Bicycle brakes versus motorcycle

Hi all i'm building a high powered e bike. I am unsure if normal bicycle disc brakes will be enough to stop me if i'm going high speeds. What are some of the differences between bicycle disk brakes and motorcycle? has anyone here built a high powered e bike?

I haven't built either, but here is the difference: MUCH thicker rotors on a motorcycle brake, so less heat warping and better resistance to stress under hard braking at speed, and generally much more robust build strength. Bicycle disk brakes were meant to replace rim brakes, not to compete with motorcycle brakes. They win at the former, and lose, badly, at the latter.

aboveandbelow69 said:

Hi all i'm building a high powered e bike. I am unsure if normal bicycle disc brakes will be enough to stop me if i'm going high speeds.

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Depends.

What do *you* call "high-powered"?

What do *you* call "high speeds"?

What is the total mass being stopped?

What kind of tires/wheels? (if there's not enough contact patch, and the wheel skids, it doesn't matter how much more brake you have; you've already braked as hard as you possibly can).

What are some of the differences between bicycle disk brakes and motorcycle?

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Size, weight, cost, stopping power, variety, etc.

Note that you can't use MC brakes on bike frames and forks and wheels without custom-building adapters for both calipers and rotors. (it's been done; there's at least one thread somewhere about that).

has anyone here built a high powered e bike?

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There are many high powered bikes here, including motorcycles and larger. I recommend looking around at the various build threads, and threads like Your Creations' before and after pics thread, etc., to get an idea of what's been done.

There are also threads like the "i'm a noob and wanna go 50mph" thread, which have many links to discussions about brakes/etc.

THere are also many separate threads about brakes, forks, wheels, threads, etc.

To narrow down the search to something readable in a reasonable time, you can search in just topic/thread titles, and display by topic/thread, for each of the single-word things you're after. And to find brakes, use brake* instead, so it finds both.

Compared to bicycle brakes, motorcycle brakes are excessively heavy, ugly, and crude. But they can dissipate a lot more energy (even if it's much less energy per weight). So if what you have is really a motorcycle, it should have motorcycle brakes.

Some of the pedicabs I build can easily total 2000 pounds gross weight, and bicycle brakes (good ones) work well for that. The key is that these trikes rarely exceed about 15 mph, so there's not an unmanageable amount of energy. A racing motorcycle of 550 pounds gross, but moving at 150 mph, packs about 28 times as much kinetic energy as the 2000 pound pedicab at 15 mph.

Look into regen for the braking aspect, along with high quality bicycle brakes will do you well. Then there is the choice of Hydraulic or Mechanical disc, some prefer Hyd's others like the field repairability of mech's.

Bike stuff can be quite adequate, when the total weight is still under 300 pounds, ( you on the bike) and speeds are not over 40 mph. Above that, it becomes quite worth it to at least move towards moped stuff, tires, rims, and thicker discs. Continuous duty above 40 mph is very hard on bike tires, despite all the racing done at high speeds down mountains. Those guys generally run a new tire every day, but you won't.

Regen can very much help bike brakes, at the fastest speeds they brake the hardest, so regen can help your speed drop to 40 mph before you start really using the disks. By 20 mph, the regen effect has diminished a lot, but the regular brakes work fine then.

All the above affects you more, or less, depending on the type of use. On a race track, sure, new tires each weekend. But if you are a 2000 pound pedicab, then hauling ass gets to be a bad idea. Both weight and speed and time of duty need consideration.

There are two factors to consider: weight and speed.

Weight can force you to build with motorcycle brakes, but speed doesn’t (not the kind of speed that most of our fast ebikes are doing). Short of 100 mph on a sub 100 lbs bike, the best of bicycle brakes are perfectly suitable and can beat the braking distance of most motorcycles. Yet, the best of bicycle brakes are more expansive than most motorcycle brakes, and that is one thing to consider.

Weight has an escalade effect: the moment you start building with motorcycle components, more motorcycle components are soon required. Then weight does command a bigger battery, and all that weight is ending up making your frame unsuitable. My point is, buid an ebike with bicycle components, or turn to building e-motorcycles. In the middle, something is always missing to make it good.

Well if you are going to go with motorcycle brakes, why not do this?
https://www.youtube.com/watch?v=eibD96dAR1g
https://www.youtube.com/watch?v=QRqqGj0psgc

Bear in mind also, if you are on a track, and need those breaks every 20 seconds, no time to dissipate heat. But normal riding 40 mph or so, no problem for bike brakes used every few min.

Only time I found myself cooking off a cheap ass 160 mm bike rotor, is when hauling ass up and down steep hills off road, or on an actual race track. But for a long mountain descent on a heavily loaded cargo bike, regen was the thing.