So you want to install a disk brake on that rear 9c...

[El_Steak]

EDIT:

With the newer Nine Continent cover design, none of these mods are required. Everything aligns perfectly, no need to dish the wheel and there is plenty of room for the disk brake. Actually, I think an 8 inch rotor would fit in the TidalForce frame. With the previous cover design, I had to go through a lot of frame mods to barely get the 6 inch rotors in.

There seems to be a lot of rear 9c kits out there but I haven't seen many setup with rear disk brakes. E-Tickets has done it with is AmpedBike 9c but that's all I could find.

Since I've just finished installing mine and it was no walk in the park, I thought I'd share how I did it so it may help someone else in the future.

Here's my setup:

- Tidalforce S750 frame from oatnet
- Rear 9c (2806) laced in 26" wheel by e-bikes.ca (pretty well centered but not perfect)
- Avid BB7 Disk Brakes (arguably the best affordable mechanical disk brakes you can get)

STEP 1: frame mods

This will be different for each bike, but since Oatnet sold a boatload of Tidalforce frames to ES member, it's probable that others will have to do the same.

The torque arm mount interferes with the disk, it has to go. (You can shim your way out of this, but you'll spread your fork A LOT). I simply removed it with my trusty dremel and 1/32" cut-off wheels.

The I.S. disk mounts could lose 1/16" to give more room to the caliper adapter.

Carefully removed with dremel and cut-off wheel, than filed flat.

 

[El_Steak]

STEP 2: Torque arms

Since I just destroyed the nice torque arm mount designed by Wavecrest, I can't use greenerwheels torque arm design. I came up with this instead:

All you need to do this is a decent jigsaw with a metal blade, a drill press, a file and a fairly thick steel plate (I "recycled" a lawnmower blade for those).

Here's how it looks once installed:

 

[El_Steak]

STEP 3: Mount the motor

Here are all the shims, washers, etc. that I used to mount the motor. They are in the exact order I installed them. Top row is right side of the motor, bottom row is left side.

Damn, just noticed the disk brake and the large diameter thin disk brake washer are in reverse order on the picture.

I have the 7-speed cassette from e-bikes.ca. I bought it because I need the small 11 tooth. Eventhough I bought 3 of them at 5$ a piece, I didn't need any of the special axel-builder washers sold by Justin.

NOTICE: You'll need to spread your forks by a good 7-8mm to make this fit (a little less with a 6-speed cassette). Doing so is fine for steel frames but not recommended for aluminum frames. That being said, the Tidalforce frame is all aluminum and I'm doing it anyways. The frame is real beefy and I'm not too worried about it failing in a catastrophic way.

 

[El_Steak]

STEP 4: Mount the caliper

I don't know about other calipers, but the BB7 won't fit. You first need to "thin" the mounting bracket. You can use the adapter that comes with the 6 inch Avid BB7 kit but I instead used one of the adapters that came with my front 8 inch Avid BB7 kit. I didn't need it to mount the disk on my front fork and it allows me to mount the caliper further to the back of the bike, leaving enough room for my rear rack mount.

I removed about 1/8" from the bottom part. I'm no machinist, but I'm a decent woodworker and I have a router and router table. I used a little jig I made, a 5$ sacrificial straight cutter and did it REALLY SLOW in about 10 passes. The adapter is aluminum so it's not too hard for carbide bits.

The adapter is attached to the jig using the side mounting holes. Make sure the screws aren't too deep or you'll cut their tip off !

Fence stopper, sacrificial bit and jig

All done...

Unless you want to mangle your fingers, don't try to hold the caliper adapter with your bare hands and don't do this without a proper jig, router table and fence setup.

 

[El_Steak]

STEP 5: Slice the screw head on the caliper

Alright, the caliper adapter now clears the disk nicely. We can install the caliper now? nop. The adjustment screw will rub on the inside of the motor case, you'll need to slice a 1/16" piece out of it. Again, the dremel with a 1/64" cut off wheel works perfectly

Be careful not to generate too much heat while you cut the screw. The surrounding ring is in plastic and you don't want it to melt.

 

[El_Steak]

STEP 6: Screw it on and enjoy !

Here you can see all the clearances. You'll see that there's no more than 1/16" between the disk and frame, caliper adapter and disk as well as between the motor cover and caliper adjustment screw. It's pretty tight but that's how I like it

Haaaa it's all done. It's not too difficult but it sure takes a lot of time to do it all. Unfortunately after all was done, I noticed that the chinese screw-on disk is warped by about 1 mm. Pretty lame for caliper adjustments. Instead of ordering a new chinese disk, I ordered this adapter that should allow me to use my Avid 6" rotor. Its the same adapter used by E-Ticket. Ebikes.ca also sells one, but they are out of stock and a bit pricey at 40$ with no rotor.

