Bicycle Mechanics - Disc brakes

I don't know about you guys but here in Montreal morning are getting chillier. I'm slowly starting to think about my winter bike. I want aluminum frame to avoid rust. I want try something new to me. Something call Disk (or Disc) brake. I never really work with disc brake. Is Disc brake bosses (the part of the frame or the fork where you attach the mechanism) are all the same for any disk brake. Or different attachment for different mechanism? DO you have good online ressources to know more about disk brake. I also want to use gear hub, something like the 8 speeds SA offers X-RK8(W) maybe the "what's about internal gear and subzero weather" question will be part of another post.

David P P

The frame will need to have the Mounts on it , and the fork to have another set.
they would both be on the left side ..

there are a few different IGH with disc mounts
Sturmey's 8 speed you need a pretty small chain ring up front ,
because other than Low the gears are all overdrive .
so with bigger wheels the ratios get huge and useless pretty soon.

A 5 speed OTOH has 2 reduction gears and 2 overdrive gears.

for a frame without the disc mounts , consider Sturmey's Drum Brake Hubs.

I want aluminum frame to avoid rust.
Stopped reading right there. All my bikes have steel frames, the average age is 15 years and two of the bikes are ~30 years old. None has any serious damage from rust (the little there was, it was easy to paint over with Hammerite). And I live in ****ing Finland!

And did you know that unprotected aluminum frames also corrode when exposed to the elements? The thin layer of native oxide on the surface of aluminum is rapidly hydrated in rainy weather or humid air. New native oxide will be formed, but it well be promptly removed by a process of hydration, as long as there is presence of water. The reason people are unaware of it, is that the the oxide and the hydroxides of aluminum aren't brown or orange.


Going with an aluminum frame "to avoid rust" is dumb.

If you use the term 'Corrosion' (instead of 'rust') it applies to both steel and aluminum.

road salt will effect both.. wash down the bike with fresh water, often.

Keep reading. My question was more about disc brake mount. Is there one standard. (We talk about bike component ,since when there's ONE single standard) I want to know what are the standards and what should I look for when I shopping around for a frame and fork to use disc brake.

Keep reading. My question was more about disc brake mount. Is there one standard. (We talk about bike component ,since when there's ONE single standard) I want to know what are the standards and what should I look for when I shopping around for a frame and fork to use disc brake.

Pretty much every bike frame and fork that is disc-brake compatible has "51 mm International Standard" also known as simply "IS mounts".

there are 'Post mount' on some MTB forks but all calipers can fit either sort.

why not drop by a Bike shop and look around a little?

I'm sorry about question that might llok stupid but I'm a newbee with disk brake

Look like The rotor is often 160mm Is the size of the rotor is important? is calipers are design for different rotor sizes or caliper can be adjust to the rotor size?
What'S about the lever. Do you have lever specific for disc brake. I know there is mechanical and hydrolic disk brake. I suppose the lever will be made for one or the other right. Will hydrolic work ok in winter?

no .. there are a different set of adapters in between the fork and the brake caliper
a bigger disc uses a adapter.. to set it in the right place .

It's easier to see if you go into a bike shop and look at how the bikes are set up.

for the discs they come in 140 160, 180 and 210.

for street riding 2 160's will be fine . harder riding off road ,
and decending at high speeds then the discs that are bigger are chosen.

Hydraulic disc brakes are going to cost you more ..

since there is a seal around the piston to hold the oil in ,
there is little possibility of contaminating the oil,
with road grit and such.

Pretty much every bike frame and fork that is disc-brake compatible has "51 mm International Standard" also known as simply "IS mounts".

Sort of, the IS mount is now just about obsolete for forks, with the post mount now the standard fitting; for the frame, post mounts are becoming more common, too early to tell if this will supersede the rear IS mount as well.

Disc brakes haven't been available for several years with IS mounts, all are now sold as Post Mounts, with IS adaptors.

What'S about the lever. Do you have lever specific for disc brake. I know there is mechanical and hydrolic disk brake. I suppose the lever will be made for one or the other right. Will hydrolic work ok in winter?
Yes, mechanical disc brake calipers are cable-activated, while hydraulic calipers are activated by a fluid in a flexible pipe and requires a suitable hydraulic lever. (actually, "mechanical" is a misnomer, as both are, essentially, mechanical).

Hydraulic brakes will work fine in winter, as the liquid used is some kind of long-chain oil, usually of mineral origin. However, I have not seen a real advantage of hydraulic vs. mechanical disc brakes. Perhaps there is, if you are into extreme sports? I don't know.

