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Hope RX4 Discs Not Warranted For Tandem Use

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Hope RX4 Discs Not Warranted For Tandem Use

Old 09-23-20, 02:13 PM
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merlinextraligh
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Hope RX4 Discs Not Warranted For Tandem Use

We spec'd our new Calfee tandem with Hope RX4 discs in part due to recommendations on here. We wanted the most robust brakes we could get. The thought was the 4 piston design Hopes would be a bit more powerful, and heat resistant than standard Shimano calipers. Jason at Calfee agreed and the bike was built with the Hope's.

As soon as we got the bike, Calfee informed us that Hope will not warrant the RX4's for use on a tandem in the U.S. Calfee is sending us free of charge 2 shimano calipers.

I still plan on using the Hope's. The Hope technical rep has told Calfee that the Hope's are fine on a tandem, and apparently they are ok with using them on tandems in Europe. The fact that they will not warrant them in the U.S. appears to be an issue of not wanting to take on the liability in the litigious U.S.

I think Calfee is being reasonable giving us the Shimano calipers. It does cover them in that its now my choice to continue using the Hopes, but I also get two calipers at no cost.

Based upon the design, and the reports of other users, I still think the Hope's are a great option, and I'll probably just keep the Shimano as a back up. Given the extremely small tandem market, there are lots of things that work fine on a tandem, but the manufacturer doesnt have an economic incentive to test, certify and warrant that they will.

Just thought I'd pass this on FWIW
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Old 09-24-20, 04:57 PM
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Thanks for posting this...I've been thinking about the RX4s for a new SRAM build. I'd be curious to know how they work for you.
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Old 09-25-20, 06:26 AM
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I messaged Hope last year in Winter asking whether the RX4's are safe for loaded tandem touring, and their reply was "the RX4s are a powerful 4 piston caliper, with larger rotors they would be suitable for tandem use".
They did not go into safety or legal aspects. I guess that they cannot take the legal risks of doing that, but based on that reply it seems that they are confident in the capabilities of the RX4's.

The only other hydro brakes that I considered for heavy loaded touring were the Zee's or Saint's.
Officially they are not compatible with Shimano STI's, but I've seen 2 independent blog posts of people pairing them with the Ultegra STI and being satisfied. The larger body and finned pads should result in a higher heat tolerance.
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Old 09-25-20, 06:30 AM
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I messaged Hope from an european email account, FYI.
Please let us know how the RX4's perform, in particular on long descents
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Old 09-25-20, 06:34 PM
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I contacted them about their MTB brakes for our flat bar touring tandem, and they were pretty insistent that I should use the V4 Downhill brakes. I did tell them that I had a serious brake fade issue with their E4 calipers, so that may have influenced their response. The V4 calipers with a vented rotor in the rear have been flawless.
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Old 09-26-20, 08:11 PM
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Based on our experience, and other accounts, I think thereís a disconnect between Hopeís technical reps, and their legal department.

Based on the European tech guys, Iím confident using them on a tandem. I think the issue is really
a legal, risk management issue for litigious US market.

So far with limited use, weíre happy with the brakes. Theyíve been used on some steep descents, but nothing really sustained yet.
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Old 10-01-20, 02:34 AM
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Originally Posted by rocknrollin View Post
Officially they are not compatible with Shimano STI's, but I've seen 2 independent blog posts of people pairing them with the Ultegra STI and being satisfied. The larger body and finned pads should result in a higher heat tolerance.
A little of the topic, of the RX4, but definitely related...

I have a gravel bike that has a post mount fork/frame, so newer flat mounts were out fo the question. It had the 785 calipers, but they've been problematic for more than a year, leaking, and even after rebuild, just seemed so much capable than my XT series brakes on my XC rig. So, I first tried to source post mount RX4, and I searched for a couple of weeks, and finally gave up 2 weeks ago and ordered the XT 8120 (4-pot) and XT 8100 (2-pot) for my gravel rig, and paired them to GRX brifters, and they work just fine, in fact I'd qualify them as "great." If you look here, Shimano lays out every lever that uses their "ServoWave" hydraulic action (pad engagement earlier in travel with a larger modulation range until "full lock"). It includes every hydraulic brifter they've ever produced for road/gravel application and all "newer" MTB levers. It makes no distinction between the lever operations, just explains the hydraulic action and implies it is operationally identical across all levers, which then stands rot reason that the calipers are designed to operate identically whether spec'd for a road or MTB group. So, I took an educated chance based on my understanding a bit about hydraulics; even if Shimano doesn't expressly discuss/describe mixing road levers and MTB calipers, knowing that they do not expressly warn (with big red letters, so to speak) against it, I was confident I could do it (and I did seek a few outside azimuth checks to make sure I wasn't off base). So, I did it, and as I said, it works great. I'd also suspect that Shimano doesn't warrant the use of the calipers in this configuration.

