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Good info on disc brakes

Old 09-20-12, 03:43 PM
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Originally Posted by PMK
I started a reply, and erased it...not worth the effort.

PK
And I started a reply to the reply you erased, but I erased that as well.
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Old 09-20-12, 04:19 PM
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Originally Posted by cafzali
But this is a very specialized situation and not one that the vast majority of cyclists will ever find themselves in. What prompted this thread was a discussion on disc brakes on road bikes. In this scenario, traditional caliper-based brakes remain more than adequate for the vast majority of people who aren't professional racers or don't have carbon rims. To me, that says it's likely to be a niche market, no matter what, just like CF frames are a niche market, etc.
I would partially agree with that statement in as much as there are a lot of people who live in the mid-west /south / south-east who tandem and they most often don't need the breaking power, but for those who live on the coast's (or mountain range areas) where there are a large mountain ranges and rarely a straight decent, they do need that kind of power.
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Old 09-20-12, 05:31 PM
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Originally Posted by PMK
I did some research on replacements and wondered, is rope or chain better when just using an anchor for slowing and stopping. Chain could be more compact for a given volume vs strength, but may weigh more, whereas a rope may have some inherent stretch, and therefore some lag before fully applying the brake.

Decisions like this become almost mind numbing.

PK
I'd suggest a "Static" rappelling or rescue rope, just enough stretch to keep you from pulling the anchor out...

Those titanium anchors are not cheap however.
Brent
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Old 09-20-12, 06:54 PM
  #104  
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Originally Posted by obrentharris
I'd suggest a "Static" rappelling or rescue rope, just enough stretch to keep you from pulling the anchor out...

Those titanium anchors are not cheap however.
Brent
So this rappelling rope would be better for mountainous terrain?

PK
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Old 09-20-12, 06:55 PM
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Originally Posted by Shimagnolo
And I started a reply to the reply you erased, but I erased that as well.
I started a reply and didn't have enough sense to erase same. This thread has convinced me to retire in Florida where we'll only need one caliper, but how to decide front or rear?

I owned a 1967 Z-28; 137 mph on the Mass Pike out of the box. Well, almost, added a racing cam. Who knew it would become a classic.
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Old 09-20-12, 07:06 PM
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Originally Posted by rdtompki
I started a reply and didn't have enough sense to erase same. This thread has convinced me to retire in Florida where we'll only need one caliper, but how to decide front or rear?

I owned a 1967 Z-28; 137 mph on the Mass Pike out of the box. Well, almost, added a racing cam. Who knew it would become a classic.
If you might retire in Florida, we'll take you, no state income tax and a good tandem club.

Just make certain on your single caliper, you run good pads for riding in the wet since we do get a lot of rain.
BTW, you will need a rear caliper only for better aerodynamics. The only time we ever use brakes is when riding with teams from other states...we constantly pedal rather than climb then coast, so the brake is to prevent any possibility of rear ending a gung ho snowbird team.

