Cycling UK Forum

Dave W

I posted some time ago how bad the braking was on the back of my tandem since converting it to Avid bb7 disc brakes. I couldn't stop the bike with the back brake only - it was hopeless.
Anyway, the solution was - ditch as much outer cable as possible - do not use full length outer cable. On a tandem it simply compresses too much with the long distance from front to rear.

Dave W

My feet froze today so it's time to look out my old neoprene overshoes. I don't like them much - they seem so bulky - are the thinner styled ones still warm?

Dave W

I have a nice Jet Black one doing nothing in my garage for sale (Wilts) only used it for half an hour.

http://www.rutlandcycling.com/27219/Jet ... ainer.html

Dave W

It's because the outer pad could push the rotor into the body of the calliper when the inner pad is worn I reckon?

Dave W

203 mm

Dave W

Well, I've binned as much outer cable as possible, taken the adjusters off and altered the final bend to the brake. No time for a spin but when we do I'll report back. Nothing left but to change the pads after this.

Dave W

goatwarden wrote:Because they are attempting to reduce the potential for customer liability issues. Full cable outer is a predictable set up whereas the myriad of frame arrangements and cable runs through stops and internal tubes is too large for them to predict performance. By stating full housing, the only significant variables influencing performance are length of cable and quality of only two housing terminations.

There is possibly an additional issue that, since the brakes were first developed for mountain bikes, full outers give better protection from muck for the cable; this is far less of an issue if you are not riding through deep mud all the time.

For your Landescape you definitely would lose out by using full outer. The Landescape frame has plenty of strong, well positioned cable stops. By using as little cable outer as possible you reduce the compressibility (equivalent to cable stretch) as the sections between cable stops will not compress (unless the lugs move) So you should get the sharpest reaction to lever pull.

Are you sure you have used the most appropriate set of cable stops? The original (Malaysian built) frames had stops to allow use of a third Vee brake on the rear; if the upper set of stops on the rear top tube were used to run a cable to a rear disc calliper I think you would get a lot of cable drag. I have not seen any of the Czech-built newer frames close enough to know whether they are the same.

Yes, that was my thinking also. There's no doubt the braking is poor on the back disc. Drop levers have so little pull anyway that even a mill or two lost in compression would affect the set up. I was seriously thinking of eliminating as much outer cable as possible and even the barrel adjuster too. Cantelever brakes don't need it so why would disc brakes be any different?

Dave W

Why do they recommend full length outer casing on the cables? Anyone know?

Dave W

The disc brake only works on one side

Dave W

Synergy.
I've found there is a cap for want of a better word that buts up to the cartridge bearing I've tried adjusting this and retightening the grubscrew - seems to have helped.

Dave W

No, I think the hub moves on the skewer. There obviously needs to be some play but I've never had a bike (or discs) where I can see it.

Dave W

Whilst rocking my tandem to and fro with the front brake on, I can see the front wheel moving from side to side (disc brakes). The only play I can find is where the hub rocks on the skewer. Anyone else had this? Is it normal and can it be cured?

Dave W

I've mentioned this before, but to get the brakes to work at all the pads have to be nearly touching the rotor. They run ok for a while until the weather and temperature changes then they come into contact with the rotor and drag themselves on. A sharp decent heats the rotor up and the pads drag again. Back them off a click and they are inefficient. Cable rub doesn't seem a problem the cam returns every time to it's stop without fail. The cables were sprayed with ptfe on assembly and were brand spanking new.
With the pads so close to the rotor a bump or simply leaning on a bend can make them drag. If special cables are required then perhaps Avid should mention this?
Maybe smaller rotors and smaller wheels are easier to set because there is less play in the wheels and less movement of the rotor.

Dave W

Drops, Shimano 105's 9 speed, Avid BB7 Road with Avid Clean Sweep 203 Rotors
Bike is a Landescape Tandem with 700c wheels.

Dave W

Spring tension is adjusted to the max. I've done this to try and prevent the pads dragging on the rotors and squealing. Probably done 200 miles now. I can pull the lever about half way and see the pads have contacted the rotor. I can also keep squeezing until the lever contacts the bar and the bike still won't stop. Front brake similar but it's far more effective.

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