That said...4-pot calipers generally are not more powerful than a 2-pot. All things equal, the braking power comes from the lever pushing the fluid into the caliper. Where 4-pots excel, and why they are popular (essentially standard at this point) with downhill MTB racers is the larger longitudinal surface of the pad AND the larger caliper body leading to better resistance to heat fade. I'd expect this with any 4-pot. I haven't read a comparison between the finned Shimano pads and the ones Hope specs, but I suspect that the overall performance difference is not dramatically different.

Long post, sorry. Bottom line, there are more options out there, if they aren't readily apparent win the Google machine.
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Old 10-01-20, 02:41 AM
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Originally Posted by merlinextraligh View Post
Based on our experience, and other accounts, I think thereís a disconnect between Hopeís technical reps, and their legal department.
Maybe. I have been back and forth between Europe and US for the last 6 years...and I have had a few issues come up which were clearly warranty issues, and even the manufacturers agreed, but because I bought the component in one place and I was initiating the warranty in another, their legal people essentially said, no dice...the warranty is different in different countries/regions. My guess is that as others have said Hope hasn't certified the brakes for tandem use in the US, and therefore will not warrant them, even though they know they work because they've done so in Europe. Also, in the US, because warranty issues fall down to state law, if you read warranty information, there are often different rules depending on the state you are in. I'd guess the issue is how warranties are extended and enforced.
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Old 10-01-20, 05:12 AM
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I totally agree with your reasoning, but I'm confused as to how are Calfee think that they are covering themselves when Shimano also explicitly states that their hydraulic disc brakes are not appropriate for tandem use? Or has this changed recently?
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Old 10-01-20, 05:22 AM
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Thatís a question specifically for Calfee...I think the real issue is that warranties are nice for getting stuff replaced when it fails. Thus, these companies will only warranty things that they have tested and verified will not fail before they extend the promise of replacement (if in their testing it was unlikely to fail). That being said, if you turn it around, just because something is not warranted does not mean it will not work or function as desired. Also, consider that on a tandem, as opposed to a one up, in the realm of braking, you are asking the brake system to haul 130-150kg (maybe more) to a stop, where the brake system is composed of parts that were initially designed and specíd to bikes where the total system weight was 60-90kg.

Just my hunch, since I am not a lawyer.
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Old 10-04-20, 08:58 PM
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Originally Posted by Badger6 View Post
. . . Also, consider that on a tandem . . . you are asking the brake system to haul 130-150kg (maybe more) to a stop, where the brake system is composed of parts that were initially designed and spec’d to bikes where the total system weight was 60-90kg.
. . .
More than that. The brakes don’t have to just stop, they have to be able to stop after ******ing all that weight for a prolonged period of time during the descent, heating up all the while. Tandems allowed to coast descend faster than singles, so need more ******ing power, before the brakes are asked to stop. I think this is where so many braking “solutions” go awry: the next latest and greatest big thing feels great coming to a stop from a short high-speed descent ...but then you go somewhere you have to do ******-braking for a couple of kilometres and pretty soon you still don’t have any brakes. And you won’t discover that your new brakes (which the manufacturer did tell you not to use, remember) actually suck at what you bought them for until you really need them.

For tandems, it’s not the peak power the brake can develop during a hard stop. It’s the power they can operate at for prolonged periods without overheating and failing.

Edit: too funny. The censor doesn’t like my correct use of a word also used as a schoolyard taunt that starts with re and ends with tard.

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Old 10-04-20, 09:14 PM
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Originally Posted by merlinextraligh View Post
. . .

