I hate disc brakes - help!

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Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: I hate disc brakes - help!

Post by Jon in Sweden »

I bought a TT bike today (didn't enjoy it, but that's another story) but in my 35km outing, I couldn't help but feel that the rim brakes were superb compared to both my hydraulic and cable disked road bikes. Strong, progressive performance.

I will look to replace my bikes with rim brake bikes as time, availability and finances allow.
pwa
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Joined: 2 Oct 2011, 8:55pm

Re: I hate disc brakes - help!

Post by pwa »

wirral_cyclist wrote: 2 Jul 2022, 12:48pm
pwa wrote: 2 Jul 2022, 6:36am
Except maybe on a tandem. I had one fail completely on a tandem, so the lever could be pulled back to the bar with no braking taking place.
What was failure mode? Pad fade from overheating, or fluid overheating fade? What type of fluid mineral or DOT?

I guess risk of brake problems is why good tandems have a third brake, usually a big finned hub brake.
I think the DOT fluid overheated. On the twisty steep lane we were on it was not safe to just let the brakes go and enjoy some speed, so I alternated between the three brakes, giving each a rest to cool. But that was not sufficient to save the rear disc brake from failure. A Hope brake with the biggest disc that could be had. Fortunately we still had two vee brakes which carried on working well enough. The suddenness of the disc brake failing shocked me.
Biospace
Posts: 2006
Joined: 24 Jun 2019, 12:23pm

Re: I hate disc brakes - help!

Post by Biospace »

pwa wrote: 2 Jul 2022, 8:42pm
pwa wrote: 2 Jul 2022, 6:36am
Except maybe on a tandem. I had one fail completely on a tandem, so the lever could be pulled back to the bar with no braking taking place.
I think the DOT fluid overheated. On the twisty steep lane we were on it was not safe to just let the brakes go and enjoy some speed, so I alternated between the three brakes, giving each a rest to cool. But that was not sufficient to save the rear disc brake from failure. A Hope brake with the biggest disc that could be had. Fortunately we still had two vee brakes which carried on working well enough. The suddenness of the disc brake failing shocked me.
This is what so few people realise with hydraulic control of disc brakes on their bikes. And the ones who don't know about brake-release-brake to allow things to cool are perhaps those least likely to change their fluid as recommended, so the risk for them is potentially worse.

I've had a few moments on tandems as the drum brake has faded and the hill has steepened (being younger I'd decided more speed was needed for cooling of all the brakes!) but the brakes continued to work no matter how hot they were. The thought of pulling on a lever one moment and getting the typical hydraulic feel and the next moment finding no resistance all the way to the bars is something I never want to experience.

Car brakes are huge, designed to take a fully loaded vehicle down the longest mountain pass in hot weather without overheating. You can make them overheat and fail, but it takes a lot of deliberate effort and accelerating as hard as possible between hairpins. Unfortunately bicycle hydraulic disc brakes are designed to be good enough for most people most of the time, which for a safety critical item is nothing less than dangerous.
Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: I hate disc brakes - help!

Post by Jon in Sweden »

I wasn't aware that you could experience hydraulic disc failure in that way. It must be frightening.

I really don't enjoy descending as a rule. At 6ft 8" and 110kg, I accelerate painfully quickly. I like to climb hills, and enjoy the challenge. I view descending as a necessary evil.
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: I hate disc brakes - help!

Post by Jdsk »

Jon in Sweden wrote: 3 Jul 2022, 5:28pmI really don't enjoy descending as a rule. At 6ft 8" and 110kg, I accelerate painfully quickly. I like to climb hills, and enjoy the challenge. I view descending as a necessary evil.
Please could we arrange some sort of exchange system?

: - )

Jonathan
Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: I hate disc brakes - help!

