I just can’t stop: Best brakes for ebikes

December 10, 2019
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Nothing sucks worse than wanting to stop quickly on your ebike and not being able to. In the last 5 years, I’ve tested dozens of different brake systems and developed some pretty strong opinions about arguably one of the most important parts of your ebike, the brakes. There are 2 main kinds of brakes: disc brakes & rim brakes that can be either cable or hydraulic. This article will talk about what brakes are most appropriate for ebikes as well as some tips to keep your brakes working in sub-optimal conditions.

This has got to be my favorite road sign of all time, how has this sign not gotten stolen yet?

Disc Brakes vs Rim Brakes

I realize this is going to be pretty controversial, but I’m going to go out on a limb here and say that rim brakes are not appropriate for ebikes. Period. I’ve tried a couple of ebikes with Rim brakes, and even with high-quality pads that work decent in optimal conditions, the braking quality degrades so quickly with rain, snow or mud that they are just a no-go. I would not consider buying any ebike with rim brakes and do not convert any bicycle you have with rim brakes to electric. It’s just too unsafe. If you want to get rid of your annoying significant other, then a high power ebike with rim brakes is the perfect gift.

Rim brakes just suck, and really cause real problems when paired up with carbon rims

With Disc brakes size matters

It’s simple physics, the larger diameter your rotor is, the less effort it’s going to take to stop your ebike. Most ebikes ship with 160 or 180mm rotors, but in my opinion 180mm is the smallest rotor you should ever consider on the front wheel. Your front wheel is going to carry 75-90% of the braking force on your bike, so it is by far the most important brake of the two. If you’re going to get a larger rotor, upgrade the front rotor. I’ve used 203mm rotors and I absolutely love them, so if you’re looking to upgrade your brakes, going to a 203mm rotor on the front is an inexpensive and easy way to massively increase your braking power. You can get an adapter for your existing brake that will move it further out and allow you to put on a 203mm rotor like this one here for $8.25. So you’re looking at $19 for two rotors (on Amazon here) and $16.50 for the adapters for a total of $35.50 before shipping and tax.

  • 160mm to 203mm = SM-MA-F203P/P
  • 180mm to 203mm = SM-MA-F203P/PM
This adapter will allow you to go from a 160mm rotor to a 203mm rotor for just a few bucks

Should I upgrade my rear rotor to a larger size?

I believe that the rear tire will tend to lock up and slip before the rotor gives out which is why I have never upgraded the size of my rear rotors (even the 160mm ones). I’m not sure if this is actually true, but when riding in the woods it feels like it doesn’t take much to lock up the rear wheel, especially when barreling down a steep slope. Keep in mind when trail riding you can get yourself into pretty bad situations when you lock up your front wheel, in snow and ice that is doubly so. When the rear tire washes out it is usually a fun fishtail, when the front tire washes out more often than not you end up on your ass.

I think ebrake cutoffs are just stupid and I don’t ever use them, learn to exercise a little thumb restraint, buddy

Incidentally, if my front brake is a lower-end one like a BB5 or BB3 I will always replace it with a BB7 brake. You can buy BB7s for about $25-30 street price brand new (not including the cable and handbrake). The BB7 will work with almost any cable brake handle on the market, so if you have ebrake cutoffs they will usually work with them as well. I never use ebrake cutoffs on any ebike I ride and if it has them I either disable them or replace them. I believe that ebike cutoffs create an ‘illusion’ of safety and your brake system should always be powerful enough to override your ebike, even on full throttle.

This gives you some idea of the size differences between different rotors, bigger is always better

Only buy 100% Stainless Steel rotors

There is a glut of rotors on the market that are aluminum with steel coating or a steel rim with a plastic center. My advice is to go with a solid stainless steel rotor. Not all rotors are created equal, some of them generate a lot of noise, others do not stop well when wet. I would check the reviews for any rotor you want to buy on mtbr.com which has the best user reviews for bike stuff on the planet that I can find.

Rust really doesn’t matter as long as it’s not on the outside part of the rotor where the pads press

I only use my rear brake most of the time, and then use both when I really HAVE to stop

I like to wear up my rear brake, in all honesty sometimes my rear brakes are pretty pathetic. They will get air in the lines or the pads will get slick, but I don’t really care that much. My front brakes are always tight and work perfectly because I never use them. As crazy as that sounds, I believe the best way to keep your front brake crispy is to just never use it except when you have to. When stopping for an emergency you should squeeze both the front and rear brakes an equal amount as hard as you can.

