Brakes for Quad > Drop Bars
We have a new-to-us Co-Motion quad with flat bars. I am more comfortable with drop bars, so I want to switch it over. I have a set of Ultegra 9-speed brifters that match the 9-speed gearing on the bike. On the braking side, the front is an Avid Single Digit, and the back is an Avid BB7 Mtn with a 203mm rotor -- I'm guessing it's the stock Avid rotor. I wanted to solicit your thoughts about setting up brakes for the Ultegra brifters. Obviously the cheapest solution is to get some travel agents, maybe a normal one for the front and an in-line one for the back. Alternatively, a BB7 Road would fit the current adapter in the back and not need the travel agent. The payload will be two adults and two kids, around 450 lbs team weight. We don't live near mountains and don't intend to do any descending. That said, the disc brake technology has advanced some since this bike was built, so I'm interested in whether anyone thinks I should be thinking about swapping the rotor or going to a different model disc caliper. There are also canti/v-brake studs at the rear, which are currently unused -- I had a half-baked idea about adding a third brake there.
Thanks for any/all input!
Gear Combo Guru
One warning is that your left Ultegra brifter is probably not compatible with the current front derailleur, but that depends on exactly which model it is.
We have a rim brake in addition to the disc on the rear of our Co-Motion tandem, operated by the stoker to manage heat build-up on long descents. I'm not sure how that would help given the type of usage that you describe.
I am much happier with our current BB7 Road setup than with the BB7 Mountain plus travel agent that I tried to setup, but couldn't get to work very well. However, other people have not had any problems with the BB7 MTN plus TA.
You mention about disc brake technology improving over the years, but not much has been released that is significantly better than the BB7s IMO. The rotor seems to have more of a difference than the brake caliper. We've been very happy using a Formula 220 mm rotor in our BB7 on the tandem, but those are no longer made. The Shimano IceTech rotors also work well with the Avid calipers.
Last edited by Chris_W; 03-15-13 at 06:00 AM.
Thanks for your input Chris, living where you do you certainly stress your brakes more than we will. I searched through the archives looking for comparisons between the BB7 mtn w/travel agents and the BB7 road. Other than your comment above, I only saw one other mention, which was in TandemGeek's post in this thread: http://www.bikeforums.net/showthread...1#post13942787
Both of you seem to strongly pefer the BB7 road over the mtn w/ travel agent solution. I'd love to hear from anyone else with an opinion on that.
Clipless in Coeur d'Alene
Due to the longer run you have on the quad, regardless of mechanical disc model you will likely need an inline travel agent or brake booster to provide a nice firm lever action when using brifters.
Originally Posted by WheelsNT
One example, Ritterview recently posted this setup:
Also, depending on cable routing, that can result in higher friction and slack that a booster will compensate for. As an example, our previous Santana routed the rear disc wire under the bottom tube and then up from under the rear BB to the top of the chainstay. That was a difficult routing to get dialed in.
Using a quality casing and wire can help a lot. My pick is Jagwire racer casing, with their Slick Stainless wire (uncoated) which can be found cheap on Amazon. We use this and have no need for any boosters with the top tube cable routing on our current and previous tandems (2 seaters).
Last edited by twocicle; 03-15-13 at 09:44 AM.
I don't recognize the brake booster there, what exactly is it?
Originally Posted by twocicle
Clipless in Coeur d'Alene
In that photo, it is the component installed between the inline cable adjuster and the disc caliper. It's called the Brake Power Booster (BPB) made by Sidetrak.
Essentially, it does the same thing as an inline Travel Agent, but also has a couple throw settings you can chose from.
Available from PrecisionTandems (in the "Brakes" section under the heading "TRAVEL AGENTS - V-DAPTORS - Brake Power Boosters - BPB") and perhaps others too.
Last edited by twocicle; 03-16-13 at 11:36 AM.
I did a quick search, but I didn't come up with the thread with that picture, or any specific discussion of the cable pull in Ritterview's setup. Can you point me to it? That looks like a BB7 Road, and if I remember rightly, Ritterview runs Campy brifters... is there a difference in cable pull with Shimano brifters?
Maybe Ritterview could chime in with some thoughts about brake feel with and w/o the BPB? He obviously values light weight componentry, so I can't see him carrying anything on his Calfee that he didn't need.
FWIW Sidetrak looks to be out of business, or at least their domain name is now up for sale. I had hoped to find some description of the BPB on their web site.
We ride a Santana Cabrio triplet. Rolling weight is between 450-550 (maybe even 600, gasp) pounds when we do loaded touring with it (maybe more, as our 8 year old son won't stop growing!). We don't have a disc brake, so I can't help you there, but I will note that we've never had stopping issues with our front and rear V-brakes (setup using TravelAgents with STI Ultegra levers) and an Arai drum on the rear.
Since you have brake studs on the rear, you could always add a V-brake back there, too, and run a dual-pull lever on it and the front brake for extra stopping power.
I'm admittedly old-school, but I'd be a bit nervous with just a single brake on the rear on a quad (and a disc at that). But, it sounds like you aren't in the hills much, so it's probably not an issue.
I don't use disks so I can offer nothing intelligent there (yet). But would like to add that I would like to do a tandem with both disks and cantilevers front and rear spanned across a pair of dual pull levers (or shared with the stoker).
Would logically seem to straddle the primary issues (real or imagined) with either type of brake and as it would pack on more stoppage (for only another 8 or 10 ounces), which is always a good thing on a 2bike... On a 4bike, I would guess the potential stoppage shortfall would be even greater on descents.
Thoughts from the crowd?