Inner Tubes

Dizeee

I wanted to ask a couple of questions re these:

1) Would a 23/25 700CC fit and work in a hybrid fitted with 700CC wheels but a tyre width of 28 possibly more? I use the smallest tubes for my road bikes which I think are usually packaged as 23 - 25, and my hyrbrid tubes I think are usually packaged 28 - 30 or similar. Surely as the tube expands in the tyre anyway it would do the same job?

2)Also am I right in thinking the quality is pretty much the same across brands, some seem to cost a lot more than others and I wonder whether I am losing out by looking for the cheaper option.

Cheers

sungod

1)
using a smaller tube will be ok up to a limit...

expanded circumference is proportional to diameter (c = πd), so 10% greater diameter, means 10% increase in circumference and of course the tube streched thinner by 1-1/1.1, c. 9%, which in turn means it'll be a bit more vulnerable to puncture/abrasion

tubes aren't infinitely stretchy, eventually you'd reach the material's limit and it'd fail

2)
tubes are much of a muchness

unless you need removable cores, light weight, or a particular valve stem length/type, may as well go for economy, though i'd be wary of sources that might be doing their bit for free enterprise by selling qc failures as good tubes

Anonymous

When you blow a tube up outside of a tyre it does not expand uniformly around the whole tube.
Think (from memory) it is around the valve that does not get bigger.

Personally I would buy the correct tubes but just give it a go and see what happens.

ugo.santalucia

I have fitted the skinniest tubes 18-25 on 32 mm Vittoria tyres and they are fine

cycleclinic

I have found conti 18-25mm race 28 are the best to use with 28mm tyres as if I try to use a tour 28 slim for example on a 28mm tyre on a standard width rim the tyre can becomes a very tight fit and that is a tight fit for me which impossibly tight for the customer.

desweller

I've sometimes found that, when using undersize tubes, I get a low spot at the valve that I can feel every time the wheel goes round. That's annoying enough for me to use the right tubes.

Anonymous

thecycleclinic wrote:

I have found conti 18-25mm race 28 are the best to use with 28mm tyres as if I try to use a tour 28 slim for example on a 28mm tyre on a standard width rim the tyre can becomes a very tight fit and that is a tight fit for me which impossibly tight for the customer.

How do you mean that the tyre is a tight fit? Do you mean getting it on the rim?
If so how does the tube affect that?

Is there any liability in fitting an 18-25 tube in a 28mm tyre for a customer?
I do not see 3mm as a problem but a customer and his 'no win, no fee' lawyer might if there is an accident and they check the tube.

Anonymous

DesWeller wrote:

I've sometimes found that, when using undersize tubes, I get a low spot at the valve that I can feel every time the wheel goes round. That's annoying enough for me to use the right tubes.

Thats roughly what I thought would happen.

Did not think you would actually feel it but just the thought of having a section of tube that did not expand in the same way, or was more stressed in its expansion is enough for me to spend a couple of £3's on something I will always need as a cyclist.

Dizeee

Cheers. I only ask as I carry a load of 23 - 25's for my road bikes but want to carry them for my odd commute on the hybrid too. Will let you know what happens if I ever have to use them!