Post by Jon in Sweden »

Jdsk wrote: 3 Jul 2022, 5:32pm
Jon in Sweden wrote: 3 Jul 2022, 5:28pmI really don't enjoy descending as a rule. At 6ft 8" and 110kg, I accelerate painfully quickly. I like to climb hills, and enjoy the challenge. I view descending as a necessary evil.
Please could we arrange some sort of exchange system?

: - )

Jonathan
Hahaha! :lol:

It's a cruel twist of fate really. Being the size I am, I'm like a Landrover Defender that loves track meets at Silverstone. Utterly and completely unsuited to the task, but having fun anyway.
Cyckelgalen
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Joined: 21 Sep 2018, 11:29am

Re: I hate disc brakes - help!

Post by Cyckelgalen »

There are several types of DOT fluids, the commonly used, polyglycol-based types 3, 4 and 5 have a boiling point of 205, 230 and 260 degrees C. That is fresh fluid out of a sealed container, once exposed to the environment it gradually absorbs humidity and the boiling point can go down by up to third (in two years roughly, reaching 3 to 4% water content).

Some brake manufacturers use DOT fluid.

Shimano (and Tektro, I believe) use mineral oil, not DOT. Shimano's is supposed to have a boiling point of 280 degrees, plus, not being hygroscopic, it won't decay as DOT fluids do.

Interesting to know. In the case mentioned above of the fluid reaching the boiling point, what brake was it and what fluid did it use?
rareposter
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Joined: 27 Aug 2014, 2:40pm

Re: I hate disc brakes - help!

Post by rareposter »

Jon in Sweden wrote: 2 Jul 2022, 8:28pm
I will look to replace my bikes with rim brake bikes as time, availability and finances allow.
Good luck with that. Availability of decent rim-brake wheels is only going to get worse, actual range of decent bikes with rim brakes is getting ever more limited and low-end too.

I'd love to know how your disc brakes can be this bad?! I know you mentioned cable discs in your original post and yes, they're terrible but no-one tries decent well set up hydro discs and says "ooh gosh, I'll go back to the rim brakes..."
Jon in Sweden
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Joined: 22 May 2022, 12:53pm

Re: I hate disc brakes - help!

Post by Jon in Sweden »

rareposter wrote: 4 Jul 2022, 9:12am
Jon in Sweden wrote: 2 Jul 2022, 8:28pm
I will look to replace my bikes with rim brake bikes as time, availability and finances allow.
Good luck with that. Availability of decent rim-brake wheels is only going to get worse, actual range of decent bikes with rim brakes is getting ever more limited and low-end too.

I'd love to know how your disc brakes can be this bad?! I know you mentioned cable discs in your original post and yes, they're terrible but no-one tries decent well set up hydro discs and says "ooh gosh, I'll go back to the rim brakes..."
I was out for 80km this morning and the discs on my Orbea (Tiagra hydraulic) were endlessly scraping. I replaced an inner tube on it (the front wheel) the other week, and since, it's catching.

I suspect that for whatever reason, the QR spindle isn't quite sitting properly, because I get more scraping depending on how I load the front wheel. I have done numerous brake resets (loosen off calliper mount bolts, hard on brake then tighten) but they don't hold.

I'm not an idiot and know my way around a bike, but I really detest this constant tinkering that's required. Additionally, I find that in the dry, I get better brake performance from rim brakes.
slowster
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Re: I hate disc brakes - help!

Post by slowster »

rareposter wrote: 4 Jul 2022, 9:12am no-one tries decent well set up hydro discs and says "ooh gosh, I'll go back to the rim brakes..."
Chris Froome does, and he has a professional mechanic to set up his brakes. And so too would probably a good percentage of the rest of the professional peloton if given a choice, but they probably keep quiet to avoid getting into trouble with team sponsors and equipment suppliers.
Bice
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Re: I hate disc brakes - help!

Post by Bice »

Only this summer have I got to use disc brakes: on a hired MTB and a lent new Woho Wildcard gravel bike.

Both sets of disc brakes were cable.

