# disc brakes on a commuter bike?



## chubmackerel (Sep 22, 2014)

I have a hardtail mtb I use to on a regular basis to commute to work. I am having a lot of trouble with my rear brake pads glazing...only the rear I have spent quite a bit of time troubleshooting this problem . I installed a new set of metallic pads a few weeks ago, was very careful to bed them in. They worked great until I rode home the other night on wet gritty roads, the green belt over here has a lot of goose shyte on the paved path.Next time I rode the bike the pads had no grip, pads were glazed. I am nearly certain that wet road spooge is causing the problem. Identical brakes on other mtb have never been a problem, never been used for commuting. I am very careful about chain lube application. I sanded the pads tonight, will bed them in again. What a hassle if I have to sand the pads over and over. Should I just accept this? maybe go back to V-brakes for my commuter bike? anyone out there have similar issues? The brakes are NOS Shimano BR-M765. Thanks


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## wschruba (Apr 13, 2012)

Rotors do need to be cleaned occasionally... How often are you cleaning yours?

Pads have a part to play on this, but they aren't the only thing to worry about in terms of contamination. A particularly filthy ride can muck up pads/discs.


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## Rustedthrough (Aug 19, 2014)

I have BB5s on my Bosanova and have had several alignment issues, but no glazing issues so far. Goose, chicken, ox, and horse shite are common in my daily use, none has caused a glazing issue. I cleaned my rotors and pads the other week, when I rebuilt the brakes on my wife's truck and had the can in my hand, and noticed sharper stopping on the bike- but not a huge difference. This was after 700 or so miles miles in a shite rich environment.

Can you see where the pads are glazed versus where they are untouched? Disc brakes on bikes have a lot more adjustment, and a lot more travel, set points than those on cars as they are designed to fit so many frames. If you haven't had it in to the LBS, this might be a good time for it. 

My discs have been un-phased by manure of any derivation, although I had a similar problem with the front end of of a Silverado 2500 a few years back. On the Chevy, there was a bad casting which didn't allow brake fluid to flow as designed, new calipers solved it. Does your rear wheel spin as freely as your front? Is it possible that your rear is dragging all the time?


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## mtbxplorer (Dec 25, 2009)

I rarely touch my BB7s. They might squeak a bit after a slush/salty ride, but it goes away after using them a few times. I'd agree with the LBS recommendation, brakes are an area where a good shop mechanic can get better results than me in much less time.


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## ghettocruiser (Jun 21, 2008)

I commuted on M765s for 5 or 6 years. This included winter riding in salty slush and also spring races in knee-deep mud. Don't think that any kind of road grime can render them totally inoperable, subtle decrease in power at worst.

If there was long-term exposure to road salt in the equation it's possible that one of the pistons seized, but even still the other piston should still let the brake work alright, just a bit of drag.

So I'm gonna say there's gotta be air in the lines. Shimano brakes are pretty easy to bleed yourself, if you've got an evening to spare.


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## bedwards1000 (May 31, 2011)

My vote is for a leaky caliper that is oozing some brake oil on the pads and fouling them. I fought with this for a year on one of my bikes. There was so little oil that it wasn't noticeable but I could only get 1 ride in before they brakes were nearly ineffective. I replaced the caliper and the problem went away.


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## CommuterBoy (Oct 4, 2007)

Just to clarify, Disc brakes on everything. :lol: This should be a given.


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## leeboh (Aug 5, 2011)

No issues with my BB-7's on crappy Boston roads. Tried organic pads?


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## Harold (Dec 23, 2003)

Yeah, I have BB7's on my commuter and they have been relatively trouble-free.

I'd agree with the contamination hypothesis. I've heard of a number of cases of subtle fluid leaks at the piston seal causing serious problems.


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## chubmackerel (Sep 22, 2014)

I am sure that the brake is properly bled, proved that by changing the faulty pads out, installing new ones solved the problem..for awhile. The brakes are NOS LX BR-M 585. I see no evidence of a leak, from what I gather a small leak would be difficult to detect? I now suspect this may be a crappy caliper design? never had so many problems with any shimano component.Tried organic with no success, currently have metallic pads on the rear.Noteworthy that the front has never been a problem.Installed these brakes about 5 months ago. Maybe just a coincidence that the pads were fine before riding home in rain and snow slush? they spray some crap on the road during the winter here.


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## bedwards1000 (May 31, 2011)

I could never find the leak until it got worse. Try not doing anything except the bedding in process. I found that some real hard braking or riding the brakes while peddling downhill would burn off the mineral oil and they would work for a while.


