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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 02-28-13, 06:21 PM   #1
Dean V
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Hope Vented Rotor + Bengal Caliper

I have just installed this on the back of our bike. Only done one ride so far but seems promising. Did several hard stops from 50mph and it worked very well. No discolouration of the disc, or warping and rubbing. With the avid rotors I had before one stop like that would turn it blue and the heat would make it warp and rub for some time afterwards.
It wasn't too hard to get the caliper to fit. Just had to strip it down and machine the groove about 1mm wider on the inboard side to accommodate the extra width of the disc.
Here are some pics. Excuse the extra length on the cable and surplus material on the caliper adapter. Haven't machined off the excess yet.

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Old 03-01-13, 12:51 AM   #2
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The soon-to-be-introduced TRP Spyre might make clearance for the Hope ventilated disc easier, as the Spyre pushes both pads together.


Quote:
Originally Posted by Bike Rumor
Perhaps just as exciting is the new Spyre dual pull mechanical disc brake. Using a lever that rotates around bolts on both sides of the caliper and pushes both pads simultaneously and evenly, we expect itíll have smooth action and a comparatively powerful feel.

Presumably this is also aimed at the road/cyclocross crowd, meaning the leverage ratio might be designed around a drop bar leverís cable pull. For the uninitiated, having both pads move inward means easier set up and the ability to have a little more space between the pads and rotor when unengaged. It also means one pad isnít bending the rotor as it pushes it into the static pad like on current calipers like Avid BB7 and Hayes CX5, among others.


Video shows operation of both pads, which might accommodate the Hope Ventilated Rotor.


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Old 03-01-13, 05:10 AM   #3
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The soon-to-be-introduced TRP Spyre might make clearance for the Hope ventilated disc easier, as the Spyre pushes both pads together.






Video shows operation of both pads, which might accommodate the Hope Ventilated Rotor.



If you boil that brake, there certainly is very little fluid to attempt a recovery of the brakes. Reminds me of when the moto oems went to smaller rear calipers and integrated rezzy / master cylinders. Next came a cottage industry of all kinds of brake heat sinks, radiators, and exotic pads or insulators. Any weight saved was lost with add ons and you still had lesser brakes.

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Old 03-06-13, 08:13 PM   #4
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If you boil that brake, there certainly is very little fluid to attempt a recovery of the brakes. Reminds me of when the moto oems went to smaller rear calipers and integrated rezzy / master cylinders. Next came a cottage industry of all kinds of brake heat sinks, radiators, and exotic pads or insulators. Any weight saved was lost with add ons and you still had lesser brakes.

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How do you boil a cable actuated brake?
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Old 03-07-13, 04:09 AM   #5
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He is talking about the caliper they show which is hydraulic with an integrated master cylinder.
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Old 03-07-13, 07:59 AM   #6
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He is talking about the caliper they show which is hydraulic with an integrated master cylinder.
I know, I was joking, the thread is about a cable actuated brake.....

Sorry.
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Old 03-07-13, 01:20 PM   #7
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We just returned from a Santana trip to New Zealand and discovered a potential issue with a Bengal caliper. About 8 of the teams did Authers Pass and it had an extended descent of about 16% ( as described by the road signs, I haven't downloaded our Garmins yet). It scared some of the stokers to tears literally. We have a Bengal on our Calfee as did the other Calfee and most of the newer Santana's have Bengals standard. We have a 203mm Hope V2 rotor and most of the Santana's had a 10 inch rotor having converted from the Winzips. Anyway at least 3 of the Bengals melted the plastic cable barrel adjuster to some degree. It is not a potential for brake failure but does allow a small amount of cable play to develop. It could still be adjusted but it does get deformed. The caliper temps on these big descents is pretty high. We all stopped at least once to allow them to cool. We all had a significant amount of pad wear but I had no rotor warp. It squealed a few times when very hot but got quiet again when it cooled. A few of the large discs stayed noisy after the descent.
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Old 03-07-13, 02:30 PM   #8
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Quote:
Originally Posted by akexpress View Post
We just returned from a Santana trip to New Zealand and discovered a potential issue with a Bengal caliper. About 8 of the teams did Authers Pass and it had an extended descent of about 16% ( as described by the road signs, I haven't downloaded our Garmins yet). It scared some of the stokers to tears literally. We have a Bengal on our Calfee as did the other Calfee and most of the newer Santana's have Bengals standard. We have a 203mm Hope V2 rotor and most of the Santana's had a 10 inch rotor having converted from the Winzips. Anyway at least 3 of the Bengals melted the plastic cable barrel adjuster to some degree. It is not a potential for brake failure but does allow a small amount of cable play to develop. It could still be adjusted but it does get deformed. The caliper temps on these big descents is pretty high. We all stopped at least once to allow them to cool. We all had a significant amount of pad wear but I had no rotor warp. It squealed a few times when very hot but got quiet again when it cooled. A few of the large discs stayed noisy after the descent.
In other words, the stokers squealed, the calipers melted and the price was steep

Which pads were you smoking?

