Disc brake compatibility with the new KH cranks

[knoxuni]

Ok that sold me. i am getting a drak and got a nimbus Dbreak and i got a disk and break left over just need some spirits now and a 29er

[Nurse Ben]

So I looked at the install in the Drak again and I think I get what Vookash was saying, it's not upside down, it's inside out. Is it my eyes or is that caliper turned wrong side out? How's the clearance on the cranks? As long as it works...

[uniShark]

Spirit Cranks take maximum of 10mm length rotor screws.

OK, I'm an idiot, but hopefully others will benefit from my experience.

Overly long screws + overly exicted mechanic + limited length holes on Spirit Crank disk mount = first picture. Not good.

Second picture is from a bit later after a lot of swearing, crying, and a trip to the hardward store. Note comparison of new 10mm screws (yes they do fit) to the longer screw that came with my Alligator rotor.

Pics 3-5 are my scary, but successful, experience of removing the broken screw.

I'm now in the process of grinding the screw heads and edge of my frame for clearance. Unfortunately I'm headed out of town for a week, so I won't get to finish my brake setup for a while. But at least I'm not losing sleep over that broken screw.

[Dartmech]

Originally Posted by Nurse Ben

So I looked at the install in the Drak again and I think I get what Vookash was saying, it's not upside down, it's inside out. Is it my eyes or is that caliper turned wrong side out? How's the clearance on the cranks? As long as it works...

Ok, the line is toward my leg and the bleed valve toward the wheel. There IS clearance but not much... It is the ONLY way to mount it though. The way the caliper must be mounted it would not work in the front, same reason for mounting in the back, it needs to be mounted behind the D-brake mount. I think with a disk hub it would theoretically go (from the left) Crank, D-Brake, caliper, frame, rotor/hub. In my case it goes Hub, frame, D-brake, caliper, rotor crank.
Haha, does that make sense? both ways the mount,caliper and rotor are in the same order. D-brake,caliper,rotor.

That was overly complicated.

It works. Tight, but works.

[TopHatPlus]

Hey guys.

I am in a semi long process of assembling the components of a disk brake system on my 26" nimbus muni. I will be getting KH spirits 127-150 cranks with the disk mount, i am planning on running the nimbus caliper adapter, and probably the kh under seat lever mount (if not from the fellow on here that makes them?) I have 2 (i think there basic...) questions.

1. I will not have the funds to purchase the actual disk brake for a while and seen on a UniGeezer video about the schlumph hub to use aluminium tape to cover the screw hole access, should i cover the screw holes for the disk brake to keep the dirt out? (getting the tape is no issue, we use it regularly at work and would need less then 1", and use a standard hole punch to cut out nice circles)

2. Are most 6" hydraulic disk brake systems compatible? I live 1/2 a block from my local bike shop, and priced out the disk brakes anywhere from $100-$200 depending on how fancy i want to get. I will probably work in part with them to learn how to properly bleed and set them up.

Thanks

Bob

[Nurse Ben]

Ok, the line is toward my leg and the bleed valve toward the wheel. There IS clearance but not much... It is the ONLY way to mount it though. The way the caliper must be mounted it would not work in the front, same reason for mounting in the back, it needs to be mounted behind the D-brake mount.

Can you mount it on the left in the same fashion or is the D Brake adaptor off set to one side (I'm at work and can't look at my unis right now)?

The Spirit cranks are machined with extra clearance, and that Tektro brake is one of the thicker hydraulics I've used, so others brakes should fit (answering TopHat's question).

@ TopHat: I would wait and see what happens as other riders put together their Spirit set ups, otherwise you could potenially have a problem, esp since you'll be waiting a while before you can test yours out.

You could also have a disc tab welded onto your steel Nimbus frame. This is what I would do, it's lighter and it positions the brake closer to the frame with better line angle.

[knoxuni]

@ nurse ben would welding a tab put a weak spot in the frame tho?

[Nurse Ben]

@ nurse ben would welding a tab put a weak spot in the frame tho?

Not really, unless the welder overheats the tubing or messes up the weld. The steel frame tubes are not heat treated.

I prefer frame mounts when I can get them, it's cleaner, easier to do maintenance, and the caliper is better oriented, but there is an additional cost for fabrication.

In comparing crank vs hub mounted disc brakes, the hub vs crank costs are the same, so the only additional work/cost is the wheel build. There are some obvious advantages to having a hub mounted disc that we don't need to discuss on this thread.

