On Aug 8, 7:53*pm, someone wrote:
On 8 Aug, 17:18, Andre Jute wrote:





When even a puttering randonneur gets up into the big bikes and the
big balloon tyres, he suddenly acquires something in common with the
leanest roadie on the skinniest tyres: he becomes a weigh weenie. For
instance, in the biggest size, 50-622, going from the 995gr Big Apple
to the 790g Big Apple Liteskin saves seven and a quarter ounces, or
damn nearly a pound between a pair of tyres.

Someone else will have to say if you lose anything in comfort or
puncture-proofing or durability by going from the standard Big Apple
to the Liteskin. I've only had the Liteskin.

In tubes the weight saving is even more. Going from the 220gr Schwalbe
Type 19 standard tube suitable for Big Apples to the 140gr
lightweight *tube Type 19a saves three whole ounces per tube.

Between the lightweight tyres and the lightweight tubes then, one
saves a pound and a quarter per bike (no spares carried! -- nearer a
pound and a half if a single spare tube is carried).

But there is a price. It probably isn't much to a racer who checks the
inflation of his tyres before every ride. But it matters, though
probably not too much, to the utility/recreation biker one finds on
balloons.

It turns out that the extra light tubes are more permeable. They lose
air more quickly. Whereas it is perfectly okay to check the inflation
in a standard Big Apple with the standard Schwalbe T19 tube every
month or even every two months in the certain knowledge that it won't
lose enough air by natural processes to go out of bounds (unless run
on the very lower limit, of course), the lightweight T19A tubed tyre's
inflation must be checked every fortnight, more often if you run them
closer to the lower limit of inflation.

After some experimentation, I have settled at running my Big Apple
Liteskins with the Type 19A lightweight tubes at 2 bar front and rear.
That gives one enough comfort and plenty of control if precision is
required in steering or handling. This is a bit higher than was
initially reported by Lou and also by me: I've gone for the slightly
higher inflation to give me a (perhaps merely psychological) margin of
error against snakebites for the occasional pothole taken at speed
while talking to the pedalpals.

Starting from 2 bar, weather cool and tyres lightly used (only short
fast sections) and thus unlikely ever to be hot for long, the T19A
lightweight Schwalbe tube self-deinflates to 1.9 bar in a fortnight
and 1.8 bar in three weeks. The permissible minimum inflation for the
60-622 Big Apples is 1.5 bar, so this is a pretty fat safety margin if
you let the inflation check go another week or fortnight.

If you ride a bike ona daily basis the manfacturers recommendations
mean diddly squat. *

What does frequency of use have to do with manufacturers'
recommendations, except in maintenance and replacement?

Bigger and softer mean more comfort. *Too soft
means reduced control or tyre detatchment. *Too hard is just too hard,
dont go there. *That 1.5 bar will be for a particular rim which you
are probably not using and will be the safe running level at which to
prevent tyre detatchment. *

I imagine the 60mm balloons are specified at 1.5 bar for the ERTRO
recommendation of IIRC 21mm which was in force when the Big Apples hit
the market. In 2006 ERTRO also condescended to permit tyres up to 62mm
on 19mm rims.

My rims are 25mm between the beads, so in theory at least, I could
reduce inflation pressure below the manufacturer's recommendation of
1.5 bar -- if I were a wiener. However bike and rider weigh in the
order of 115-118kg, so 1.5 bar is probably a sound guess at a minimum,
and for safety 1.6 bar asd a practical minimum. My roads have the
occasional pothole, which I often take at speed, which is why I like
2.0 bar. I did however for a couple of months run the tyres at 1.8
bar, falling to sometimes 1.65 bar before I reinflated, and there were
no adverse effects.

Your weight is also a consideration,
apparently 100kgf fits all. *So if you adjust your weight to 100kgf
all will be well.

I'm not worried about all being well with my tyres and tubes. I've
already laid in spares. If I lose 15-18kg, I'll be so svelte, I'll
have to give up cycling and become a model. You're out of this world,
Trevor. As if anyone would just lose an ungodly amount of weight to
suit the rating on their bicycle tyres...

Andre Jute
Visit Jute on Thisthatandtheother
http://www.audio-talk.co.uk/fiultra/...20ARISING.html