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## Harold (Dec 23, 2003)

you definitely have contamination issues. finding the source is the trick. maybe your front tire was flinging the salty, oily grime onto your rear brake cause the contamination. Hard to say until you start eliminating variables.


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## chubmackerel (Sep 22, 2014)

Harold said:


> you definitely have contamination issues. finding the source is the trick. maybe your front tire was flinging the salty, oily grime onto your rear brake cause the contamination. Hard to say until you start eliminating variables.


Very good advice, thank you. I will stay off the greenbelt to begin with. such a frustrating problem.


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## chubmackerel (Sep 22, 2014)

bedwards1000 said:


> I could never find the leak until it got worse. Try not doing anything except the bedding in process. I found that some real hard braking or riding the brakes while peddling downhill would burn off the mineral oil and they would work for a while.


leaking at the piston? I keep looking there....carefully, it is possible.I wipe all hose connections and calipers down with alcohol so as to make it easier to find a leak.Thanks to everyone for the posts.


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## wschruba (Apr 13, 2012)

If it's leaking from the piston, the backs of the pads will have an oily ring on them. It is probably the most common leak, as debris gets pulled between the piston and the bore, consequently tearing or displacing the square-edge seal behind.

If that is the case, you can try extending the pistons and swabbing the sides with a qtip dipped in alcohol. If that doesn't fix it, and the brakes are less than a year old, it is a warranty concern.


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## rogbie (Jun 20, 2011)

The discs may be contaminated as well. Use emery cloth (Scotch pad) and lightly scour each face of the discs (using a piece of wood as a sanding block reduces uneven scouring). Clean with brake cleaner or rubbing alcohol sprayed onto a lint/oil free rag (paper towels are best). Let dry thoroughly. Scour the pads again by placing medium grit sand paper face up on a flat surface, with even pressure scour pad ~10 times (I like to go 5 in one direction, 5 in opposite). Spray or wipe pads with lint/oil free rag, let dry. Replace and ride.

If that doesn't solve the issue, it's a leaking seal in or at the caliper.


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## chubmackerel (Sep 22, 2014)

An update on this exciting issue.....my brakes I sanded down the pads, cleaned rotor with alcohol and waited until the roads were dry to gently bed them in. The brake works fine now, I think I can rule out improper bleeding technique. This was a metallic pad that I replaced just about a month ago. So this leads me to the conclusion that the most likely culprit is wet road crud that has been glazing only my rear brake. I do not recall ever having this type of problem with my BB7s so I commandeered and refit my daughters bike to commute to work. So far riding on the same route with somewhat similar conditions I have had no problems. Is it possible that maybe these older pads from 2006 be more prone to glazing? not sure.This has turned into a somewhat interesting research project I am only going to use the bike with the brake problem only on dry days. I forgot well BB7s perform, rather nice modulation and uber reliable, just rather heavy.Still no evidence of a leak at the caliper, been carefully looking for one.


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## chubmackerel (Sep 22, 2014)

*Finally found the problem*



bedwards1000 said:


> I could never find the leak until it got worse. Try not doing anything except the bedding in process. I found that some real hard braking or riding the brakes while peddling downhill would burn off the mineral oil and they would work for a while.


So it turns out you are quite right, the leak was eventually very obvious:madman: this sucks since this caliper was only a few months old. I think the old LX calipers are of poor design? I went back to BB7s on this bike. Thanks so much for your help, I kept on looking for that leak


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## bedwards1000 (May 31, 2011)

Great to hear that you found it. Sucks that it died so soon. At least you know that it isn't road grime and you can use a disk brake bike as a commuter. 

I have BB7s on my pugsley. They work great but squeal and howl quite a bit. I also can't get them adjusted so they won't squeak when pedaling hard but I think that is the flexy frame.


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## car bone (Apr 15, 2011)

chubmackerel said:


> So it turns out you are quite right, the leak was eventually very obvious:madman: this sucks since this caliper was only a few months old. I think the old LX calipers are of poor design? I went back to BB7s on this bike. Thanks so much for your help, I kept on looking for that leak


I had similar low grade shimanos that totally lost braking power, got replacements and they went bad after about a year of light commuting. Tried out formulas and they had much more power, but instead required regular maintainence (too regular imo). Tried some bb7s and not looking back. Hydros are good when they work but is a hassle when they don't, as opposed to the bb7. Its a wire and 2 pads on a lever/arm (ok 1 on the moving arm), almost idiot proof. If/when they stop working its pretty obvious whats going on and how to fix it.