And here's the bike so far. Still lots to do before it's ready to roll.

 

[ambroseliao]

Amazing work, El_Steak. You are terrific with machining parts and figuring out complex setups!

Congrats. I am about to do my S-750 rear disc brake 9C motor as well.

Ambrose

 

[recumbent]

Nice work on that disc brake adapter, and those torque arms are nice and compact also. Just make sure you check your wheel nuts after the first ride, the rest of the build should go easy for you.

 

[Ypedal]

Excellent work man !!!! very well done !

I have 5 more of these frames, ( had 6, used one for my RC setup ) .. i will be following your lead on this !hehe...

Thank you !
G

 

[nicobie]

Good job on the adapter, it turned out nice. I liked the way the 8" rotor looked, too bad it was bent.

A lot of people are afraid to use wood working tool on aluminum but I do it all the time too. I just use cheap carbide tooling and toss them when they start to get dull. I even sprung for a carbide tipped blade for my MiniMax 16 band saw. (cuts like butter )

 

[lifepo4ever]

nice job !!

I hope to not have the same problem with my norco and 2807 rear wheel

 

[StudEbiker]

Awesome work. Thanks for posting. I had about given up on using a rear disc with 9c but this gives me hope!!

 

[El_Steak]

Thanks everybody.

Hopefully this will help a member or two. I got so much information out of this forum that I felt it was only fair that I take the time to contribute a little something.

 

[oatnet]

Nice Handiwork! I like seeing creative solutions.
Looks like it is shaping up nicely - what fork did you go with?

-JD

PS - I missed this thread, glad you posted a link on the for-sale thread so I could find it.

 

[El_Steak]

I went with a cheap entry-level Marzocchi MZ comp fork. I got it new for a hundred canadian dollars. I only read the reviews after buying the fork (I never do that usually) and it turns out the reviews are pretty bad on the fork so it might not have been a good choice.

That being said, even though its no good at riding crazy downhill trails and taking 6 foot drops, it might be perfect for urban riding, pot holes, curbs and the likes. I haven't tried it yet so I can't tell

 

[E-Ticket]

Yes, those clearances are tight - but you made it happen.
Impressive work on your disk brake mount and torque plates!

Thanks for sharing. 8)

 

[El_Steak]

Yes, those clearances are tight - but you made it happen.
Impressive work on your disk brake mount and torque plates!

Hey, you're the first one who did it. If not for your post showing your clever aluminum angle bracket I would probably not have pursued the idea.

So thanks to you

BTW, I ordered and received the same adapter and disk you used on your motor. Its a perfect fit and allows me to use the original Avid BB7 160mm disk. I'll update the pictures soon.

 

[athead]

Ah, nice post, only wish I had to tools to make a similar mod myself! Anyone know of a brand of calipers slim enough to fit without any aftermarket mods? I'm currently installing my E bike kit rear hub and the caliper has made a nice circular scratch on my motor . I removed it, but I have a bad feeling about NOT having rear disc brakes on my new rig!

 

[hydro-one]

Hi!!! Great job on the brake setup!! I will be doing that same thing in a few days if all goes well!! Take the fork back if you still can. Its very entry level , elastomer damping, clunk, bottom out kinda stuff........you wont be happy. Go on pinkbike.com and find a used bomber , z1 , dj1 , something with rebound hydraulic damping!!!!!!!!!!!!! Please



Mike

 

[spike]

Has anyone tried this Crystalyte disk brake adapter from e-mtb or ebikes.ca on the 9C?
http://www.e-mtb.com.au/bike-parts-c-71.html?zenid=896076e372a9faa8589610b3c0acbe8c

 

[will_newton]

Here's my build showing an install of Avid BB7 rear 207mm disc brake onto an e-bikekit 9c hub motor. I used the adapter mentioned earlier from bicycledesigner.com I had to do a little work on the adapter and use some extra washers to get everything working.

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=14432

 

[will_newton]

stock disk setup video from e-bikekit.com
http://www.youtube.com/user/EBikeKit#p/u/14/dMZSBsCuI1Y

 

[auraslip]

I'm a little bit late to this thread.........

I'm wondering how the hell you're supposed to tune the brake up. You can't reach the wheel side rotor adjustment screw with the caliper installed! I'm guess a whole bunch of trial and error?

 

[El_Steak]

I'm wondering how the hell you're supposed to tune the brake up. You can't reach the wheel side rotor adjustment screw with the caliper installed! I'm guess a whole bunch of trial and error?

The red plastic "knob" on the BB7 has notches all around. I just take a flat head screw driver, put it in a notch and push.

 

[auraslip]

Smart ass makin' me look dumb