Why aren't hub/drum/roller brakes suitable for touring?

Question

I've got a Dutch town bike with Shimano IM80 roller brakes. They're brilliant. Maintenance free, clean, and effective.

I've been looking at getting a long range touring bike for an initial 3 month camping/hostel trip to Japan, and so I need a more suitable bike. It's probably best that I stick with what I know and like, but it seems that everyone says roller brakes just won't do it.

Why is this? Here's a summary of the issues and my initial thoughts.

• "They can't cope with sustained braking on descent."
  Is this because of temperature? The cooling fins on a Shimano IM81 roller brake are huge compared to disc brakes. Why is this a problem?
• "They can't handle heavy loads."
  I give lifts to adult passengers on the back of my heavy bike (a total weight of at least 150kg) and while braking performance is affected it's not catastrophic.

I would really appreciate answers that address the technical performance and safety issues that mean hub brakes aren't recommended. I'm aware maintenance (particularly in the field), weight, interoperability, and style are other factors that need consideration independently from the operation. Thanks!

Answer 1

Their main problem is your first bullet hypothesis: They can't cope as well with sustained braking on descent, as that is where brakes are challenged the hardest.

Even with the extra cooling fins, on a long descent, the brake may overheat, and may catastrophically fail. Riders using roller brakes have reported the brakes getting hot enough to ignite the internal lubricants inside the hub when making descents on tandems or loaded bikes.

Even if you had cooling fins the size of the wheel, you are generating heat inside the hub, and that heat has to travel out to the fins, which is surprisingly slow. Going down a mountain, you theoretically could have your hub start on fire, while the outer parts of the cooling fins could be cool to the touch. Disc brakes don't have that as the source of the energy is at the caliper which is on the outside of the rotors, but even then those have failed from overheating too.

The weight aspect on its own isn't too big a deal, even with heavy loads, you can only slow down so much before you are completely stopped. However, when descending, you can drag the brakes and build up heat faster than it can be dissipated, and combining a descent with a heavy load doubles the demands on the brakes.

Ultimately, every bicycle brake system turns kinetic energy into heat, and has a maximum wattage it can operate at continuously. What increases the wattage is greater deceleration or greater loads.

If you were touring across Iowa, you'd be totally fine. Japan is pretty mountainous. If you are going to only be traveling where the terrain is pretty gentle, you'd probably be OK. If you are going into the mountains though, you'll want a different brake system.

Answer 2

I have some BR-IM45s, and some BR-IM70s (which have large cooling fins), on a couple of my bikes, although they're only used for relatively lightly-loaded commuting (typically only around 20m per day, load of around 15kgs, rolling along at 15mph). They're actually pretty easy to strip down and service, though this simply consists of disassembly, degrease, regrease and re-assembly. IME, under these conditions, the brakes need a strip down and relube about every 6-9 months to maintain the best performance (decent modulation with good braking power).

On the BR-IM70 front, for example (please see photos), the shoes brake against the inside of a 'drum' which is part of the cooling disc, so I imagine the heat in the disc itself can escape fairly well, but the heat in the shoes can only really travel through the grease and on into the disc, which I doubt is a very effective method of cooling the shoes, especially as they, like the 'drum', are made of metal.

If the brakes (well, mine, at least) aren't relubed regularly enough, they tend to lose braking power, unless the lever is pulled quite hard, at which point they 'grab' and brake sharply. This wears the metal shoes inside the brake quite rapidly, and if it goes on long enough, permanently reduces the braking power. For example, the 45s I've got were on a used bike I bought, and despite a strip-down and regrease, have never braked particularly well - they just don't have the stopping power any more.

BTW, just squirting more grease into the hub, as Shimano recommend, is not a very good way to keep the brakes running; all it does is mix old grease with new, with mediocre results. It's much better to degrease the parts completely, and then regrease.

In terms of fast descents, I've obviously never had to push mine on a commute, but I tend to slightly alternate the braking power between front and rear brakes on descents, and I've not had any problems with my roller brakes cooking grease. With a heavier bike on a longer descent, I'd feel confident on a mild gradient, but I'm not sure I'd bet my life on them going down a steep slope, unless I was keeping my speed down most of the way.

If I was back doing some relaxed touring with the ~15kgs I used to ride with, and not regularly doing a lot of mountainous riding, I'd personally be happy using roller brakes, but then I tended not to ride for more than 2-4 weeks at a time anyway.

Answer 3

As has been pointed out, closed brakes are not ideal from the standpoint of disipating the energy built up through friction. This has also been experienced in the automotive world, where drum brakes were standard during many decades. Some would say they still are, e.g. on rear axels of light commercial vehicles such as pick-up trucks.

However, although there have been accidents (even truck accidents) at times, they seem to have occurred mostly in mountain regions and with drivers at the wheel who were not used to driving in such conditions. Mountain drivers are/were used to "listening" to the feel of their brakes, and knowing when to back off, slow down -or even stop completely, and take a break- before the brakes became completely non-responsive.