Sort of, the IS mount is now just about obsolete for forks, with the post mount now the standard fitting; for the frame, post mounts are becoming more common, too early to tell if this will supersede the rear IS mount as well.Is that so? Post mounts are so rare where I live, that I have never seen a fork with one, In Real Life. I know they exist, I know what they are, I have seen pictures. But never IRL.

EDIT: to be completely explicit, I have never seen in real life a fork like this:
http://www.bike198.com/wp-content/uploads/2009/03/fork-post-mounts.jpg



Disc brakes haven't been available for several years with IS mounts, all are now sold as Post Mounts, with IS adaptors.That's true.

Yea IS tab Bikes are shipped with the right adapter to mount the caliper , as they build it up.

Is that so? Post mounts are so rare where I live, that I have never seen a fork with one, In Real Life. I know they exist, I know what they are, I have seen pictures. But never IRL.


Given that Rock Shox, Manitou, Magura, DT Swiss, Marzocchi, are Post Mount only now, and have been for several years, not sure what forks you are looking at.

If you look at the Suntour range, their MTB forks are all Post Mount, you have to look at the treking / non-MTB ranges to find IS mounts now. Road discs fork manufactures don't seem to have made up their mind yet, ENVE & Colnalgo use Post Mount, others are using IS

non suspension forks are more likely IS, because the tabs are a more common braze on.

IE rigid Forks..

Well, I'll keep my eyes out for post mounts on forks. I want to touch one.

Disc Brake Mounting Standards (http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1638-51mm-international-standard-74mm-post-mount)

Look like The rotor is often 160mm Is the size of the rotor is important? is calipers are design for different rotor sizes or caliper can be adjust to the rotor size? On the design/theoretical side, larger rotors will exert more reactive-torque for any given clamping-pressure from the pads (generates more deceleration). In the practical usage end, you run into manufacturing, cost, weight and maintenance questions as well. So there's a balance of sorts. The leverage-ratio of the lever-to-caliper typically incorporates a certain rotor size in mind. And the curvature of the pads are designed for a certain rotor size as well. In the end, as long as the components match and fit, that's all you'll want to be concerned with.

So Montreal, i think avid bb7 mechanical disc brakes with full housing would fit the bill, that's what works for me in the Boston MA area.

You guys still havent addressed mounting the disk to a wheel. Rim brake wheels typically dont have hubs that can mount disks. DO I understand there is more than one style of disk mounting?

-SP

Disc Hubs and Rotor types. (http://www.pricepoint.com/TechPages/TECH_Page_Rotor_Types.htm)

Rohloff uses a 4 bolt disc: http://www.rohloff.de/en/products/speedhub/brake_discs/index.html

6 bolt rotors can be used on centrelock hubs with an adapter but centrelock rotors can't be used on 6 bolt hubs.

Shimano-Centerlock-To-6-Bolt-Adapter (http://www.jensonusa.com/!ehZjKs42o0EbXeJzKCxGPA!/Shimano-Centerlock-To-6-Bolt-Adapter)

Probably also worth mentioning that there are two types of mechanical disc brake calipers, Road specific and Mountain specific. The two types have different pull ratios for use with certain levers.

Road versions work with drop bar levers and cantilever type levers.
Mountain versions work with v-brake levers or linear brake levers.

Here some pic for you. I'm ok about Disk brake caliper mount standard for frame and fork. I beleive my frame have the 51mm International standard. But the mount doesn't look like any other mount saw when I googled it. What you guys thinks.

I freecycle a set of disc hub at my bike coop. The front already have a disc 180mm attach with 6 torx bolt says Fuji on the hub. The rear is Quando, no disc for that one but a cassette 8speed that look new. (not in the picture).

With the bike coop I have the choice between 7 disc brake caliper.

TEktro IO, Lyra or Aquila. Says Lyra and Quila are "Ball bearing cable actuated mechanical disc brake" ??? what exactly is that?
other choice are Shimano BR_M416 front or rear and Shimano BR-M495

They are all mechanical and takes 160 rotor. I beleive they all take V-Brake lever.

Thank for you advise everyone.272810272811272812272813

Going to a parts expanded diagram for like Avid, which I have downloaded a PDF,
there is a ring shaped ramp
that is rotated by the arm with the cable attached to it, it increases the pressure
exerted on the Movable pad, pressing it against the disc..
to facilitate rotation between the stationary pad pressure plate and pressure transfer ,
from the ramp ring , which rotates, there are a few bearing balls in the mechanism.

I beleive they all take V-Brake lever.



The Tektro Lyra is a road disc brake, cross it off the list if you're going to use v-brake levers.

Here some pic for you. I'm ok about Disk brake caliper mount standard for frame and fork. I beleive my frame have the 51mm International standard. But the mount doesn't look like any other mount saw when I googled it. What you guys thinks.