Looking forward to reading a complete trip report and about your compact gearing, maybe in another thread.

Last edited by twocicle; 03-07-13 at 02:36 PM.
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Old 03-07-13, 02:45 PM   #9
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In other words, the stokers squealed, the calipers melted and the price was steep

Which pads were you smoking?

Looking forward to reading a complete trip report and about your compact gearing, maybe in another thread.
EBC semi metallic
trip report to follow
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Old 03-07-13, 03:23 PM   #10
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About 8 of the teams did Authers Pass and it had an extended descent of about 16% ( as described by the road signs, I haven't downloaded our Garmins yet).
Is this the segment of which you speak?

West Coast Road Climb
Arthur's Pass, Canterbury, New Zealand

Distance....0.4mi

Avg Grade....16.6%

Lowest Elev....2,234ft

Highest Elev....2,550ft

Elev Difference...316ft
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Old 03-07-13, 05:27 PM   #11
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Is this the segment of which you speak?

West Coast Road Climb
Arthur's Pass, Canterbury, New Zealand

Distance....0.4mi

Avg Grade....16.6%

Lowest Elev....2,234ft

Highest Elev....2,550ft

Elev Difference...316ft
probably I will download the garmins and get the whole profile as there was a fair amount of descent before it really got steep and then more moderate after. Narrow road with exposure on one side and guard rails. Part of it was an elevated road/bridge with exposure on both sides. Every team treated it with respect and I think everyone said it was one of the steepest they had descended. It was very dramatic in the view so it was intimidating.
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Old 03-07-13, 05:55 PM   #12
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Quote:
Originally Posted by akexpress View Post
probably I will download the garmins and get the whole profile as there was a fair amount of descent before it really got steep and then more moderate after. Narrow road with exposure on one side and guard rails. Part of it was an elevated road/bridge with exposure on both sides. Every team treated it with respect and I think everyone said it was one of the steepest they had descended. It was very dramatic in the view so it was intimidating.
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Old 03-07-13, 09:58 PM   #13
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Originally Posted by akexpress View Post
We just returned from a Santana trip to New Zealand and discovered a potential issue with a Bengal caliper. About 8 of the teams did Authers Pass and it had an extended descent of about 16% ( as described by the road signs, I haven't downloaded our Garmins yet). It scared some of the stokers to tears literally. We have a Bengal on our Calfee as did the other Calfee and most of the newer Santana's have Bengals standard. We have a 203mm Hope V2 rotor and most of the Santana's had a 10 inch rotor having converted from the Winzips. Anyway at least 3 of the Bengals melted the plastic cable barrel adjuster to some degree. It is not a potential for brake failure but does allow a small amount of cable play to develop. It could still be adjusted but it does get deformed. The caliper temps on these big descents is pretty high. We all stopped at least once to allow them to cool. We all had a significant amount of pad wear but I had no rotor warp. It squealed a few times when very hot but got quiet again when it cooled. A few of the large discs stayed noisy after the descent.
Dumb question: Is there any risk that such high temps in that area could begin to affect the integrity of the rear stays on the carbon bikes?
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Old 03-07-13, 11:16 PM   #14
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Dumb question: Is there any risk that such high temps in that area could begin to affect the integrity of the rear stays on the carbon bikes?
I don't think that is a dumb question and I have thought about it but the brakes may be self limiting. By the time they are that hot they are off gassing at the pads so badly that you are losing braking power quickly and you feel the need to stop and let them cool. I would like to have a infra red heat sensor but it is not a normal ride tool so I don't know how high the temps are. Water sprayed on the rotors instantly boils and steams. The seat stays are a bit from the caliper and only have two points of contact via the raised brake mount so it may mitigate the heat somewhat.
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Old 03-08-13, 04:36 AM   #15
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I don't think that is a dumb question and I have thought about it but the brakes may be self limiting. By the time they are that hot they are off gassing at the pads so badly that you are losing braking power quickly and you feel the need to stop and let them cool. I would like to have a infra red heat sensor but it is not a normal ride tool so I don't know how high the temps are. Water sprayed on the rotors instantly boils and steams. The seat stays are a bit from the caliper and only have two points of contact via the raised brake mount so it may mitigate the heat somewhat.
This is the easy way to check without adding any weight or tooling.

http://www.tempil.com/products/thermax/10-level-strips

If you can obtain the performance specs of the resin system used by Calfee, you will have your answer.