PK
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Old 09-22-12, 07:11 AM
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Originally Posted by PDub62
This is the first I've seen this thread and wanted to provide some info on a brake failure we had w/ a Santana w/ the WinZip disk brake on the rear. We were touring in the Adirondacks pulling a BOB trailer; we had only had the bike for a couple of months so I hadn't had to do any maintenance w/ the brake up to that point. Coming down a long, steep, straight stretch I was feathering the rear brakes to keep our speed under 35 mph when we flew by a museum that my wife wanted to stop at so I started to get on the brakes harder so we could stop and turn around. As I did that the rear brake started sqealing super loud and faded away to nothing; luckily I was able to stop using just the front brake but it took a while and scared the heck out of us. Since my confidence in that much touted brake was pretty well shot, when we returned home from the trip I added a rim brake on the rear wheel w/ a cyclocross brake lever. Now if the disk brake fails again I have another option to help me stop. In general I like having the disk brake because of its stopping power but it's nice to have a backup. We have a newer Cannondale road tandem w/ disks but we've never taken that into any mountainous areas and probably won't after reading about the risks in this thread!
Hi PDub,
That must've been a scary moment. Apologies if you already knew this and you had your reasons, but from your description, the problem may have started from feathering the rear brake down the hill. Lightly holding a disc brake on just gets the rotor and caliper hot, then when you wanted to slow down fast, it was already too hot and failed. Since you weren't feathering the front, it was able to stop you all by itself (which is impressive for a tandem plus bob-trailer). So, instead of being 'afraid' of your discs, I'd go back out there and try some different techniques. Best of luck.
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Old 09-22-12, 03:20 PM
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Originally Posted by cafzali
But this is a very specialized situation and not one that the vast majority of cyclists will ever find themselves in. What prompted this thread was a discussion on disc brakes on road bikes. In this scenario, traditional caliper-based brakes remain more than adequate for the vast majority of people who aren't professional racers or don't have carbon rims. To me, that says it's likely to be a niche market, no matter what, just like CF frames are a niche market, etc.
Ummm, no, I disagree. We're a heavy team, 470 at last math, who moved from San Antonio TX to eastside Seattle WA this summer. We'd anticipated a workout going up the hills, but I didn't expect the brake challenges going down. One night, we smoked our brakes such that both couldn't stop us on a downhill, and we rode home with a horrible scraping sound as the rotor had warped bad enough to drag with the brakes off. Another time, northbound on Vashon Island, we took the side street to descend to the ferry dock (as peds/bikes should do), and I couldn't stop at the bottom; I had to choose between diving to the left with hopes the oncoming traffic wasn't going to turn across our path, diving right and hope that I could steer into the shoulder quick enough to not get flattened by traffic, or hope for a hole where I could stay straight and plunge off the curb onto the rocky beach. We're going to buy some ICE-XT rotors soon in hopes that fixes it, but maybe we have to go for the Bengal calipers too.
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Old 09-22-12, 03:26 PM
  #109  
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Originally Posted by p2templin
Ummm, no, I disagree. We're a heavy team, 470 at last math, who moved from San Antonio TX to eastside Seattle WA this summer. We'd anticipated a workout going up the hills, but I didn't expect the brake challenges going down. One night, we smoked our brakes such that both couldn't stop us on a downhill, and we rode home with a horrible scraping sound as the rotor had warped bad enough to drag with the brakes off. Another time, northbound on Vashon Island, we took the side street to descend to the ferry dock (as peds/bikes should do), and I couldn't stop at the bottom; I had to choose between diving to the left with hopes the oncoming traffic wasn't going to turn across our path, diving right and hope that I could steer into the shoulder quick enough to not get flattened by traffic, or hope for a hole where I could stay straight and plunge off the curb onto the rocky beach. We're going to buy some ICE-XT rotors soon in hopes that fixes it, but maybe we have to go for the Bengal calipers too.
Yes, we do have some steep, though relatively short descents here. This 305 lb. team has found them challenging with rim brakes. Obviously a disc is just a rim brake with less mass. Doesn't necessarily work better in the dry. They heat up really quickly. It takes a longer descent to cook a rim caliper or a tire.
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Old 09-24-12, 07:50 PM
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Originally Posted by CaptainHaddock
Not knowing how big the decent was, so I can't say that my experiences have been the same, other than to comment that I descend with my wife and dog in his Burly Nomad (making a team weight of about 340) and have not had any problems at this point. Further I feel like it should be pointed out that you yourself state that you had not performed any preventative maintenance at that point, and you may very well have caused your own problem.
The descent was big; in the Adirandack mountains the roads seem to be long and straight with sweeping curves but few switchbacks. If I recall right the downhill was several miles long.

As far as preventative maintenance on the disk brake; I live in Wisconsin in an area with few hills and we only had a few hundred miles on the bike at the time so the brake was essentially new when we took this trip. The pads had been seated when we bought it so I don't think it was a lack of maintenance that was ths issue. As has been pointed out in this thread elsewhere, feathering the brakes was my problem. Santana touts this brake as an alternative to the Arai drum brake so I wasn't aware I shouldn't ride the brake to arrest speed. I will say that Santana does have good customer service; I called them to ask for advice on brake pad adjustment while on the side of the road and they talked me through the process over the phone so we were able to complete the trip despite severely wearing the pads on this one stop. As a side note, I now install new pads and carry a spare set whenever we tour so I'm ready for anything. It amazes me that you can wear out a set of pads in one descent!
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Old 09-24-12, 08:09 PM
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Originally Posted by wheelspeed
Hi PDub,
That must've been a scary moment. Apologies if you already knew this and you had your reasons, but from your description, the problem may have started from feathering the rear brake down the hill. Lightly holding a disc brake on just gets the rotor and caliper hot, then when you wanted to slow down fast, it was already too hot and failed. Since you weren't feathering the front, it was able to stop you all by itself (which is impressive for a tandem plus bob-trailer). So, instead of being 'afraid' of your discs, I'd go back out there and try some different techniques. Best of luck.
Thanks for the feedback. I definitely learned some things reading this thread about how to brake on long descents. I haven't run into the issue since that trip but I also haven't taken it down any mountains that extreme since then either. I do like the stopping power of disk brakes; since I have both a disk and a v-brake on my rear wheel I've been able to do a direct comparison of the stopping power and I can say the disk beats the rim brake hands down. We just got a Bullitt cargo bike w/ Shimano SLX hydraulic brakes and those are some awesome binders; I love the feel of those brakes. I hope someone can figure out the heat dissipation issue so they'll work on tandems some day.

