Jaywalk3r

I'm identifying components for a new touring/expedition bike that I expect to ride for 10K+ miles of commuting/utility before it's first tour. To begin this extended tryout period, I'd like to try the following:

I want to run a hydraulic disk brake up front, with a mechanical brake, with an Avid Speed Dial 7 lever, in the rear. The point is to be able to transfer, in the field, the rear brake to the front, in the event the hydraulic brake fails. With BB7s, this would be an easy swap to make in the field (provided one was prepared to cut cable and housing, or had precut spares).

This combo should, in principle, provide all of the benefits of hydraulic brakes (any disc brake can provide far more braking power than required to skid the rear wheel on even a loaded tourer), along with the field repairability of the mechanical disk brakes. Being left with a mechanical disk front brake and no rear brake is far better than being left with a hydraulic disk rear brake and an in-op front brake.

The rear rotor is Rolhoff specific (4-bolt), so both the mechanical caliper and the hydraulic caliper should ideally work on the same rotor. I plan to use the largest rotor the manufacturer supports with the front fork. I'm willing to size my rear rotor so that I don't need to carry an extra adapter, if necessary and possible. What parts will I need, beyond the levers, assembled calipers, and cables/hoses to ensure this will work?

I've ordered a Hope Tech 3 V4 brake on a whim, partially because reviews suggest excellent modulation, which is the greatest benefit of hydraulics for me on a commuter. I had planned to use BB7s in the rear, but will consider other options. I guess a secondary question would be can I run the V4 calipers on a thinner non-Hope rotor? (My preference is full brake late in the pull-stroke.)

Thank you.

base2 

It seems like you have put a lot of thought into your brakes. As far as hydraulics, to me, it seems like a solution looking for a problem. Lots of buck for not much more bang than conventional. Others will disagree. Does the deciding factor, modulation in this case, make that much of a difference in a commuter to justify the cost? That's a personal judgement.

I will kick this over for consideration: Heat capacity is the ultimate limiting factor in any braking system. Some racing bikes come with 140mm Icetech rotors because the intended duty cycle is "late, hard, & momentary" and in that use 140mm with cooling fins and laminated aluminium cores is sufficient. For down hill or off road, it's a similar duty cycle, but greater heat load duration than road racing. The rotors are larger (180, 185, 205 millimeters and larger) to dissipate heat better and consequently offer better mechanical advantage at the expense of modulation over smaller rotors. For heavy loads, & long descents, you need a system with greater capacity still. Keeping 250-300 pounds of gear, self, & bike in check for long decents is going to build a lot of heat and it has to go somewhere.

If it were me, I'd forgo front rear interchangability in favor the raw stopping power of mechanical advantage and heat dissipation of a large rotor. Especially in dense urban traffic where stopping "now!" could be the difference between a car/pedestrian collision and pedaling on calmly.

Mechanical brakes are fixable should difficulties arise. To whit: Any brake cable can be cut to length. A hydraulic line at a ma-n-pa in fly-over-country may be a bunch of time waiting on a special order. The trade off is the likely hood of hydraulics having problems at all.

Full disclosure: I had a 160mm Tektro and hated it. Brake fade, & more than once, meant there was nothing left when it mattered. A few warped rotors and worn out pads later, I upgraded to Bb7's on a 180mm rotor. Finally enough to come to a stop from 30 down a 7 percent grade unloaded, with just myself...even if pad adjustment is a pain. From there, my next bike has TRP Spyre and 180mm IceTech on Shimano centerlock hubs. Huge improvement over the BB7's if such a thing were possible and pad adjustment is a breeze. Easily modulates and has more than enough power.

Hubs are another issue, cone and cup has been the way for a century. It's convienent, field serviceable and adjustable. Cartridge bearings not as much. The striking difference is price. Hope, Chris King, DT Swiss, and others can be big $$$. The field servicable Shimano cup/cone can be pretty cheap by comparison.

Your choice though.

base2 

...so In short, I am advocating for a larger rotor than you think you need, combined with the good modulation you probably already have.

Front/rear interchangability I wouldn't be worried about. Each has different concerns. Any ol' 160mm in the rear ought to be more than enough provided the front is good.

Jaywalk3r

Thanks for the reply. :-)

I do plan to use the largest rotor that is compatible with the front fork. I just want one that can be used with both calipers, in the event the hydraulic brake fails.