I thought the MTB ones were absolutely fine, and a considerable improvement on my experience of rim brakes doing long descents ... especially if you are going to come down rock strewn tracks 1,200 metres down the Dalmatian mountains, or similar.

The gravel bike disc brakes were more questionable. They certainly stopped the bike, but the front juddered a bit, and the actual control of braking was worse than all my bikes with calipers and V brakes. It needed some re-setting, and the axles were quick release which might be the problem.

I am in no hurry to adopt disc brakes: they are an obvious improvement for MTBs, and largely optional for everything else.

If I cycled on dirty roads in winter, I would consider them. But I live in London and the roads are generally pretty clean (leaving aside glass, discarded nitrous oxide canisters etc). I have never worn through a wheel rim.

All brakes have to be maintained. I completely stripped down and regreased the Shimano 105 brakes on my 12 year old Trek road bike, and replaced all inner and outer cables, and the result is highly effective brakes. They can lock the wheel easily in the dry, and they work effectively in the wet. The Campagnolo road bike brakes (Avanti) have always been very good, and better than the Shimano ones.

As I never laid down serious money for disc brakes, I am not vehement in their defence. But there are those in my club who have disc brakes on road bikes, and who regret them.

There are huge advantages in keeping things simple.
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Biospace
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Re: I hate disc brakes - help!

Post by Biospace »

Cyckelgalen wrote: 3 Jul 2022, 8:01pm Interesting to know. In the case mentioned above of the fluid reaching the boiling point, what brake was it and what fluid did it use?
pwa wrote: 2 Jul 2022, 8:42pm
wirral_cyclist wrote: 2 Jul 2022, 12:48pm
pwa wrote: 2 Jul 2022, 6:36am
Except maybe on a tandem. I had one fail completely on a tandem, so the lever could be pulled back to the bar with no braking taking place.
What was failure mode? Pad fade from overheating, or fluid overheating fade? What type of fluid mineral or DOT?

I guess risk of brake problems is why good tandems have a third brake, usually a big finned hub brake.
I think the DOT fluid overheated. On the twisty steep lane we were on it was not safe to just let the brakes go and enjoy some speed, so I alternated between the three brakes, giving each a rest to cool. But that was not sufficient to save the rear disc brake from failure. A Hope brake with the biggest disc that could be had. Fortunately we still had two vee brakes which carried on working well enough. The suddenness of the disc brake failing shocked me.
Brake fluid which is hygroscopic does sound daft, but if water finds its way in to a mineral oil system, it tends to pool together at the lowest point, often the caliper. The result is a boiling point 50C lower than damp conventional brake fluid (which given a small volume of water can boil very fast indeed) and one which could be frozen solid on a chilly winter's morning.

I would still choose mineral oil in a braking system, DOT fluid is nasty stuff in almost every way.
Biospace
Posts: 2006
Joined: 24 Jun 2019, 12:23pm

Re: I hate disc brakes - help!

Post by Biospace »

Bice wrote: 4 Jul 2022, 6:27pm
There are huge advantages in keeping things simple.
Yes! A bicycle is engineering poetry when at its finest.

Adding disc brakes loads up the frame and forks unevenly with forces in the places you'd choose to avoid them and tries to remove the front wheel from its dropouts. Contrast this relatively dumb application of engineering with how the French multi-purposed their small front racks (50s-70s) by using to the cantilever braze-ons as points of attachment, so bracing the brakes, forks and the rack itself as well as providing rigid location for the mudguard and lamp.

Using the spoked wheel's rim as twin braking surfaces is a similarly logical and brilliant example of engineering dual-purposing, stiffening the wheel and providing two enormous, super-cooled discs.
pwa
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Joined: 2 Oct 2011, 8:55pm

Re: I hate disc brakes - help!

