Innertube sizing (17x1.1/4)

[[email protected]]

Anyone know whether a Schwalbe SV4 16x1.3/8 innertube will be ok in a
17x1.1/4 tyre.

The tube I've been sold has
37-340 16x1.3/8
28-349 16x1.1/8
37-349 16x1.3/8
28-355 18x1.1/8
400 x 35A
on the box and I've been "convinced" that it will be ok (not ideal but
ok).

But I really need a bigger tube, 32-369. I was told in the shop
(cyclesurgery) that I'll struggle to get 17x1.1/4 now but a quick
google now I'm back at work suggests that I need the 28-47x355-400 SV5
innertube which does seem to be available.

(For the front wheel of an old windcheetah - and I really don't need a
blowout at 40+mph!)

Tim.

 

[James Thomson]

<[email protected]> a écrit:

> Anyone know whether a Schwalbe SV4 16x1.3/8 innertube will
> be ok in a 17x1.1/4 tyre.

I've forwarded your question to the Moultontalk (as you probably know, 17 x
1 1/4" is the Alex Moulton AM clincher size) list on Yahoogroups. If there's
a response, I'll post it back here.

> But I really need a bigger tube, 32-369. I was told in the shop
> (cyclesurgery) that I'll struggle to get 17x1.1/4 now but a quick
> google now I'm back at work suggests that I need the
> 28-47x355-400 SV5 innertube which does seem to be available.

Moulton AM dealers should keep suitable tubes in stock. I'm out of touch,
but Condor used to stock AM bikes.

James Thomson

 

[Dave Larrington]

In news:[email protected],
[email protected] <[email protected]> tweaked the Babbage-Engine to
tell us:
> Anyone know whether a Schwalbe SV4 16x1.3/8 innertube will be ok in a
> 17x1.1/4 tyre.
>
> The tube I've been sold has
> 37-340 16x1.3/8
> 28-349 16x1.1/8
> 37-349 16x1.3/8
> 28-355 18x1.1/8
> 400 x 35A
> on the box and I've been "convinced" that it will be ok (not ideal but
> ok).
>
> But I really need a bigger tube, 32-369. I was told in the shop
> (cyclesurgery) that I'll struggle to get 17x1.1/4 now but a quick
> google now I'm back at work suggests that I need the 28-47x355-400 SV5
> innertube which does seem to be available.
>
> (For the front wheel of an old windcheetah - and I really don't need a
> blowout at 40+mph!)

I used to use Michelin's 349 inner tubes in the 369 front wheel of my
Kingcycle. No problems save that they seemd to make the tyre a little
harder to get on.

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
If you are choking on an ice cube, simply pour a jug of boiling
water down your throat and presto! The blockage is almost
instantly removed.

 

[Rob Morley]

In article <804dd4d1-0e6b-4937-b4e0-
[email protected]>, [email protected]
[email protected] says...
> Anyone know whether a Schwalbe SV4 16x1.3/8 innertube will be ok in a
> 17x1.1/4 tyre.
>
> The tube I've been sold has
> 37-340 16x1.3/8
> 28-349 16x1.1/8
> 37-349 16x1.3/8
> 28-355 18x1.1/8
> 400 x 35A
> on the box and I've been "convinced" that it will be ok (not ideal but
> ok).
>
> But I really need a bigger tube, 32-369. I was told in the shop
> (cyclesurgery) that I'll struggle to get 17x1.1/4 now but a quick
> google now I'm back at work suggests that I need the 28-47x355-400 SV5
> innertube which does seem to be available.
>
> (For the front wheel of an old windcheetah - and I really don't need a
> blowout at 40+mph!)
>
It will work fine. It may be a little more susceptible to punctures,
but you're unlikely to have a blowout - those are usually caused by tyre
or rim failure, not tube failure.

 

[James Thomson]

"James Thomson" <[email protected]> a écrit:

> I've forwarded your question to the Moultontalk (as you probably
> know, 17 x 1 1/4" is the Alex Moulton AM clincher size) list on
> Yahoogroups. If there's a response, I'll post it back here.

Well,

"Steve Palincsar" writes:

> I've got 16 x 1/38 Pyramid tubes (marked 36-349) in my AM; got them
> from Gilbert Anderson at North Road Cycles, a US Moulton dealer.
> They work fine. I've not seen the Schwalbes.