This build is about making zero compromises, and configuring the very best touring/commuter/utility bike that I can, based on research that I've done and hard-earned experience acquired as a commuter and tourer. (I don't claim that my desired specs are the best specs for anyone else.) I don't plan to pay for bling, but I don't mind paying for many years worth of bang up front in order to obtain the best value over the next few decades. For example, Chris King headsets offer excellent value, provided one is okay with buying 25+ years worth of headset all at once. If not, a Cane Creek 40 will work perfectly fine for a few years or longer, and is a perfectly adequate solution for most people.

I will add that I'm neither prone to upgrades (except when replacement is already required) nor buying new bikes. This will be my first new bike in ~9 years, and hopefully the last for even longer. I'd prefer it to be well-configured right from the start. A nice bike is still much cheaper (and usually more fun) than a nice car. :-)

gauvins

[I am considering upgrading my bike with hydraulic disc brakes. My reason for sticking with v-brakes is the potential for damaged rotors when flying or taking the train].

Based on what I've read, hydraulic failure is very rare. So rare in fact that you may well consider a round-the-world trek on hydraulics that you'll maintain whenever you ride in a more civilized area and, in the unlikely event of a catastrophic failure, make do with whatever brake you can find where you happen to be. (i.e. buy cantilever, or v and install it until you can find spares).

Using different technologies front and rear doesn't seem to offer much of an upside.

Jaywalk3r

I've also heard that quality hydraulic brakes are, in practice, highly reliable. My tendency is to brake very hard, often. My BB7 on my current bike is easier to set up and reduced maintenance compared to the rim brake it replaced, but it is not what I would consider low maintenance in absolute terms.

In this case, the upside to an all-disk mullet is that, in the event of front brake failure (rear brake failure isn't such a concern), I don't have to search beyond the bicycle to source, in a remote area, a quality replacement brake that can be installed in the field. Such a configuration offers the benefit of a hydraulic disk brake in front without any meaningful loss of braking performance in the rear, since the rear wheel is so easy to lock up with most any moderately well adjusted brake. The utility value of the rear brake is substantially increased if it can serve as a field swappable front brake. Nearly everything I take on tour has a primary and a secondary purpose. Why not add the rear brake to that list? I don't see any downside, provided I make the effort to ensure compatibility.

To that end, I'm simply trying to learn exactly which brackets, rotors, and/or calipers I need to use or avoid to make that happen. What are the critical numbers I should be watching? If I use a 203mm rotor with the Hope caliper, will a BB7 caliper fit that same bracket correctly, or would I need an Avid specific one? What brands can I use that allow the same calipers and brackets? Can the Hope Tech 3 V4 calipers be used on thinner, non-Hope rotors?

gauvins

yes yes, I understand what you are trying to do. My point is that the likelihood that the hydraulics will fail is such that you may prefer to install two hydraulics and to face the music in the (unlikely) event of a failure.

Will follow this thread with great interest.

corrado33

Why not just install a front rim brake as well if you want redundancy? People have toured on rim brakes, and you'd never use it unless you were in the unlikely event that the hydraulic brake failed.

Front rim brake + rear disk > front disk alone.

Jaywalk3r

The reason that configuration is less preferable is that with mechanical brake in the rear, I have two shots at a front brake. With hydraulics front and back, if the front brake fails, which is just as likely as it would be with a mullet setup, I'd be left with only a rear brake, which is far worse than being left with only a front brake.

Why give up the ease of maintenance of mechanical brakes to enjoy the reliability of hydraulics when it is possible to have the best of both worlds?

Jaywalk3r

I've found disk brakes to be far better, in terms of effectiveness, ease of setup, and reliability, than rim brakes. I have no desire to ever again own a bike with a front rim brake, certainly never on a fully-loaded tourer or a four-season commuter.

I strongly disagree. A disk brake up front, with no rear brake, is far better than a rim brake up front and a disk brake in the rear. My rear brake might get used as much as 1% of the time, but I doubt it's that frequent, probably only a tenth of that. I'd much rather have a more effective front brake, and no rear brake. Front and rear brakes are not equally important.

corrado33

Disk brakes are GOOD, but as a backup, a rim brake is the easiest/quickest solution. They work perfectly fine, just not as well as a disk brake. Well kept v brakes are MARGINALLY worse than disk brakes. You forget that ANY brake is capable of stopping you/locking the wheels, it's the modulation that's better with disk brakes.

You are far overcomplicating this.

