Bengal Brake Update…

Back in March we started a product test of the Bengal MB700T disc brake on our Calfee tandem, but really haven’t offered much in the way of feedback since then. So, here’s a short status update:

During the initial use of the Bengal it worked really well.  However, we seemed to be getting an inordinate amount of brake squeal, vibration and ‘chatter’ after about 100 miles of use.  I tried cleaning the rear rotor, which made the issues go away for about the next 40 miles, but it soon returned.  So, I put on an Avid disc rotor to see if I could isolate the root cause as being something caused by the Bengal rotor.  Nope, that was’t it: the Avid rotor squealed too.  The brake caliper also seemed to drift out of alignment a bit as we also experienced a lot of brake rub during that first longish test ride after some local outings. As much as I adjusted the inner pad, the brake rub just kept coming back.

I reported the initial findings to our friend Mark Johnson out at Precision Tandems who provided the brake and we noodled over a few options for next steps to see if we couldn’t isolate the problem.  I wondered if the chatter wasn’t coming from the brake pads vibrating on the magnetic pistons used on the Bengal vs. the springs found on Avid’s brake to keep the brake pads “fixed” to the pistons and thought about putting a dab of “Brake Quiet” on the pads.  We also wondered if the brake pads just didn’t agree with our climate and Mark sent out a set of EBC Gold pads.

Timing is everything, and we suddenly found ourselves in the middle of the tandem rally season so the brake project got sidelined while we rode our new-to-us, and refreshed Precision Triplet and our Calfee fitted with rim brakes and the Topolino’s through the rest of the Spring and Summer.

As we came into Fall, I re-installed the Bengal on our Calfee and opted to switch out the stock brake pads for the EBC Gold pads that Mark sent and also did a “start from scratch” installation of the Bengal caliper and rotor. I should also note that we’re using our conventional 36h wheels this time vs. the Rolfs used on the initial run. Shouldn’t make any difference, but a data point none-the-less.

With about 200 miles on the bike with the Bengal it’s too soon to tell if we’ve broken the code on dialing in the Bengal, but so far the rotor’s running true with no chatter at all and the grip-slip vibration is gone.  The EBC Gold pads have a much more “grippy” bite on the rotor and shorten stopping distance vs the OEM pads.  Unfortunately, our local rides aren’t exactly heavy-brake demand territory here around the house, so it may be a while before we really get to test them under really demanding conditions. We’ll be headed up to Chattanooga one day next weekend, but I don’t think we’ll be up there on the days when our friends doing a three-day “freeloader weekend” will be taking on the thigh-burning, knee-popping, lung-burning monster climbs with the equally challenging descents.

More to follow but, at least at the moment, I’m starting to feel the love for these Bengals again.

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About TG

I've been around a bit and done a few things, have a couple kids and a few grandkids. I tend to be curmudgeonly, matter-of-fact and not predisposed to self-serving chit-chat. Thankfully, my wife's as nice as can be otherwise we'd have no friends. My interests are somewhat eclectic, but whose aren't?
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9 Responses to Bengal Brake Update…

  1. Peter Leiss says:

    Timely article as i just ordered 2 bengal calipers to replace my Avid BB7’s I will test them well before we go to the Alps next year.

  2. Richard James says:

    We’re enjoyed the silent stopping power of Hope V-Twin hydraulic disc brakes (V-Twin master cylinger + M4 four-piston calipers): https://www.dropbox.com/s/bog4rmotag1vdss/IMG_1231.JPG

    Pads auto-adjust (no manual cable adjustments), modulation is excellent in both front and rear (especially nice to have on dirt roads), and heat capacity has not been a problem (we’re a large team and like to tour in the mountains– Cascades, Green, and White mountains so far in 2012).

  3. @Richard: What size Hope sawtooth rotors are those? They look fairly small… may I ask what the total “ready to ride” team weight is?

    • Richard James says:

      203mm rotors, and we’re 360lbs ready to ride. Our other tandem-ish sport is doubles sculling

      • Ah… must be those whitewall tyres playing tricks on my eyes. I’ve got Hope M4’s on my MTB and knewn they can be paired up with the V-Twin remote masters… have always been curious how they would fair on a tandem! Any reason you chose not to use the floating rotors… being lighter, more resistant to heat-warpage and only a little bit more expensive?

      • Richard James says:

        Hope says vented rotors are only for V2 calipers, and V-Twin is a “Race” sized master cylinder (i.e. too small for V2)

  4. @Richard: Hope have lots of rotors. All (X2/M4/V2) brakes have the fixed rotor (like yours). All have floating rotors. X2 & M4 are common (sawtooth design), V2 uses a special one with a wider track. The V2 also has a super special vented-floating rotor. I’m just talking the “regular” floating rotors for your M4, rather than the special V2 specific vented ones.

    As an aside, the V2 gets discontinued as of the end of this month…

  5. Gary Anderson says:

    Curios to learn about any new updates on the Bengal MB700T…Currently using the bb7 w/ the 250mm rotor on a Santana and am having the ‘chiming/chatter/ChaChing’ issue. My riding buddies hear me coming for some distance. Thx

    • TG says:

      The 203mm rotor continues to run true on the Calfee and “fairly true” during a 3-day test on our triplet at the Southern Tandem Rally. In regard to the latter, I have noticed the Bengal rotors seem to be a bit more pliable and prone to going a bit out of true vs the Avid rotors, as the triplet had developed a slight rotor rub after the 3rd day of riding. Mind you, this was light duty for the rear brake as we were in dead-flat terrain and the rear brake was used mostly for feathering / speed control in tight quarters. The Bengal rotor also still seems to exhibit a very slight but noticable “pulsing” that I have not been able to eliminate through cleaning or use.

      As for the 250mm rotors that Santana specs, I suspect the additional diameter of the rotor simply exacerbates any tendency for rotors to develop minor warp or out of true conditions, where the only solutions are to: (a) closely monitor and re-true the rotor on a regular basis, (b) open up the pads / reduce the maximum braking force a bit to allow for some additional run-out room in the caliper, or (c) either accept the ChaChing noice or consider going to a smaller rotor that’s less prone to beign out of true.

      Back to the Bengal caliper, I think it’s a very good choice for anyone who anticipates putting a lot of heat into their disc brakes: that seems to be its strong point. For all-around use and all but the most demanding conditions, the Avid BB7 is probably just fine and continues to have only one weakness: plastic parts that don’t stand up to extreme heating in extreme use conditions. However, I still don’t see that as being a “major issue” that I’ll explain in a future blog entry on the Bengal & disc brakes.

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