Just to let you know, that if any of you are out there using a Decathlon B'Twin Chain Checker, then you should bin it.
I have used one for over three years. I only got 1000-1250 miles out of an 8-speed chain before the checker said it was worn. I always found this weird, because I am not heavy (only 68 kg) and I wipe and lube the chain after every second or third ride. In Lennard Zinn's opinion, a light rider who looks after his chain should be getting 3000-5000 miles out of a chain.
In early March I got a new bike with full Shimano 105 groupset and a KMC X11 chain. After the first 250-300 miles I checked the chain, and the Decathlon checker was showing it as almost worn. Absolutely insane.
So I bought the Park Tool CC3.2 checker, and sure enough it showed an almost brand-new chain as it was, i.e. almost brand new. The chain has now done over a 1000 miles and the Decathlon checker shows it as completely worn (i.e. the checker is lying flat on the chain). Of course, the Park Tool checker shows the chain as practically new. The Park Tool checker has not even begun to fall into the gap on the chain. I have two very good photos that show the difference between the two tools, but it does not seem possible to upload photos here.
On my first road bike with the 8-speed chain, I should only be, at the worst case, on my first replacement chain after the original chain. However I have bought four or five chains, due to the absurdly inaccurate Decathlon tool. This means a waste of £40-50 (I bought good-quality chains from the likes of KMC and SRAM, but thankfully at good internet prices): not a great sum in the grand scheme, but it is the principle isn't it?
How can Decathlon produce something so completely lousy? A few people have posted reviews on their website (I included) to say the tool shows excessive wear, but Decathlon are still selling it. Makes you wonder if their cycle helmets will actually work in the event of a crash .
If like me you were a fool and bought the Decathlon checker, then I advise you to see the light and buy the Park Tool checker or one of equivalent quality. If not, you will waste money on replacing chains that still have thousands of miles left in them .
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