Bafang CST with Avid BB5 160mm

[patpatbut]

Dear all,

I have a bike with Avid BB5 disk brake + 160mm

Would it fit Bafang CST motor? I heard only 180mm will fit but Avid does not have 180mm rotor..

What is the best option for me?

Thanks
Pat

 

[Deleted member 4366]

You can use any 180mm or bigger rotor. It doesn't have to be an Avid one. When you get the 180mm rotor, you'll need a caliper adapter that doesn't need to be an Avid one either.

 

[patpatbut]

You can use any 180mm or bigger rotor. It doesn't have to be an Avid one. When you get the 180mm rotor, you'll need a caliper adapter that doesn't need to be an Avid one either.

Hi Dave,

Would you mind to tell me why the 160mm does not fit?

This bike brake is like this



If I do need to change it to 180mm, what adaptor and rotor do I need?

Also I have heard Shinamo 180mm rotor does not fit Avid BB5.

Thanks
Pat

 

[Deleted member 4366]

The motor is too close to the disc, so there's not enough room for the caliper unless it's very thin on that side. A 180mm disc takes the caliper further out to the bit where the motor tapers inwards, so there's more room.

Is that a photo of your frame? If not show me a photo of your frame so that I can recommend the correct adapter. That caliper doesn't look like a BB5 either!

 

[patpatbut]

Hi Dave

This one is exactly the same on by bike



Do you think there is enough room for 160mm?

Thanks
Pat

 

[Deleted member 4366]

You can use this adapter assuming that your present disc is 160mm.
A2Z PMPM180 +20/25mm Post Mount Calliper Adaptor Bolts A2ZW58 - Brake Spares - Disc Brake Adaptors - A2Z PMPM180 +20/25mm Post Mount Calliper Adaptor Bolts
As you have a post mount, all you need is some longer bolts and two 10mm spacers, which is what this one is.It's a bit more tricky to go from 140mm to 180mm.

You'll only know whether there's enough room for your caliper with a 160mm disc after you've fitted the disc to the motor. The caliper doesn't know or care who's rotor you have fitted. The motor has he standard six holes for the rotor screws. Some Shimano discs have a different fitting arrangement. Maybe that's your problem, but as long as the rotor has the six holes it'll work. Show us a photo of it, so I can confirm.

 

[eHomer]

I have Magura hydraulic calipers on my bike, but I have fitted a larger than standard rotor on the front, and it does have the two standard types of caliper mount, so it shows the differences and a spacer.

The front disc is a post mount fitted with an adapter to convert it to the Magura's IS mount, which also acts as a spacer to enable the 200mm disc to be fitted. Quite a good mod really, as it increases the stopping power, though can put more strain on the spokes.

The rear disc on the frame is IS mount, so the Magura caliper bolts straight on for the standard sized 160mm diameter rotor.

Here's a link to where I bought my adapter: | Chain Reaction Cycles

(The photos are of my Giant Trance bike before I fitted Dave's MXUS hub motor.)

 

[patpatbut]

Hi Dave and ehomer,

Thanks again. My rotor is 160mm and I have got this adaptor

Avid CPS 180mm Rear/ 200mm Front Post Mount Adaptor | Evans Cycles

Does it do the same thing as you mentioned above?

Pat

 

[Deleted member 4366]

Yes it does.

 

[patpatbut]

Do you know what 180mm rotor will fit this adapter with Avid BB5?

Thanks again
Pat

 

[Deleted member 4366]

Any rotor with the standard 6 holes. All discs are compatible with all calipers.

 

[patpatbut]

Some rotors only support resin pad not metal pad. Does it matter?

I am thinking to get shimano RT56m

Pat

 

[patpatbut]

Can anyone help me with this?

Thanks in advance
Pat

 

[eHomer]

Can anyone help me with this?

Thanks in advance
Pat

Sorry Pat, I've never heard of it.

I've always just found the same as Dave said, rotors all seem to have the same standard 6 hole fittings, with the different outer overall diameters being the main variation.

I had one bike where I had to buy shim spacers to move the rotor outwards on the shaft, but they were just metal too.

I'm trying to think why a resin pad might be needed, but would have thought that metal to metal would transfer the braking torque to the hub better than any sort of resin buffer. I would imagine that would just transfer more of the braking torque onto the 6 bolt threads, as a shear load.

(Just a theory though)...

 

[patpatbut]

Sorry Pat, I've never heard of it.

I've always just found the same as Dave said, rotors all seem to have the same standard 6 hole fittings, with the different outer overall diameters being the main variation.

I had one bike where I had to buy shim spacers to move the rotor outwards on the shaft, but they were just metal too.

I'm trying to think why a resin pad might be needed, but would have thought that metal to metal would transfer the braking torque to the hub better than any sort of resin buffer. I would imagine that would just transfer more of the braking torque onto the 6 bolt threads, as a shear load.

(Just a theory though)...

Thanks eHomer,

Would shimano RT56 180mm work on Avid BB5?

PAt

 

[Deleted member 4366]

Jeez! How many more times are you going to ask the same question. Just bolt the 'kin thing on. You have everything you need. No need to worry. Can I make it any clearer than that.

 

[patpatbut]

Jeez! How many more times are you going to ask the same question. Just bolt the 'kin thing on. You have everything you need. No need to worry. Can I make it any clearer than that.

Sorry Just to make sure

I will see how it goes now

Pat

 

[Alan Quay]

Some rotors only support resin pad not metal pad. Does it matter?

I am thinking to get shimano RT56m

Pat

I assume the OP is talking about the material the brake pad is made of. They come in a few different types - sintered metal, and organic being two examples.

http://m.pinkbike.com/news/brake-pad-information-2009.html

 

[eHomer]

I assume the OP is talking about the material the brake pad is made of. They come in a few different types - sintered metal, and organic being two examples......

Dohh !!

Quite right Mike, God knows how I missed the word "pad".

I was just thinking blindly about the disc rotors.