So far with limited use, weíre happy with the brakes. Theyíve been used on some steep descents, but nothing really sustained yet.
Please do let us know how well they work once youíve had a chance to actually test them, instead of just being happy with performance under conditions that a good set of dual-pivot short-reach rim brakes can match.
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Old 10-04-20, 11:56 PM
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Originally Posted by conspiratemus1 View Post
More than that....For tandems, itís not the peak power the brake can develop during a hard stop. Itís the power they can operate at for prolonged periods without overheating and failing.
Certainly. The finned pads and oversized caliper bodies of Shimano seem well suited to this task. Their brake solutions seem to offer the best option for doing exactly what you're describing to give both the maximal power (though I bet any disc brake gets close on this) and prevent fade, which is a problem even for a one-up bike because physics is physics. That said, braking safely while descending is a "problem" whose solution is both technical and technique.

Glad you explained the filter, because I was struggling to decipher the word that was missing...and yes, spot on proper use.
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Old 10-05-20, 07:22 AM
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Originally Posted by Badger6 View Post
Certainly. The finned pads and oversized caliper bodies of Shimano seem well suited to this task. Their brake solutions seem to offer the best option for doing exactly what you're describing to give both the maximal power (though I bet any disc brake gets close on this) and prevent fade, which is a problem even for a one-up bike because physics is physics. . . .[emphasis added]
ĒSeemĒ is not ďdoesĒ. Physics is an experimental science. Conjectures can be tested. (Which is why physicists sometimes mock the merely observational disciplines as mere stamp collecting (attributed to Rutherford whose own Nobel was in Chemistry, not Physics, likely because the Nobel committee didnít fully grasp what he had accomplished in transmutation.)
So, people who tout new brakes need to show that they do resist heat fade during sustained use to ******** speed on a long hill. Thorn in the U.K. and Santana in the U.S. do this in selecting brakes for their tandems. (I have no connection with either company. I do own an old Santana, with rim brakes.)

Hereís the scenario I worry about. You have a familiar long descent with hairpins connected by tangents. Conventional technique is to coast as fast as you dare in the straights, brake hard for the bends, then use the higher speed in the following straight to let the brakes cool. Fancy stuff on the brakes ought to let them cool faster when they arenít being used, sure, so you reach the bottom under control and able to stop at the intersection. Especially with some practice on it.

Now, suppose you have to follow a loaded coal truck or a camper caravan down that hill much slower than you can coast and you canít pass. So you are using the brakes in the tangents, too. Will their little fins be able to dissipate heat under continuous use, plus going even slower in the bends? Show me that they can. We have descended some truly scary paved roads in Europe where we really did have to brake the whole way down and stopped frequently to allow brakes, of various designs over the years, to cool. And Iím not including the marquee mountains and cols like Ventoux and Tourmalet, which donít require continuous braking. Some narrow twisting little road in the Dolomites can be scary challenging if the bends come right on top of each other.

Thing is, as tandem teams get heavier, they become less willing and able to climb up into the high country to find these descents, so their expectations of brakes are diminished. They regard quick two-finger stopping from the hoods as an adequate test. Then they turn their tandem into an electric motorcycle and discover that theyíve still got plain old crappy bicycle brakes intended to help an ectomorphic bike racer get through a hairpin, not brakes that the loaded coal truck needs.
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Old 10-05-20, 11:22 AM
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I said "seem" because I have neither conducted bench tests nor can I locate (granted, I haven't tried too hard either) any kind of real world scientific tests (the kinds with controls that reduce variables). But, having a working knowledge of physics and engineering, I can guesstimate pretty well on these things, but nothing I'll dispense a definitive opinion on. Hence my vague reference to physics being physics....slowing/stopping 90kg of mass vs 140-150kg (or more, as you've alluded to) is different, I should have been much clearer on that point.

