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Disc Brakes PITA
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Disc brakes are a pain to change flats, so pros just change bikes (which makes sense for speed anyway) according to the announcers of the TdF. Does this translate to tri bikes also?
Last edited by: wjoiner: Jul 7, 18 21:49
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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How does brake type dictate to easy it is to change a flat?
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Re: Disc Brakes PITA [gmh39] [ In reply to ]
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Announcers stated it is difficult to keep the brake from rubbing after a tire change - never touched one and found it curious so thought I would throw it out there.
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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I've used them on MTB, not so much on road. Brake rub can be a problem after removing and re-attaching a wheel, you sometimes need to loosen the skewers, adjust and re-tighten. I don't see how the it's any difference between re-attaching a wheel with a fixed flat and attaching a new wheel though, seems if there's a risk of brake rub the risk would be the same for both.
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Re: Disc Brakes PITA [cartsman] [ In reply to ]
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My bad, they were changing out bikes (not wheels), updated the original post to reflect. Hope this isn’t an issue in 5+ years when I’ll be in the market for a new bike.
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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How would this translate to tri's where there is not a support vehicle with spare wheels or bikes?
You have to repair the puncture and while a through axle disc brake wheel is a little slower to remove and install there would only be a few seconds in it.
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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I've got 4 sets of thru axle wheels with three different hubs: 2 Zipps, 1 White industries, 1 DT Swiss, but all 6 bolt disc brake rotors. I can say that although every wheel set is 15x100 (f) and 12x142 (r), if I set up my brakes for one hub and then switch to another wheel set with a different hub, my disc brakes will rub the pads.

For the TDF, there would be a good chance that taking a neutral Mavic disc wheel has a high probability of rubbing unless the team was already running Mavic disc wheels.

For anyone else that is going to take the wheel out, change the flat, and put it back in the frame, no you shouldn't see brake rub after a tire change*.

*Provided you didn't grab the brake lever with the wheel out and closed the pads.
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Re: Disc Brakes PITA [geauxTT] [ In reply to ]
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geauxTT wrote:

For anyone else that is going to take the wheel out, change the flat, and put it back in the frame, no you shouldn't see brake rub after a tire change*.

*Provided you didn't grab the brake lever with the wheel out and closed the pads.
That's bound to happen. My MTB wouldn't fit in my car without taking the front wheel out and many times have i touched the lever. So annoying I switched to mechanical (non-hydraulic) disc brakes instead. I'm in the market for a new bike and it seems the default is hydraulic disc brakes... not a fan of that. It's all good when they work until you get an air bubble and need to start messing around with bleed kits which sometimes work and sometimes don't. Real PITA.
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Re: Disc Brakes PITA [Benv] [ In reply to ]
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Benv wrote:
geauxTT wrote:


For anyone else that is going to take the wheel out, change the flat, and put it back in the frame, no you shouldn't see brake rub after a tire change*.

*Provided you didn't grab the brake lever with the wheel out and closed the pads.
That's bound to happen. My MTB wouldn't fit in my car without taking the front wheel out and many times have i touched the lever. So annoying I switched to mechanical (non-hydraulic) disc brakes instead. I'm in the market for a new bike and it seems the default is hydraulic disc brakes... not a fan of that. It's all good when they work until you get an air bubble and need to start messing around with bleed kits which sometimes work and sometimes don't. Real PITA.

All hydraulic disc brakes that i know of come with a spacer that you wedge between the pads anytime you remove a wheel. Most shops probably have a bunch of these just laying around. Some of these are brand and model specific, but there are several that will fit just about any brake. I have a few older Bengal spacers that conveniently clip to the brake lines, so I always have them with me...



"I'm thinking of a number between 1 and 10, and I don't know why!"
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Re: Disc Brakes PITA [Warbird] [ In reply to ]
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Yup I had that, and one day lost it... just like I probably won't have it with me on an actual ride.
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Re: Disc Brakes PITA [Benv] [ In reply to ]
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To Benv - I take both wheels out of my mountain bike to put it in my car to travel to where I ride. On average I ride twice a week as a minimum. Rough maths suggests I've put the wheels into and out of my bike in the region of 600 times over the last 3 years. I could count on one hand the number of times my pads have moved. I'd give hydraulic brakes on your mountain bike another shot if I were you - you were either unlucky or something was wrong.

