Avid BB7 Cable Disc Brakes for E bikes.
This is based on my experience with these brakes for 3 years on a 1500W BBSHD bike that can go 35mph, and has a 24Ah battery. Like any DIY
project it's up to you to be sure you have the skill, tools, and experience to do this work correctly. If not pay somebody who does to do it
for you. I actually had these brakes on this bike for 20 years, but the E bike conversion required some upgrades.
1- Get big rotors 200mm F and 180mm R works well. This give you leverage for stopping from high speeds. Some older rotor sizes are 203mm, and
185mm. The brackets are a little different. There are 220mm rotors out there. Skip 160mm for E bikes. The older brackets list rotor size and
position, 203f,185r the newer ones have an offset number like +20mm,+40mm, base size is considered 160mm f/140mm R, so a pair of +40mm brackets
will work. Unfortunately nobody sells a BB7 kit for Ebikes with everything in one place (hint, hint). They all seem to come with organic pads.
My advice- don't bother with them on an Ebike (seei.tem 3).
2- There are original Avid BB7s, and newer SRAM BB7s (from 2008) They look different but work the same. The older ones had an anodized finish
the newer ones are painted unless you get the MTB S model. E bikes can blister the paint on the newer ones. The new painted ones have a window so
you can see the pads easier. The newer ones have a larger inner adjusting knob. There are some knockoffs out there. Real BB7s do not have a
threaded cable adjuster on them. The older ones are good if a bike came with those, the newer BB7 MTB S version is good too. The painted ones
work just fine, but the paint may not hold up 100%.
3- Use metallic brake pads for an Ebike. The 28mph legal limit is fast enough to glaze the organic pads these come with. SRAM makes some, EBC
and Jagwire do too. The same pads fit Avid juicy hydraulic brakes. They can boil the fluid on those. The BB7 can handle the extra heat. The
metallic pads last about 5X as long as organics. This means they are actually less expensive to use. You will also not have to spend all your
time adjusting them. Every couple days will do.
a- These are hard pads and will need to be bedded in to the rotors. They won't feel that good until you do this.
b- They must be installed on clean rotors. Especially if they've had organic pads on them. A light scufff with sandpaper works.
c- They can get noisy if they aren't kept adjusted. If just the outer pad is hitting the rotor under light braking it can "ring". Tighten the inner pad adjuster
and it should go away. They will produce a soft hissing sound that organic pads do not.
4- Avids aren't fussy about cables and levers. MTB levers will work, and normal cables work also. They will stop your bike just fine. But
there is a lot to be gained fine tuning and upgrading these items. Response and sensitivity can rival some hydraulics if you do it right.
a-High performance brake cables like Jagwire. They're stainles steel, not galvanized. They're pre stretched so will hold adjustment better.
They're pulled through a die to make them round and smooth on the outside. The housings are Teflon lined, and don't compress. At least get
decent cables.
b- On an Ebike you will probably use the levers that came with brake switches. An upgrade would be Avid Speed Dial FR7 adjustable ratio
levers. You can fine tune the leverage and front to rear balance with these. You would need to add switches if you use them. Some riders don't
use switches (I do).
c-Consider upgrading the cable housings at this point for compressionless Teflon lined ones.
d- You can eliminate as much cable housing slack as you can with hard metal lines in some places. This is kind of an advanced mod but helps
some. Avid called theirs Full Metal Jacket. (see items 6-7) Some fabrication skills required.
Installation.
The attaching bolts on these have spherical washers, and slotted holes. They can basically align themselves.
Note: BB7s are a little strange in that Avid says to set them up off center on the rotor. 2/3 towards the inside.
1- Install the pads, and install the bolts loosely.
2- Adjust the pads so they hold the caliper 2/3 in from center. Hold in the caliper lever so it grips the rotor and tighten the mounting
bolts.
The pads and rotor should be aligned to each other now.
3- Looking at the rotor from the edge adjust the inner pad first so the rotor doesn't bend when you apply the brake, but the wheel still turns
freely. Any tight spot means the rotor isn't straight.