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## CommuterBoy (Oct 4, 2007)

Am I the only one that's never had an issue with a hydraulic disc brake? Two pairs of Hayes and a pair of Shimanos, and no drama. I bled one once just because I shortened the cable. Otherwise nothing but replacing the pads. 

I have BB7's on the commuter, and I completely agree with the idiot-proof awesomeness factor there. I haven't had another brake that lets me swap wheelsets with different rotors and adjust the pads so quickly. Swapping to the studs is a 1 minute or less operation.


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## wschruba (Apr 13, 2012)

CB, I've encountered very few issues with hydros, but I have seen the above happen, especially with cheaper shimano brakesets. Don't know if it's the voyage over via container, air transport, or whatever, but every 5-6 pairs, I'll get a (new) bike that has leaking pistons. Totally up to the shop to catch something like that before it goes out, but then, most places can't be arsed to sit their own arses on the bike they just built to make sure it works.

Me personally? It's a wash, since I don't ride aggressively enough (or have the terrain that I will ride) that demands disc brakes. Despite the coastal conditions here, the roads are pretty clean, all told, so rim wear isn't a huge issue for me. The mountain bike has them mostly to say that I have them, and I can't say that I've had much in the way of issues with them, other than bleeding them as regular maintenance over the course of 3 years.


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## jeffscott (May 10, 2006)

CommuterBoy said:


> Am I the only one that's never had an issue with a hydraulic disc brake? Two pairs of Hayes and a pair of Shimanos, and no drama. I bled one once just because I shortened the cable. Otherwise nothing but replacing the pads.
> 
> I have BB7's on the commuter, and I completely agree with the idiot-proof awesomeness factor there. I haven't had another brake that lets me swap wheelsets with different rotors and adjust the pads so quickly. Swapping to the studs is a 1 minute or less operation.


Probably....I get leaks in the extreme cold, and wet pads when I go in and out from the cold...

But I was just riding summer or "nice days" no problems.

BTW I swap tires.... never have a problem with Shimano hydros.... occasionaly issue with cable tension, due to wonky dropouts, but that is a quarter turn on the adjuster at most.


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## Kleebs (Mar 18, 2014)

CommuterBoy said:


> Am I the only one that's never had an issue with a hydraulic disc brake? Two pairs of Hayes and a pair of Shimanos, and no drama. I bled one once just because I shortened the cable. Otherwise nothing but replacing the pads.
> 
> I have BB7's on the commuter, and I completely agree with the idiot-proof awesomeness factor there. I haven't had another brake that lets me swap wheelsets with different rotors and adjust the pads so quickly. Swapping to the studs is a 1 minute or less operation.


I've never had any issues with my hydros either, so i'm a little surprised to hear all the horror stories. Other than replacing pads, I've never had to do anything to my entry-level shimanos in 4+ years of mountain biking.

BB5's on the other hand......how I loathe you!!!!


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## bedwards1000 (May 31, 2011)

I've had problems with both Shimano & Avid Elixir seals both ridden in the cold. The Avids are a pain to bleed IMO. Teeny-Tiny barb fittings with hoses that tend to blow off at just the wrong moment requiring a total re-do.


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## ghettocruiser (Jun 21, 2008)

CommuterBoy said:


> Am I the only one that's never had an issue with a hydraulic disc brake? Two pairs of Hayes and a pair of Shimanos, and no drama. I bled one once just because I shortened the cable. Otherwise nothing but replacing the pads..


I had had issues, but compared to the other components on the bike they are not at all frequent. I bleed my own shimano brakes once a season or less and have the shop bleed the elixers about as often. They both usually work fine all winter long.

The BB7s remain in a box in my basement. I didn't dislike them, but they weren't on the same page as the hydraulics, IMO. I'll find a new application for them one of these days.


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## CommuterBoy (Oct 4, 2007)

I sometimes wonder at the necessity of regular bleedings... it's mineral oil, I mean, what's going on in there that's necessitating fresh fluid every year? Even ridden extremely hard, it's not the kind of crazy heat that's going to cause problems. I never bleed mine. Going on 8 years with the Hayes 9's on my hardtail, nothing but new pads... Ridden from 100*F to 5 below zero F (below zero rarely...regular rides in the teens though). 

I've had dirt bikes with hydraulic clutches that use the same fluid... I had to bleed one of those once... same concept. Sometimes I think we cause problems by fussing with them too much. 

