What causes punctures on the rim side ?

mjw123

Hi,

At weekend repaired punctures to both front and back on my new Sportif Bianco, cursed my bad luck but though hey ho one of those things.

Went out again y/day and unbelievably both tyres punctured again, I assumed it was my bad repairs but both were new holes. I located the position of both new and old punctures and all of them seem to be on the rim side. The rims are clear of sharp edges etc so i'm at a loss as to what's happening here, the holes are little slits not circular holes you'd get from a thorn etc.

Any ideas ? - i wondered if i'm pumping the tyres too hard ? - using a track pump but no gauge on it.

Starting to spoil my enjoyment of a great bike !!

tia,
Mike.

cycleclinic

Any sidewall cuts? Could it be a piched tube that has failed under inflation? Difficult to tell from a distance.

desweller

Sounds like the rim tape is not covering the holes to the spokes well enough to me.

Do the punctures line up with the rim holes?

rolf_f

mjw123 wrote:

Any ideas ? - i wondered if i'm pumping the tyres too hard ? - using a track pump but no gauge on it.

More likely not hard enough. TBH, the question isn't worth asking until you've got yourself a decent track pump with a gauge. Tyre pressure is essential to get right and you can't guess it. You need to top the air pressure up pretty much weekly and if you don't have a pressure gauge you probably won't be doing that.

sungod

as above, small slits in a tube is often a sign of pinch flats, these occur when the pressure is too low - you go over a bump and the tyre compresses so far that the tube is nipped between tyre and rim, causing one or two cuts (aka snakebite)

try inflating to a known 'safe' pressure, say 95-ish front 105-ish rear (check tyre pressure rating which is embossed on the sidewalls, for road tyres these should be within the range), if you are on the heavy side then add 5psi, more if really heavy, but stay within the limit embossed on the tyres

road tyres are low volume high pressure, they lose pressure much faster than softer fatter tyres, how fast depends on tube type etc., expect to top up pressure at least once a week, more often if the tubes are lightweight, a pump with a gauge is handy