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I have a Trek T 100 tandem, replaced the original cantilever brakes with Shimano V-brakes. I have never gone down a mountain with the tandem fully loaded, so I am wondering if I can plan a trip with a major descent (either asphalt of unpaved road). My wife and I together weigh about 150 Kg, a full load might be another 40 kg.
I have seen tandems rigged with an additional disc brake operated by the stoker, but my frame does not support a disc brake.
So, any advice on whether I can consider a major descent (lets say down to Santiago de Chile over the Andes?). Do I need a new bicycle or can I handle the descent with care?. Is an unpaved descent any worst or in a sense better (because I am not temped with speed)?
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I'm guess that what you saw was not a disk break but a drum brake. It should work on your bike and is probably exactly what you're looking for.
Check to see if your rear hub is threaded on the left hand side and if frame has a fitting along the left rear chain stay that looks like this...
http://www.precisiontandems.com/photos_files/pacman.jpg
If so, you should be able to acquire and bolt-on an Arai drum brake for your tour... and I'd encourage you to do so. An Arai is a supplemental drag brake that can withstand prolonged use and the associated high heat that builds up on long descents. You can learn much more about Arai drum brakes at Precision Tandem's web site: http://www.precisiontandems.com/arai.htm
Whether a descent is safe or not is will be determined by whether the brakes fail or not. This can be through heat overload giving a puncture for rim brakes or other mechanical failure for disc brakes, or the brakes simply wearing out because the brake pad material is used up. Given that the route you mention will probably have been successfully covered by others on tandems in the past, I would expect that a good set of well-adjusted V-brakes applied by an experienced rider should be fine. What you are probably worrying about is heat build up. The santana tests on tandem disc brakes indicate that rim brakes are better than most bicycle disc brakes in terms of heat dissipation.
Simple physics shows that heating of the brakes is determined by angle of descent, speed of descent and the weight you are arresting. However it's not that simple since rider A may apply the back brake only to to maintain say 15mph, while rider B will allow the bike to accelerate freely, regulate speed at 30+mph by braking hard with one brake only, and only decelerate to 15mph by braking hard for bends. All other things being equal, rider A will put much more heat into the brakes than B, mainly because A's energy will be disipated by increased wind resistance.
In my opinion there is a lot of scary talk about brakes x or y being suitable or unsuitable for tandem use. I believe most of this comes from the Santana brake tests, which showed that if you ride down with the brakes on continuously, almost all brakes will overheat and fail. That shouldn't be news to anyone, and anyone riding that way in practice would be foolish. The posting from Santana shows this - sitting behind a tractor with the brakes on down a hill until the brake fades is a bit stupid. Better to take a break (sic) by the side of the road until you can zoom down it.
http://tandem-fahren.de/Mitglieder/Christoph_Timm/components.html#brakes (Christoph Timm brakes page)
http://search.bikelist.org/getmsg.asp?Filename=tandem.9711.0546.eml (Santana brake tests and protocol)
Depends on how severe the hills are and what speed you are prepared to take them at. I do not ride mountains- up or down, as they don't exist in my part of the country. However I have taken some severe hills offroad for about 1/2 a mile that required the brakes on most of the time. The disc's were showing a dull orange glow by the end, and no loss of braking power. If I am braking that much- then it is a severe hill and I realise that. Now if I was talking about doing that sort of hill with panniers and rim brakes- I would take a couple of stops on the way down to allow things to cool a bit.
If the hills are that severe and I was touring- I would think about a drum brake. You can use this as a drag brake, which is not the way to use a disc. I use disc's front and rear, and these do not cause me a problem- but then As I have said- I am not taking in mountains.
Given that the route you mention will probably have been successfully covered by others on tandems in the past, I would expect that a good set of well-adjusted V-brakes applied by an experienced rider should be fine.