Think about it this way. If you're touring fully loaded, in order to access your disk brakes to remove the rear one and replace it on your front, you'll have to remove ALL of your packs, both wheels, likely your racks, then change the disk brakes around, then replace everything. That's going to be a ROYAL PAIN in the butt. If you have a rim brake already installed, all you have to do is replace the lever, attach the already installed cable (zip tie it to your rack before you use it) and you're good to go. No need to remove racks, no need to remove packs. Easy peasy. Fix the hydraulic brake when you come to your next bike shop.

We have ridden and toured on rim brakes for many many decades before disk brakes came along. You're far over prioritizing them.

If not a rim brake, why not a hub brake/roller brake? Weatherproof even better than disk brake.

And edit, if you're only using your rear brake 1% of the time, you should really learn how to brake properly, especially when touring loaded, especially with disk brakes. (Overheating much?)

Jaywalk3r

Not quite. Brakes are pretty much all equal when installed in the rear (on a typical upright solo bicycle). On the front, their performance varies greatly. In an emergency situation, the difference between a rim brake and a disk brake can very easily be the difference between a close call and a trip to the morgue.

No, I'm not. I know what I want. I know why I want it over any alternate option. The overcomplicating is coming from people who neither understand my needs better than I do, nor have given as much thought to the matter as I have. I asked for technical information to implement my solution to eliminating the reliability vs. easy maintenance tradeoff (as it pertains to brakes on tour), not advice. Frankly, I don't care why you're intimidated by disk brakes or are in love rim brakes.

Yes. That's about an hour, start to finish, if I'm taking my time. Less than half that if I'm in a hurry. It's a very simple operation. Loading/unloading a bicycle after more than a week on tour is a very fast procedure.

??? It's only marginally more difficult than patching a punctured tube. It certainly isn't difficult or complicated by any stretch of the imagination, and takes a lot less time than getting rim brakes adjusted just right.

First, the bike isn't equipped to take rim brakes, being designed around superior options. Second, hydraulic brakes use hoses, not cables, so there wouldn't be an "already installed cable". Everything I had to do with my solution, I'd have to do with yours, plus carry an extra brake and spend more time with the repair, only to attain an inferior outcome.

Yes, in the past. Cars also used to all come with cable actuated, non-disk brakes. Both vehicle types have moved on with the times as superior technologies have been introduced. It's one thing to not adopt new technology just for the sake of changing. It's quite another to refuse to acknowledge the obvious shortcomings of a legacy technology.

Exactly one of us should get right on that.

"The fastest that you can stop any bike of normal wheelbase is to apply the front brake so hard that the rear wheel is just about to lift off the ground. In this situation, the rear wheel cannot contribute to stopping power, since it has no traction." - Sheldon Brown

When down to one brake, it is better to have that brake on the front. Thus, any setup that offers a high probability of replacing a failed front brake with the working brake from the rear is superior to a setup that requires going without a front brake, having only rear brake remaining, in the event of a front brake failure.

xenologer

Remember that a front disk adapter for 180, doubles as a rear disk adapter for 160

200/180, 180/160, 160/140

a 180 rotor up front, and a 160 in the rear seems reasonable, and when you swap the caliper, you just take it's adapter with it. no worrying if the calipers can trade compatibility then

Jaywalk3r

Thank you.

Are adapter brackets interchangeable between brands? For example, if I wanted to pull the BB7 caliper from a 160mm rear rotor and put it on a 203mm front rotor, from which the (hypothetically) in-op hydro caliper was removed, do I just move the BB7 caliper from the rear and reuse the bracket from the hydraulic caliper? Or are the brackets specific to a caliper brand, suggesting I should maintain a 20mm difference between rotor sizes so I can move the bracket with the caliper? Ideally, I'd run 160mm rear and 203mm front, but I'm fine with 183mm rear rotor.

HerrKaLeun

I don't think a redundant rim brake up front will work since with disc brakes you likely have rims not made for rim brake. Also that adds weight, if that matters to you. You could just carry an additional mech. brake and carry with you.

I recently upgraded my front and rear mech. disc brake to hydraulic and never would go back. I don't think reliability is an issue with hydraulic brakes. and if, you still have the rear brake. If you only have one brake (even if you mount the rear to front) you should not really ride at all or only cautiously since that brake also could fail. If you ride cautiously and slow, it doesn't matter where the brake is.

