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Avid BB7 cable disc brakes for E bikes.

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    Avid BB7 cable disc brakes for E bikes.

    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.‚Äč
    Last edited by Retrorockit; 01-12-2023, 07:18 AM.

    #2
    My bike had rim brakes when it was new. In 2004. Disc brakes were still controversial for bikes back then. Since it's a hardtail it ended up with about 2' of flexible brake housing at the rear it didn't really need.
    I replaced that with 1/8" T.D. (3/16" O.D). hydraulic brake steel tubing. The Jjagwire Teflon lining fits inside, and the metal ferrules from the old flex lines go over the ends so they fit in the frame lugs.
    I did have to drill the brass end pieces to 1/8" for this. I stuck one end in the caliper and bent it to run to the frame lug, and cut it to length. To install it I took out 1 of the cliper bracket cross bolts and loosened the other. The caliper swung up, and the hard line could be installed w/o changing the caliper alignment. It's kind of funny that my cable brakes have actual hydraulic lines going to them. The Avid rubber boot fits over them just fine also.

    The Jagwire Elite link kit is what I used for this.
    https://jagwire.com/products/diy-cab...link-brake-kit
    Other options.
    Last edited by Retrorockit; 01-12-2023, 09:13 PM.

    Comment


    • Retrorockit
      Retrorockit commented
      Editing a comment
      BB7 tip.
      On the newer large knob calipers do not grab the knob with pliers if it gets tight. The knob snaps over a stationary ring on the caliper. It will just be harder to turn. Get a Torx wrench and turn it in the center.from the other side.
      A word on the similar BB5 calipers. They are not suited for E bike use. Metallic pads are listed, but I've never actually seen any. Those do have a barrel adjuster for the outer pad. This means pad adjustment and cable adjustment are not separate. As the pads wear the lever will be in a different position, changing leverage and travel. Aside form having ball bearing actuation they aren't much better than low end stuff.

    • Retrorockit
      Retrorockit commented
      Editing a comment
      I've suggested older BB7 equipped MTBs for donor bikes. They were upper mid level bikes when new and would also have decent forks, and strong wheelsets. 26" bikes are no longer popular for offroad use. Replacing the triple chain rings with 1x8-9 speeds works well for an Ebike. The low price of chains and cassettes makes them service parts.
      Unless you find a DH bike with metallic pads and big rotors the brakes will need a couple upgrades for E bike use. The parts for this are readily available and DIY simple.

    #3
    I took another look at the jagwire I got from Amazon and realized it was even worse than I thought. I was light gage wire core only and I just figured it was shifter cable. But it's actually dropper cable. Hah. That word was hard to read in the packaging and the word dropper didn't mean much to me anyway till yesterday. Inconvenient, but Amazon is great for returns. That's a $30 cable right there. Hah. I would not have had time to install them anyway. I got pretty sick from October till December so I lost a bunch of time in getting most everything done. Not anything like covid, just a hereditary malfunction that went crazy infected on me. But it finally cleared up and I don't have to worry about operations till some other time. After my vacation I'll start the next round of bike upgrades. When spring hits, I'm gonna be getting all kinds of begging to help people with this and that and then Ill turn the screws to get favors of my own. Gotta get that ALIexpress order in so I got everything I need for a huge summer transformation.

    Click image for larger version  Name:	20230120_172043_rotated.jpg Views:	0 Size:	2.38 MB ID:	159230
    Last edited by stts; 01-20-2023, 02:43 PM.

    Comment


    • Retrorockit
      Retrorockit commented
      Editing a comment
      I think I ordered mine directly form Jagwire. Universal Cycles, or Modern Bike would be others.. I avoid Amazon, or Ali if i can help it.

    • stts
      stts commented
      Editing a comment
      I'm poor, so I'm kinda stuck living the discount and used stuff life. Good thing I can make what I need. Or find it in the trash. Hah I found a lawn areator machine in the trash. All rusty and chain drive wore out. Milked that sucker back to life and aerated my lawn without having to rent one. But ever since I got it, it's rained so much that I don't need it. Now I may paint it purdy and sell it. Those things are rather pricey even used. I always bring back trash from my florida trips. Hah. Oh yea, most definitely will sell it. I'm in down sizing mode. Gotta cash out everything not worth hauling south. Likely 2025 is my moving year.
      Last edited by stts; 01-20-2023, 11:07 PM.

    #4
    Most of my life I was in that situation. Right now i can afford the luxury of trying several things to see what works, and share what I find out. But I still do cheap thrills too. Like the zip tie mod. But to get it working 100% I bought just about every chain idler I could find. Worked my way up from cheapest to what really worked. It turns out the $65 part is what was needed. Cost me about $200 to figure that out LOL. So when I say "The only thing that costs more than doing it right the first time, is doing it right the second time" there is a little bit of "Do as I say, not as I do" going on there.
    I no longer have a warehouse full of tools to work in. But my back ground in factory maintenance lets me relate to having the skill to fix it right the first try. It's just that parts are cheaper than storage/work space here. If you're working with BB7s you can just stick them on the bike with any old cables, and they will stop your bike first time every time. I got into the fancy cable thing because I was testing some TRP Spyke calipers, and TRP said they needed them. I bought some TRP Spyres by mistake too. The BB7s are still on my E bike. But now with fancy cables. They do make a difference. But if you need time to save up for the good stuff it shouldn't be a problem. I spent about $400 on TRP R&D to figure out the BB7s I already had are still the way to go. So I'm not just being a retro-grouch when I recommend using them. I learned most of what I know doing exactly what you're doing. I'm still doing it in a different way.
    One nice thing about the BB7 separate cable adjustment form the pads is you can set them up with a slight tension on the cable with the brakes released, and your brake levers don't rattle over bumps any more.
    Last edited by Retrorockit; 01-21-2023, 06:13 AM.

    Comment


    • Retrorockit
      Retrorockit commented
      Editing a comment
      It's official Avid BB7s properly set up will do a stoppie. I had to do one in traffic at night. Some dork absolutely had to come speeding up to the already red light and slam on his brakes to stop in the crosswalk. There is no cross lane to take there for those who like to pretend they're in a car. Crosswalk only from the greenway.

    • Retrorockit
      Retrorockit commented
      Editing a comment
      Part of the problem was I had left my Blackburn yellow side strobes on the charger and didn't have them on like I usually would. They really make a difference.

    #5
    This is helpful info. I'm converting a bike that came with BB7's. I was thinking originally I'd swap them for hydraulics, but I'll probably just keep them and see how well they work with metal pads. The Jagwire Elite Link cables look awesome too. Do you need to get the mountain version for BB7s, or does the road version work?

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    #6
    Manufacturers claim that multi-layer rotors (like Shimano IceTech) are less prone to warping. Has anyone found that to be true in practice? It could be another way to upgrade mechanical brakes to get them to stay quiet more consistently. I have mostly only ridden with fairly basic rotors.

    Comment


      #7
      I think it depends on what your needs are. if long runs down the mountain are considered then probably 2 piece rotors, and anything else will help. It's flat where I live so one hard stop every now and then is all I need. Standard rotors haven't been a problem for me. When my rotors aren't straight I just figure I bumped against something. Maybe I'm wrong?.

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