4- Before adjusting the outer pad you should get the cable adjusted at the lever as much as you can. Turn the cable adjuster at the brake
lever all the way in. Now install the cable to the caliper. Pull the cable tight, and push any slack out at the caliper lever, before
tightening the lock bolt. Now check at the lever for any free play. You want the lever on the brake to move when the lever on the handlebars
moves with no delay. Use the adjusting barrel. But if it comes very far out you need to move the cable at the caliper clamp, and try again.
Apply the brakes pretty hard a few times to set the cable. It should feel firm and hold it's adjustment. It shouldn't move very much. Brakes
work on pressure not movement.
5- You should be able to adjust the outer pad so the wheel spins free. Ride the bike and break in the pads and readjust them. This would be a
typical installation.
6- Fine tuning the brakes. With the bike sitting still apply the brake cable pretty hard while looking for any movement of the cable housings.
This is wasted motion. The housings are too long or curving around for no reason or are just compressing. Sometimes hooking the 2 cables
together where they cross can help. Square off the cut housing ends can help. This is where you decide whether to go for high end cables,
housing and maybe hardlines or not. Slicker cables, and stiffer housings are where you will get that solid responsive feel hydraulics have. The
plastic hoses on hydraulics flex too BTW.
7- There is another adjustment on the BB7. The return spring tension is adjustable. There is a tiny Allen screw near the shaft of the caliper
lever. If you have smooth slick cables, and have gotten all the slack and mush out, this can be loosened up so instead of feeling the return
spring when you pull the lever you will feel what the brake pad is doing. If you left the friction and mush in the system then you will feel
that instead. The one nice thing about doing all these fussy little things is they are pretty much permanent. Once setup the only adjustment
should be the inner pad first, then the outer pad. Because any play in the lever will be from pad wear. The barrel adjuster is to adjust slack
out of the cable. Check the levers for play before you ride, and adjust it if needed while the brakes are still cold. OK it ain't hydraulics. It
won't leak, boil the fluid, get air in the system, or spit a piston when you take a wheel off. Not likely to cut a hose either. Judging by the
blistered paint on my rear one you could probably set them on fire and not notice. The paint problem happens on the side of the caliper towards
the bracket, so you can only see it with the bike upside down.
8- If you have more than one wheelset you can get rotor shims for 6 hole rotors to shim one rotor out to match the other.
This is based on my experience with these brakes for 3 years on a 1500W BBSHD bike that can go 35mph, and has a 24Ah battery. Like any DIY
project it's up to you to be sure you have the skill, tools, and experience to do this work correctly. If not pay somebody who does to do it
for you. I actually had these brakes on this bike for 20 years, but the E bike conversion required some upgrades.
1- Get big rotors 200mm F and 180mm R works well. This give you leverage for stopping from high speeds. Some older rotor sizes are 203mm, and
185mm. The brackets are a little different. There are 220mm rotors out there. Skip 160mm for E bikes. The older brackets list rotor size and
position, 203f,185r the newer ones have an offset number like +20mm,+40mm, base size is considered 160mm f/140mm R, so a pair of +40mm brackets
will work. Unfortunately nobody sells a BB7 kit for Ebikes with everything in one place (hint, hint). They all seem to come with organic pads.
My advice- don't bother with them on an Ebike (seei.tem 3).
2- There are original Avid BB7s, and newer SRAM BB7s (from 2008) They look different but work the same. The older ones had an anodized finish
the newer ones are painted unless you get the MTB S model. E bikes can blister the paint on the newer ones. The new painted ones have a window so
you can see the pads easier. The newer ones have a larger inner adjusting knob. There are some knockoffs out there. Real BB7s do not have a
threaded cable adjuster on them. The older ones are good if a bike came with those, the newer BB7 MTB S version is good too. The painted ones
work just fine, but the paint may not hold up 100%.
3- Use metallic brake pads for an Ebike. The 28mph legal limit is fast enough to glaze the organic pads these come with. SRAM makes some, EBC
and Jagwire do too. The same pads fit Avid juicy hydraulic brakes. They can boil the fluid on those. The BB7 can handle the extra heat. The
metallic pads last about 5X as long as organics. This means they are actually less expensive to use. You will also not have to spend all your
time adjusting them. Every couple days will do.
a- These are hard pads and will need to be bedded in to the rotors. They won't feel that good until you do this.
b- They must be installed on clean rotors. Especially if they've had organic pads on them. A light scufff with sandpaper works.
c- They can get noisy if they aren't kept adjusted. If just the outer pad is hitting the rotor under light braking it can "ring". Tighten the inner pad adjuster
and it should go away. They will produce a soft hissing sound that organic pads do not.