That said, I have had several friends who have had issues with hydraulic Avids. I've only had BB7's...no Avid Hydros. I dunno...you get what you pay for? Seems like maybe issues with the entry level stuff from Shimano?


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## jeffscott (May 10, 2006)

CommuterBoy said:


> I sometimes wonder at the necessity of regular bleedings... it's mineral oil, I mean, what's going on in there that's necessitating fresh fluid every year? Even ridden extremely hard, it's not the kind of crazy heat that's going to cause problems. I never bleed mine. Going on 8 years with the Hayes 9's on my hardtail, nothing but new pads... Ridden from 100*F to 5 below zero F (below zero rarely...regular rides in the teens though).
> 
> I've had dirt bikes with hydraulic clutches that use the same fluid... I had to bleed one of those once... same concept. Sometimes I think we cause problems by fussing with them too much.
> 
> That said, I have had several friends who have had issues with hydraulic Avids. I've only had BB7's...no Avid Hydros. I dunno...you get what you pay for? Seems like maybe issues with the entry level stuff from Shimano?


I only bleed when the lever gets soft, usually sometime in March, but this year I had to do it in January....pretty much certain is is due to leaking oil.


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## bedwards1000 (May 31, 2011)

CommuterBoy said:


> Seems like maybe issues with the entry level stuff from Shimano?


Middle of the road, Shimano XT. I replaced it with a cheaper caliper and haven't noticed any difference, except it works.

I only bleed them when they have issues for the reasons you mentioned.


jeffscott said:


> I only bleed when the lever gets soft, usually sometime in March, but this year I had to do it in January....pretty much certain is is due to leaking oil.


I've never had one stop leaking once it starts.


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## BlowtorchBob (Jan 8, 2015)

Why not just mechanical brakes on a commuter?


Practicality is the name of the game when it comes to commuting and if your brakes start leaking it depletes the purpose of having a reliable bicycle. Not to mention you could also be late because of a leaky front brake.


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## car bone (Apr 15, 2011)

I agreez. I gave up on hydros a long time ago.


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## CommuterBoy (Oct 4, 2007)

BlowtorchBob said:


> Not to mention you could also be late because of a leaky front brake.


Or much faster :eekster:


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## jeffscott (May 10, 2006)

BlowtorchBob said:


> Why not just mechanical brakes on a commuter?
> 
> Practicality is the name of the game when it comes to commuting and if your brakes start leaking it depletes the purpose of having a reliable bicycle. Not to mention you could also be late because of a leaky front brake.


I ride every day...I go through lots of brake pads...

I don't want to adjust anything I don't have to. hydro's work better longer and with less maintaince


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## BlowtorchBob (Jan 8, 2015)

What Kool-Aid have you've been drinking?


Hydraulics have some of the easiest adjustment when it comes to pads,cable, and mounting hardware. If you cant loosen an Allen bolt and adjust on the road what makes bleeding a brake while riding anymore easier?


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## Carton (Sep 15, 2014)

BlowtorchBob said:


> Hydraulics have some of the easiest adjustment when it comes to pads,cable, and mounting hardware.


I agree 100%. It's the closest there is to set it and forget it.


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## BlowtorchBob (Jan 8, 2015)

I'll have what you guys are having.


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## wschruba (Apr 13, 2012)

To each his own. Not sure what crusade you're gunning for, but the braking needs (and wants) of this group varies from none, to calipers, to cantilevers, and beyond.

Not everyone wants to screw with pad adjustments, no matter how simple...hydraulics work for them. Some people don't want to deal with the possibility of leaking, cables work for them.

Keep an open mind and try to keep our (very supportive and civil) discussion, just that.


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## BlowtorchBob (Jan 8, 2015)

Sounds good,


Just trying o have some fun.:thumbsup:


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## Rustedthrough (Aug 19, 2014)

wschruba said:


> Not everyone wants to screw with pad adjustments, no matter how simple...hydraulics work for them. Some people don't want to deal with the possibility of leaking, cables work for them.
> 
> Keep an open mind and try to keep our (very supportive and civil) discussion, just that.


Thanks for that.

I've got mechanical disks on both bikes, and have no experience with hydraulic disks below 80f or over any long testing. Do the hydraulics suffer in extreme cold, relative to mechanicals? Or is this argument just hokum?


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## wschruba (Apr 13, 2012)

Under say, 20F, mineral oil brakes will start to lose lever feel, but will return to normal once the system heats up. This is a serious issue for people who are going a long time between applying brakes. Much lower, and leaks begin to form at the seals, as the chemistry of the seals can't deal with the cold. DOT brakes can go a bit lower, but ultimately suffer from the same issues.

