So how did Pederson Self Energizing brake work?
- Thread starter tintin40
- Start date
they had a cam in them that moved the brake arm toward the rim in an
"in and forward " type motion so the pad rubbing the rim pulled it in tighter
same effect can be simulated by fitting 10mm bore canti's to an 8mm brake post ,wont have the modulation but feels similar
these were not recomended for the front as they could be a bit severe
"in and forward " type motion so the pad rubbing the rim pulled it in tighter
same effect can be simulated by fitting 10mm bore canti's to an 8mm brake post ,wont have the modulation but feels similar
these were not recomended for the front as they could be a bit severe
suburbanreuben
Old School Grand Master
Imagine granny getting her tit caught in the mangle.
It's the same principle.
It's the same principle.
focomat 1c
Retro Guru
The simplest explanation, if you consider the left rear brake, is this :
Imagine the existing brake pivot is replaced by a very coarse bolt with a standard right hand thread.
The LH brake arm no longer has a smooth bearing surface to fit on a standard brake pivot. Instead it has a matching very coarse internal thread.
In effect the brake arm has become a 'nut' that is screwed onto the
threaded brake pivot.
In operation, as the brake arm moves toward the rim, it also moves forward
in the same direction as the rim. The effect of the brake pad rubbing on the
rim also encourages the brake arm to move even further towards the rim.
This is known as a 'self servo' effect, and has to be very carefully designed
to avoid grabbing. The pitch of the 'thread' is one of the critical factors,
along with selection of appropriate brake pad materials.
There is an internal spring,as with conventional cantilevers, returning the
brake arm to its resting position. The pitch of the ' thread' is so coarse that
the brake arm moves forward more than it moves in.
Pedersen offered the design in both front and rear versions to Suntour,
who manufactured the rear version only under license. The front version
was considered too dangerous, as any distortion/buckling of the rim
could bring the brake pad accidentally into contact with the rim, actuating the self servo effect with potentially damaging results.
If you do choose to run the front version, use generous clearances between
brake pad and rim.
Imagine the existing brake pivot is replaced by a very coarse bolt with a standard right hand thread.
The LH brake arm no longer has a smooth bearing surface to fit on a standard brake pivot. Instead it has a matching very coarse internal thread.
In effect the brake arm has become a 'nut' that is screwed onto the
threaded brake pivot.
In operation, as the brake arm moves toward the rim, it also moves forward
in the same direction as the rim. The effect of the brake pad rubbing on the
rim also encourages the brake arm to move even further towards the rim.
This is known as a 'self servo' effect, and has to be very carefully designed
to avoid grabbing. The pitch of the 'thread' is one of the critical factors,
along with selection of appropriate brake pad materials.
There is an internal spring,as with conventional cantilevers, returning the
brake arm to its resting position. The pitch of the ' thread' is so coarse that
the brake arm moves forward more than it moves in.
Pedersen offered the design in both front and rear versions to Suntour,
who manufactured the rear version only under license. The front version
was considered too dangerous, as any distortion/buckling of the rim
could bring the brake pad accidentally into contact with the rim, actuating the self servo effect with potentially damaging results.
If you do choose to run the front version, use generous clearances between
brake pad and rim.
Rev Cannon Dale
Old School Hero
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I had a full set of Scott SE brakes...
The biggest problem was the threads were made of composite and failed pretty easily. That and the inital set up being a PITA...
Had no problems with the front being grabby or severe.
Went back to Ritchey logic canti's and Winwood polymer blocks in the interests of reliability...
The biggest problem was the threads were made of composite and failed pretty easily. That and the inital set up being a PITA...
Had no problems with the front being grabby or severe.
Went back to Ritchey logic canti's and Winwood polymer blocks in the interests of reliability...
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