Problems with putting tyre back on

[jimboalee]

Collective noun - "a Spanner of mechanics".

 

[Iainj837]

In 'The Bicycle Wheel' by Jobst Brandt, ( I'll check when home ), he has a diagram of the forces a tyre exerts on the rim. The inner tube width makes no difference. If the tyre is too large, it will want to roll off the clincher.
It's reasonably OK on an MTB where the inflation pressure is less than 60 psi, but on a road bike where 100 psi + is pumped in, the tyre could very well be lifted off the seat.

The psi is 90, well thats what it says on the side of the tyre

 

[Iainj837]

Like I said the tyre on the bike is what was on it since i bought the bike, also I have done 2'600 miles so they are due for new tyres

 

[Iainj837]

Sorted I think I took the wheel and tyre to the LBS and all he did was push the inner-tube up and then down and now the tyre is sitting on the rim

 

[peanut]

good so you're all sorted then.


Like I said the tube was trapped under the bead of the tyre and was pushing it off when inflated.
If you do change your tyres it might be worth considering 25c instead of 28c which is more an off-road tyre width for MTB's .
28c are very hard work on the road

 

[Iainj837]

I wonder why a 28 mm tyre was fitted on a touring bike ?

 

[Iainj837]

if I had a 25 mm tyre would I need a new tube

 

[peanut]

I wonder why a 28 mm tyre on a touring bike ?

good question Iain

Lots of bikes are built up by shops of a mixture of bits . Usually whatever is cheapest or simply to-hand.

Its why you see sub £500.00 bikes with a Shimano Tiagra rear mech, a no-name chainset, a cheap front mech from Tywan and so on.

If you are riding 90%+ on good roads most folk on here would probably recommend 25c rather than 28c .
The difference in the amount of effort required to reach a reasonable speed will be considerable.

I personally use 23c on my road bikes although I have several 20c tyres I used for Tri's etc

You could probably use the same tube although I don't know what you have.? Most tubes will say they are good for 23c-28c
if your tubes are better suited to 28c MTB tyres it could explain why your tyres beads are not sitting on the rims easily. Too much bulk to fit a narrow 18mm rim you see boyo

 

[peanut]

http://www.ribblecycles.co.uk/productdetail.asp?productcatalogue=CONTTYRR400

http://www.ribblecycles.co.uk/productdetail.asp?productcatalogue=MICHTUBE250

just some samples of what might be suitable. Usually next day delivery from Ribble.
Take some time to look through and also Wiggle Cycles etc .

 

[Iainj837]

Thanks peanut,

 

[jimboalee]

OEMs, Original Equipment Manufacturers will fit whatever is cheap and available. 28mm tyres are heavier and the experienced cyclists don't buy them, prefering a lighter 25mm tyre.
So 28mm tyres are surplus to stock and the OEMs negotiate a favourable cost for them.

Go for the weight saving. They will reduce the radius of gyration. Keep the weight of the wheel as close to the hub as possible - light tyre.

 

[peanut]

OEMs, Original Equipment Manufacturers will fit whatever is cheap and available. 28mm tyres are heavier and the experienced cyclists don't buy them, prefering a lighter 25mm tyre.
So 28mm tyres are surplus to stock and the OEMs negotiate a favourable cost for them.

Go for the weight saving. They will reduce the radius of gyration. Keep the weight of the wheel as close to the hub as possible - light tyre.

That raises an interesting question Jimbo.

If we used smaller wheels to put the weight closer to the hub ...would we go faster ?

(peanut removes the wheels from his vacumn cleaner...)

 

[jimboalee]

Yup,
Reducing the radius of gyration of the bike wheel not only makes the whole thing lighter, but also makes it easier to accelerate. Think of the diameter of a propeller on an aeroplane, and the design of a motorcar engine’s flywheel. Your legs are doing the same to the rear wheel.