For extreme conditions, nothing will beat a cable actuated brake with sintered metal pads for versatility. Drum brakes (Sturmey Archer still produces these, BTW) are right up there, too, since their operation is completely unaffected by road/trail conditions. Their great downside is that you don't get many choices (as far as looks or axle/cassette/etc compatibility). There are a handful of discussions about drum brakes around here, as well.


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## Rustedthrough (Aug 19, 2014)

^Thanks. I'll keep the bb7s on my winter bike, and still consider upgrading the bb5s on the better weather bike.

Are there real improvements to be seen in hydraulics over bb7s for the slow but heavily loaded commuter/ light tourer? Or, does an upgrade to bb7 from 5 make sense?


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## Rustedthrough (Aug 19, 2014)

OP, I didn't mean to bogart your thread.


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## chubmackerel (Sep 22, 2014)

No problem. The BB7s were sitting in a box in my garage, old 2006 model.Ordered new pads and did a thorough cleaning and new cables. I am sure some hydras will work great, I just dont want to spend a lot of money on my old Sette commuter. Hanging around the LBS Seems I hear more complaints about brakes than any other component, usually from the mechanically challenged. I need to clarify, I have only had problems with old LX BR-M585 calipers. Some last for years.. a few do not. Next prem bike I build I am going to try Magura Next MT4 brakes . I prefer mineral oil.


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## GTR-33 (Sep 25, 2008)

chubmackerel said:


> So it turns out you are quite right, the leak was eventually very obvious:madman: this sucks since this caliper was only a few months old. I think the old LX calipers are of poor design? I went back to BB7s on this bike. Thanks so much for your help, I kept on looking for that leak


Sorry to say this but just because they are NOS brakes doesn't mean they're new. Just because they haven't been ridden doesn't mean that they aren't worn out. In your OP you mentioned the brakes in question were NOS M765 XT. M765 brakes are about a decade old. The pads, oil and seals aren't designed to last a decade and are wear items worn not only by use but also by time. If the seals are leaking it might has something to do with how old the brake actually is. The oil will break down the seals over time and it doesn't take much debris to tear/deform old dry rubber seals. Have you ever tried to blow up a ten year old balloon or stretch a ten year old rubber band?

You get what you pay for. I wonder how many people that claim to have issues with Shimano brakes are using "NOS" brakes.


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## jeffscott (May 10, 2006)

wschruba said:


> Under say, 20F, mineral oil brakes will start to lose lever feel, but will return to normal once the system heats up.
> 
> Much lower, and leaks begin to form at the seals, as the chemistry of the seals can't deal with the cold.
> 
> For extreme conditions, nothing will beat a cable actuated brake with sintered metal pads for versatility. Drum brakes (Sturmey Archer still produces these, BTW) are right up there, too, since their operation is completely unaffected by road/trail conditions. Their great downside is that you don't get many choices (as far as looks or axle/cassette/etc compatibility). There are a handful of discussions about drum brakes around here, as well.


What a crock

I have been running hydros in the winter for 10 years...No lever fade down to -36C with mineral oil.

Only problem small oil leak below -20C....

Biggest problem in the cold is rotor icing happens with snow below -17C....applies to both mech and hydro and rim brakes.

That and water condensing in the pads if the bike is stored inside....that takes about 40 vertical feet to dry them up.

What I see most through the winter is couriers (rim brakes). Commuters vees or canti's (old bikes), then hydros.....then the very odd mech disk or some other hub.

Basically the brake type is driven by the type of bike purchased (or stolen) rather than any thought towards winter issues.

I am including all the bums and bottle pickers that ride all winter long as well.


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## BlowtorchBob (Jan 8, 2015)

Can you prove that theory with science and proofs??


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## car bone (Apr 15, 2011)

jeffscott said:


> What a crock
> 
> I have been running hydros in the winter for 10 years...No lever fade down to -36C with mineral oil.
> 
> ...


I've had shimanos completely freeze up at around -20C, the megas would still work by then. Also the shimano levers would get pretty hard, or at least harder before that. The coldest my bb7s have endured so far is -16/18 or so, didn't feel or notice any difference at all.

Leaving a bike out in -20C for a day is a bad idea with shimanos, or even for an hour imo.


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## jeffscott (May 10, 2006)

car bone said:


> I've had shimanos completely freeze up at around -20C, the megas would still work by then. Also the shimano levers would get pretty hard, or at least harder before that. The coldest my bb7s have endured so far is -16/18 or so, didn't feel or notice any difference at all.
> 
> Leaving a bike out in -20C for a day is a bad idea with shimanos, or even for an hour imo.