This is less of a problem with disk brakes, as they have larger areas in contact with ambient air, air circulates more rapidly around them, and the areas that actually generate heat (where the pads rest) are completely exposed to the air. Bicycle caliper brakes are a bit of the same, but even better in the sense that the metal getting heated has even more area (the whole wheel rim). However, caliper brakes are applied to the outside of the wheel, and not near to the axis such as with disk brakes. This has its drawbacks (more tendency to go over the front wheel), which is probably why dirt track descent riders all go with disk brakes.

I would tend to think all types of brakes could serve your purpose well, but that hub brakes will need more attention from you, specially when going down long descents. You will need to stop more often, to let them cool off. On the other hand, you seem to be familiar with them already, and you will be on holiday, so...

Have a nice trip!

Answer 4

Sheldon Brown has this to say about disadvantages of roller brakes:

Disadvantages? [...] Only large Rollerbrakes with large cooling fins have enough heat dissipation for speed control on downgrades -- no Rollerbrake is suitable for use as a drag brake on a cargo bike or tandem. There have been reports of grease's catching on fire during long descents! Overheating to this degree will require replacement of the brake, and rebuilding of the adjacent hub bearing.

That doesn't sound like something I would want to deal with on a touring bike.

Answer 5

I do have experience with both IM-70R/F roller and Sturmey Archer XL-FD (90mm) and X-RDC (70mm) drum brakes. Same bike, same usage, same city commuting. My experience shows that IM-70s bake oil on descents and fail. It happens on fast long descents. I do have a 1 km long fast descent (up to 60kph). When you try to stop the bike quickly at the end of it IM-70s get so hot that they bake Shimano proprietary brake oil. They do still brake but continuing using them would simply destroy them. I come home, overhaul the hub, clean the baked oil and then it runs again. Actually I have learned to apply both brakes gently and to avoid the baked oil. However, I consider braking to be one of the most important functions on the bike and I simply cannot accept such reliability. And yes, I do ride agressively. So I used IM-70s for a year for my commuting until I was fed up with overhauling.

And then I bought Sturmey Archer XL-FD and X-RDC. The front 90mm brake simply rocks! I can brake with only the front brake with full power on the same descent and it is strong and never overheats. Yes, it is warm/hot but it never overheats. The rear 70mm brake is much weaker and spongier but it does not overheat either.

Actually I do prefer the SA drum brake over disk brakes for commuting. The brake force modulation is wonderful, disk brakes have more on/off feel. Anf I do own disc, drum, caliper and V-brakes in my stable at the moment.

The other important thing is maintenance, which with SA drums are practically none. They just run always and forever without any maintenance.

If I would go for touring I would chose SA drum brakes out of any type I own.

Answer 6

Dutch town bikes are the norm in Japan (I live in Japan BTW). Most Japanese Dutch style bikes have a rim brake up front and a drum brake in the rear. Rim brake is for help going down hills and the like. As mountainous as Japan is the cities tend to be flat with hills. Most Japanese ride down hills no problem on a dutch bike. However, most Japanese walk their bike up hills.

Long story short, dutch bikes are everywhere in Japan and drum brakes are the norm so get riding.

Answer 7

Roller brakes are suitable for touring

I've been using Shimano Nexus BR-IM70-R(ear) roller brake for the last 10 years (48 kkm, a few tours some in mountains) as my main brake. Many times I had sore fingers from squeezing brake levers and I've had 1 failure. I think it was 2 years ago, I cycled down a very steep (15 % ? 20 %? - I had an altimeter but I don't remember numbers) stony track and I gradually lost braking power. I smelt smoke and the cooling fan reached about 100 Celsius degrees, checked by saliva. It was dangerous because the front V-brake had been broken. With the working front brake probably I might cycled further. I walked rest steep slope and cycled back home ~30 km. I applied grease and I've cycle more.

After 10 years modulation is a bit moody but it still does work. My first grease appliance decreased a little bit performance. I'm not a good mechanic so I haven't taken apart my roller brake. I use a v-brake lever, not recommended but it allows to pull more cable to minimize drag in a resting position. I've just bought a new bike with mechanical disc brakes because it's cheaper than ordering a wheelbuilding and a brake. After a few km I'm not sure it was right choice.

From my practice I think roller brakes are safer than V-brakes because of water and mud resistance. If one can't have a disc brakes a roller brake will be a very good upgrade.

(from flikr)

This bike, also with a roller brake, I share with my sister. Most of my pictures on Flickr are made during bike trips and tours.

Answer 8

I'd say their biggest disadvantage in this use, would be the drag they create. With loaded bike, it'd really make a big difference, as, for me, who is used to "normal brakes", it's already noticeable and annoying in relaxed, commuting riding.

Typical drum brakes however, would make much more sense, as they share ease of maintenance and weather immunity with rollerbrakes, while not generating any drag. Sturmey Archer ones seem to have the best reputation, though I can't say much, as I never rode one.

However they'll never be as powerful as rim, or disc brakes, which can be troublesome on heavy-loaded bike, especially on descents.

Hope I helped ;).