Why no V-brakes on Fat Bikes?

[Balmorhea]

My last pair of disc pads had gotten some oil on them somehow, and that was the end of those disc pads.

A tiny drop will do it. Even greasy fingerprints on a rotor can permanently screw up a set of disc brake pads. It’s frustrating sometimes, how susceptible to contamination they are. At least most of them are pretty easy to replace.

 

[MadRhino]

.... on disc's that dont last long and when you get any kind of oil on them they are no good no more.

And why would your disc have some oil on it?
Calipers don’t leak on rotors, the reason why they are not installed on top, just in case they ever leak. And, if you’ve touched them with greasy fingers, clean them. And if you touch your didc with greasy fingers, you are even more likely to touch your rim.

Your 650mm rim has nothing to compare with a brake rotor, and hydro rim brakes are busting rims in a day if you try them on any but the best trial rims specific for hydro brakes. My HS22 are collecting dust since such rims are impossible to find most of the time, and some are as expansive as a good brake caliper.

Good rim brakes are doing the job at bicycle speed, but very unreliably in dirty conditions. And as soon as your rim is not mint and straight anymore, they are absolute sh*t. At high speed with the weight of ebikes, you need both hands on the front brake lever to even come close to the braking distance that can be achieved single finger with a big hydro disc brake.

 

[MadRhino]

On the other hand, you have to replace a disc rotor any time it gets a good bump into something. Wheels aren’t fragile like that.

Come on. At bike parks, we see a dozen damaged rims a day, and hardly one rotor a week.

Most rotor damaged you will see in a city, are from idiots who are piling all the family bikes on each other in the mess of the garage.

 

[Balmorhea]

On the other hand, you have to replace a disc rotor any time it gets a good bump into something. Wheels aren’t fragile like that.

Come on. At bike parks, we see a dozen damaged rims a day, and hardly one rotor a week.

Most rotor damaged you will see in a city, are from idiots who are piling all the family bikes on each other in the mess of the garage.

I think parking in public bike racks and carrying bikes in cars or trucks accounts for most of the bent rotors I see. Those things don't generally harm wheels, though.

 

[boytitan]

Think of linear pull brakes aka V-brakes as having a 650mm inch rotor and not a measly 160mm or 205mm rotor. Yes 650mm is 26" which is the rim, now 29" is 730mm, how common is a 29" with V-brake sidewalls well lemme do a quick little check. Judging solely on the small rim pictures at Chain Reaction Cycle, very few are. I couldnt find any out of the 12 or 18 I did a quick once over. Clicking on the rim link to get the quick details, 2 didnt specify one way or another. I'd imagine it'd be quite hard to find a 29'er in machined sidewall for v-brake.

My last pair of disc pads had gotten some oil on them somehow, and that was the end of those disc pads.

Cars use disc brakes, motorcycles use disc brakes, dirt bikes use disc brakes. We are not about to perpetuate the chalo crap of rims being like a giant disc brake. They aren't close to performing like that since the brake contact area is smaller than a disc brake. Rim brake pads are like what 10 mm in height with 30 mm of usable rim surface. Also I have had rim brakes on my first ebike constantly have the brake move in the brake holder something that is a none issue disc brakes. I was using properly mounted kool stop pads and still had issues over having to adjust every x amount of miles. Disc brakes stay put. Rim brake material doesen't compare. I don't know what the material is in rim brake pads but with a disc brake I have metal on metal.

 

[Balmorhea]

Cars use disc brakes, motorcycles use disc brakes, dirt bikes use disc brakes.

They use big heavy draggy disc brakes. Bicycles don't use those. They could, but they don't because then the bikes would suck.

We are not about to perpetuate the chalo crap of rims being like a giant disc brake.

Well, rims are larger in diameter than a disc rotor, have more mass and surface area than a disc rotor, and are made from a material with far better thermal capacity and conductivity than a disc rotor. So in those regards, rims aren't like disc rotors, but rather much superior.

Rim brake pads are like what 10 mm in height with 30 mm of usable rim surface.

With few exceptions, the contact surface of a rim brake pad is larger than that of a disc brake pad. Even at the extremes, they're not that different in area. The swept area of a rim is far bigger than that of a disc rotor, though.

Also I have had rim brakes on my first ebike constantly have the brake move in the brake holder something that is a none issue disc brakes.

Poor mechanical aptitude is not an indictment of the technology, but only of the user.

 

[boytitan]

Cars use disc brakes, motorcycles use disc brakes, dirt bikes use disc brakes.

They use big heavy draggy disc brakes. Bicycles don't use those. They could, but they don't because then the bikes would suck.

We are not about to perpetuate the chalo crap of rims being like a giant disc brake.

Well, rims are larger in diameter than a disc rotor, have more mass and surface area than a disc rotor, and are made from a material with far better thermal capacity and conductivity than a disc rotor. So in those regards, rims aren't like disc rotors, but rather much superior.

Rim brake pads are like what 10 mm in height with 30 mm of usable rim surface.

With few exceptions, the contact surface of a rim brake pad is larger than that of a disc brake pad. Even at the extremes, they're not that different in area. The swept area of a rim is far bigger than that of a disc rotor, though.

Also I have had rim brakes on my first ebike constantly have the brake move in the brake holder something that is a none issue disc brakes.

Poor mechanical aptitude is not an indictment of the technology, but only of the user.

You ignored the material difference, and regardless of how well rim brakes are put in place the speed and weight of a ebike cause them to shift over time. Metal brake pads>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>what ever rim brake pads are made with. Its not a 1-1 comparison of rim brakes are bigger disc brakes it doesen't work like that. Drum brakes also have more surface mass than disc brakes and absolutely no one calls drum brakes better.

 

[Balmorhea]

The best drum brakes can discharge more heat for longer durations than the best disc brakes. They are genuinely clean and unaffected by moisture and contamination. Drums have lower maintenance, longer wear life, and less likelihood of accidental damage than discs or rim brakes. So in these regards, they are better than discs. That's why I have them on three of my bikes, just like I have discs on two of my bikes and rim brakes on most of them.

It's true that drums don't have as much initial bite as good discs, just like discs don't have the sustained power dissipation of the best drums or rim brakes.