double flat tyres

[skippa85]

Hi all! First post here, thought i would reach out and grab some opinions. I just arrived home from from transporting my bike on the roof of my car (bike is a Cannondale SuperSix Evo). I use a front fork quick release mount on the roof rack with the front tyre on the back seat, my commute is 85kms of highway and i drive it at night, every 4 days for the last few years, all trips with my bike on the roof and i have never had any problems at all in the past. Arrived home tonight to find both my tyres flat, they were at an estimated 80-90 psi when i left. I have tried re-inflating them but they both wont hold air. Inner tubes are Kenda 700x18/23c one of which is only a week old, Tyres are Maxxis Refuse 700x23c and wheels are Mavic Cosmic Elites. Im going to pull them down in the morning and have a closer look but just thought i would see if anyone has any ideas why both tubes would spring leaks, at the same time, while one is inside the vehicle and the other is on the bike on the roof of the vehicle, i'm a little blown away honestly. Thanks for any responses.

[ColinOldnCranky]

It may be worth checking the valves, If you have a pump that has some fine particles in it then it could be some fine grit is stopping the valves from seatting properly.

But any statitician would tell you that a sample size of two is insufficient. My money would be on simple coincidence as an explanation.

[AUbicycles]

This is a strange one. Find out the cause... for example did you ride over a patch of broken glass and collected small shards.

Inspect the tyre surfaces. Take out the tube but also mark (with chalk or tape) the valve position with respect to the tyre.

Pump up the tubes and holding it in a bucket or tube of water, work out where the air is leaking. If it is the valve on both, check the valve hole on the rims that it is not too sharp. If it is otherwise another spot on the tube, you can then look at the tyre around the spot of the puncture and check closely for any obvious signs.

Let us know what you find out.

[skippa85]

Thanks for the replies, yeah ill do all that. I last rode the bike 24hrs before i traveled home with it and the tyres were still inflated when i left for home (i work out of town and ride at night after work then on the last day come straight home). Hoping when i pull them down after breakfast it will yield some answers. Ill report back.

[lone rider]

Bindi season. Very easy to get double punctures in my experience.