Allow us to demonstrate the wrong way to hail a cab, this is what happens when you ride ebikes with crappy front hub motors and rim brakes you dummy

For the love of all that is good, don’t get lube on your rotor

This has happened to me more than once I’m embarrassed to say. Usually, it happens when I am testing out a new kind of lube in a spray can and I’m not careful enough about where it is pointed. A single drop of lube on your rotor can compromise the rotor and the pad. I recommend to NOT use spray lube and only use chain lube from a dropper style container. I buy lube in giant 1-liter containers for $10 here and then pour it into a temporary container and ‘suck’ it up with the smaller eyedropper style bike lube containers. If you get lube on your brake the only solution I have found is to replace both the pads and the rotor, doing one or the other just won’t fix the problem and will cross-contaminate the part you don’t swap out.

If you lube like this, you will eventually get some lube on your rotor, it’s inevitable

Bleed your brakes the proper way, like a leech

I used to send my hydraulic brakes to the shop to get bled, it seems like I could never get all the air out of the lines. I discovered this youtube video below on bleeding brakes and I realized that the reason I was not getting the air out of my lines is that I was not tapping on the line and the brake housings. Following the instructions on the video below, I was able to completely bleed my hydraulic brakes correctly. That is really saying something. Make sure to remove your pads and wheel when bleeding, use a bleed block to compress the caliper and don’t overtighten the nipples (this is a life-rule really, your partner will thank you).

Hydraulic or Cable brakes?

I have ridden both kinds of brakes extensively. Most of my brakes on my ebikes are Avid BB7 cable brakes. The BB7 is the highest quality cable brake I have used and it is inexpensive, works well when the caliper is adjusted properly and is almost zero maintenance. The BB7 cable brake is about equivalent in performance to a mid-level hydraulic brake without the regular maintenance hydraulics require. The Avid pads seem to last a long time and stop well in all conditions. The big problem with cable brakes that I’ve found is that in the wintertime water can suck up into the cable and freeze up if you leave the bike outside. Hydraulic brakes seem to need to be bled about once every 2-3 years, and they often get squishy if you ride a lot in the cold as I do. Talking to the bike mechanic at my local bike shop, he says that my brakes often are filled with a lot of water, as he thinks that the hot\cold cycling causes condensation inside the brake and the brake fluid seeps out and is replaced by water. This is pure conjecture, but it might be accurate, I just don’t know. High-end hydraulic brakes will tend to work better than any cable brake you can find, so if you can afford it and really care about stopping on a dime then that’s probably the way to go.

If you bleed your brakes, only use whatever kind of fluid is already in there

An improperly aligned caliper will not stop well at all

A lot of the time if I’m not getting the braking performance I expect it’s because the caliper has moved and is not aligned properly. With the wheel on, look through the top of the caliper with the brakes not depressed and check the alignment of the rotor with the caliper. If it’s not aligned right then loosen the two adjusting bolts and line it up and retighten. If you have a BB& cable brake you can then tighten done the pad to right before it starts rubbing on both sides. That’s really all you have to do to adjust the BB7 cable brake. There are brake disk spacers that you can slide in to get perfect spacing on either side of your brake, but I never use them. In fact, to be perfectly honest I never knew what they were until I researched this article.

You can buy disc pad spacers, but I always just use a light and my eyeballs

If your rotor is worn or warped just replace it

It costs about $10 for a cheap bike rotor, if you have issues with your rotors you should always just replace it. If it is warped and you can hear it rubbing intermittently while the wheel turns? Replace it. If you wear down your pads to the metal and then have a whole ride of metal screeching against metal? Replace it. I’ve worn the pads and rotor down so far that my brakes have thrown the pads and then destroyed the caliper as it mashed against the rotor. Don’t do that.

When in doubt, replace it

Don’t buy cheap ‘fake’ brake pads

I’ve tried at least a dozen different cheap brake pads from Alibaba, eBay, and Amazon. Frankly, they all sucked. I’ve found that springing $20 for manufacturer pads is probably the smartest thing you can do. They seem to last about twice as long, work better in wet or snow conditions and am I really going to risk my life to save a few bucks? Wait, don’t answer that. If you shop around for the right pads for your brake system then you should be able to find ones that are genuine from American resellers at a decent price. There are hordes of fakes on eBay and Alibaba sold as the real deal (often shipped from China), so don’t believe the hype.

