Disk vs Rim brake

I’m considering buying a second hand KH 36" as I’ve never owned a 36 and am keen to do some long distance road touring soon. I tried it out and loved it: the mounting didn’t seem to be a problem, although I guess becomes a different kettle of fish once you have heavy panniers swaying you about.
My main concern/question is regarding the break system. Looking on unicycle.com and kris holms website, it seems all modern KH 36ers have hydraulic disc breaks, but the one I’m thinking of buying as a rim break. I can’t seem to find this model online so presume it’s quite old. I’ve read that one major disadvantage of rim breaks is that using them in wet/muddy conditions, the grime and accumulate on the rim and interfere with the breaking mechanism whereas a disk break is more reliable in all conditions. On the other hand I’ve read that rim breaks are easier to repair yourself manually?

Would love any advice you could give me about whether it’s worth me buying the second hand rim break one or buying a newer disk break one?

Many thanks in advance
Mike

I’ve got no experience with rim brakes, but I did order one of these yesterday.

It’s a disk brake adaptor, so there are ways to retrofit older unicycles to disk brakes. Some of the Kris Holm cranks have holes for attaching brake disks to, so even if the hub is not configured for it you still can probably switch to disks if you really want to in the future.

Cool, where did you get that? is it used particularly for converting rim break to a disc break set up?

That’s available at unicycle.com under the brakes and mounts section. I’m not sure how well it will work on a KH unicycle however as it was designed for inboard brakes. It might be that you can simply reverse it and use it for outboard brakes as well. I’m sure there’s a way to retrofit it though.

IMHO the only maintenance needed with both systems is replacing the pads which is slightly easier on a rim brake, with most disk brakes you have to remove the wheel. I’d still go for the disk brake for the following reasons:

  • For a rim brake the wheel has to be perfectly true for them to work well. If a spoke snaps on your tour the brake can become unusable. You also can’t tighten a loose spoke because this leads to some untrueness (wait, that’s not a word - what’s the word I’m looking for?)

  • After some prolonged time of usage either the rim or the disk will be worn and needs replacing. It’s easier to replace a disk.

  • A disk brake doesn’t clog with mud and works reliably in any conditions, dirt, rain…

(but that said, the only experience I have with rim brakes is from a 24’’ muni, not a 36er)

thanks for the advice. By ‘true’ do you mean perfectly straight, as in a broken spoke might cause a small raise/trough a particular point of the rim, resulting in less contact if the rim break with that section of the rim? As to your second point, I wasn’t aware of that. Like you, I’m also only used to riding a 24" muni.

Do you know how much an older version of a KH 36er with a rim break should be? The problem I have is I can’t figure out how much it should originally cost so I’ve no idea if the person I’ve found who wants to sell his 4 year old one is reasonable or not as I’ve nothing to compare it to.

It’s always hard to figure out fair prices for used unis, since there isn’t really any comparison. Also, look at the condition, and do the full math, replacing a bunch of small wear items (tire, bearings, pedals) can add up.

If you don’t have a lot of hills where you ride, a well setup rim brake could be all you “need”. If the deal is good, saving some cash for everything else that you might suddenly need for touring (bags, clothing, etc.) might be nice. I’ve personally noticed quite often those small things can have much more of an impact on my riding experience than a higher quality uni.

If you are looking at buying new, I’d consider other brands too. (look at this thread: https://unicyclist.com/t/opinions-on-best-36er/ )

Depends on what rim brakes you are talking about. If you are talking about a set of v-brakes or calipers, you need less tools to repair them and set them up (an allen key is pretty much all you need usually). I think from a difficulty perspective, rim and disk brakes are equally “difficult” to set up, they just have different problems.
If you are comparing to Magura hydraulic rim brakes, you’ll need to bleed them just like you would on (hydraulic) disk brakes, so you’d need to buy a kit for that. Bleeding them is a bit of a learning process, but not too hard either, or if you don’t want to do it, it’s a pretty standard and cheap thing to have a bike shop do it (every 2 years or so should be fine for a 36").
I used to think that disk brakes are fiddly and difficult too, but my experience with them has been the opposite. Set them up once, change brakepads/disk when necessary, no trouble inbetween.

That’s less of an issue then a wheel that’s out of round laterally. In this case the brake force will be very unevenly distributed and the brake might even touch the wheel at some point of a revolution without braking.

I ride my 27.5 and my KH36 way more than my 24’’, but they both have disk brakes. So the 24’’ is the only one with rim brakes.

I originally rode a 36er without brakes (or even a handlebar) for a long time, I only added a brake later. If it comes with a rim brake, use it. But you should be able to retrofit a disc brake, either inboard (hub mounted, using a suitable hub… yes, this would entail a full wheel rebuild) or outboard (crank mounted, e.g. spirit cranks). If your uni frame doesn’t have a tab, use a d’brake as picutured upthread. I’ve attached a d’brake mounted on the left side on one uni and on another uni, the right side, you might have some spacing to work out, but it generally works for either setup.

Personally, if buyung a 36er, I’d try to get something with a splined crank interface, avoid cotterless, though a 36er is the uni I would be least likely to do dropping or hopping on.

Amd for me, my 27.5, 29, 36er all ended up with disc brakes, and only the 24" muni had a rim brake.

If it’s 4 years old then it should be compatible with a disk brake already and all you’d need to do would be add the disk to the crank and the caliper to the mount.

KH unicycles have been created with disk brake compatibility since 2012.

The d’brake adapter has its down sides for use with an outboard disc (mounted on the crank rather than the hub) certain brake calipers, particularly mechanical ones, are thicker on one side. I tried a shimano mechanical caliper on my nimbus oracle 36 and the caliper hit the spokes.