For what it's worth, I would make no such assumptions and would only make a recommendation on a descent that I had personally made under similar conditions or had reliable reports from others of similar size/experience/equipment who had made the descent. Granted, any descent can be made on any bike if you are careful and opt to stop frequently or perhaps even walk the most challenging sections. However, with the foreknowledge that you will have a tandem carrying in excess of 400lbs of riders and gear and that you will be encountering long descents on a self-supported tour, a supplemental drag brake is cheap insurance.
Moreover, if a tandem team plans to tour in areas where they will encounter descents on unpaved or unimproved roads -- as was noted by Xanti Andia in his last sentence -- then a supplemental drag brake is absolutely recommended.
What you are probably worrying about is heat build up. The santana tests on tandem disc brakes indicate that rim brakes are better than most bicycle disc brakes in terms of heat dissipation
You may need to check your sources and timelines on this last comment. The description of the brake tests that you attempted to link to at Hobbes was made back in 1997, a few years before Santana even began to offer its Formula rear disc and before the Avid BB7 began to make appearances on tandems. I don't believe that Santana or anyone else has ever made the case that rim brakes have more heat capacity than the current mechanical discs or the reliable Arai drum brake. While all three types of brakes will suffer from fade due to outgassing as the brake pad materials overheat, only the overheating of rim brakes carry the risk of a tire failure which, depending speed and conditions, could cause a serious crash. Overheating the other two types of brakes can certainly do damage to the components under the most extreme conditions, but as they are used well into fade condition and overheat they don't create a secondary crash condition like a rim brake will. Moreover, you'd really have to knowingly abuse the heck out of a disc or drum before they'd fail catastrophically (mind you, we're talking mechanical discs, not hydraulic which are more succeptible to catastrophic failures) as both types of brake devices will provide tactile, audible, and in some cases visual or aromatic indications that failure is imminent.
In my opinion there is a lot of scary talk about brakes x or y being suitable or unsuitable for tandem use.
I don't necessarily disagree, but only to a certain extent. There have been many different brake tests and reports that have been less than useful when applied to real-world riding conditions. However, there are also many real world examples of brake system failures, the most prevailent being tire blow-offs due to rim heating from rim brakes. There are many other types of failures and I would note that we have experienced both total rim brake fade while riding off-road on some very fast fire road descents (more specifically, the rear brake pads melted and the rubber was deposited on the stoker's seat post) as well as hydraulic brake system lock-ups. We have come close to 100% rim brake fade on our road tandem while attempting to get the bike stopped after encountering some unexpected road damage on a very steep and fast descent and are still unsure why our tires didn't blow off the rims given that we run relatively narrow (23mm and 25mm) tires.
Hence, the search for the "better tandem brake system" continues. However, through it all the Arai drum has remained the defacto supplemental brake for loaded touring or heavy teams that will encounter challenging descents. The new mechanical disc brake designs are beginning to earn a fairly good reputation among sport riders for being an excellent compromise brake system that don't necessarily need a supplemental drum brake, but who want a brake they can abuse if needed that will not cause a tire blow-off.
Below are the links you intended to provide:
http://tandem-fahren.de/Mitglieder/Christoph_Timm/components.html#brakes
http://search.bikelist.org/getmsg.asp?Filename=tandem.9711.0546.eml
Just my .02
I like the Arai drum brake. The wife and I are big people and the guy building our tandem recommended the drum brake as we planned to carry heavy loads.
Over the Andes? Total weight in the 400-pound range?
Would definitely go along with the suggestion of the Arai drum brake addition to your tandem for such an adventure. The Arai has the best track record, over many years of usage, and could be more readily available than some of the more 'exotic' brake systems, whether mechanical or fluid operated discs. Some of the plastic parts on discs have been known to melt when said disc is overheating . . .
And if you have water to spare, a liberal dose on the overheating brake would accellerate the cooling off a bit.
Just our opinion.
Pedal on TWOgether!
