weird brake problem...
#1
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Thread Starter
weird brake problem...
Hello All,
I have an early 90's Santana road tandem. I have just purchased a set of wheels with dyad rims with HF08 hubs to allow the use of an Arai drum as a drag brake. The problem is that the brakes won't fit...
The center-to-center distance across the brake mounting bosses on the seat stays is quite narrow at 73mm. Putting in a dyad rim which is 24mm wide, causes problems...
It seems like I have two issues:
1. The standard pads are long and go forwards between the seat stays. However, there isnt room between the seat stays for both the rim and the brake pads. So I need shorter pads that don't protude forwards between the seat stays.
2. The Avid SD-7s like many V-brakes, have pads that stick out a long way from the V-brake arm (towards the rim), presumably this is for mud clearance. Therefore if the mounting bosses are not widely separated and the rim is wide, then you end up with the V-brake arms stuck out at some crazy angle. I have already arranged the washers to get the pads closer to the brake arm and am now considering grinding the washers down to a minimum thickness in order to gain a couple of mm
I figure that a set of cantilevers with short pads might be made to work, but I'm not crazy about this solution. So stopping short of buying another set of wheels with a much narrower rim can anyone point me towards some alternate brakes?
thanks
mike
I have an early 90's Santana road tandem. I have just purchased a set of wheels with dyad rims with HF08 hubs to allow the use of an Arai drum as a drag brake. The problem is that the brakes won't fit...
The center-to-center distance across the brake mounting bosses on the seat stays is quite narrow at 73mm. Putting in a dyad rim which is 24mm wide, causes problems...
It seems like I have two issues:
1. The standard pads are long and go forwards between the seat stays. However, there isnt room between the seat stays for both the rim and the brake pads. So I need shorter pads that don't protude forwards between the seat stays.
2. The Avid SD-7s like many V-brakes, have pads that stick out a long way from the V-brake arm (towards the rim), presumably this is for mud clearance. Therefore if the mounting bosses are not widely separated and the rim is wide, then you end up with the V-brake arms stuck out at some crazy angle. I have already arranged the washers to get the pads closer to the brake arm and am now considering grinding the washers down to a minimum thickness in order to gain a couple of mm
I figure that a set of cantilevers with short pads might be made to work, but I'm not crazy about this solution. So stopping short of buying another set of wheels with a much narrower rim can anyone point me towards some alternate brakes?
thanks
mike
Last edited by Al Bundy; 02-25-08 at 10:51 AM. Reason: clarity
#3
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I can picture your problem but don't have a solution yet. I just bought a Santana tandem with Cantis and plan to convert to SD-7s so I am interested in seeing how this works out. I am building up a Velocity Aeroheat rear 9 speed wheel for the bike which has the same profile as the Dyad so it looks like I will be in the same boat.
#4
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Thread Starter
I haven't got it on the road yet, but I think it will be OK. I have ground down the offending part of the brake pad holder (metal bit) and now have enough clearance (2mm on each side before pad hits the inside of the seat stays), provided the whel stays true...
A better solution would be to use shorter pads and if necessary I could just cut the front half inch of the pads off. This would make the pad very asymmetric with respect to the place where the force is applied so I am not keen to do this.
The problem of the lever arms sticking out is still there: grinding the pads or cutting them short makes it a workable solution not a great one. I may also grind down the cupped washers between the pad and the lever in order to reduce this.
cheers
mike
A better solution would be to use shorter pads and if necessary I could just cut the front half inch of the pads off. This would make the pad very asymmetric with respect to the place where the force is applied so I am not keen to do this.
The problem of the lever arms sticking out is still there: grinding the pads or cutting them short makes it a workable solution not a great one. I may also grind down the cupped washers between the pad and the lever in order to reduce this.
cheers
mike
#5
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I don't have the SD-7 but rather the SD-5 and I have played with different pads, including pads by Jagwire that come with pad holders. I have also measured MEC pad holders. My comments and conclusions:
– There are 2 sets of spherical washers (name?) on each cantilever posts. There are two thickness that allow more flexibility. Make sure you have the thinner pair on the inside.