I am familiar with the kinds of descents you're describing. And, yes, the technique you described (though not what I was thinking) is not possible in that situation. That said, though I am not a tandem rider, but understanding the nature of braking a tandem, the rear wheel is hugely important (as in it is actually critical to stopping the bike). A big finned rotor (203mm) with a big caliper body with finned pads, preferably metallic, will undoubtedly shed heat better than a small rotor, no fins, organic pads, small caliper body. Again, the problem is that the component manufacturers aren't testing these setups, and I think that is where the reticence/refusal to warrant them for tandems comes from. It's unfortunate, but the reality is that in the modern litigious society we live in that is also dominated by huge conglomerates that ONLY care about quarterly profit statements, the tandem market is small enough for them to regard it as niche and not worth their time, which is maddening. But, hey, I feel for you, because I bought a bike 5 years ago that is amazing to ride, but is obsolete (post mounts not flat mounts) and then the industry changed, and then I decided to use MTB calipers and everyone said it wasn't recommended...but some common sense and experience with brake setups, and basic understanding of engineering and physics, I knew it would work. Sorry to ramble, I guess my real point here his that even if Hope or Shimano or Whomever won't warrant a particular setup, with some careful research a satisfactory solution can be had. Moreover, if a company will warrant a setup in one country, but not another, that is not indicative of something not working, it is indicative of the nature of warranty law, which is a subject I know nothing about, except that buying a bike in Europe does not mean it will be covered in the US.
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Old 10-05-20, 01:43 PM
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Warranty and product liability law are separate but related concepts. The manufacturer’s limited warranty means that if it breaks within a certain period of time, they’ll replace or repair it at their option but, by using the product, you agree that they are not responsible for consequential damages flowing from the failure of their product. Under common law, everything sold is warranted to be fit for purpose, so without this limitation on warranty, the manufacturer would be responsible, at common law, for consequential damages. Now, many jurisdictions have passed statues that restrict the ability of the two parties to the contract (buyer and seller) to agree to limit liability in this way, so notwithstanding the manufacturer’s denial of liability for consequential damages, they actually have some. Which is why people sue the ladder manufacturer when they fall off a stepladder while drunk..., er, “struggling with mental health problems”.

But these state and provincial laws passed in the name of consumer protection do have the effect of making some products not worth the legal risk of developing. For products that already exist, much of the defence in a suit would be in the labeling: “Do not install or use these brakes on tandems”, would be a defence but the plaintiff would argue that the manufacturer knew that people don’t obey product labels and sold the brakes anyway, so they are still liable. Deep pockets always pay when someone is crippled. So rather than criticizing manufacturers for not wanting to bankrupt their shareholders in liability lawsuits, or have someone’s quadriplegia on their conscience, you might point the finger at over-zealous state legislators who write the liability laws.

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Old 10-05-20, 08:03 PM
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Does anyone know if there are finned pads for the Hope RX4s? I didn't see them on the website.

thanks,
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Old 10-07-20, 06:57 PM
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Originally Posted by bwebel View Post
Does anyone know if there are finned pads for the Hope RX4s? I didn't see them on the website.

thanks,
That's the charm of words like "seem": you can attribute speculative benefits to features that don't even actually exist.

But such imaginary fins would have to be the size and weight of a china dinner plate, to keep the brakes cool enough to work on a really grim downhill. What bicyclist wants to carry a brake with that kind of weight up a hill?
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Old 10-07-20, 09:52 PM
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Conspiratemus:
Like you, I doubt that the RX4 calipers will be up to the task of a loaded touring tandem on a steep long hill. I had a set of Hope E4 brakes get smoking hot and fade badly in a 45 MPH to zero panic stop on a 10% slope with a howler of a tail wind.

I know that the V4 calipers with the 203 mm vented rotor are up to the challenge. They are what Hope recommended to me and they have proven themselves time and again.

But maybe they are being used by a light team on a tandem which will not be loaded for an extended tour. Or maybe merlinextraligh is one of those folk who just have to P on the electric fence for themselves.

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Old 10-08-20, 10:56 AM
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I don’t see using Hope RX4’s and 203 mm rotors as peeing on the electric fence. People are riding tandems in the mountains with Shimano 785 brakes. By all accounts, the RX4’s have better stopping power and modulation than the Shimano’s

I get that the primary concern, however, is heat. The 4 caliper design of the Hope’s should manage heat at least as well as the Shimano’s if not better.

Comparing them to to Hope E4’s and V4’s is a bit difficult because it’s hard to find current data on the size of the Pistons. The E4’s use 4 14mm pistons, whereas the RX4’s use two 16mm pistons, and 2 14 mm pistons. The additional area of the two larger pistons should give the RX 4’s better heat dissipation.

As to the V4’s, as of 2016, they were reported to use the same 16-14 setup now used in the RX4’s.https://www.mbr.co.uk/reviews/disc-b...tech-3-v4-disc. However, Hope’s 2013 data shows 18-16. Assuming that the V4’s still use the 18-16, would put the total piston area a bit smaller that the V4’s but bigger than the E4’s

Also, The shimano compatible RX4’s using mineral oil, which is hydrophobic, are less likely to boil, than the V4’s with a touch of water in their DOT Fluid.

