406 tyre suggestions

Tim Hall said:

Yesterday I knackered my 47 x 406 tyre on the front of the Pino.
(Descending Ditchling Beacon, rim brakes, E = 1/2mv^2, E has to
go somewhere, wheel gets hot, tyre popped off rim, tube goes off
like a gun shot.)

Anyway, this also stuffed the bead on the tyre.

I'm looking for a replacement, something not as fat, say 35ish,
but capable of 6 or 7 bar (the Pino is a tandem).

This is a common problem on tandems where the speed can build up
alarmingly without continuous braking. Have you thought about a
hub-mounted drag brake? Can't help with a tyre suggestion, I'm afraid,
but I don't think any tyre will stand up to continuous rim braking on a
descent, even at low speed. You might try a private e-mail to Jobst
Brandt. I hear he has been working on developing an insulating rim tape
to address just this problem. I don't know how far along he is with it
though.

--
Dave...

On 11 Apr 2005 02:59:03 -0700, "dkahn400" <[email hidden]>

Quoted message said:

Tim Hall said:

Yesterday I knackered my 47 x 406 tyre on the front of the Pino.
(Descending Ditchling Beacon, rim brakes, E = 1/2mv^2, E has to
go somewhere, wheel gets hot, tyre popped off rim, tube goes off
like a gun shot.)

Anyway, this also stuffed the bead on the tyre.

I'm looking for a replacement, something not as fat, say 35ish,
but capable of 6 or 7 bar (the Pino is a tandem).

This is a common problem on tandems where the speed can build up
alarmingly without continuous braking. Have you thought about a
hub-mounted drag brake?

Unfortunately the Pino can't take a drag brake as well. (Sachs 3 x 7
hub). Hmm, thinking back a bit, Sachs do do a hub brake version...

I did read somewhere an article by, I think, Chris Juden, with
calculations showing that continuous braking was worse for heat build
up than stretches of speed with max braking at the corners. This was
far an Alpine style hairpin road.

Quoted message said:

Can't help with a tyre suggestion, I'm afraid,
but I don't think any tyre will stand up to continuous rim braking on a
descent, even at low speed. You might try a private e-mail to Jobst
Brandt.

Chris Juden rides with our section of the TC, so I'll see what he has
to say. It is the first time in 6 years we've had the problem.

A first step might be to reduce the m part of the equation. This
would make cycling up hills easier too.

Tim

Tim Hall said:

On 11 Apr 2005 02:59:03 -0700, "dkahn400" <[email hidden]>

Quoted message said:

Tim Hall said:

Yesterday I knackered my 47 x 406 tyre on the front of the Pino.
(Descending Ditchling Beacon, rim brakes, E = 1/2mv^2, E has to
go somewhere, wheel gets hot, tyre popped off rim, tube goes off
like a gun shot.)

Anyway, this also stuffed the bead on the tyre.

I'm looking for a replacement, something not as fat, say 35ish,
but capable of 6 or 7 bar (the Pino is a tandem).

This is a common problem on tandems where the speed can build up
alarmingly without continuous braking. Have you thought about a
hub-mounted drag brake?

Unfortunately the Pino can't take a drag brake as well. (Sachs 3 x 7
hub). Hmm, thinking back a bit, Sachs do do a hub brake version...

I did read somewhere an article by, I think, Chris Juden, with
calculations showing that continuous braking was worse for heat build
up than stretches of speed with max braking at the corners. This was
far an Alpine style hairpin road.

Seems to me that the relevant equation is not e=mv^2/2 but e=mgh - you
probably arrive at the top of the hill with relatively small kinetic
energy. If you descend a fixed (vertical) distance with a fixed mass
(both reasonable assumptions) then the energy dissipated will also be fixed.

Mark Atherton

"none" <""mark\"@(none)"> wrote in message
news:[email hidden]...

Quoted message said:

Tim Hall said:

On 11 Apr 2005 02:59:03 -0700, "dkahn400" <[email hidden]>

Quoted message said:

Tim Hall wrote:

>Yesterday I knackered my 47 x 406 tyre on the front of the Pino.
>(Descending Ditchling Beacon, rim brakes, E = 1/2mv^2, E has to
>go somewhere, wheel gets hot, tyre popped off rim, tube goes off
>like a gun shot.)
>
>Anyway, this also stuffed the bead on the tyre.
>
>I'm looking for a replacement, something not as fat, say 35ish,
>but capable of 6 or 7 bar (the Pino is a tandem).

This is a common problem on tandems where the speed can build up
alarmingly without continuous braking. Have you thought about a
hub-mounted drag brake?

Unfortunately the Pino can't take a drag brake as well. (Sachs 3 x 7
hub). Hmm, thinking back a bit, Sachs do do a hub brake version...

I did read somewhere an article by, I think, Chris Juden, with
calculations showing that continuous braking was worse for heat build
up than stretches of speed with max braking at the corners. This was
far an Alpine style hairpin road.

Seems to me that the relevant equation is not e=mv^2/2 but e=mgh - you
probably arrive at the top of the hill with relatively small kinetic
energy. If you descend a fixed (vertical) distance with a fixed mass
(both reasonable assumptions) then the energy dissipated will also be

fixed.

Quoted message said:

Mark Atherton

In fact the faster you descend, the less energy is dissipated in the brakes,
because aerodynamic drag assists the braking! Chris Juden did the calcs on
this within living memory.

We use an Arai drag brake on the front wheel of our Bike Friday Tandem
Two'sday, and Conti Top Touring tyres.