To the OP - However, as someone else pointed out above, if you are changing to a different set of wheels pads will almost always rub unless you happen to get very lucky. As a result getting a spare wheel from neutral service is likely to be something of a gamble.
Last edited by: rmt: Jul 8, 18 13:07
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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wjoiner wrote:
Disc brakes are a pain to change flats, so pros just change bikes (which makes sense for speed anyway) according to the announcers of the TdF. Does this translate to tri bikes also?

There are a couple issues here. Yes, it can be tougher to change a wheel very quickly in a stage race like the TDF, because when you change a wheel, the disc rotor has a very small space to slide in to inside the caliper.

People are also touching on the issue of rotors rubbing the pads, which can also happen for more than one reason. First, left-right location of the rotor isn't perfectly consistent between different hubs. Nor do I imagine that all rotors share a perfectly consistent thickness.

But the big one that many people don't understand is that for any disc brake bike with standard quick release skewers, there is a big X factor... even with just one bike and one wheel, if you loosen and tighten the skewer, the rotor doesn't always end up locating in the same place between the pads. If you've never seen it, trust me. I've confirmed with some big wheel manufacturers that this absolutely happens. You close the skewer lever once (with weight down on the bike, ensuring the axle is square in the dropouts) and the rotor is right between the pads. Open the lever and close it again - now the rotor is rubbing one pad. It's fiddly and annoying. Thru axles tend to do a much better job of consistently locating the rotor in the same spot.

Also, just in general, disc brakes tend to require at least double the amount of fiddle / adjustment time over their lifespan compared to standard rim brakes. And I think I'm being very conservative when I say double - with some systems it could be 10x more when you bring annual fluid bleeding (with DOT systems) and bike box travel into the mix.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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But they work better in the rain and on mtn decents! They also burn and cut things better too!


Current trend is threaded thru axle. So you need an allen wrench to unthread it. You'ld see mechanics run out there nascar/f1 style with cordless drills, until one cross threads an axle and then the bike is useless. Thus it is just faster and easier to hand them a fresh bike.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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gregk wrote:
But the big one that many people don't understand is that for any disc brake bike with standard quick release skewers, there is a big X factor.

Quick release skewers on disc brake equipped wheel? Never seen such a thing, in fact I thought that it wasn't safe to use anything but a through axel due to the added rotational torque produced when actuating a disc brake - it can pull the axel out the bottom, even with "lawyer lips" in place.

My 2017 Roubaix with disc brake wheels has a through axel with a "skewer type" handle that is used to tighten it up. I have changed flats on both ends of that bike several times and never had rotor rub afterwards. I could see a problem if you changed the entire wheel (inadvertently actuate the brake with the rotor removed), but no one is going to do that in the field, let alone a race. (Well, maybe the pros, but...)

"...the street finds its own uses for things"
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Re: Disc Brakes PITA [AutomaticJack] [ In reply to ]
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AutomaticJack wrote:
gregk wrote:
But the big one that many people don't understand is that for any disc brake bike with standard quick release skewers, there is a big X factor.


Quick release skewers on disc brake equipped wheel? Never seen such a thing, in fact I thought that it wasn't safe to use anything but a through axel due to the added rotational torque produced when actuating a disc brake - it can pull the axel out the bottom, even with "lawyer lips" in place.

My 2017 Roubaix with disc brake wheels has a through axel with a "skewer type" handle that is used to tighten it up. I have changed flats on both ends of that bike several times and never had rotor rub afterwards. I could see a problem if you changed the entire wheel (inadvertently actuate the brake with the rotor removed), but no one is going to do that in the field, let alone a race. (Well, maybe the pros, but...)

Yup, there are lots of bikes out there with QR axles and disc brakes (including a ton of pre-thru axle mountain bikes). I've owned several. Some manufacturers add in some measures of safety, such as very large lawyer tabs, or forward-angled front dropouts (i.e. Salsa brand forks). My current gravel/CX bike has QR axles and disc brakes. Surly Straggler front fork. Front QR tends to fiddle with the disc rotor location quite a bit. If I have to remove the front wheel for travel (i.e. in a car), I always have to bring tools with me, because I might have to re-position the caliper before I can ride.

Thru axles help, as mentioned. But then you've got to mess with adapters for roof racks and some repair stands.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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gregk wrote:
AutomaticJack wrote:
gregk wrote:
But the big one that many people don't understand is that for any disc brake bike with standard quick release skewers, there is a big X factor.