Rudy and Kay/zonatandem
We agree with Tandemgeek and Zonatandem. We have crossed the Andes From Santiago, Chile to Mendoza, Argentina and back. We did it by rental car. It is very steep, the road is narrow, full of motorized trafic and the turns are extremely sharp. With a 400 # rig even with V-brakes and Arai brake I will take it very easy. You may have to make several stops to cool the Arai brake wich will must likely smoke.
Might be worth looking at:
http://www.karennben.com/
This couple clocked up some mileage, includng through South America, with a custom Bob Jackson frame, Rohloff hub and Hope disc brakes. The follow up advice section posted in June 2006 is really useful.
In the end with the Trek bike mentioned braking options are probably going to come down to what can be fitted.
Enjoy the trip.
They've got some truly remarkable roads outside of North America. At one time in my life, I would take trips to Guatemala & Mexico City around Easter time to compete in Masters stage races. On one trip to Guatemala, after the racing was over, I rode into Antigua. This old colonial town is located deep in a valley below Guatemala City. There are separate roads to get there and to return. The road there is very steep and much shorter than the road back, which is far more gradual. The downhill grade was so steep that I overheated the rear tire. As I recall the heat melted the adhesive on one of the patches (or something similar to that, I forget) i had glued on the tube. In any event, the tire blew, but I was able to stop the bike without crashing. And as I also recall, the road was so steep I had trouble slowing down the bike, and this was a single.
I would anticipate roads in Chile to be equally crazy steep.
Also, last weekend we did Jack's Pass in Washington on the tandem. Crew weight is 320 lbs, and the steel Kuwahara tandem has Tektro mini-V's in front and a Tektro long-reach dual pivot sidepull on the rear (both with Kool-Stop pads). When the pavement ends near the top of Jack's Pass (about 2500') there is a tough 4-km gravel climb followed by about 9 km of gravel descent. We were able to coast down the gravel at a controlled 20 to 30 kmh without overheating the rims by applying the front brake for 6 seconds, letting the bike roll for 3, applying rear brake for 6 seconds, and rolliing another 3. This way, each rim is heated for 6 seconds, then allowed to cool for 12.
What would be a cool invention would be a small heat sensor and wireless transmitter, powered by a small camera battery that would be installed in one of the spoke nipple wells inside the rim, underneath the base tape. This would transmit to a display mounted on the handlebar and would give you the tire temperature. This way, you could see if either tire was reaching the red zone and you could decide what to do accordingly. I've also thought of attaching small jets just ahead of the brakes, attached with tubes to a small water reservoir and activated by pushing a small pump on the handlebars. When the water spray turns to steam as it hits the rim, it's time to stop!
- L.
Might be worth looking at:
http://www.karennben.com/
This couple clocked up some mileage, includng through South America, with a custom Bob Jackson frame, Rohloff hub and Hope disc brakes. The follow up advice section posted in June 2006 is really useful.
Enjoy the trip.
We just came back from a week's mountainbiking in the French Alps with the tandem - team weight 290 lbs, tandem some 42 lbs. For this trip we had Hope Mono6 discs installed, replacing Magura Julies. These Hopes are really amazing! On the steepest of descents, the tandem could be stopped completely where some of the solo bikes didn't manage to come to a full stop anymore. The brakes never faded but got a bit smelly :p My conclusion: get them if you want real stopping power. To which I should add that there are other very strong disc brakes like Maguras Gustav M. But that doesn't look half as nice as the Hope Mono6 ..... :D
Agree fully with Ihbernhardt about the on/off breaking front to rear, and possible short pause in between, while descending long and steep grades.
While we are a rather 'light' team (he 135, she 110) we were told by so-called tandem 'experts' that we could not possibly descend an over 7,000 foot high, 12 mile long, average 7% grade with lots curves, of Kitt Peak in AZ without the benefit of a 3rd brake on our tandem. Utilized old Mafac cantis only with Scott/Matthauser pads. On/off braking worked great (don't let the speed build up and dive into the corner-type panic braking) for half the descent. Then pilot's fingers started cramping! Stopped, checked the rims (they were 'touchable' warm, but not hot) and did the remainder of the descent the same way.