– Monobloc brake pads are thinner than padholders with pad refills. When set identically, I estimate that the monobloc pads are about 1,5-2 mm thinner, so your brake arms will be less opened than with the pad holders. In other words, that would help.
– Monobloc brake pads are also 3-4 mm thinner overall, so they fit much better when you have limited clearance between the rim and seat stays.
– I generally use Kool Stop Salmon Mountain brake pads. If you need just a bit of extra clearance under the stays, it's easy to file them.
– There are 2 sets of spherical washers (name?) on each cantilever posts. There are two thickness that allow more flexibility. Make sure you have the thinner pair on the inside.
– Monobloc brake pads are thinner than padholders with pad refills. When set identically, I estimate that the monobloc pads are about 1,5-2 mm thinner, so your brake arms will be less opened than with the pad holders. In other words, that would help.
– Monobloc brake pads are also 3-4 mm thinner overall, so they fit much better when you have limited clearance between the rim and seat stays.
– I generally use Kool Stop Salmon Mountain brake pads. If you need just a bit of extra clearance under the stays, it's easy to file them.
#7
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Aeroheads may be 20 but the Aeroheat that I am using is advertised as 24 and appears to use the same or at least a similar extrusion to the Dyads. Mine measures 23mm wide at the machined braking surface. I saw my new bike breifly on Sunday but forgot to bring a ruler to measure the curent setup which is LX Cantis. I should be picking up the bike in the next couple of weeks as the snow melts and my bike shed gets cleared out. I'm waiting for new spokes now. I ordered the wrong size and noticed while lacing the wheel last night. Oops
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I don't have the SD-7 but rather the SD-5 and I have played with different pads, including pads by Jagwire that come with pad holders. I have also measured MEC pad holders. My comments and conclusions:
– There are 2 sets of spherical washers (name?) on each cantilever posts. There are two thickness that allow more flexibility. Make sure you have the thinner pair on the inside.
– Monobloc brake pads are thinner than padholders with pad refills. When set identically, I estimate that the monobloc pads are about 1,5-2 mm thinner, so your brake arms will be less opened than with the pad holders. In other words, that would help.
– Monobloc brake pads are also 3-4 mm thinner overall, so they fit much better when you have limited clearance between the rim and seat stays.
– I generally use Kool Stop Salmon Mountain brake pads. If you need just a bit of extra clearance under the stays, it's easy to file them.
– There are 2 sets of spherical washers (name?) on each cantilever posts. There are two thickness that allow more flexibility. Make sure you have the thinner pair on the inside.
– Monobloc brake pads are thinner than padholders with pad refills. When set identically, I estimate that the monobloc pads are about 1,5-2 mm thinner, so your brake arms will be less opened than with the pad holders. In other words, that would help.
– Monobloc brake pads are also 3-4 mm thinner overall, so they fit much better when you have limited clearance between the rim and seat stays.
– I generally use Kool Stop Salmon Mountain brake pads. If you need just a bit of extra clearance under the stays, it's easy to file them.
#9
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Thread Starter
many thanks to all,
I have got the wheel in place and I think provided the wheel stays true then I will be OK. If I break a spoke it might get interesting though.
I have the spring tension on the brake arms set high and this pulls out any slack in the cable so that the back of the brake pads stay hard up against the seat stays. It's certainly workable at the moment, but I will have a look at the monoblock pads and this may be the long term solution. The extra mm or two will make a big difference in peace of mind.
again thanks to all,
Mike
I have got the wheel in place and I think provided the wheel stays true then I will be OK. If I break a spoke it might get interesting though.
I have the spring tension on the brake arms set high and this pulls out any slack in the cable so that the back of the brake pads stay hard up against the seat stays. It's certainly workable at the moment, but I will have a look at the monoblock pads and this may be the long term solution. The extra mm or two will make a big difference in peace of mind.
again thanks to all,
Mike
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I ordered a pair of the thin line Salmon kool stops along with the spokes for my new 9 speed wheel. We pick up the bike on the 15th. I'm probably building the wheel tonight. We'll see how it all goes and report back.