I freecycle a set of disc hub at my bike coop. The front already have a disc 180mm attach with 6 torx bolt says Fuji on the hub. The rear is Quando, no disc for that one but a cassette 8speed that look new. (not in the picture).

With the bike coop I have the choice between 7 disc brake caliper.

TEktro IO, Lyra or Aquila. Says Lyra and Quila are "Ball bearing cable actuated mechanical disc brake" ??? what exactly is that?
other choice are Shimano BR_M416 front or rear and Shimano BR-M495

They are all mechanical and takes 160 rotor. I beleive they all take V-Brake lever.

Thank for you advise everyone.272810272811272812272813

Yes, IS mounts, both frame and fork.

hey guys, just a update on my disc brake project. I'm learning a lot in the process of building this bike. First of I had to find adapteur for the caliper and and frame. From what I understand the adapteur will adapt your caliper to whatever rotor size you are using. I got the adapteur I needed for my 160mm rotor. Last night I really thought I can finish that project and do the maiden voyage this morninig. Well turns out that disc bike project is no different that other bike project... there's always something... The biggest problem is that the bolt that fix the adapteur for the front caliper to the fork is too long and goes throught the rotor, so wheel can't spin. That's a no go.276297 I'm going back to the lbs to ask if he has shorter bolt. Another question do you always use lock-tite on bold for diskbrake.
2nd observation. When I looked at different disk mount for the rear caliper I realise that the mount on my frame was kinda different. (look at picture in previous post) much further back, what I saw most of the time the mount are close to the seatstays. When I mount the caliper and pass the cable and see the 'natural cable route', the first word that pops in my head is ...'ugly as can be' in the picture a draw in red what I call the natural cable route. In blue is somewhat I think can be done. What you thoughts about that. 276302
3rd observation what are those cable braze on. Too big to hold the cable... if I need electric tape to hold it in place what's the point of those braze on? is not some kind of c-clip cable guide.

thanks for your helps.

David P P

I have not seen a real advantage of hydraulic vs. mechanical disc brakes. Perhaps there is, if you are into extreme sports? I don't know.

Not sure I see much of a difference either, other than cost and repair factors. If a cable breaks, you replace it. If a hydraulic line breaks, you have a mess. The repair would also be a bit more complicated I'd suspect, as you have hydraulic fluid pressure to contend with, rather than simple cables. I'd also have to think you'd need to bleed the lines and such like a car.

In general, disc brakes rock! I don't want to ever go back to calipers. Disc brakes are just so much less worry and maintenance, and stop on a dime. I'm not saying calipers aren't good brakes, discs are just a lot better all around, especially for commuting with a lot of stop and go.

That brings up hubs. I have an 8 speed nexus with a belt drive, and absolutely love it. I would say the only thing better than an 8 speed hub would be a Rouloff 14 speed hub. It's also about $1400. Someday I'll have one though. For tooling around town at lights and in traffic and commuting, a hub is the way to go. If I had a Rouloff 14 speed with carbon drive on a good tough frame suited for light trails and the street with a good set of mechanical disc brakes, I probably wouldn't need anything else honestly.

Wow, that's easiest the ugliest dropout I've ever seen - but I think I can answer why. With a regular, seatstay mounted brake, the caliper is likely to interfere if you want to mount a rack or a fender. A more common way to get around that is to mount the brake on the chainstay instead - but that requires redesigning the rear triangle. An extra bend is needed a few inches in front of the dropout to widen the angle enough to make room for the caliper.
The makers of your frame has choosen a different route - keep the frame design(and any associated jigs and tooling) just use a "generously cut" dropout and stick the brake onto the rear. Functionally I can't see that it should matter.

The cable braze-ons probably looks that way to be compatible with hydraulic brakes as well. Hydros are usually sold with levers and calipers all hooked up, bled, and ready to go. Not many riders can be bothered to cut and adjust the brake lines, so braze-ons has to allow for that. And yes, a sleeve is used to make the hose stay in place. There are usually other braze-ons where you're expected to use zip ties to hold the hose in place.

To tidy up your installation you can try either a v-brake noodle, or a travel agent set only to act as a pulley wheel.

.. I have not seen a real advantage of hydraulic vs. mechanical disc brakes. Perhaps there is, if you are into extreme sports? I don't know.

Hydros are stronger, no doubt. More braking for less finger force. They're also a tad smoother, a little better modulation. Functionally, mechanicals are perfectly adequate, byt hydros are "nicer".

You will want Mudguards next, their strut will give you another place to secure the cable run.

and maybe a rear rack to keep some stuff in ..