The Shimano's did not freeze up because of the mineral oil or seals...you may have had some water in the hydro fluid or something else exterior to the hydro fluid.

As far as leaving a bike in the cold doesn't matter...except you do have to melt it out to get it cleaned up or just get the ice out of the moving parts.


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## CommuterBoy (Oct 4, 2007)

I've never had temperature effect either hydros or mechanicals. I have had water get in there and freeze and mess with a caliper, once. Brought the bike inside for a while and it fixed itself as things thawed out. I agree that hydros are as close to set-it-and-forget-it as possible (except when swapping wheelsets with different rotor brands). I have equal love for hydraulics and mechanicals, as long as the mechanicals are BB7's. Disc brakes are awesome. I love disc brakes. Nice hydraulics can't be beat on a mountain bike. I use BB7's on the commuter because of the simplicity and road lever compatibility. 
I have never experienced any lever fade or anything weird with hydros in extremely low temps. My theory on that is climate... maybe in a more wet climate you get some condensation build-up on the rotor at really low temps that can cause that feel?


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## jeffscott (May 10, 2006)

CommuterBoy said:


> My theory on that is climate... maybe in a more wet climate you get some condensation build-up on the rotor at really low temps that can cause that feel?


Ah rotor icing

Happens about -17C to -20C going down a hill the the brake can heat the rotor up hot enough to melt snow roost.... As soon as you let of the brake it is cold enough that a thin film of water will freeze on to the rotor..

Next time you hit the brake you get zero friction....not even enough to start melting the ice.

Solution hammer the brake on and off as hard as possible...this seems to bend the rotor (since nothing is absolutly true) enough to get a little friction...once you have a little friction it melts pretty quick and you are back to wet brakes.....

Remember drag the brake or it will just do it all over again....after a 2 mins of dragging the thing is dry enough to work again....can be a drag plowing snow with the brake on though.

Water can get into the hydro system via the caliper seals...just a little melt water gets pulled in when the calipers retract and there you are stuck......has never happened to me cause my brakes leak out oil when it gets real cold.


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## CommuterBoy (Oct 4, 2007)

I don't think water got into my hydro system when I had freezing issues (once)... I think it just messed with the caliper itself. No leaks before or since, and an hour inside fixed it. 

I've never had the rotor icing issue either (though it sounds scary!), just my theory on why some think the lower temps do something magical to the mineral oil... I've never had a low temp related issue... granted, relative humidity here is in the single digits, and I keep my bikes inside at night.


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## wschruba (Apr 13, 2012)

Just to be perfectly clear, the problem isn't the oil itself, it's with the seals.


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## mtbxplorer (Dec 25, 2009)

Thankfully I have only had rotor icing once with the BB7's, and luckily it was not at a critical moment, and also self-corrected through grabbing more brake more longer.


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## jeffscott (May 10, 2006)

mtbxplorer said:


> Thankfully I have only had rotor icing once with the BB7's, and luckily it was not at a critical moment, and also self-corrected through grabbing more brake more longer.


Must have been scarey.....it scared the grammer right out of you


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## CommuterBoy (Oct 4, 2007)

jeffscott said:


> Must have been scarey.....it scared the grammer right out of you


*scary
*grammAr

:shocked:


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## bedwards1000 (May 31, 2011)

Scary Grandma!


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## blockphi (Mar 26, 2012)

bedwards1000 said:


> Scary Grandma!


Scary grahamcracker?

I've never had any major issues with disks on my bikes and have heard that in a gritty/dirty environment that disks have a bit of an advantage in that you never have to worry about chewing through the braking surface of the rim - thus requiring a wheel rebuild.

I've ridden in all kinds of weather and temps and there are some times when the performance isn't quite as good as normal, but I think this would be the same with rim brakes - wet surfaces don't have as much friction. Cold's never been an issue.


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## rogbie (Jun 20, 2011)

A note on rim wear from rim brakes vs. disc rotor wear:

Dirt and mud wear out disc brake pads and rotors much faster than the braking surface of a rim.

My only bikes with disc brakes are my trail bike and jumping bike. I go through a two sets of pads and a set of rotors every year. My rim brake bikes, that see far more use, need new rims every five years and new pads every one-two years. This experience is backed up by years of work in a shop. 