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Old 03-08-13, 07:25 AM   #16
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probably I will download the garmins and get the whole profile as there was a fair amount of descent before it really got steep and then more moderate after. Narrow road with exposure on one side and guard rails. Part of it was an elevated road/bridge with exposure on both sides. Every team treated it with respect and I think everyone said it was one of the steepest they had descended. It was very dramatic in the view so it was intimidating.
Arthurs Pass road was completely rebuilt since we went up and down on it about 20 years ago on our first tandem (with Arai drum). The old road was steeper and narrower (one way for part of it) . Wonderful ride though. That was the only time I felt the Arai fading even with my wife applying it fully.

There are about 50 Japanese tourists who has pictures of us climbing so slowly up the switchbacks back in Japan somewhere.
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Old 03-08-13, 08:08 AM   #17
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Just had to strip it down and machine the groove about 1mm wider on the inboard side to accommodate the extra width of the disc.
What kind of machine tool did you use to machine the groove?
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Old 03-09-13, 11:59 PM   #18
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What kind of machine tool did you use to machine the groove?
4mm long series slot drill in a vertical (bridgeport or similar) milling machine.
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Old 03-11-13, 02:18 AM   #19
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I was just speaking to a Kiwi about Arthurs Pass. He said he used to drive buses there, and heard stories of other drivers once or twice having to stop on the steep section of the road. They couldn't get the bus going again with a full load of passengers on board, so all the passengers had to get off, the driver got the bus started, then the passengers would get back on as the bus crawled along without stopping. I guess that section is pretty steep!

One big difference that we noticed about the pass roads in New Zealand compared to what we're used to in the Alps is their lack of consistency in the gradient. If you know that you need to climb 600 metres in the next 8 km then the road has to have an average gradient of 7.5% (assuming no downhill sections); in Europe, the gradient will therefore be between about 6% and 9% for each km, with much of it being between 7% and 8%; in New Zealand, you cannot make this assumption, and it's just as likely that you'll have one km at 11%, then a couple at 3%, then one at 9%, one at 6%, 5%, then finish with 13% and 10% kms. Even on a section of relatively newly-constructed switchbacks up the side of slope, where the terrain was not a factor in determining the gradient, the first km was at 9% and the second at 6%. With a fully-loaded touring tandem weighing over 200 kg (450 lbs) then you really feel those >8% gradients, even with super-low gearing. We were missing the more predictable Swiss road engineering quite a lot when riding around New Zealand.

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Old 03-11-13, 08:28 AM   #20
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I was just speaking to a Kiwi about Arthurs Pass. He said he used to drive buses there, and heard stories of other drivers once or twice having to stop on the steep section of the road. They couldn't get the bus going again with a full load of passengers on board, so all the passengers had to get off, the driver got the bus started, then the passengers would get back on as the bus crawled along without stopping. I guess that section is pretty steep!
...
The old road had no switchbacks and went straight up the north side of Otira gorge until close to the top where there were some switchbacks built on scree slope. The problem was that the scree would shift due to earthquakes. They were running out of scree to (re)build the road onto. So they built the new road you rode on.

Sections of the old road was incredibly steep (>>20%) on a tandem. Our Arai drum brake was sizzling and our rims were quite hot when we came back down even though the temperature was only about 10C and it was drizzling. This was not a place to let your bike run freely.

The only "road" that we had ridden that was steeper was an Austrian bike path we were following south of Hallstat which went straight up a hill.
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Old 03-11-13, 12:52 PM   #21
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We can attest to the different gradients and inconsistency. I downloaded our Garmins and saw both climbs and descents of 20% throughout the trip. None of those was super long but were mixed in with10-14%. The Auther's pass had a short section of 20% on the descent and lost about 2500ft in about 6 miles. I put our bike back together and checked the Bengal and the melting was confined to the plastic barrel adjuster cover and core of the barrel adjuster is alloy so this really isn't a problem, nothing like our Mt Ventoux Avid melting.. I just cut it off and will leave it off unless I can find a larger knurled barrel adjuster to fit it. I replaced the pads as they we down to about .5mm. We probably got about 2000 miles out of the pads as we had done Cycle Oregon, a tour of Turkey and New Zealand plus some miles before these trips. These three trips had combined climbing/descending of about 80,000ft so I an pleased about the brake pad life. We are not a light team at about 330 so your results may be better. It seems the places we like to ride are full of climbs and descents so we may not represent a good average as we seldom put in lots of flat miles. the Hope V2 rotors are still fine and nice and true. I am convinced the alloy spiders are the key for tandem rotors.
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