Please forgive the long winded account - but I’ve got a day off and thought I would write something. 
Rode into central London for work and parked up, took my lid off to be greeted by a hissing sound coming from the bike - my heart sank as It was obviously the sound of a nail or something in the rear tyre - I had been working long hours all week and had a long day of work ahead of me and the last thing I needed was working out how I was going to get this bike 40 miles back to base on a flat tyre.
I remembered that I had a can of holts temporary tyre repair in my tank bag - however I hadn’t used it before and had no idea if it would work or not, plus it had been sitting in the tank bag unused for about three years so I was not sure if it was even past it’s sell by date.
In the past nails in the tyre had usually resulted in slow punctures which I spotted after I had got back home - this time though the air was p1ssing out and the tyre would be as flat as a pancake in a couple of minutes.
I moved the bike forwards a few feet from where it was parked (which was difficult as the tyre was totally flat by now) to turn the tyre and and locate the puncture site - I spotted a large phillips type screw stuck in the tyre at an angle - I realised that I must have picked it up only moments before - as the last few hundred yards of my commute takes me up a small side road and past a spot where a lot of heavy construction work is taking place.
I got the can of temp tyre repair out and read the instructions - which said to remove the object which caused the puncture from the tyre and position the valve into a ‘ten to ten’ position before screwing the flexible perspex tubing which is fitted to the top of the can onto the tyre valve.
I got a phillips screwdriver out of the bikes toolkit and unscrewed the screw from the tyre - I put the tyre in a ten past ten position rather than the recommended ten to ten as in the ten to ten position the exhaust can/chain/pillion footpegs got in the way of the tyre repair can.
I pressed down on the button on the top of the can and saw the foam go into the tyre through the can’s clear perspex tube - for a couple of minutes the tyre stayed flat and nothing seemed to be happening except for some large gobs of foam coming out of the puncture hole - I thought ‘crap - this stuff is just some gimmik that doesn’t work’ - but a minute later the tyre started to inflate and harden and the foam stopped exiting the tyre - basically the foam gradually sealed the tyre which then allowed the gas in the can to inflate the tyre.
After about four minutes the can was spent and I detached it from the tyre - the tyre was partially inflated and fairly hard - I sat on the bike and paddled it forwards a few feet and it seemed rideable - although the instructions on the can recommend a top speed of 30 mph with stops every fiteen minutes to check the condition of the tyre. I thought that’s gonna be fun - riding home at 30 mph - I’ll have to ditch the motorway and take the back route - I knew I was going to have to leave work late anyway that night and the prospect of getting back past midnight after limping back home on a partially inflated tyre was a bit of a downer.
Anyway - I came back to the bike after work that night wondering if I would get home at all. At first I threaded my way slowly through the streets out of central London hoping the tyre would hold up - which wasn’t a problem as these streets are full of traffic and slow anyway even at 11p.m. at night. Riding the bike it was obvious that the rear wheel was under-inflated - but in a straight line it felt quite safe and rideable - I kept my lean angles down as with the rear tyre at a relatively low pressure the sidewalls of the tyre would be a lot weaker than usual.
30 mph felt ok and as I got farther out of London I felt confident enough to raise my speed to 40 and then 50 mph which also felt ok - although I kept the bike pretty upright and allowed a lot of more time and room for braking.
I felt confident enough to get on the motorway and cruised back at 60mph - although I reckon I could have done 70 no problem - when I got home the tyre looked fine and did not feel especially hot. In retrospect I probably could have stopped and inflated the tyre to the proper psi at a service station - but I thought it would be better to leave it alone seeing as it was doing ok.
Anyway - this stuff worked for me and got me out of a tight spot - so I reckon it’s worth having a can in your tankbag.
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_220357_langId_-1_categoryId_165547
There are a couple of reviews slagging it off - but it worked for me and lot of other riders have also given it praise.