Not a problem for us.
Even with better brakes (whether cantis, V-brakes, drum, discs or whatever combinations thereof) available now, proper braking technique is still paramount.
Just our observation.
Pedal on TWOgether!
Rudy and Kay/zonatandem
Agree fully with Ihbernhardt about the on/off breaking front to rear, and possible short pause in between, while descending long and steep grades.
While we are a rather 'light' team (he 135, she 110) we were told by so-called tandem 'experts' that we could not possibly descend an over 7,000 foot high, 12 mile long, average 7% grade with lots curves, of Kitt Peak in AZ without the benefit of a 3rd brake on our tandem. Utilized old Mafac cantis only with Scott/Matthauser pads. On/off braking worked great (don't let the speed build up and dive into the corner-type panic braking) for half the descent. Then pilot's fingers started cramping! Stopped, checked the rims (they were 'touchable' warm, but not hot) and did the remainder of the descent the same way.
Not a problem for us.
Even with better brakes (whether cantis, V-brakes, drum, discs or whatever combinations thereof) available now, proper braking technique is still paramount.
Just our observation.
Pedal on TWOgether!
Rudy and Kay/zonatandem
Same here: since 1990 we run Magura hydraulic rim brakes. When used in the aforementioned 'on-off' mode, even steep descents won't give any trouble. Most of our tube blowouts occured when mountainbiking with the tandem. Especially with a rigid fork you sometimes need to let the bike roll slowly over rocks and boulders. Lack of cooling (due to the very low speed) caused a blowout sometimes.
With discs, there's no more overheating of rims. And the Hope Mono6 I described in a previous reaction are pretty awesome anchors!
We just came back from a week's mountainbiking in the French Alps with the tandem - team weight 290 lbs, tandem some 42 lbs. For this trip we had Hope Mono6 discs installed, replacing Magura Julies.
Given that we have Hopes older 4-pot Enduro hydraulics on our off-road tandem, I'd have to assume that the six-pot Mono-6Ti models are outstanding as well. However, and if someone has some empirical data or experiences that suggest otherwise, I'd still be reluctant to recommend the use of hydraulic discs on a road tandem that will be used under demanding brake conditions. Off-Road use... absolutely.
As for the couple with the Bob Jackson trekking tandem, that's a toss-up. For mixed-use on both unimproved and off-road conditions as well as tarmac, while I'm more likely to recommend dual rim brakes and an Arai drum brake to a team on a list like this, for myself I'd also likely opt for disc brakes... but most likely mechanicals with brake bosses for rims brakes as a back-up. However, for riding on tarmac and making challenging descents I would definitely be mindful of how much heat I was putting into hydraulics, even when using Motul 600 brake fluids on a DOT system like Hope's. Again, we have successfully overheated our Hope 4-pot brakes running DOT 5.1 brake fluid on a long and steep compacted gravel road. Fortunately, the failure mode was a lock-up of the rear brake as the hydraulic fluid expanded beyond the open system's master cylinder capacity vs. a compression fitting letting go...
Anyway, as I said, if others have had good results using hydraulics on steep, fast asphalt descents I'm all ears on the details. Until then, at least for a 700c wheeled, skinny-tire road tandem, the Arai drum or a mechanical disc for those who don't need the full capabilities of the Arai remain my preferred solutions.
On your Demonchaux tandem whe use 2 Magura hydro brakes and a rear disk Hope Mono6. Front magura et rear disk for the captain.
Nice for stop when fully loaded. Whe don't effraid when speed is up 70km/h and the stocker use rear magura rim to prevent that the disk does not go up too much in temperature.
When whe use the 3 brakes, it's like a stick in the wheels .
On your first tandem, 1970 LEJEUNE, we had a postponed drum, it heated exaggeratedly.