Kris designed the Spirit cranks to work with his new frame. On the same note, UDC designed the D Brake to work with the Oracle and Oregon hubs on Nimbs frames. So anything else may require some fiddling including frame grinding and D Brake modifications.

From my experience working with KH (29, 26) and Nimbus frame (Oregon, Stealth), the D Brake and Oracle/Oregon hub combos work perfectly with no fiddling required.

[Dartmech]

The D-brake has recesses on the front (text side) for the mounting screws. The caliper needs to be mounted to the rear.
The KH frames with mounts were really what these cranks were intended for.

ALSO I haven't gotten to the trails yet, but riding around the street, if free mounting aggressively (i.e. a lot of pressure on the disc crank) I can hear/feel the disc rub the caliper... So there is some torque flexing going on. I don't see this as an issued after getting going, I just thought I'd make sure everyone knows.

[knoxuni]

Shoot I still have no clue what I want

[Dartmech]

I'm 100% satisfied with the way things worked out. IF that helps.

[uniShark]

Originally Posted by TopHatPlus

Hey guys.

I am in a semi long process of assembling the components of a disk brake system on my 26" nimbus muni. I will be getting KH spirits 127-150 cranks with the disk mount, i am planning on running the nimbus caliper adapter, and probably the kh under seat lever mount (if not from the fellow on here that makes them?) I have 2 (i think there basic...) questions.

1. I will not have the funds to purchase the actual disk brake for a while and seen on a UniGeezer video about the schlumph hub to use aluminium tape to cover the screw hole access, should i cover the screw holes for the disk brake to keep the dirt out? (getting the tape is no issue, we use it regularly at work and would need less then 1", and use a standard hole punch to cut out nice circles)

2. Are most 6" hydraulic disk brake systems compatible? I live 1/2 a block from my local bike shop, and priced out the disk brakes anywhere from $100-$200 depending on how fancy i want to get. I will probably work in part with them to learn how to properly bleed and set them up.

Thanks

Bob

1. Sounds like a good idea, although cleaning out the holes for the one time you put on the rotor wouldn't be too big of a deal.

2. Yes, most.... I'm finding clearance on my older KH frame to be very tight. Bigger crank spacers may be necessary, although I'm trying to avoid them to ensure my cranks have a tight fit on the splines. It will be interesting to hear how the Nimbus frame turns out with this retrofit.

[Tucson Uni]

Got back to work on my 36 guni disc brake setup. I shaved the screw heads (probably a little too much, the heads stripped a little tightening them down), and shaved the outside of the bearing holder on the frame. Now I can put the wheel on the frame without the disc bolts rubbing on the frame.

Now the next problem. The brake mount adapter is 1 cm wide. This is wider than the gap between the frame mount and the rotor. I could put the crank on with less torque (I compromised already by cranking it to 35nm instead of 45nm). I guess my only real choice is to grind down the adapter a couple of mm (maybe just where it goes against the frame mount).

[TopHatPlus]

So it looks like i will be modding a few things... i am okay with that! The D brake mount is pretty cheap so a few mods on it are no big deal. I will keep posting my findings as they happen. Depending on how my funs look for the next month i may be doing all this sooner then expected.

@ unishark

I figured covering the holes just takes the effort out at a later time of cleaning them out. I get frustrated with dirt gets packed into these things and i spend all kinds of time trying to clean it out and get it back to new in order to make it work. I will post a picture when i get them.

Pretty excited to get the cranks... the 165mm are just to big for my short legs... i feel like i am doing to splits at 3-9 and i am kneeing myself in the chest at 12-6 with my other foot just able to reach. The torque on them is pretty huge but my ability to pick up an speed is lost in the reaching aspect. I think i am running 114mm cranks on my 20" Norco muni, its what ever came stock, they are VERY SHORT! almost feels radiculeous to ride but i can ride 100x more aggressively with them than i can even on my brothers 20" Nimbus with 135mm cranks. He is going to be swapping his out for like 85mm >_<

[Tucson Uni]

Okay, here it is. The disc brake and everything seems to be functional - finally! Lots of shaving - shaved the bolt heads on the rotor, shaved the bearing holder on the frame, shaved the adapator for the braking mechanism, and a tiny bit off of the brake mount on the frame.