Poor old bike chains, they get the absolute worst of the muck and the miserable conditions on the roads, and we rarely look after them as well as we should. Eventually, even the toughest chains get worn out and signs of stress begin to show. This tool from XLC, the TO-S69 Chain Wear Indicator, will help you assess how far your chain has stretched and whether it’s time for it to be replaced. A stretched out chain can be the reason your gears are ‘skipping’ when you pedal hard, and in some extreme cases they can even snap while you’re riding. The tool is two-sided, so it can be used with either aluminium and titanium sprockets, or steel ones. The wear rates are 0.75% for aluminium and titanium, and 1% for steel.