Sorry for my poor language...;:rolleyes:
Jyves
France
http://enfinletandem.blogspot.com/
Given that we have Hopes older 4-pot Enduro hydraulics on our off-road tandem, I'd have to assume that the six-pot Mono-6Ti models are outstanding as well. However, and if someone has some empirical data or experiences that suggest otherwise, I'd still be reluctant to recommend the use of hydraulic discs on a road tandem that will be used under demanding brake conditions. Off-Road use... absolutely.
As for the couple with the Bob Jackson trekking tandem, that's a toss-up. For mixed-use on both unimproved and off-road conditions as well as tarmac, while I'm more likely to recommend dual rim brakes and an Arai drum brake to a team on a list like this, for myself I'd also likely opt for disc brakes... but most likely mechanicals with brake bosses for rims brakes as a back-up. However, for riding on tarmac and making challenging descents I would definitely be mindful of how much heat I was putting into hydraulics, even when using Motul 600 brake fluids on a DOT system like Hope's. Again, we have successfully overheated our Hope 4-pot brakes running DOT 5.1 brake fluid on a long and steep compacted gravel road. Fortunately, the failure mode was a lock-up of the rear brake as the hydraulic fluid expanded beyond the open system's master cylinder capacity vs. a compression fitting letting go...
Anyway, as I said, if others have had good results using hydraulics on steep, fast asphalt descents I'm all ears on the details. Until then, at least for a 700c wheeled, skinny-tire road tandem, the Arai drum or a mechanical disc for those who don't need the full capabilities of the Arai remain my preferred solutions.
Given that the original mail was enquiring about decents in South America the experiences of Karen and Ben would seem to be directly relevant. It would also seem to address the information request that you have on road descents as they have a stated top speed (90 km/hr I think) - although not 100% clear where this was.
Having sucessfully used our Hope Mono M4 disk as the main brake on roads in the Peak District and Pyrenees I an intrigued at the difficulties reported by yourself and others with these systems. This is reinforced by the favourable reports from off-road users. I struggle to see that the 26" wheels and 1.3" tyres on our tandem are favouring hydraulic disk brakes vs a 700C equiped bike.
What is it that you are doing differently on road compared to off ?
Given that the original mail was enquiring about decents in South America the experiences of Karen and Ben would seem to be directly relevant.
Terrain and experience, absolutely relevant. However, unless what sound like relatively inexperienced tandem cyclists are willing to have a custom trekking tandem built, the equipment recommendations aren’t practical for their 700c Trek T100 tandem.
Personally, I found their diary and post-tour tips to be fascinating, educational and a welcome source of new data – along with your own experiences in using hydraulic discs on asphalt. Moreover, their results with the Hope Mono Ti 6 & Goodridge lines is quite an eye opener.
What is it that you are doing differently on road compared to off?
Speaking for myself, I don't think I would have a problem managing a road-going enduro tandem fitted with dual hydraulic brakes. I have for many years managed our road tandems on less than “sane” high speed descents using only rim brakes; however, prudence and good reports on the Avid BB7 road disc allowed us to add a dedicated rear-mechanical disc brake equipped tandem to our stable for mountain adventures. It's also worth noting that our builder and several others whom we know have also been having good success with dual Avid mech. disc equipped tandems that are used extensively in the Alps and Pyrenees. In this regard, and although I haven’t seen any test results, I suspect that dual disc-equipped tandems may have as much collective heat capacity as a dual rim equipped tandem + rear drag drum brake.
However, from a practical standpoint, I try not to assume too much about the skills, experience, and disposable income of other riders and, with few exceptions, offer what I would characterize as "conservative" recommendations. With that in mind, my own experience with our hydraulic disc equipped off-road tandems and the testing I've seen on hydraulic disc brake systems suggests that while the newer systems have outstanding heat capacity the cost, complexity, and human factors are still barriers to their use on 700c road tandems.
