarello Tandem.

The bike came standard with Avid disc brakes on both wheels. I added a caliper to the rear wheel which I control with the right brake lever up front.

The rear disc was re-cabled and is now controlled by my "lovely stoker" with a bar end "shifter" (acting as a friction brake lever).

She ratchets in however much brake I call for. We use a verbal scale of 1 to 5. 1 being just a touch of brake. 5 being....give it all to me baby!

I like the drag/disc combo for 2 reasons.

1. We do climb LOTS of hills and therefore have long descents to contend with. Using the rear disc keeps us from overheating the rims.
2. My hands also fatigue on those long descents with prolonged braking and having the friction lever for the stoker gives me some much needed relief.

We have NEVER overheated a disc. They actually seem bulletproof to me.

If anyone has any other questions, let me know.

Jeff & Jo

http://gallery.me.com/jaguar508#1000...&bgcolor=black

http://gallery.me.com/jaguar508#1000...&bgcolor=black

Our input to a couple of above comments:

Yes, Kay and Rudy are a rather 'light' team at just under 250 lbs (that's total for the 2-of-us).

Have had fingers cramp up a bit on an 11 mile 6% very curvy mountain descent (Kitt Peak in southern AZ, 7,000+ ft. altitude) and had to stop half way down for a few minutes to relax them digits. Felt the rtims and they were warm (not hot) after on/off braking with old Mafac cantilever brakes. Finished the descent without any issues.
A lot also depends om your method of braking.

If your team feels more comfortable with a 3rd brake, by all means get one.

Just our experience . . .
Pedal on TWOgether!
Rudy and Kay/zonatandem

Jeff! Welcome to the forum! And I'm sorry we didn't have time to chat more on the tandem but you guys were busy fixing your chain.And No I didn't take offense at all. Thanks for the info. I'm still thinking about our seven mile descent we're gonna have in June on the way down to LA.

See you out on the road and beautiful bike. Congrats!

Ya know, for the life of me I have never understood people who buy high-end sports cars painted some dull, bland "earth tone". If you can afford to go in style, why hide it??!!

Same goes for bicycles, IMHO, and yours is a BEAUTIFUL ride!

If you have ever experienced serious brake fade then you will not go without a backup brake on a tandem ever again.

If you want a happy smoker you normally need to take drag breaks every five miles or so, normally about half way up each hill. Normally the wheezing lets you know when to stop. :)

Welcome to BF! Sounds like a good braking system and process.
I wish we had some up- and downhills around central Indiana so that I would need a drag brake.