Quick release skewers on disc brake equipped wheel? Never seen such a thing, in fact I thought that it wasn't safe to use anything but a through axel due to the added rotational torque produced when actuating a disc brake - it can pull the axel out the bottom, even with "lawyer lips" in place.

My 2017 Roubaix with disc brake wheels has a through axel with a "skewer type" handle that is used to tighten it up. I have changed flats on both ends of that bike several times and never had rotor rub afterwards. I could see a problem if you changed the entire wheel (inadvertently actuate the brake with the rotor removed), but no one is going to do that in the field, let alone a race. (Well, maybe the pros, but...)


Yup, there are lots of bikes out there with QR axles and disc brakes (including a ton of pre-thru axle mountain bikes). I've owned several. Some manufacturers add in some measures of safety, such as very large lawyer tabs, or forward-angled front dropouts (i.e. Salsa brand forks). My current gravel/CX bike has QR axles and disc brakes. Surly Straggler front fork. Front QR tends to fiddle with the disc rotor location quite a bit. If I have to remove the front wheel for travel (i.e. in a car), I always have to bring tools with me, because I might have to re-position the caliper before I can ride.

Thru axles help, as mentioned. But then you've got to mess with adapters for roof racks and some repair stands.

My dual suspension MTB has QR and discs...never had a wheel positioning problem taking them in or out.

Same with my initial gravel "Frankenbike", which was built with a Salsa Vaya fork (forward facing dropouts).

My current gravel rig (Jari) is still using QR on the rear (for wheel compatibility to already acquired wheelsets reasons)..again, no issues.

Then again, I also run/ran cable actuated discs on all of those, so I probably set the pad clearance a bit "looser" than what a hydro setup ends up at...



http://bikeblather.blogspot.com/
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Re: Disc Brakes PITA [Tom A.] [ In reply to ]
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It seems hit and miss for me. QR MTB suspension forks seem to do well in general. I don't know if it's because they have thicker dropouts and/or more stringent safety/manufacturing standards then rigid CX/road forks? Who knows. Could be dropout alignment, inconsistent paint application, etc. But I've had wheel manufacturers tell me it's a known issue.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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gregk wrote:
It seems hit and miss for me. QR MTB suspension forks seem to do well in general. I don't know if it's because they have thicker dropouts and/or more stringent safety/manufacturing standards then rigid CX/road forks? Who knows. Could be dropout alignment, inconsistent paint application, etc. But I've had wheel manufacturers tell me it's a known issue.

I think the bigger issue (QR or TA) is hub to hub differences in the disc mounting surface to the dropout distance. That causes me to adjust caliper position more (when swapping between wheels) than anything...until I get frustrated enough and finally shim the hub with the furthest distance so that all my wheels match.

But, then throw in another wheel...and all bets are off :-/



http://bikeblather.blogspot.com/
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Re: Disc Brakes PITA [wjoiner] [ In reply to ]
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Mountain Bike with QR disc: never a problem with taking off and on any wheelsets and rubbing - ZERO issue.
Cross/Gravel bike using QR disc: same - never had an issues....ZERO
New road bike TA with two disc wheelsets although they are using the same hubs. All I needed to do was true up each rotor to take away any out of alignments on the rotor and now I can switch between both wheelsets and have ZERO rubbing issues. I guess the true test will be when I get a wheelset with a different hub (center lock). I assume someone makes some shims for the rotors in case there is any sort of deviation between the hubs.

Side note, I had to bleed a brake on my road bike and it took all of under 60 seconds. I didn't do a "full bleed" which could be done in under 5 minutes, but just did a "quick bleed".........pulled the pads off, opened the reservoir....tapped out any air bubble, filled the reservoir and was good to go!
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Re: Disc Brakes PITA [Tom A.] [ In reply to ]
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I haven't actually measured hubs to see if that is where the variations are. It could also be in the discs.
I also have a QR road bike with hydro discs and have never had a problem with alignment after wheel removal.
If the dropouts are parallel and aligned correctly when the frame/fork is made there is no reason for a problem with QR.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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gregk wrote:

Also, just in general, disc brakes tend to require at least double the amount of fiddle / adjustment time over their lifespan compared to standard rim brakes. And I think I'm being very conservative when I say double - with some systems it could be 10x more when you bring annual fluid bleeding (with DOT systems) and bike box travel into the mix.