If you can buy the brake pads in retail packaging, they are probably not fakes

No part of your ebike is as important as the brakes, but all too often it is the part that is most often ignored. If you want to be able to stop when you want to stop, then you need to put some love and attention into your ebike’s braking system. When you really need to stop, and you can, you’ll have no one to thank but yourself.

Ride On.

A special thanks to Rick Elensky, without whom I would never have used the word ‘whom’ in this article. Rick only uses the brakes when he feels called to, the rest of the time you better just get the hell out of his way.

This spacer will allow you to have perfect pad spacing when you tighten down your caliper alignment bolts, I never use it though and I’m still here

Karl Gesslein is a degenerate hooligan of the highest caliber living in upstate NY. His passion for e-bikes and all things sustainable causes him to be obsessed with climate change and finding solutions that will keep humanity from becoming extinct from our own hubris. His personal blogs include electricbike-blog.com, awaken-spirit.org & chestnutparadise.com.


9 Comments

  1. Karl, this is a great article. Now if I can only find BB7’s for $30 as you claim I can get rid of my BB5’s which aren’t so hot.

  2. While there are some great points, this article also has some advice that’s just bad.

    First, brake cutoffs should be on any cadence-based bike.

    Second, use both brakes at the same time, all the time. If you rarely use the front, you won’t have the experience to use it fully when you need it. People are already (irrationally) afraid of front brakes, let’s not encourage that.

    Maintain both brakes. Letting your rear go to pot just because you’re too lazy to maintain it isn’t ok, even if the front does most of the work.

    A properly set up hydraulic will generally be lower maintenance than a cable-actuated brake, as they self-adjust for pad wear. BB7s in particular tend to be fiddly on pad adjustment if you really want to keep the lever tight. If you have to bleed more than once every year or two, there is something wrong with your brake.

    Some hydraulic brakes have problems in extreme cold, but anything sold in the US should be safe down to 0 degrees F. If a brake feels spongy in the cold, it needs bled, same as if it feels spongy any other time.

    • David Dye, Are BB7’s as fiddly as BB5’s. I thought they were a significant upgrade. Thanks.

      • The BB5 only has pad adjustment on the inner pad. The outer pad requires cable adjustment which changes the geometry at tthe caliper lever over time.
        The BB7 takes a larger rectangular pad, and has independent pad adjustmesnt w/o disrubing the cable at either end. Sintered metallic pads are avialable for the 7 due to it’s downhill racing credentials.IMO BB5 are OK up to 20mph ( normal bike speeds). But after 25mph you need an upgraded system.

    • I haven’t had issues with the BB7’s being fiddly. I turn the red dials and adjust the pads a couple times a year and that is it.

      I ride all winter long, the average temp in Ithaca is 40 degrees. Something with the cold makes the Hydraulic brakes get air in them, I don’t know what it is, didn’t pretend to know in the article either.

      Thanks for reading and commenting.

  3. I agree with using BB7 brakes. Mine are 180mm front and rear because I already had them. At 35mph street riding I feel the rear upgrade is needed, and I run metallic pads (sintered copper). These don’t fade at high speed and wear much better than organics. A little noisy and not as good in the wet (squeeze harder). Don’t try this with hydraulic brakes. E bike use is way beyond what biccyle brakes are intended for and metallic brakes can boil the fluid in a hydraulic setup. I’m leary of hydraulic bicycle brakes on an E bike and see no reason to use them. Large BB7s and metallic pads are an old school downhill racing setup with heavy bikes going fast. If your hydraulics aren’t rated for that type of use then I would be worried. While braking power changes with disc size, heat rejection requirements increases with speed (exponentially) and weigh. Bigger is better for this also, but disc velocity through the pad goes way up also on an Ebike. Partly from speed, and partly from rotor size.Organic lining can boil oils in them and cause gas or oil to get between the pad and rotor. This will happen only under severe use (when you really need them the most). Metallic pads won’t do this. They can be noisy and grabby if you use them on rotors that have had organic (oily) pads on them. Sanding may be required to sesolve this.When I bough my BB7 copper pads, they fit Avid Juicy also, but they said odn’t use them with the hydro brakes. That was all I needed to hear.

  4. Great article. Pretty much agree with everything top to bottom except the braking technique. I actuate the rears first, then the fronts for a solid stop with both axles slowing my fat ass down. I am jealous of the Shimano bleed video… With Maguras you just haul ass fast to get the system tightened back up.

  5. I agree with most. Only one thing I missed in the other comments. When replacing a disc, you always should replace the pads too. If you do not do that the disc will worn out very fast again.

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