So white like that , don't lay it down in the snow, you may not find it again.. :rolleyes:


cable brakes, pad wear adjuster is You..

Hydraulics do some auto adjust, but, you have to stuff a 'keeper' in the caliper
so the first touch of the brake lever the pads don't fill the gap, preventing getting
the wheel back in.

And presently No drop bar hydraulic brake levers..

but you may want MTB bars to use Pogies to help keep your hands warmer anyhow..

..If a cable breaks, you replace it. If a hydraulic line breaks, you have a mess. The repair would also be a bit more complicated I'd suspect, as you have hydraulic fluid pressure to contend with, rather than simple cables. I'd also have to think you'd need to bleed the lines and such like a car.

I don't think I've ever heard about someone breaking a brake hose, but I guess it can happen. Maybe snagging a branch, or a bash against something hard in a crash.

Bleeding, sure, that may be required occasionally.
Mostly an issue if you try to improvise something as opposed to using a kit adapted for the purpose. With the gear, it's no big deal.

Pressures - I don't know.
So far, the industry has mostly used permanently crimped connectors, but now there seems to be a trend towards user-friendly, reusable connectors that can be opened and closed pretty much at a whim.
What little I have read about them has all been good.
In general, hydros are amazingly reliable. Some may require bleeding, but outright, serious failures are really, really rare.

I hear you dabac. The odds of anything going seriously wrong per say are somewhat remote, but the lines are under high pressure when breaking. Overtime, hydraulic systems tend to spring leaks and fail, and I'm curious myself just how well these systems will hold up over time. Hydraulics also tend to become messy animals, slowly dripping fluid onto the ground or machinery. Cables obviously come with their own share of problems, but, they're cheap, clean, and very simple to maintain.

I've heard hydraulics are much more responsive myself, and would agree, they should work better. But.... When I squeeze my mechanical disc levers they stop great, and with little effort. I don't think I'd ever really need to improve that for what I do honestly.

I think the primary difference between hydraulic and mechanical is more a function of your bank account. If you have plenty of money, go with the best of the best, because you'll never be disappointed. If you're more practical, and don't have money to burn, mechanical discs are an excellent choice as well. Either way, you won't be disappointed in disc brakes.

2nd observation. When I looked at different disk mount for the rear caliper I realise that the mount on my frame was kinda different. (look at picture in previous post) much further back, what I saw most of the time the mount are close to the seatstays. When I mount the caliper and pass the cable and see the 'natural cable route', the first word that pops in my head is ...'ugly as can be' in the picture a draw in red what I call the natural cable route. In blue is somewhat I think can be done. What you thoughts about that.
276302
3rd observation what are those cable braze on. Too big to hold the cable... if I need electric tape to hold it in place what's the point of those braze on? is not some kind of c-clip cable guide.


I'd look at trying something like this (http://www.ebay.com/itm/New-MTB-Bicycle-Bike-V-Brake-Cable-Roller-Guide-Red-1-Piece-/370623420561) to eliminate the big loop you're going to have with your brake cable from that unusual disc mount.

Can't tell what sort of cable mount is on the frame from the photo.
Does it look similar to the following?

http://upload.wikimedia.org/wikipedia/commons/thumb/3/36/Bicycle_Frame_Cable_Stop_1.JPG/570px-Bicycle_Frame_Cable_Stop_1.JPG

dabac: My first plan was to have a rack and mudguard on my bike so it will somehow "camouflage" the cable. no biggie.
for the braze-on you are right we told me they are ment to be compatible with hydro cable. My caliper are mechanical so He's going to bring the sleeve or adapteur tomorrow I'll snap a picture to show to the crowd.
About the long bolt he just suggest me to cut and file it. This is what I would have done, but I always prefer to use to right stuff. He will get me a shorter one.

I ask the guy about lock-tite. Seems that every single bolt have blue or white lock-tite. The 6 bolt to fix the rotor has blue locktite + tightening plates. the bolt to fix the adapteur use white lock-tite and the bolt to fix the caliper to the adpateur have blue lock tite. When I ask him he told me to use clear nail polish. I totally can picture myselft sneaking in my wife's makeup stuff to fletch nail polish and blame my daughter about the disapearing nail polish.

cobba: not really it look something like this.
276332

So, the braze on for the brake line. They will fit the hydraulic line just fine ,they are too big for a regular brake line. Go to your bike store, they should have a plastic adapter to snap into the braze on.

Disc Brake Mounting Standards (http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1638-51mm-international-standard-74mm-post-mount)

Great info. I don't do disks and thus hadn't a clue. But looks like someone starting to plan for a new bike and wants to go with disks would be wise to spec the frame for the "74mm Post Mount". Thanks for link.