Brakes Disk Brake Performance Expectations

Discussion in 'Bicycle Repair' started by WorkingOnWise, Jun 26, 2008.

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  1. I have a 2007 model year Motobecane mountain bike that I am modifying to motorize. I love the bike until it comes time to brake. It has front and rear disk brakes, Tektro Aquila mechanicals, with 6" rotors, and no matter how tight I set the pads, I can not lock the front on pavement, and barely lock the rear.
    It's a weird feeling because it does have great stopping power. I mean, when I squeeze down, it hauls to a stop with authority, but not anything more. I run out of lever before I run out of courage. If I didn't know better, I might think the thing had ABS!
    I expect a brand new bike with Tektro Aquila disk brakes to outbrake anything except hydros. I think I should be able to lock both wheels pretty easily. Not that I want to go sailing, but if they wont lock now, will they be safe with the added weight of a trailer, a motor, and packed for camping? I thought brakes was the last thing I would have to worry about on this bike. I have a hard time believing that it's the levers, since it's all factory. Surely they knew what levers to put on, didn't they? Or am I expecting too much from the brakes?
    Last edited by a moderator: Jun 27, 2008

  2. Nevermind

    After 24 hours with no reply here, I went over to the mtbr forums and searched a bit. It seems I am expecting too much from my disk brakes, and my best solution is to ditch them for a good set.
    What a shame huh? Well, I guess I'll see what I can sell them for on craigslist.
  3. BSA

    BSA Guest

    I would have thought tht locking the wheel is a bad thing. I was always under the impression that one of the advantages of disk brakes was that they brake more without locking up the wheel.

  4. I think you are referring to the fact that disk brakes allow better modulation, so you have better control of the braking power available, making it easier to provide more stopping force without going suddenly from just slowing the wheels to stopping them. I call it twitchy or touchy brakes when they don't modulate well.

    Here's an example of my issue with not being able to lock up the wheels.
    We all know that if you hit the front brake when we are off the bike and just walking it, it'll be really easy to flip the bike. If we hit the rear brake, it'll be just as easy to lock the rear, and it takes very very little lever travel or effort to do it.
    When we ride, there is a lot more weight on the bike, so even at equally slow speeds, it takes considerably more effort to lock the wheels.
    The heavier a vehicle is, and/or the faster it travels, the more friction the brakes have to be able to produce to stop the vehicle safely.

    This is because of the friction needed to stop the vehicle.
    My concern is that if the stock brakes cant produce enough friction to lock the wheels at a normal load, there's no way it will be able to provide friction to slow the bike properly with a 100lb load of gear on it and a 200lb trailer behind it.

    When I worked on street rods, we had a simple rule. We always always gave the vehicle more stopping power that we gave it go power. If we could over-power the brakes, we didn't have the right brakes on the car.

    I figure if I cant flip the bike at any load I can handle, and any speed I care to go, I don't have enough braking power yet. Then it's up to me to modulate them properly so I don't actually "superman"
    Did it once on a road bike. Them things are heavier when they come down on your back!

    The other side is I really really don't want to go with hydro's. It's my personal opinion, but I just think there are too many things on hydros that can leave you brakeless. Things that on mechanicals I can at least half way rig for some braking ability if I get into trouble out in the woods.

    I'm gonna try a set of BB7's and give the Tektros to my step son. He's scared ride so fast that he'd need to slam on the levers so they'll be perfect for him!