"Peter Ludwig" <peter.ludwig@> writes:

> No, this is the Nr.4 tube, but you need Nr.5 for an AM.

> (Short look at Schwalbe's website tells it)


Thanks Peter.

Just to clarify, the question comes from someone who knows
that this isn't the recommended tube, and knows that the
recommended tube is larger than the one he has. Have you
tried a Schwalbe Nr. 4 tube in an AM tyre?

James Thomson


> Sorry, I misunderstood. But I've used (different) undersized tubes
> and the[y] started to fail after maybe 500km.


"Chris Eley" writes:

> I'm not sure if it was a Schwalbe, but I've certainly used a 349
> tube in a 369 tyre, when riding my AM7 but having forgotten to
> take the right tube in my toolkit (often happens- another reason
> I want to convert the AM to 349

> It is possible, but such a stretch that it's hard to get the
> tyre back onto the rim, so definitely NOT recommended!

> One problem is that I'm loathe to buy new tubes, so my
> remaining 17" tubes are covered in patches and well past
> their best-before date!


"Tony Clarke" <TonyClarke@> writes:

> A problem I've encountered with using the wrong-sized tube,
> is that it inflates unevenly. This can apply to the profile of the
> tube as well as its nominal RSD. A too-small tube will sit in the
> well of the tyre and cranking any amount of pressure into it
> can still leave the rolling surface deformable. Ditto putting a
> narrow section in a wide tyre. You would imagine that an
> inner tube, being a relatively soft structure, naturally forms to
> the shape of the harder tyre surface and provide even force, but
> it is not so: the tube rubber has its own fixed stresses and will
> express these in subtle ways - sometimes not so subtle, as we
> all know if you put too BIG a tube inside a tyre. The inflation force
> will make the tube lift the bead out of the rim shoulder or otherwise
> distort the cover, as there is a mismatch between the required
> pressure to tension the tyre and the volume of air pumped in to
> achieve it.

> Most misery-making is the tube that's supposed to fit, but doesn't.
> I vividly recall riding to BoA one year on 340 Dunlops with
> inside them a DuroTyre (cheap Indonesian rubbish, I now know)
> inner *marked* as suitable for 340-349-355 tyres and the correct
> section. It would not achieve the proper pressure or anything like it
> without attempting to escape from the bead or otherwise doing
> python-eating-puppy impersonations inside the tyre that produced
> bulges and eventually a tread stress rip. Never again! The Dunlops
> themselves were fine, other inners worked, and I might have had
> a rogue mis-boxed tube, but I wasn't inclined to test a further
> sample after the repeated roadside grief.


So there.

James Thomson

 

[[email protected]]

On Dec 18, 6:07 pm, "James Thomson" <[email protected]> wrote:
> "James Thomson" <[email protected]> a écrit:
>
> > I've forwarded your question to the Moultontalk (as you probably
> > know, 17 x 1 1/4" is the Alex Moulton AM clincher size) list on
> > Yahoogroups. If there's a response, I'll post it back here.
>
> Well,
>
> "Steve Palincsar" writes:
> > I've got 16 x 1/38 Pyramid tubes (marked 36-349) in my AM; got them
> > from Gilbert Anderson at North Road Cycles, a US Moulton dealer.
> > They work fine. I've not seen the Schwalbes.
> "Peter Ludwig" <peter.ludwig@> writes:
> > No, this is the Nr.4 tube, but you need Nr.5 for an AM.
> > (Short look at Schwalbe's website tells it)
>
> Thanks Peter.
>
> Just to clarify, the question comes from someone who knows
> that this isn't the recommended tube, and knows that the
> recommended tube is larger than the one he has. Have you
> tried a Schwalbe Nr. 4 tube in an AM tyre?
>
> James Thomson
>
>
>
> > Sorry, I misunderstood. But I've used (different) undersized tubes
> > and the[y] started to fail after maybe 500km.
> "Chris Eley" writes:
> > I'm not sure if it was a Schwalbe, but I've certainly used a 349
> > tube in a 369 tyre, when riding my AM7 but having forgotten to
> > take the right tube in my toolkit (often happens- another reason
> > I want to convert the AM to 349
> > It is possible, but such a stretch that it's hard to get the
> > tyre back onto the rim, so definitely NOT recommended!
> > One problem is that I'm loathe to buy new tubes, so my
> > remaining 17" tubes are covered in patches and well past
> > their best-before date!
> "Tony Clarke" <TonyClarke@> writes:
> > A problem I've encountered with using the wrong-sized tube,
> > is that it inflates unevenly. This can apply to the profile of the
> > tube as well as its nominal RSD. A too-small tube will sit in the
> > well of the tyre and cranking any amount of pressure into it
> > can still leave the rolling surface deformable. Ditto putting a
> > narrow section in a wide tyre. You would imagine that an
> > inner tube, being a relatively soft structure, naturally forms to
> > the shape of the harder tyre surface and provide even force, but
> > it is not so: the tube rubber has its own fixed stresses and will
> > express these in subtle ways - sometimes not so subtle, as we
> > all know if you put too BIG a tube inside a tyre. The inflation force
> > will make the tube lift the bead out of the rim shoulder or otherwise
> > distort the cover, as there is a mismatch between the required
> > pressure to tension the tyre and the volume of air pumped in to
> > achieve it.
> > Most misery-making is the tube that's supposed to fit, but doesn't.
> > I vividly recall riding to BoA one year on 340 Dunlops with
> > inside them a DuroTyre (cheap Indonesian rubbish, I now know)
> > inner *marked* as suitable for 340-349-355 tyres and the correct
> > section. It would not achieve the proper pressure or anything like it
> > without attempting to escape from the bead or otherwise doing
> > python-eating-puppy impersonations inside the tyre that produced
> > bulges and eventually a tread stress rip. Never again! The Dunlops
> > themselves were fine, other inners worked, and I might have had
> > a rogue mis-boxed tube, but I wasn't inclined to test a further
> > sample after the repeated roadside grief.
>
> So there.
>
> James Thomson

