Adding Disc Brakes (pics please)

Unicycles and Equipment
1

I’m wanting to add a disc brake to my Nimbus 26er to convert it to Muni. Is this difficult to do? Surely some of you have already done it. Any tips and especially PICTURES would be greatly appreciated.

2

Which nimbus frame do you have? It depends on your frame which method will do it.

3

Hub

You need to add a disc, IT means you need disc hub or Spirit Cranks for brake you need D’brake adapter And brake holder under your saddle

4

It’s a Nimbus II 26er. I can put a max 2.8×26 tire on it which will work fine. Thanks
Rob

5

I’ve retrofitted disc brakes on both my Nimbus 36er and my Nimbus II 26 (same as yours).

You basically have three tasks:

[LIST=1]

  • Mount the rotor. You have two options here:

    [LIST=a]

  • Mount it on the inside of the frame, on the left hand side of the wheel. You'll need to rebuild your wheel with a disc hub, which is the main disadvantage. The advantage is that you can use any cranks you like. This is how Nimbus does it.
  • Mount it outside the frame, on the right hand side of the wheel. The rotor is mounted to the right hand crank in this scenario. You can keep your current hub but you're locked into using KH Spirit cranks. This is the how KH does it. [/LIST]
  • Mount the caliper. Again there are two options:

    [LIST=a]

  • Weld a mount onto your frame. This is the nicest option (KH and newer Nimbii use welded mounts) but is a bit of a hassle if you're not handy with that kind of thing.
  • Use a bolt on mount (the Nimbus d'Brake is the most commonly available). This replaces the bottom bearing cap on the side of the wheel with the rotor. It's a lot simpler than welding on a mount but is slightly less strong and is a bit of a pain to adjust when replacing the wheel in the frame. [/LIST]
  • Mount the brake lever.

    [LIST=a]

  • If you use handlebars then just mount the brake lever there.
  • If you don't use handlebars then you need an underseat lever mount. Note that although that one says it's for KH saddles it will work for some Nimbus saddles too (I use it on my Nimbus gel saddle). There is a more universal two-bolt version if you're worried about compatibility. [/LIST] [/LIST]

    On my unis I’m using an external rotor with Spirit cranks and the d’Brake caliper mount. I’m pretty happy with them, but I’d prefer a welded caliper mount and may pursue this in the future. Here are some pics of my 26er and my 36er. I can dig out some more pics if you’re interested in anything specific.

    One thing to note - there are actually two versions of the d’Brake in circulation. The original one is the one I have on my 26er and it fits with no worries. The newer version I have on my 36er, and it’s beefed up a bit from the original. I had some clearance issues with it hitting the spoke elbows and had to file it down a bit. This is the bare aluminium you can see in the photo. This is probably not a problem if you mount it on the left hand side of the frame, and indeed may be something specific to my particular 36er.

    • 6

    As the Nimbus 2 has CNC machines bearing housings, you just need to use the Nimbus d’Brake. Just assure, that it lies planar on the frame (1st bolt), otherwise you’ll have to use a washer.

    The rest will look like mine, but without the adapter piece between d’Brake and frame.
    http://www.unicyclist.com/forums/showpost.php?p=1617688&postcount=1252

    7

    Guys, you’re the best! lightbulbjim, I think I’ll just build my 26er to look like yours. Are those 150/127 cranks? Very nice looking. Very helpful. Thanks!

    Rob

    8

    Those are 137/117, but crank length is personal preference anyway.

    9

    Hey guys, I finished my Nimbus II 26er mods tonight and appreciate your help.

    1. I bought the d-brake and DID have to file down the lower bolt
    2. I’m still having some clearance issues with the disk brake and can hear it rub on about 25% of the disc when spinning
    3. The brake cable so close to my pedal makes me a bit nervous but I suppose I’ll get used to it

    I took it for a short ride and it seems to work just fine (other than pads rubbing on the disk brake). Any thoughts on what I can do to make it better?
    Thanks

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    10

    Looks good. If you position the uni just right you should be able to look down the caliper and see daylight between the rotor and each pad. Turn the wheel slowly and you’ll see where the rotor is out of true and which side it’s rubbing on. If it’s only a small section which rubs then you can just bend the rotor gently so that it clears that section, rotate the wheel a bit and repeat. If it rubs most of the way around then you probably need to adjust the caliper position slightly to get a better starting position and then start truing. Eventually you should be able to get it to clear the pads throughout the whole revolution of the wheel.

    You can get a fancy rotor truing tool or just use your fingers. If you use your fingers it can be worth it to clean the braking surface with rubbing alcohol afterwards to remove any oil from your skin.

    Once you get the rotor true it shouldn’t move unless you kick it or similar. I think they often end up a bit wonky from being tossed around during shipping.

    11

    You used the original bolts of the brake, this is why you had to file it down. But so the bolt’s head is only supported by s mall ring of material. Take other bolts. Normal ISO socket head screws have a smaller diameter and will fit fine in the holes of the d’brake.

    12

    Good advice from lightbulbjim. I would add: the two disc brakes in my Munies used to rub as well when first installed. I did follow similar advise to the above and despite making it better I never managed to get rid of all the rubbing (I am not very patient with doing little tweaks…). However after a few rides most of the rubbing disappeared :slight_smile: