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Old 2019-12-11, 10:08 PM   #2356
pierrox
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Quote:
Originally Posted by lobbybopster View Post
OK, let's get it on the rubber side down.
It happened! Finally!

Took ages because I was not crazy about using a Magura Louise or Clara since those are essentially bending the disc towards the non-piston side of the caliper. I sourced a Magura Gustav brake on eBay - those are still popular among downhill MTB riders and are surprisingly expensive for a 10 years piece of kit. The Gustav is also a caliper with a non-piston side like its contemporary friends but it has two pistons on the other side. And the whole caliper is mounted on what Magura calls a 'hanger' on which it can slide sideways. Basically it's a floating caliper, a technology used in cars and motorbikes for decades before opposite pistons became the norm.

I learnt about the details of this brake the hard way: the one I bought was surprisingly cheap... because it didn't have the hanger. It took ages to source the right one (Magura offered 11 different models at one point!) and at a reasonable cost. Special thanks to Magura USA (not DE...) for pointing me in the right direction.

Here is the hanger - fork is upside down. I had to grind it a bit as it was too close to the rotor. The rotor is very close to the fork, more than usual.



The caliper in place - again, fork is upside-down:



And with the wheel in place. You can see how narrow it is on the spoke side of the rotor. The nice thing is I could go back and re-lace the wheel with the spokes in a more usual 3 way crossing. I guess it's still popular with downhill riders as it lets you build a stronger wheel with not much dishing unlike modern calipers - Magura also offered a Gustav hub back in the days:



Ok, all in place now:



And the whole beast:



I still have to optimise the angle the caliper makes with the rotor with .2mm washers which should arrive by the end of the week. Magura's literature claims there will be a constant rub noise but no actual rub: "the wheel can spin 10 rotations without stopping". In my case, the angle is partly due to the frame not being super straight. An issue I had with my KH frames and which is also present on the Mad4One frame. I check the wheel in a truing stand, and it's perfectly aligned...

I'll need to make some kind of KH starfighter/spooner thingy to have a better grab of the brake handle. I have some spare L shape trim which should do the trick.

This build went on for ages but I'm happy I took that challenge. I've been wanting to put the Schlumpf in a 32" wheel - except there is no way to have rim brakes on those - so now I know I can do it. And in theory, the 32" wheel will fit just perfectly in this Mad4one frame...

Thanks again for Lobbybopster for sending me down the rabbit hole of Schlumpf disc brakes! It's been fun and a learning experience.
(ok now I have to go try the thing, but the weather hasn't cooperated lately)
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Old 2019-12-12, 10:18 PM   #2357
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Nice! I bought a set of Magura Gustav M over 10 years ago for Freeride MTB and at the time it was absolutely amazing, years ahead of any other disc brake. Actually, the brake is still awesome and super durable. The newer competitors from Shimano/SRAM and co now make brakes with as much power that are also lighter, but nothing I've had is so solid and lasts like the Gustav. Yes, the adapters are kind of a pain and the rotor sizes nonstandard - 210mm (I modified a Shimano adapter to run a 200 disk a few years back). And yes, the floating saddle is a decent design. When checking it by hand mine always seemed to "stick" but then in use it always seemed fine.
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Old 2019-12-13, 12:25 AM   #2358
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It finally happened

Congratulations, you have the "Rubber Side Down" I can call you number 9. The nineth on the road and only in frame disc Schlumph (Smurf) in Europe.

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Old 2019-12-13, 08:10 AM   #2359
pierrox
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Quote:
Originally Posted by lobbybopster View Post
Congratulations, you have the "Rubber Side Down" I can call you number 9. The nineth on the road and only in frame disc Schlumph (Smurf) in Europe.