Many unicyclists don’t like outboard discs because the rotor (brake disc) is more prone to damage. The flip side of that is a potentially stronger wheel because it will be a symmetrical build, as opposed to a disc hub where the spoke flanges are not symmetrical.

Mechanical rim brakes (v brakes) are pretty universal, any bike shop in the world will have spares whereas they may not have the specific pads for your disc caliper in stock. Depending on the touring you plan this may matter.

I have d’brake mounts with kh moments on my 29er and 36er and a magura rim brake on my 24, in use there’s very little difference. As mentioned above, both require wheel removal to replace the pads, both required bleeding on initial set up, both have enough power to stop me.

Honestly, people can argue for one or other with sound points, but Id say go for whatever is available in your budget, and don’t worry about which is ‘best’.

I wouldn’t get a 36 with Magura rim brakes for the purpose of loaded touring, but that doesn’t mean that that unicycle isn’t a good choice.

If you are serious about using it for touring, I would get it if you can upgrade the parts and still have it cheaper than buying new. Factor in the price of a d’Brake adaptor, a mid-range disk brake, KH Spirit cranks, and possibility a new tire/bearings/etc. assuming the wheel is in good shape.

I was an early adaptor to disk brakes and they really are superior in a lot of ways but not 100% better in all circumstances.

A big positive of disk brakes is they are not as affected by frame flex, which can be a significant issue with 36ers. Fortunately the old (and new) KH frames are quite stiff and do a pretty good job of preventing rim brake pads from rubbing when pedaling hard. If you are loading down the frame for touring you might still get rubbing from the comparatively stiff KH frame.

To deal with the issue of frame flex many unicyclists ran “frankenbrakes” which were Magura HS33 slave pistons actuated by a HS11 lever. This gave more pad travel than any stock setup and worked well. The problem is that they were obsolete 10 years ago and finding spares isn’t the easiest thing anymore.

V-brakes are less affected by rim contact from frame and wheel flex but you would need an adaptor plate. They used to be common when trials bikes used Magura rim brakes but might be harder to find now. Once you have a good adaptor, V brakes are by far the easiest to fix and find parts for in remote areas.

If the ability to fix things on the road with minimal resources is a priority forget everything else I’m writing, buy the used KH and swap out the Magura rim brakes with some long arm V brakes.

If upgrading a non-disk ready (pre 2012) KH 36 you would do well with a d’Brake and Spirit cranks. With the proper 6mm spacer, the Spirit cranks put the disk 1.5 mm further away from the bearing centre than a hub mounted disk so you would likely need to add washers between the d’Brake and the caliper mount to push it out a bit. At this point it might work brilliantly, or you might have some chattering and resonance issues. This is fixed by adding a brace between the top bolt on the d’Brake and the frame. Search “Hugo Strut”.

That was probably more info than you wanted to know., but yah, if you want the best preforming setup go disk, if you want the easiest to fix anywhere in the world, buy that unicycle and convert to V-brakes, or if you don’t mind the occasional rub and aren’t afraid of obsolete but fantastically powerful hydraulic rim brakes get it and ride it as is, but I don’t think it’s the best setup for loaded touring.

Good luck!

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My experience with disc vs rim brakes:

  • Disc brakes are smoother than rim brakes, wich are important on a 36’er, and the reason why I choose a disc brake

  • With a disc brake it’s hard to see how much of the brake pads are left.

  • Setting up a rim brake requires more ‘fiddling’ to get it right.

  • I can’t remember ever having problems with a rim brake and an untrue wheel

  • My rim brakes (Magura HS 33) has been more durable than my disk brakes (Tektro, Shimano)

Question:

  1. Has anyone experienced brake failure going down hill on a 36’er with either type of brake? If so, how did that go?

  2. Do you have a plan in case of brake failure on a 36’er? What’s the plan (if it’s too steep to keep pedaling)?

I’d just get off and walk

I was thinking that when you ride down a steep hill on a 36’er dismounting in a safe fashon could be a problem. How would you get off?

I suppose it depends how fast you’re riding.

I was thinking that the brake would be most likely to fail while using it hard, which would suggest stopping, or substantially slowing down with your weight hanging off the back of the unicycle.
If it failed in that situation, you’d be most likely to fall off the back, which although you might land on your arse, would be preferable to whizzing off down the hill uncontrollably.

My experience with bicycles is that even if the wheel is not true, rim brakes will still function. You might have to adjust them a bit on the sloppy side in order to avoid rubbing, but if your wheel is only a few millimeters out of true the rim brakes should still work fine. Often the brakes will continue to work on a wheel that is badly out of true. They’ll rub and cause friction, but they’ll float from side to side as the rim pushes them.

Also, discs can and do get bent as well.

Isn’t this only true for V-brakes (or catilever) but not for hydraulic ones like the magura?

Nope, the hydraulic ones will also happily float from side to side (albeit with a bit more resistance as the hydraulic fluid has to be pushed through the hose from one side to to the other).

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Generally when brakes “fail” one gets off as soon as possible by whatever means necessary. Think Maverick Vinales at the AustrianGP getting off at 200kph when the brakes failed. You know it is only going to get worse.

I have never had a brake failure as such but a disc brake on my 36 bit unexpectedly hard once and I had to step off. The speed wasn’t a serious problem but it was a fairly steep hill and a long way down to the road surface in front after taking the step off. Landed hard on my heel which is also more likely on a down slope. Hurt for weeks.

I couldn’t see anything wrong with the brake and it hasn’t happened again. I had been riding the uni for months and knew both the hill and the normal brake characteristics quite well. No sign of contaminants. I wonder if the D-brake flexed and jammed it.

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