A rim brake is, essentially, a disc brake. A really big disc brake. Disc brakes on commuters and road bikes are clever marketing up-sales. Yes, discs have advantages over rim brakes, but they have their drawbacks as well. The main advantage of discs (stopping power) doesn't really add anything to a commuter/road bike. The disadvantages of discs are more of an issue for commuters. Reliability, maintenance, cost, and life-span of product all figure badly against disc brakes compared to rim brakes. 

Hydraulic brakes require bleeding at least once a year, have issues in extreme cold/heat, and seals only last so long before they fail and are, generally, not user serviceable (once they fail, "Zrrp, they're in the dumpster"). Road contaminants are another factor for discs on commuters. A small amount of oil on a rotor can cause disc brakes to glaze and become nearly useless. Rim brakes use a polymer for the pads that clean the rim as they wear down, negating most road contaminants. Disc brakes put large forces on weak points of a frame/fork. So, those frames/forks tend to use reinforcements and are heavier than a rim brake frame/fork. (Not that a half pound is much in regards to commuting.) Speaking of weight, a disc hub is heavier and is susceptible to braking forces that can shorten the life of the hub.

For the right application, disc brakes are wonderful. But for commuting/road riding, they fall short of the traditional rim brake system.


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## jeffscott (May 10, 2006)

rogbie said:


> A note on rim wear from rim brakes vs. disc rotor wear:
> 
> Dirt and mud wear out disc brake pads and rotors much faster than the braking surface of a rim.


Sorry not buying into that...

I have 50,000 km since 2005 on a set of XTR brakes....and rotors....rotors probably have 25,000 km on them (I have usually end up running two wheels sets)...

Rotors still fine, seals leak only when it gets really cold.

I go through pads maybe one set a year..

I ride all through a long cold salty winter, and ride the same bike and rotors for trail riding.

These rotors were also used for one Transrockies, and all the training up to the Trans Rockies.

Cantis and Vee rims do not have that type of life, and a set of pads a year would be good for those brakes as well


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## ghettocruiser (Jun 21, 2008)

I also get far longer life out of rotors than rims due to braking wear. My cross bike wheelset now has "ultra lightweight sidewalls" and I'm no longer gonna put the tire pressure over 50 PSI to coax some more life out of them. A set of MTB rotors with similar mileage look the same as when I bought them.

And of course, replacing rotors takes maybe 25% the time and budget of replacing rims.

Pads last me longer on disc brakes as well, although by a narrower margin.


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## mtbxplorer (Dec 25, 2009)

rogbie said:


> Yes, discs have advantages over rim brakes, but they have their drawbacks as well. The main advantage of discs (stopping power) doesn't really add anything to a commuter/road bike.


I can't agree with that, I need to stop NOW a lot more often on my commute than when trailriding. I find it is much safer to ride in the flow of traffic with discs (actually just a front disc), even in good weather, and in bad weather I find them essential. They make my ride more fun as well, because I can zoom up to a stop sign and stop quickly, rather than having to slow much further in advance.


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## Rustedthrough (Aug 19, 2014)

^ I second that sentiment. When some clown in a Tahoe hooks me in the turn lane, a city bus just drifts in front of me to a stop, or a joker in a Monte Carlo pulls out of the alley in front of me, the need to stop is every bit as real as it is on a trail.


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## Texan-n-Fla (Sep 22, 2013)

mtbxplorer said:


> I can't agree with that, I need to stop NOW a lot more often on my commute than when trailriding. I find it is much safer to ride in the flow of traffic with discs (actually just a front disc), even in good weather, and in bad weather I find them essential. They make my ride more fun as well, because I can zoom up to a stop sign and stop quickly, rather than having to slow much further in advance.


Completely agree. Having recently made the switch from rim brakes to disc, I can say I won't be going back. Even with low end Tektro Lyra crap, they still work better than supremely adjusted Single Digit 7's and PS Travel Agents.


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## ghettocruiser (Jun 21, 2008)

Certainly the next CX bike I shop for (could be a few years away) will have hydraulic disks. But I don't think at theis point I'd be willing to go through the hassle and expense of changing the bike over until hydraulic STI road levers are readily available on the market. 

And I can't really ever see wanting them on my road bike.... I just don't apply the brakes on that bike enough for discs to make sense... I go for a 100km ride in the country and use the brakes maybe five times on the entire ride. There aren't any road descents around here that require more than two or three seconds worth of braking the whole way down, even in the rain.