I also intend to upgrade to sintered pads that are less susceptible to fade at high heat.
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Old 10-08-20, 11:07 AM
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And as a practical matter, you can’t use V4’s with Shimano Di2 levers, so whether V4’s have better heat modulation becomes an academic question.
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Old 10-08-20, 01:03 PM
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merlinextraligh:
the V4 do indeed have a bigger piston than the E4, they use a larger pad than the E4, and because the V4 is also wider you can use the vented rotors. I started with a 203 mm Icetech rotor front and rear, but even after the switch to V4 calipers, the rear did distort from heat. The vented Hope rotor has not distorted. I consider my experiences with the E4 and the Icetech to have been my version of peeing on the electric fence. Trial, error, update, repeat. We survived without a crash, but we had one very close call with smoke pouring off the calipers and only minimal stopping power until they cooled.

Unfortunately, mineral oil has the nasty property of floating on top of water, so if any does happen to get into your system, the boiling point of the water is very low. If it is in the caliper, the brake is compromised. Yes, I change my DOT fluid on a regular basis. And the Castrol SRF has a dry boiling point of 320C and a wet equilibrium boiling point of 270C, which is pretty good. Here is SRAM's take on the subject: https://sram.zendesk.com/hc/en-us/ar...r-mineral-oil-

I understand that with drop bars you are limited to the RX4 calipers. And I suspect that you are a lot lighter than Mrs. Dan and myself, and our full load of gear. If I wanted a drop bar setup, I suspect I would try to get a hold of the now discontinued Hope V-Twin master cylinder.
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Old 10-08-20, 03:17 PM
  #23  
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Originally Posted by DangerousDanR View Post
merlinextraligh:
the V4 do indeed have a bigger piston than the E4, they use a larger pad than the E4, and because the V4 is also wider you can use the vented rotors. I started with a 203 mm Icetech rotor front and rear, but even after the switch to V4 calipers, the rear did distort from heat. The vented Hope rotor has not distorted. I consider my experiences with the E4 and the Icetech to have been my version of peeing on the electric fence. Trial, error, update, repeat. We survived without a crash, but we had one very close call with smoke pouring off the calipers and only minimal stopping power until they cooled.

Unfortunately, mineral oil has the nasty property of floating on top of water, so if any does happen to get into your system, the boiling point of the water is very low. If it is in the caliper, the brake is compromised. Yes, I change my DOT fluid on a regular basis. And the Castrol SRF has a dry boiling point of 320C and a wet equilibrium boiling point of 270C, which is pretty good. Here is SRAM's take on the subject: https://sram.zendesk.com/hc/en-us/ar...r-mineral-oil-

I understand that with drop bars you are limited to the RX4 calipers. And I suspect that you are a lot lighter than Mrs. Dan and myself, and our full load of gear. If I wanted a drop bar setup, I suspect I would try to get a hold of the now discontinued Hope V-Twin master cylinder.
I know the V4ís have bigger pistons than the E4ís, as I stated.

The RX4ís have 2 bigger pistons than the E4ís.

whatís unclear between the now dated 2012 chart, and the link I posted is whether the current V4ís are any bigger than the RX4ís

As for mineral oil vs DOT Fluid, Shimanoís take is of course the opposite.

Not apples to apples, but Iíve seen a lot of cars boil DOT fluid on the track. Many Porsche clubs wont
let you on the track with
brake fluid over 3 months old.
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Old 10-09-20, 03:11 PM
  #24  
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We’ve now done a full on panic stop bombing down a 23% grade. The rear wheel locked almost immediately, and the front was at the threshold of locking. Had to let off a bit to avoid swapping ends.

So, the braking power of the setup is clearly limited by tire friction, as opposed to the brakes themselves.

Should be be able to test out heat fade tomorrow with a twisty narrow 13% descent that goes on for several miles.
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Old 10-14-20, 03:54 PM
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Rained out from Hurricane Delta this weekend. So didnít do the ride with the long descent.

Today however did a 1000 foot vertical descent and tried to really abuse the brakes.

On a descent that weíd normally do 35-40 miles an hour, I dragged the brakes continuously and kept the speed around 10-15mph, and pedaled to add to the load on the brakes.

After a full 5 minutes of dragging the brakes, there was no fade, no odor, no change in the brake lever feel or travel, and when I did let it run at the steepest portion just at the end, we were able to stop quickly from 40mph or so.

Iím not sure this answers how well the brakes will do on a very long technical descent. However, the fact they stood up well to this intentional abuse makes me pretty confident.
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