Cheers, thanks for that.

I've ordered some SV5 tubes. I'll hang on to the SV4 as they're a "get
me home" option and maybe I'll change the Brompton to presta valve
(although I don't know whether that's a good idea with the rim drilled
for schraeder. Googling, some people say yes, some say no and some say
only with a rubber grommet)

Tim.

 

[Rob Morley]

In article <[email protected]>, James
Thomson
[email protected] says...

> "Tony Clarke" <TonyClarke@> writes:
>
> > A problem I've encountered with using the wrong-sized tube,
> > is that it inflates unevenly. This can apply to the profile of the
> > tube as well as its nominal RSD. A too-small tube will sit in the
> > well of the tyre and cranking any amount of pressure into it
> > can still leave the rolling surface deformable. Ditto putting a
> > narrow section in a wide tyre. You would imagine that an
> > inner tube, being a relatively soft structure, naturally forms to
> > the shape of the harder tyre surface and provide even force, but
> > it is not so: the tube rubber has its own fixed stresses and will
> > express these in subtle ways - sometimes not so subtle, as we
> > all know if you put too BIG a tube inside a tyre. The inflation force
> > will make the tube lift the bead out of the rim shoulder or otherwise
> > distort the cover, as there is a mismatch between the required
> > pressure to tension the tyre and the volume of air pumped in to
> > achieve it.
>
> > Most misery-making is the tube that's supposed to fit, but doesn't.
> > I vividly recall riding to BoA one year on 340 Dunlops with
> > inside them a DuroTyre (cheap Indonesian rubbish, I now know)
> > inner *marked* as suitable for 340-349-355 tyres and the correct
> > section. It would not achieve the proper pressure or anything like it
> > without attempting to escape from the bead or otherwise doing
> > python-eating-puppy impersonations inside the tyre that produced
> > bulges and eventually a tread stress rip. Never again! The Dunlops
> > themselves were fine, other inners worked, and I might have had
> > a rogue mis-boxed tube, but I wasn't inclined to test a further
> > sample after the repeated roadside grief.
>
If you fit a much too narrow tube then there may be a region that fails
to expand to fill the tyre, because (especially cheap) tubes can have a
thicker region where they are joined. A slightly too large diameter
tube can usually be coaxed in with a little effort without it folding
and causing problems. A much too wide tube can be fitted as a get-you-
home measure by pleating it and taping it together (the tape is just to
let you fit it, it will probably fall off when inflated) although it
will chafe and fail after a while. If you manage to fit the wrong size
tube /properly/ it should work reasonably well for some time without,
but because it's often not easy to get the tube in the tyre and the tyre
properly seated and up to pressure you'll get people telling you it
can't be done.