4- Avids aren't fussy about cables and levers. MTB levers will work, and normal cables work also. They will stop your bike just fine. But
there is a lot to be gained fine tuning and upgrading these items. Response and sensitivity can rival some hydraulics if you do it right.
a-High performance brake cables like Jagwire. They're stainles steel, not galvanized. They're pre stretched so will hold adjustment better.
They're pulled through a die to make them round and smooth on the outside. The housings are Teflon lined, and don't compress. At least get
decent cables.
b- On an Ebike you will probably use the levers that came with brake switches. An upgrade would be Avid Speed Dial FR7 adjustable ratio
levers. You can fine tune the leverage and front to rear balance with these. You would need to add switches if you use them. Some riders don't
use switches (I do).
c-Consider upgrading the cable housings at this point for compressionless Teflon lined ones.
d- You can eliminate as much cable housing slack as you can with hard metal lines in some places. This is kind of an advanced mod but helps
some. Avid called theirs Full Metal Jacket. (see items 6-7) Some fabrication skills required.
Installation.
The attaching bolts on these have spherical washers, and slotted holes. They can basically align themselves.
Note: BB7s are a little strange in that Avid says to set them up off center on the rotor. 2/3 towards the inside.
1- Install the pads, and install the bolts loosely.
2- Adjust the pads so they hold the caliper 2/3 in from center. Hold in the caliper lever so it grips the rotor and tighten the mounting
bolts.
The pads and rotor should be aligned to each other now.
3- Looking at the rotor from the edge adjust the inner pad first so the rotor doesn't bend when you apply the brake, but the wheel still turns
freely. Any tight spot means the rotor isn't straight.
4- Before adjusting the outer pad you should get the cable adjusted at the lever as much as you can. Turn the cable adjuster at the brake
lever all the way in. Now install the cable to the caliper. Pull the cable tight, and push any slack out at the caliper lever, before
tightening the lock bolt. Now check at the lever for any free play. You want the lever on the brake to move when the lever on the handlebars
moves with no delay. Use the adjusting barrel. But if it comes very far out you need to move the cable at the caliper clamp, and try again.
Apply the brakes pretty hard a few times to set the cable. It should feel firm and hold it's adjustment. It shouldn't move very much. Brakes
work on pressure not movement.
5- You should be able to adjust the outer pad so the wheel spins free. Ride the bike and break in the pads and readjust them. This would be a
typical installation.
6- Fine tuning the brakes. With the bike sitting still apply the brake cable pretty hard while looking for any movement of the cable housings.
This is wasted motion. The housings are too long or curving around for no reason or are just compressing. Sometimes hooking the 2 cables
together where they cross can help. Square off the cut housing ends can help. This is where you decide whether to go for high end cables,
housing and maybe hardlines or not. Slicker cables, and stiffer housings are where you will get that solid responsive feel hydraulics have. The
plastic hoses on hydraulics flex too BTW.
7- There is another adjustment on the BB7. The return spring tension is adjustable. There is a tiny Allen screw near the shaft of the caliper
lever. If you have smooth slick cables, and have gotten all the slack and mush out, this can be loosened up so instead of feeling the return
spring when you pull the lever you will feel what the brake pad is doing. If you left the friction and mush in the system then you will feel
that instead. The one nice thing about doing all these fussy little things is they are pretty much permanent. Once setup the only adjustment
should be the inner pad first, then the outer pad. Because any play in the lever will be from pad wear. The barrel adjuster is to adjust slack
out of the cable. Check the levers for play before you ride, and adjust it if needed while the brakes are still cold. OK it ain't hydraulics. It
won't leak, boil the fluid, get air in the system, or spit a piston when you take a wheel off. Not likely to cut a hose either. Judging by the
blistered paint on my rear one you could probably set them on fire and not notice. The paint problem happens on the side of the caliper towards
the bracket, so you can only see it with the bike upside down.
8- If you have more than one wheelset you can get rotor shims for 6 hole rotors to shim one rotor out to match the other.
Comment