Diagnostics on bike issue

[passionate off roader]

I've got to take my bike in to be looked at as there's clearly something not quite right with it, but thought I would ask on here as well, to see if anybody has any clue what it might be.

Basically with every wheel revolution, the back wheel feels as though it's bumping on something. I've turned the bike upside down to have a look and spun the wheel, but can see nothing obviously amiss. There's no distortion of movement, and the wheel is not out of true. The entire mechanism feels tight and secure, and the tyre is fully inflated.

So I'm at a bit of a loss.

 

[vfr400]

It might help to say what sort of bike you have.

 

[Nealh]

If the lump/bump once every revolution is felt when riding, then look at the shape of the tyre circumference as you rotate the wheel. Sometimes a pronounced unevenness can be seen in one spot or one can see the tyre wall at the rim edge isn't uniform in a particular spot.
If tubes are fitted it could be an ill fitting tube causing the issue, sometimes it can get lumpy around the valve /tyre juncture. An incorrect sized tube or badly fitted tube prior to inflating can cause the tyre not to seat or sit evenly on the rim.

 

[passionate off roader]

It might help to say what sort of bike you have.

Juicy Ticket.

 

[passionate off roader]

If the lump/bump once every revolution is felt when riding, then look at the shape of the tyre circumference as you rotate the wheel. Sometimes a pronounced unevenness can be seen in one spot or one can see the tyre wall at the rim edge isn't uniform in a particular spot.
If tubes are fitted it could be an ill fitting tube causing the issue, sometimes it can get lumpy around the valve /tyre juncture. An incorrect sized tube or badly fitted tube prior to inflating can cause the tyre not to seat or sit evenly on the rim.

Thanks, useful info. I'll take a look.

 

[Darren Hayward]

I had this and it was the rim tape that was slightly kinked so I trimmed it with a pair of scissors by a couple of mm at the kink point and problem solved.
My advice, forget the shop and take off the tyre and check the tube, rim tape and tyre shape. Learning to solve basic stuff like this will save you hundreds if not thousands of pounds over the life of the bike. If you really can't do it yourself then pay close attention in the shop to see how they do it.

Darren

 

[sjpt]

If the lump/bump once every revolution is felt when riding, then look at the shape of the tyre circumference as you rotate the wheel. Sometimes a pronounced unevenness can be seen in one spot or one can see the tyre wall at the rim edge isn't uniform in a particular spot.
If tubes are fitted it could be an ill fitting tube causing the issue, sometimes it can get lumpy around the valve /tyre juncture. An incorrect sized tube or badly fitted tube prior to inflating can cause the tyre not to seat or sit evenly on the rim.

Absolutely.

If it isn't sitting evenly be careful riding before fixing it, as it could be about to blow off the rim.

When fitting (at least with tyres with inner tube) always inflate to somewhere around 1/4 pressure and make sure the fit on the rim is even all round. At that low pressure you should be able to manipulate any bumps by hand. And then fully inflate and double-check the fit; it it's wrong you'll have to lower pressure right down again. If you are unlucky the tyre may have developed a permanent bulge from being ridden with the fit wrong; in that (rare) case you'll have to replace the tyre.

 

[passionate off roader]

In the end I called a local bike repair shop and the guy advised that to him it sounded like a tyre pressure problem - I should make sure before doing anything else that the tyres were properly pumped up. I will admit the tyres didn't feel rock hard, but they certainly didn't feel soft. The problem was that I only had a small hand pump, which no matter how much I pumped, never seemed to get the tyres any harder. So I bought a floor pump with a pressure gauge, off Amazon. Used that and the tyres were rock hard in no time.

Then tried the bike and the problem was solved. Never thought it was that simple. I'd have expected that kind of bump each revolution if I'd got a puncture.

Thanks for all your suggestions above, gents.