1. Environmental Differences / Road vs Off-Road: Low rolling resistance tires on asphalt road descents tend to yield higher speeds that necessarily cause significantly higher brake energy (and heat) to be generated when controlling that speed compared to off-road conditions. That's not to say that you can't reach very high descent speeds in off-road conditions; however, while I don't have any data handy to back this up, my personal experiences and observations on other tandem teams who ride off-road suggest most teams tend to ride their tandems off-road at significantly lower speeds because of terrain limitations, traction issues, and because stopping distances are significantly longer due to the very low coefficient of friction between off-road tires and unpaved roads. As stated earlier, this doesn’t in and of itself preclude the successful use of hydraulic discs on paved roads with steep descents; however, improper use of hydraulics when they are the primary brake system could lead to a catastrophic failure IF overheating were allowed to occur (not hard to do if someone rides the brakes on a long, steep paved descent) and the hydraulic system failed vs. brake lock-up.. Fear mongering? Maybe…
2. Complexity: First and foremost, the only drop-bar compatible hydraulic brake levers still on the market that I'm aware of are the ones sold with Magura’s HS-66 hydraulic rim brakes. Perhaps there is a way to integrate a remote, in-line master cylinder, but as designed the HS-66 lever does not support an open hydraulic system. The HS-66 levers are also brake-only, which may not be an issue with a trekking tandem that was to be equipped with non-integrated, grip-shift (i.e., Rohloff), bar-end or down tube shifters. However, given the proliferation and widespread use on tandems of Shimano, Campagnolo, and now SRAM integrated brake lever shifting systems, this lack of brake lever options beyond the stock MTB-flat bar levers with integrated master cylinders is a design constraint that bears some recognition. Also, hydraulic brakes – while truly not that complex – require specialized knowledge with regard to proper installation, hydraulic line assembly, bleeding and, for DOT systems, periodic fluid replacement to ensure maximum heat resistance. The mechanical discs, on the other hand, can be used with stock Shimano, Campy, SRAM and other road brake levers and don't require much more knowledge for installation and maintenance than is needed for other types of cable-operated bicycle brakes... although a good read through of the instructions is needed as not all of the adjustments are intuitive.
3. Cost: With an MSRP of $340/ea (USD) and what seems to be a going selling price of $300/ea (USD) for just the caliper & rotor, the Hope Mono 6Ti is an exceedingly expensive way to achieve what is probably only marginally better brake performance than you can achieve with rim brakes plus an Arai drum. While there are other, less expensive hydraulic disc brakes suitable for off-road tandems, they're still significantly more expensive than the mechanical discs and rim plus ~$120 Arai drum brake alternative with, again, not a significant gain in braking performance. Now, if you’re building a dedicated trekking tandem that will have a Rohloff rear hub, the Arai drum brake is not an option. Thus, the only alternative beyond a rim brake is a rear disc system. For off-road applications, there are several other advantages to discs and, to a certain extent, even the hydraulic systems. Again, I have no qualms about paying a premium for outstanding hydraulic disc brakes on an off-road tandem.
4. Human Factors: This essentially gets back to how people use the different brake systems. A supplemental drag brake is a fundamentally different approach to speed control than primary braking systems, rim or otherwise. Ideally, drag brakes are set up using a dedicated, friction shifter control that can be used to pre-load the rear wheel with constant brake energy that is operated by either the captain or stoker. On tandems that don’t have drag brakes, the rear brakes are often times used as a drag brake when unexpectedly steep or challenging conditions develop. The latter creates two undesirable conditions: one is the possibility of hand cramps / fatigue from prolonged brake lever operation and the other is overheating the rear brake. While the installation of discs as primary brakes can mitigate a rim/tire overheat and potential tire blow-off, it does not address the hand cramp issue. Moreover, disc brakes have their own failure modes under overheating conditions as already mentioned, some of which are better or worse than others.
More than you cared to read, I'm sure… but thought I'd give you the benefit of my perspectives.
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