It's interesting to me that I haven't seen any mentions of drag brakes on this thread. I realize they are big and heavy and not necessary for a road bike (the initial focus of this thread) but it seems like a great option for tandems; I'd take a little extra weight for the security of being able to stop!
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Old 09-24-12, 09:53 PM
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Originally Posted by PDub62
Thanks for the feedback. I definitely learned some things reading this thread about how to brake on long descents. I haven't run into the issue since that trip but I also haven't taken it down any mountains that extreme since then either. I do like the stopping power of disk brakes; since I have both a disk and a v-brake on my rear wheel I've been able to do a direct comparison of the stopping power and I can say the disk beats the rim brake hands down. We just got a Bullitt cargo bike w/ Shimano SLX hydraulic brakes and those are some awesome binders; I love the feel of those brakes. I hope someone can figure out the heat dissipation issue so they'll work on tandems some day.

It's interesting to me that I haven't seen any mentions of drag brakes on this thread. I realize they are big and heavy and not necessary for a road bike (the initial focus of this thread) but it seems like a great option for tandems; I'd take a little extra weight for the security of being able to stop!
We have an Arai drum drag brake that I bought off ebay. There's a thread on this forum about adapting a new manufacturer's drum. Our wheel with the drum weighs 2 lb. more than our wheel that doesn't have a drum. Some of that may be in the different hub. We use it for touring, and for that application would not be without it! Going down some long 12%-14% grade on a bad road surface with fully loaded panniers and the drag on is just fine. Without the drag would not be just fine.
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Old 01-03-13, 11:30 AM
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Magura Launches Study on Road Discs

From Bicycle Retailer magazine, Dec 2012:

POSTFACH, Germany (BRAIN) — Disc brakes on road bikes? Not so fast says Germany’s brake specialist, Magura.

Magura has launched a study logging how a number of test riders use disc brakes over miles of European roads before deciding whether the technology is an option for the company.

“The biggest concern is overheating since average and top speeds are much higher for road bikes than mountain bikes,” said Stefan Pahl, Magura’s bicycle product manager and engineer.

Click here for the rest of the story including some math behind their concerns. Some very interesting reading.
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Old 01-05-13, 02:41 AM
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Originally Posted by rhino919
From Bicycle Retailer magazine, Dec 2012:

POSTFACH, Germany (BRAIN) — Disc brakes on road bikes? Not so fast says Germany’s brake specialist, Magura.

Magura has launched a study logging how a number of test riders use disc brakes over miles of European roads before deciding whether the technology is an option for the company.

“The biggest concern is overheating since average and top speeds are much higher for road bikes than mountain bikes,” said Stefan Pahl, Magura’s bicycle product manager and engineer.

Click here for the rest of the story including some math behind their concerns. Some very interesting reading.
Basically the "study" mentioned but not detailed is a marketing slant to put a spotlight on Magura's hydraulic rim brakes for road use. It otherwise says very little... oh look, he winced again
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Old 01-11-13, 10:20 PM
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On a bit of tangent here: coming from the mountain biking world. Hydraulic disc brakes are one of the technologies that 'changed everything'. they work in all conditions with one finger on the brake lever and the rest available for steering (gripping the grip).
Now I'm going to try a 10'' rear disc on my Santana arriva, but for a couple of different reasons. 1: arai drum brakes are hard to find now. 2. a third brake operated by my 10 year old stoker really helps to keep him engaged as a team member. I call for brake I get brake OR "dad do you need some brake?"
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Old 01-12-13, 12:14 AM
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Originally Posted by joe@vwvortex
Let me ask this question - do you really need disc brakes on your car when for all those years we had drum brakes which were more than adequate to stop the vehicle?
AFAICR the drum brakes did stop the car eventually but modern discs are a lot more efficient.
However it should be noted that the rotors are slightly thicker than those on a bicycle and because of the extra mass can dissipate a lot of heat relatively quickly and are less likely to warp. The calipers and housings are also more robust that one finds on a bike!

Also check the dimensions of the disc brake on the front wheel of your modern Japanese sports bike!

Beefier brakes on a bike would work better under sustained braking but you would have the extra weight penalty getting the bike up the hill!

Mike
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Old 01-12-13, 12:30 AM
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Non touring tandemists can switch off here but I have recently acquired a Thorn Raven twin touring tandem running 26X1.75 tyres.

This comes as standard with Shimano V brakes with the option of CSS coated rims with appropriate matching pads.

WE haven't been out in the wet yet as Australia is in the grip of a heat wave but so far riding flat bar using flat bar Shimano XT levers they are more than adequate. I am very pleased with the performance.

Thorn recommends the letting the bike run then braking hard to wipe off speed then release method mentioned above in this thread.

Another benefit is that the rim/pads combination runs clean and does not generated the black dust which we had on our old entry level tandem with aluminium rims and black pads. the V brakes on that bike do a pretty good job also.

Mike
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