Post by pwa »

Cyckelgalen wrote: 3 Jul 2022, 8:01pm There are several types of DOT fluids, the commonly used, polyglycol-based types 3, 4 and 5 have a boiling point of 205, 230 and 260 degrees C. That is fresh fluid out of a sealed container, once exposed to the environment it gradually absorbs humidity and the boiling point can go down by up to third (in two years roughly, reaching 3 to 4% water content).

Some brake manufacturers use DOT fluid.

Shimano (and Tektro, I believe) use mineral oil, not DOT. Shimano's is supposed to have a boiling point of 280 degrees, plus, not being hygroscopic, it won't decay as DOT fluids do.

Interesting to know. In the case mentioned above of the fluid reaching the boiling point, what brake was it and what fluid did it use?
Hope Mono TI with the largest disc (230?) and with DOT fluid. Because it was in the first year of use and hadn't done many miles, the tandem still had the first lot of DOT fluid as supplied by Thorn Cycles.
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Cugel
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Re: I hate disc brakes - help!

Post by Cugel »

Jon in Sweden wrote: 4 Jul 2022, 10:22am
rareposter wrote: 4 Jul 2022, 9:12am
Jon in Sweden wrote: 2 Jul 2022, 8:28pm
I will look to replace my bikes with rim brake bikes as time, availability and finances allow.
Good luck with that. Availability of decent rim-brake wheels is only going to get worse, actual range of decent bikes with rim brakes is getting ever more limited and low-end too.

I'd love to know how your disc brakes can be this bad?! I know you mentioned cable discs in your original post and yes, they're terrible but no-one tries decent well set up hydro discs and says "ooh gosh, I'll go back to the rim brakes..."
I was out for 80km this morning and the discs on my Orbea (Tiagra hydraulic) were endlessly scraping. I replaced an inner tube on it (the front wheel) the other week, and since, it's catching.

I suspect that for whatever reason, the QR spindle isn't quite sitting properly, because I get more scraping depending on how I load the front wheel. I have done numerous brake resets (loosen off calliper mount bolts, hard on brake then tighten) but they don't hold.

I'm not an idiot and know my way around a bike, but I really detest this constant tinkering that's required. Additionally, I find that in the dry, I get better brake performance from rim brakes.
Q/R axled wheels are more inclined to sit in the drop outs at a very slight variance to their previous position there, after you remove and replace the wheel. Even a teeny-weeny difference at the axle is magnified into a much larger deviance at the circumference of a disc.

"Much larger" is still a small absolute value .... but so are the clearance gaps between the disc and their brake pads, so a Q/R wheel is much more likely to rub after a wheel removal and replacement than is a wheel with an axle threaded into the drop-outs. This is why better disc brake frames use such threaded "through" axles. The relocation after a wheel removal is automatic and much more accurate (i.e. identical to the previous location of the axle in the drop outs) with such "through" axles, so far less chance of brake rub.

*************

Another possibility is a slightly warped disc. Again, the warp may be very small (too small to easily see with the naked eye) but since the disc-to-pad clearances are very small, a rub may still occur at just one spot on the disc. You can check it if you put your specs on (well, I have to) and spin the wheel slowly whilst looking vertically down the plane of the disc. But noting where the disc rubs and where it doesn't is probably the only way to spot a potential warp-spot

There are small tools that go over the disc's edge then act as a lever, so you can bend the disc straight. This is not easy to do with accuracy, as you can imagine, but it can be done if you're very careful with the positioning of the tool and the bending force you apply.

***************
Although wary myself of disc brakes when they began to appear on road as well as MTBs, I've come to much prefer them for their feel, especially the ability to modulate their grip to a much finer degree and to brake on steep descents without getting "cramp i' the knuckles". Once you know how, any bleeding or pad change is quick and easy. It seems much easier to install, adjust and keep-adjusted hydraulic disc brakes than it is to perform those tasks with cantilevers or even standard brakes.

Cable disc brakes - not so good.

Of course, many don't ever install their standard brakes properly, neglecting toe-in, pad-to-rim matching and so forth. They just don't notice. :-)

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
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