If overheating front brake is a concerns, use larger rotor and possibly a more expensive brake with cooling fins. Sounds like you plan to have lot of luggage and on long descents I see your concern.

Maybe once you installed your front brake and shortened the lines yourself and bleed the air you gain more confidence. They are far better. You have two opposing pistons moving (mech brakes mostly only move one), no cable stretch, larger advantage etc.

You also could use a rear hydraulic brake and as long as you can move the hydraulic line without having to bleed. Then you just roll the (too long for front brake) brake line around your handlebar for that time.

When I upgraded my brakes I planned to keep the rear mech. brake because I'm cheap and assume it is not used often. but once I had my front brake and saw how easy it is to adjust and set up I went for the hydraulic rear brake. Sounds like you buy all new hardware, I would not waste time on mech. brakes when hydraulic brakes are so cheap these days.

If your hydraulic brakes are properly sized (front rotor!), of good quality and properly maintained I don't see danger of failure. and that is what the second brake is for anyway. You probably have 100 drive train failures and 1000 flats before you have one brake failure.

Edit: you could carry a bleeder kit on your tour if you really want to swap brakes

corrado33

Someone's never heard of overheating brakes and how you should cycle between the front and the rear to avoid it, especially with disk brakes..., especially on a loaded bike. Perhaps if you cycled your brakes you wouldn't have to worry about the front ones failing? Or, you know, not have to worry about overheating them at all...

But no, go ahead, just drag the front brakes down the huge hill with your loaded bike. We'll see you at the bottom, fortunately we'll be the ones still rolling.

And how much is your rear lifting off of the ground with the bike being loaded?

Exactly how long have you been riding? Cause a rear brake makes a hell of a difference in most riding I do.

Jaywalk3r

You're making it much more complicated than it needs to be.

The benefit of hydraulic disk braking is realized in the front brake. (Supposedly, I've not yet tried firsthand) they have better modulation and require even less maintenance than mechanicals, while providing at least as good stopping ability (within the thermal limitations of the rotor) as mechanicals.

The benefit of mechanical disk brakes (compared to hydraulic disk brakes) is that they can easily be serviced in the field. Many levers are interchangeable, right and left, allowing front and rear brake systems to be appropriately and easily cannibalized in the field. Their value is realized when things start going wrong. They allow one to literally make the best of a bad situation.

Mechanical disk brakes and hydraulic disk brakes have different modes of failure. They are unlikely to both succumb to the same environmental conditions, at least not likely without the frame connecting them also be affected (e.g., as in a crash). Combined failure of the two independent reliable systems is highly improbable.

A rear brake is next to useless, compared to a front brake. It provides very little stopping ability; it works much slower and over a much longer distance, regardless of rim brake, mechanical disk, or hydraulic disk. Without load or lightly loaded, I only very rarely use my rear brake. On tour, I use it only slightly more. Absent physical impact or negligence, a mechanical disk rear brake is unlikely to fail. It's somewhat protected and seldom used. It's a perfect spare front brake, stored right where it can be marginally useful until such time it's needed up front.

Therefore, one can get virtually all of the performance and reliability of hydraulic disk brakes, along with virtually all of the benefits associated with mechanical disk brakes' ease of field repair, by using high quality hydraulic disk brakes up front and high quality mechanical disk brakes on the rear. And in doing so, one decreases the probability that they are left without a properly installed front brake compared to either all hydro or all mechanical. It's a win-win-win.

The only trick is getting the details of all the sizes correct to ensure the mechanical caliper is compatible with the front rotor. Hence this thread.

On tour, not having a rear brake would add an item to my To Do list, and I'd make an effort to get it sorted out sooner rather than later, but it wouldn't otherwise change my normal pace any, unless I had steep descents to worry about. (The funny thing about bicycle touring is that the descents are only rarely as steep as the ascents! ;-) ) On the other hand, having only a rear brake is a very big deal to me. I find great comfort in being able to come to a rapid stop without requiring my path to intercept a large object!

Jaywalk3r

Far more often than not, overheating brakes are not an issue. Most hills, most places, can be coasted down without concern. And if I had to descend in brakes, with only one brake, you can be sure it would be my front brake.