LobbyBopster
Thanks a lot!
Now I have to master that thing!
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Old 2019-12-13, 01:48 PM   #2360
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That "Thing"

Quote:
Originally Posted by pierrox View Post
Thanks a lot!
Now I have to master that thing!
You are the Master of "That Thing" Go enjoy it to the max!
Well Done, looks Great.
Mark

Last edited by lobbybopster; 2019-12-13 at 01:50 PM. Reason: jumped the gun-i
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Old 2019-12-13, 09:20 PM   #2361
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Brake Hanger

That brake mount is similar to the AMP (Mercedes bike) and ROCKSHOK floating disc brake mounts. I will check the inside size.
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Old 2019-12-14, 10:50 AM   #2362
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well done pierrox. weren't you supposed to mount it on the 32er in the first place?
Cause for a 29er this is a lot of hard and complicated work while magura rim brakes work very well with a g29 (unless you want to do very technical and steep downhill muni).
Anyway, I showed up because on the 3rd photo I see some scratchs on the left pedals. Did you do that yourself to let some clearance for the disc brake or did the brake make those scratches?
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Old 2019-12-14, 08:06 PM   #2363
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The Disc!

Rim brakes (Magura etc.) are great, but bend the rim out on trail and its a good walk. Not so with disc, and this was not hard to make at all.
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Old 2019-12-14, 08:24 PM   #2364
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Quote:
Originally Posted by lobbybopster View Post
Rim brakes (Magura etc.) are great, but bend the rim out on trail and its a good walk. Not so with disc, and this was not hard to make at all.
Feel free to tell me if you find another one in your garage... maybe Europe needs other schlumpf with left side disc brake
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Old 2019-12-14, 09:41 PM   #2365
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Quote:
Originally Posted by UniDreamerFR View Post
well done pierrox. weren't you supposed to mount it on the 32er in the first place?
Cause for a 29er this is a lot of hard and complicated work while magura rim brakes work very well with a g29 (unless you want to do very technical and steep downhill muni).
Anyway, I showed up because on the 3rd photo I see some scratchs on the left pedals. Did you do that yourself to let some clearance for the disc brake or did the brake make those scratches?
You're right on the 32" but since I had all the parts to easily do this with the 29", I decided to start with it as a "proof of concept". I needed to make sure it would work before buying lots more parts with no 100% guaranteed result. The only cost originally was 18 new spokes to re-lace the wheel with the adapter. Next step was to get the frame. And indeed, now I can make a G32". First I want to ride it and really get into it. I'm still not sure the Schlumpf is for me.

You have an eagle eye! I forgot to mention that with the disc rotor being close to the fork, and regular bike not having pedals on their front wheel, one of the shaft of the caliper holder protruded a little and was rubbing the left crank. Since it has a thread to put a bolt, I didn't want to cut it. So I did two notches on the crank it self. And overdid it a bit actually!
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Old 2019-12-20, 03:01 PM   #2366
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Quote:
Originally Posted by lobbybopster View Post
Rim brakes (Magura etc.) are great, but bend the rim out on trail and its a good walk. Not so with disc, and this was not hard to make at all.
Why would this be any different with rim brakes than without...? You could bend the disc on the trail and it'd get stuck in the calipers just as good as a rim brake would.

That being said, I cannot stand rim brakes on my 29er. They feel FAR too grabby, even after adjusting the hydraulics to make it more spongy. Completely unusable for the uni-use case of drag braking down hills.
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Old 2019-12-20, 04:22 PM   #2367
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Rim Brakes

"IF" Your Muni breaks a spoke or you crash it and the wheel becomes untrue, it will not rotate easily through the rim brake. but an in frame disc on hub is not affected. It's infinately harder to bend a disc inbetween the fork, and if you do your probably not walking home.

Quote:
Originally Posted by Piece Maker View Post
Why would this be any different with rim brakes than without...? You could bend the disc on the trail and it'd get stuck in the calipers just as good as a rim brake would.

That being said, I cannot stand rim brakes on my 29er. They feel FAR too grabby, even after adjusting the hydraulics to make it more spongy. Completely unusable for the uni-use case of drag braking down hills.
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