Spherical dear boy, spherical.
H: Hubs, Wheels and Tyres Eight inch brake ?
- Thread starter Julian R.
- Start date
Flat and Round are not mutually exclusive. Spherical is definitive!
All very confusing in the fog of misconception and illusion
Baaa
All very confusing in the fog of misconception and illusion
Baaa
Maybe we had too many shims ?, I wanted to open up the shoe holes, But it was Ron's job, So he picked up the biggest file I have ever seen and did the job,These shoes had been relined many years ago, Don before he died had done a lot of the jobs since the 70s, But we had to make a bike out of lots of bits. Cheers Bill.
Interesting discussion. Let's not forget that force is a vector quantity so that it has both magnitude and direction so upward forces cancel out downward ones.
While I don't want to get too caught up in this fun conversation it seems to me that the balance beam splits the applied cable 'reactive' force to either brake arm and that the additional downward motion from this outer cable gives an overall cable velocity ratio of 2:1.
For my two cents worth, for an applied cable tension of 100N force on the upper cable you get slightly less than 100N force applied at each brake arm (due to frictional losses). The cost of this is that for every unit displacement at the brake end we get twice the displacement at the lever end - hence minor flexure within the drum brake system being magnified 2 X at the handlebar lever.
I've just replaced my front brake cable with a nice one from the Spares Company and am very pleased with the firmer lever. Can't wait to try it out.
While I don't want to get too caught up in this fun conversation it seems to me that the balance beam splits the applied cable 'reactive' force to either brake arm and that the additional downward motion from this outer cable gives an overall cable velocity ratio of 2:1.
For my two cents worth, for an applied cable tension of 100N force on the upper cable you get slightly less than 100N force applied at each brake arm (due to frictional losses). The cost of this is that for every unit displacement at the brake end we get twice the displacement at the lever end - hence minor flexure within the drum brake system being magnified 2 X at the handlebar lever.
I've just replaced my front brake cable with a nice one from the Spares Company and am very pleased with the firmer lever. Can't wait to try it out.
I cannot see where the confusion lies here, it seems simple to me although I may be wrong, it seems you are only taking the pull into account but travel needs to be included in the equation (force x distance) the standard system to me doubles the pull on the brake arms by sharing the travel between both (so you have say 100lbs pull over say 1" divided by 2 =200lbs/in) for both
Whereas with the twin cable you are trying to move both the arms the full amount with the same effort (100lbs pull over 1"=100lbs/in) for both
Whereas with the twin cable you are trying to move both the arms the full amount with the same effort (100lbs pull over 1"=100lbs/in) for both
Regarding the above are we forgetting that the beam is only the middle lever here I wonder? however, my argument is really against the beam and its flexibility and operation not a rocking handlebar compensator which is what I am fitting I have found the item in Scott technicalities by an engineer who fitted a vincent type system rather that the Scott pully arrangement and found it better, however, he quotes other sources here is that part:
I don't think the spring is to help the brakes pull off, I think it's so there is a positive off position for one brake allowing the other to find it's own off position whereas without the stop they could react against each other, possibly one with stronger springs holding the other on a fraction.
I cannot say that I am surprised at the discussion. I am perfectly happy to know that the Vincent front brake system is superior to the twin cable system, which I have always used. I wonder about those who use the two cable system (including all the major motorcycle manufacturers) that chose to do so when a far superior system was available. Having said that I don't understand why the Vincent brakes are so mediocre. I know we have discussed all the individual component problems, but I am not sure why the entire system works so poorly that there are owners using the twin cable system with braking performance that seems to match the stock brake system empirically.
I do find it interesting that so many decades later there is so little common understanding about cable pull brakes!
David
I do find it interesting that so many decades later there is so little common understanding about cable pull brakes!
David
If I pull the handle bar lever back to 10 pounds the other two spring scales read 20 pounds. If I pull the handlebar lever back the two scales both move the same amount. What have I got wrong?
Is that 10 lbs on the lever ? What you really need is a twin cable set up using the same lever.