Jonathan Garvey 4 As my bike has small 16 inch wheels and no spokes but rather aluminium sections it was difficult to fit the very small bottle nozzle into the valve . For small tyres with no room better to buy a plastic syringe with tube to inject. For larger bikes I am sure it is easy . Had a small puncture on a spare tube, found the hole and put my finger over it. It was sealed within seconds ( do not know if this still works under pressure as I have not used it yet