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## BrianMc (Jan 5, 2010)

^ You are lucky in your road situation, ghettocruiser. I have had to use all the cool stops and deep vees had to offer when braking for idiots, Not many times but once is enough. I agree that I likely brake three to six times in my favorite route, but brakes are insurance. You need what you need when you need it. It seems that wet discs perform better than wet rims in that regard. I know my drum brake errand bike does.


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## ghettocruiser (Jun 21, 2008)

BrianMc said:


> ^ You are lucky in your road situation, ghettocruiser.


Yes. Spending weekdays crawling from red light to red light in rush hour hell, I do appreciate those weekend open roads with absolutely nothing in the way.

I do sometimes commute on my road bike in the summer, but not in the rain, and the difference between a 6700 caliper and a M775 disk on a dry road is, IMO, marginal.


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## car bone (Apr 15, 2011)

yeah. seriously though rim brakes are not, ac tually never ever even remotely as powerful as discs. I've had reynolds 830 bikes with xtr v-brakes AND ceramic rims, and they were nowhere close to even the cheapest disc sh1zzle brakes. I have bb7 now and they are great. I'm running them with cane creek non-shifter drop bar brakes. Really great. good feel and good power. Maybe v-brakes has some qualities that are better. but as a brake on a commuter bike they are not as good. I have also tried hydraulic rim brakes, maguras. but even these don't stand a chance to discs. And now its even more factors to factor in. Since these are close to the ground. The rim I mean. yeah fuk that.


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## CommuterBoy (Oct 4, 2007)

I dunno about replacing rotors all that often...am I doing something wrong? My rotors seem to last many years until I bend them by crashing and hitting them on a rock...then I need a new one. Pad/rotor wear being faster than rim/pad wear is not lining up with my experience.

I agree that a rim brake is just a giant disc brake... with an inherently flexy caliper that has a much more difficult time overcoming the faster rotational speed of the outer edge of the giant disc while using a smaller braking surface, compared to a piston design with much more strength and less flex mashing into a larger braking surface at a point closer to the hub.

Ask anyone riding a motorcycle with rim brakes how they feel about...er, wait.


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## CommuterBoy (Oct 4, 2007)

rogbie said:


> Hydraulic brakes require bleeding at least once a year, have issues in extreme cold/heat, and seals only last so long before they fail and are, generally, not user serviceable (once they fail, "Zrrp, they're in the dumpster"). Road contaminants are another factor for discs on commuters. A small amount of oil on a rotor can cause disc brakes to glaze and become nearly useless.


Disc brakes here for at least the last 10 years, and I haven't found any of these things to be true.


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## leeboh (Aug 5, 2011)

rogbie said:


> A note on rim wear from rim brakes vs. disc rotor wear:
> 
> Dirt and mud wear out disc brake pads and rotors much faster than the braking surface of a rim.
> 
> ...


 Yowzer, where to start. I love my disc brakes, work well on all my bikes. I would never go back to rim, ever. I pedal in the Boston, MA area, yourself? So much crap on the roads, dirt, salt, sand, slush, cleaning my rim brakes every week? No thanks. My BB7s need no work, ever, I turn the barrel adjuster 1-2 times per year, while pedaling. Love them for touring( can you say overloaded bike @ 35 mph?), mt biking and commuting. I have never worn out a rotor, ever. Just because your experience says one thing, it does not hold true for others. Got rain, slush, snow, road crap? Discs rule. Pedaling a road bike in sunny CA, FL or AZ, not so much.


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## woodway (Dec 27, 2005)

Here is a hybrid hydraulic disc system that works with STI levers: TRP Products HY/RD.

I run them on my CX commuter (replaced BB7's) and they give better braking performance plus they self-adjust as the pads wear.

The rotors on my commuter have over 18,000 miles on them and don't look like they need replacing to me. I probably would have gone through a couple of rims by now if I were using rim brakes.


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## Texan-n-Fla (Sep 22, 2013)

I'm debating BB7s or the HY/RD to replace the Lyras I currently have. Are the TRP's worth the price difference?


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## wschruba (Apr 13, 2012)

The HY/RDs are dynamite. If you want a less expensive [cable] option, look at the Spyre/Spyke. They're dual-actuating cable brakes. Tektro (AKA Tektro Racing Products) has really stepped up their game in the premium line these past few years.


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## woodway (Dec 27, 2005)

Texan-n-Fla said:


> I'm debating BB7s or the HY/RD to replace the Lyras I currently have. Are the TRP's worth the price difference?


IMHO, absolutely. Better stopping power, better modulation, self-centering, self-adjusting. No more screwing with the adjustment knobs on BB7's!


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