I think double is excessively generous. Pretty much anything that goes wrong (at the regular maintenance level) with mechanical rim calipers can be fixed in a few minutes with a new cable or pads.
Bleeding, pad alignment, sticky pistons, contaminated pads are all things that can waste considerable time individually. Had to sand the flat mount surface on my fork the other day as the lacquer was uneven so the pads were impossible to align. Today the pistons are not retracting fully (on a few month old set of brakes).

I was at a manufacturer presentation once where they said that they were pushing disc brakes and the shops should be happy about it because it would mean more workshop $ as consumers wouldn't be able to deal with the above at home.


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Re: Disc Brakes PITA [cyclenutnz] [ In reply to ]
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cyclenutnz wrote:
gregk wrote:


Also, just in general, disc brakes tend to require at least double the amount of fiddle / adjustment time over their lifespan compared to standard rim brakes. And I think I'm being very conservative when I say double - with some systems it could be 10x more when you bring annual fluid bleeding (with DOT systems) and bike box travel into the mix.


I think double is excessively generous. Pretty much anything that goes wrong (at the regular maintenance level) with mechanical rim calipers can be fixed in a few minutes with a new cable or pads.
Bleeding, pad alignment, sticky pistons, contaminated pads are all things that can waste considerable time individually. Had to sand the flat mount surface on my fork the other day as the lacquer was uneven so the pads were impossible to align. Today the pistons are not retracting fully (on a few month old set of brakes).

I was at a manufacturer presentation once where they said that they were pushing disc brakes and the shops should be happy about it because it would mean more workshop $ as consumers wouldn't be able to deal with the above at home.

Yeah, as you know, it can really vary a lot depending on many factors - caliper mounting style, frame quality / prep, hydraulic vs mechanical, type of fluid (DOT needing at least annual fluid changes vs "lifetime fluid" for mineral oil), thru vs QR, weather, manufacturer of brakes (I seem to have fewest issues with Shimano). It's a big mixed bag. But if you compared the two extremes, it could get pretty ridiculous. For example, a pair of Dura Ace road brakes located in the standard position, with externally routed cables vs. a DOT hydraulic system that's internally routed on an over-painted flat mount frame, and the rotors aren't straight, and the pistons are sticky, and the brakes get recalled, etc... the latter could take 20x or more service time over the lifetime of the bike.

The biggest issue I have with disc brakes in general is recurring noise. Even when I make the rotors PERFECTLY straight, and use organic / resin pads, and everything's clean, and everything's bedded in properly, and yadda yadda - noise seems to creep back eventually. Call it squeal, squeak, sqwawk. It's worse in the cold and/or wet. Basically I've gotten really good at cleaning pads and rotors, and doing a ton of sprints / stops in my neighborhood to bed them in. Oh, and rebuilding BB7 calipers helped to quiet them down a good amount.

Where I've ended up for my personal bikes is that I use discs where the performance benefit is pretty big (i.e. MTB and CX), or I simply cannot find a frame without it. The latter is becoming more of an issue. For the average cyclist with a day job and family, road rim calipers are definitely the best choice. And I'd add that "mid reach" (which used to be "standard reach") are the smart option, with clearance for 30-32mm tires.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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Disc brakes = PITA. Got it! Sticking with my rim brakes.
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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gregk wrote:
Where I've ended up for my personal bikes is that I use discs where the performance benefit is pretty big (i.e. MTB and CX), or I simply cannot find a frame without it. The latter is becoming more of an issue. For the average cyclist with a day job and family, road rim calipers are definitely the best choice. And I'd add that "mid reach" (which used to be "standard reach") are the smart option, with clearance for 30-32mm tires.

This^^^^



http://bikeblather.blogspot.com/
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Re: Disc Brakes PITA [gregk] [ In reply to ]
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I have a 'no DOT fluid in my life' policy. Which fits well with my (less strict) no SRAM policy.
My best hydros are cheap tektros on the around town MTB, have never touched them and they've never squealed or missed a beat.
Our MTB ones require a lot of love to stay squeal free.
My gravel/training bike looks at a puddle and starts squealing, then has grit rubbing after the puddle. The squealing does go away of it's own accord though (maybe the backing that campag have on the pads works).
Whereas my rim brake bikes ignore that sort of thing and only require an occasional pad and rim clean to make sure there is no debris - no sandpaper, cleaning alcohol or blowtorch required.


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