Anything my rear brake can do, my front brake can do, most of it better. I just have to be aware that Ive lost ~40% of my heat capacity by not having access to the rear rotor. That's better than losing ~60% by not having access to the front rotor. Come back and talk to us after you've had a physics class. ;-)

I may or may not have more bicycling experience than you, with only 30,000+ miles in ten different states over the past ~9 years, but it appears I might've learned a bit more from the limited experience I have had. ;-)

Jaywalk3r

None with rim brakes. I can lift it (while actively trying to keep it down) with the BB7 with a light (<20 lbs) load, but definitely not a touring load. It remains to be seen with hydraulics. I cannot speak to their stopping ability.

I stop fast and short a lot. That's my typical stop under most (non-touring) circumstances. In the event an emergency stop is required, I like to just be able to stop normally, allowing me to focus my attention on the situation that required the stop, rather than the stop itself. If hydraulics offer better stopping or better modulation, I'll love them.

I'm happy with BB7s, especially mated to Speed-Dial levers. They stop well and have pretty good modulation. However, recently an old retrogrouch strongly suggested that it's time to abandon mechanicals for high quality hydraulics on my new build. After consideration, I realized that it was not logical for me to choose a Rohloff based on its reliability, despite a more inconvenient repair in the less likely event it's necessary, and then reject hydraulics because BB7s are more easily repaired/cannibalized in the field. Then I realized I could relatively easily have the best of both worlds without giving up anything, really, except for the aesthetics of having the same lever on both sides of the bar.

HerrKaLeun

I'm not the one making it complicated. My advice is to install two good and well serviced hydraulics on front and rear and not worry about swapping them. In front you likely want 180 mm rotor and a brake with added cooling fins.

At the moment you only have one brake left, you should go as slow as possible, if at all. Not because of the stopping power, but because that brake could fail too.

I don't know if you had hydraulic brakes before. If you haven't use one, install one, service one, and you see how simple and superior they are.

You make some very good points and seem to have a good understanding of brakes and their inherent issues. Obviously it is your choice how you proceed. We merely give advice that was asked for :-)

Leebo

I use BB7's on three bikes, 180 front and 160 rear rotors. Seems simple and trouble free. Works well. Why not go that route? Did some touring this summer, the Karate Monkey weighed 70 or so pounds, plus my 230 lbs, no issues on NH hills. Well down hills anyway.

Jaywalk3r

That would miss the point completely. It's a touring bike. The setup you suggest, two hydraulic brakes, is demonstrably less reliable, more likely to leave me without a front brake. It's also an unnecessarily small front rotor.

When on tour, whenever possible, each item should have a primary use and a secondary use. For example, my phone served as my primary communication device, while serving as a backup GPS device. My notebook computer served as my secondary communications device, etc. My approach allows the one brake to be primarily tasked with rear braking, while being a backup front brake, adding highly desirable redundancy without any appreciable extra weight.

Um, no. Not having a front brake is a Very Big Deal. Not having a rear brake is of very little immediate concern in most terrain. It's no reason to limp along. Having one brake is certainly less than ideal, but one good front brake provides more stopping power and reliability than two of the brakes that people had to tour with in eras gone by. It's perfectly fine to proceed normally for a day or three. One just needs to keep in mind that they are down to their last brake. It's no different than proceeding normally after installing ones last spare tube.

Had you read the opening post before you started offering unsolicited bad advice, you'd know that a) I've not used hydraulic brakes before, and b) I'm building the bike up to be ridden for many thousand commuting/utility miles before taking it on tour. In hindsight, one of the best things I did to prepare for my last tour was to use a bicycle on which I'd already ridden many thousands of miles. It allowed me to avoid most of the first time touring pitfalls (e.g., one very well dialed in hand position is better than lots of untested hand positions, rain pants really are worth their weight and bulk, even in the summer.)

It doesn't matter how simple and reliable hydraulics are. My configuration is still demonstrably more reliable than yours, because mine all but guarantees that when down to one brake, that brake is a front brake. Any solution that fails in that regard is inferior, period. Any experienced bicyclist should understand why being left with only a front brake is far better and safer than being left with only a rear brake.

I asked for no advice. I've considered all of the ifs and have made a well-informed decision regarding how to proceed, broadly. I asked specifically for technical information only.

Jaywalk3r

I love my BB7. However, (high quality) hydraulic disk brakes have a reputation for being even more reliable and lower maintenance, making a front brake failure less likely, compared to mechanicals. I'm all about ensuring I have a backup, with contingency plans, but the prospect of increasing the reliability of the primary brake justifies trying hydraulics. I'll likely have thousands of miles to decide whether or not I trust them enough to tour with them.