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The bike is a Specialized Camber 29, about five months old, from a shop about 220km away.

Something feels different in my ride, and I'm wondering what it is.

  • the rear goes sideways in sand much more often,
  • there's an different running sound from the rear tyre, at a different pitch than before,
  • the rear tyre is about 3mm taller than the front tyre, measured with callipers from the inside of the rim to the valleys in the tread,

After a flat rear tyre last Thursday, I took the wheel to a local bike shop 70km away, who took the initiative to insert the old tube as a covering for a new tube. There was already a protective layer of some sort between the tube and the tyre. The region is known for thorns, but there was no evidence that a thorn caused the flat. I put the wheel back in. I'm wary of blaming this event, because I don't have enough experience.

I ride twice daily for half an hour each time, on dirt roads, for about 6km.

I lack the tools and strength of hands to repair the wheel myself, and have no other riders nearby.

There's a possibility that my failure to maintain the suspension system may have caused the problem; but I don't know enough about it to tell. It has been left alone for the life of the bike.

There's a possibility that recent light rain may have changed the sand.

The rotation markers on the tyre are pointing in the right direction.

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All 3 things that feel different points to different tire-pressure. Was the pitch of the sound higher or lower? –  Eric Smekens Jun 30 at 6:17
    
Sounds to me like a tire pressure difference, though if they did something funky with the tube that might be it. You need your own tire pump with built-in pressure gauge, and you need to get your own tire changing tools. Unless you have some major disorder, strength should not be an issue. –  Daniel R Hicks Jun 30 at 11:28
    
Even if you can't change tires and adjust your tire pressure yourself, you should be able to specify your preferred pressure to the shop. Vittoria has a pretty good calculator. Also note that any calculator's suggestions are just that: suggestions. Look at it as a starting point and adjust your tire pressure to be higher or lower based on your preferences and riding conditions. –  jimirings Jun 30 at 11:58
    
Since bike tires need to be filled at least weekly, and 2-3 times a week for high-pressure tires, a good bike pump (with gauge) or access to some sort of tire inflation facilities is pretty much mandatory for anyone who does any regular cycling. –  Daniel R Hicks Jul 1 at 0:03
    
Thanks all. Tyre pressure can't be measured at the moment, though from bouncing the wheel on concrete it feels a much higher pressure than before. My inflation facilities are limited to electric car pump, and the Presta adapter sold to me by the first bike shop doesn't open the valve stem on the new tube. Different stem height. So I shall look into good bike pump with gauge. I've not needed to fill the tyres for five months; 29x2.1. @Daniel, disorder is nerve entrapment in wrist, excessive force causes pain and immobility days later, but nothing at the time. –  James Cameron Jul 1 at 4:33

2 Answers 2

The protective layer is known as "rim tape". The old tube shouldn't remain within the tire - the only thing inside the rim should be the rim tape and the new tube.

You may have different tire pressures than before - have you tried playing with them?

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Under inflated? –  andy256 Jun 30 at 9:09
1  
The way he describes it it isn't rim tape. There are "old school" techniques of using an old tube inside or tire outside the new tire to add additional puncture protection. I agree that tire pressure is very likely an issue, though. –  Daniel R Hicks Jun 30 at 11:31

Like many comments, it sounds like it's at least partially related to a change in tire pressure. There's also the external change in tire tread that could contribute to the sound change. If you listen to a large knob tire on a road versus a small knob one, they sound totally different. Your tread might be starting to wear, thus giving a different sound.

The extra tube inside the tire might contribute to the height difference if some of that tube got stuck under the bead between the tire and the rim, though 3mm would be quite a bit; however, adding that bit of material plus the inherent tolerances in product sizing, it's possible.

Lastly, as you mentioned, it could be due in part to a change in the riding surface. Hard pack will definitely sound different than gravel or soft sand. And wet or dry sand will handle differently as well, especially if you have a tire with limited tread.

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