A while back I posted an item that talked about Co-Motion making dual Avid BB7 mechanical disc brakes their OEM brake offering on many of their tandem models. I included a posting from Dwan Shepard of Co-Motion I prompted him to make at the Hobbes list as a way of addressing some lingering concerns that tandem enthusiasts had about disc brakes. You can find that blog entry HERE.
Recently, on another tandem discussion forum, another reader once again dredged-up something posted on a tandem manufacturer’s Website that continues to call into question whether Avid does or does not consider it’s BB7 disc brakes suitable for tandems. In reading that material, anyone who was new to tandems and tandeming would certainly walk away with a belief that the BB7, “ …is not sanctioned or recommended by Avid, and voids the manufacturer’s waranty [sic]” and, “…is not a safe choice for tandems“. In fact, that’s exactly what happened with our friend at the other forum who noted, “If Avid says that the BB-7 is not recommended for tandem use, I’d believe it. But that’s just me.”
Well, me being me, and having used the Avid BB7 on our own tandems since 2003 as have many of our friends and hundreds of tandem enthusiasts, I had thought the confusion over Avid BB7 suitability for tandems that was stirred-up back during Interbike 2003 had subsided. Moreover, I couldn’t recall ever reading anything from Avid or SRAM that even addressed tandems in their literature.
Just to be sure, I checked all of the SRAM warranty info, Avid BB7 installation guides and tech manuals for 2008 – 2010 and could not even find the word ‘tandem’ mentioned, never mind any weight limitations, etc. I then contacted Tech Support at SRAM. After the tech rep checked through all of the disc brake documentation, she confirmed there is nothing contained in SRAM or Avid’s BB7 mechanical disc documentation that applies any limitations for using Avid’s BB7 mechanical disc brakes above a given weight or that even mentions tandems. As an example:
As we chatted about Avid’s brakes and tandems the basic conclusion the Tech Rep and I came to was that the BB7s were quite simply another brake option for tandems, just as the various rim brakes sold by SRAM that can also be used as primary brakes on a tandem. There was a mutual understanding that neither Avid’s rim brakes nor disc brakes are designed to be used as a drag brake, which falls under the heading of ‘improper use’. This was also true back in 2003. So, by the end of my discussion with the SRAM Tech Rep it was pretty clear that Avid doesn’t warn against the use of their BB7 on tandems or even mention tandems in any of its product documentation, owners manuals or warranty. Pretty interesting… but not surprising at least from my point of view.
I say this because, for the most part, in my discussion with component manufacturers over the years most have typically said they leave it to the OEM bike and tandem builders to develop their products and specify the use of components that they believe to be prudent for the intended use of their bikes and tandems, to include any weight or use requirements. This is why you’ll also note that rim brakes as well as just about every other non-tandem specific bicycle component found installed on a tandem is neither approved for, nor prohibited for use on a tandem. Check it out: derailleurs, cassettes, hubs, cranks, chains, headsets, etc. It is true that some manufacturers impose maximum rider weights (e.g., Campy) on their bicycle components, and most tech support folks will tell you when history has proven that certain components they sell that are sometimes installed by consumers on tandems simply don’t hold up well when used on a tandem. But, if you check the documentation, very few components carry endorsements or prohibitions related to tandem use. Again, it falls back to the OEM / builder / retailer / consumer to make the most appropriate component choices for the intended use of a given tandem and team.
So, this brings us back to the posting from Dwan Shepard this past February which provided an objective overview of the BB7’s use on tandems, from which I’ve extracted the following key points related to this Blog entry:
Of course, rim brakes are simple and mostly reliable, and familiar enough to most of us that we feel comfortable with them. However, for many people, rim brakes are inadequate for tandem touring. So, why not combine rim brakes with a supplemental disc brake? That argument has played itself out many times here on Tandem@Hobbes over the years. If you’ve been sitting back and observing, you may recall claims by one tandem expert or another stating that discs were not “tandem specific”. That myth got its start back when people like myself and Bill McCready began querying disc brake makers Hope, Avid, Hayes and others about using their brakes as a supplement to rim brakes. Without exception, these brake makers shuddered when they heard how tandem riders used the Arai brake. It’s true- no disc brake can take that kind of punishment.
But, let’s not forget, the Arai brake itself has never been a very good brake on its own. It’s an old warhorse, sure. Because it has so much mass, you can apply it and let it drag forever and it will get nice and hot, but to its credit, it won’t fail. By itself however, it does a lousy job of slowing your bike, which is why you’ve probably never seen a bike equipped with front and rear Arai drums.
Now, back to those disc brake manufacturers: Every one of them stated unequivocally that their brakes should be used as the PRIMARY brakes on a tandem. While they all expressed concern over their brake’s use as a “drag”, none were concerned about their brakes being used to stop a tandem. If you’ve tried a good disc brake on a tandem, you know it doesn’t take long to discover why disc brakes have become more commonplace than cantilevers on all kinds of bicycles.
Bottom Line: Trust but verify….