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Decathlon B'Twin Chain Checker

by roadbikepilgrim
Wed, Jun 16, 2021 15:11
16

Hi there,

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 indecision .

Cheers,

roadbikepilgrim

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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16 comments

Avatar
Chris Hayes | 3 years ago
0 likes

Decathlon is a great store, but I wouldn't have thought precision tools was something that you'd outsource to China.  Stick to Park. 

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Dave Dave | 3 years ago
1 like

In practice, the whole idea of measuring chain wear is nonsense. Chains don't wear out before they're going to be replaced anyway, on the whole. If they are so worn that they ought to be replaced, it's obvious without measuring.

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Sriracha | 3 years ago
0 likes

According to The Guru, "There are also special tools made to measure chain wear; these are a bit more convenient, though by no means necessary, and most -- except for the Shimano TL-CN40 and TL-CN41 -- are inaccurate because they allow roller play to confound the measurement of link-pin wear."
https://www.sheldonbrown.com/chain-wear.html#measure
I'm sure there used to be a whole illustrated discussion of the issue on his pages, but that bit seems to have vanished.

I just measure 12 links with a steel ruler whilst the chain is hanging up after waxing (doesn't everyone do that?)

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hawkinspeter replied to Sriracha | 3 years ago
2 likes

You're probably thinking of this page: http://www.pardo.net/bike/pic/fail-004/000.html

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wtjs | 3 years ago
0 likes

Checking against a new chain would presumably work- this tool must show a new one as at least half worn. The trusty Rohloff tool doesn't even begin to 'sink' on a new chain.

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andystow | 3 years ago
5 likes

It always pays to check your chain checker against good chain checker checker before using it.

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roadbikepilgrim replied to andystow | 3 years ago
1 like

I am not convinced by that argument. Are you suggesting that people should simultaneously buy a premium product and a budget product, to verify whether the budget product does its job?

How was I or anyone to know that the Decathlon tool would be so inaccurate? I had my suspicions after using it, as described in my original post, but chains are standardised. If you decide to design a checker that is going to fit between a number of links with the value x , then you get y, which is a precise figure based on the standard lengths of links and gaps in a chain. Your checker then needs to be 0.75y long on one side and 0.5y long on the other. Not exactly a difficult engineering and manufacturing challenge, so one just assumed the tool must have been right, even though chain life was so short.

I can only be faulted for not trusting my own judgement and buying a different tool earlier. Decathlon are to blame for a dud design, which they did not bother to test or compare to other similar tools to assess real-world performance.

Avatar
wycombewheeler replied to roadbikepilgrim | 3 years ago
0 likes

buy both and return the expensive one if they match, and return the cheap one if they don't.

Although reports on the restocking practices of various online retailers makes the ethics of this approach questionable.

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andystow replied to roadbikepilgrim | 3 years ago
3 likes

roadbikepilgrim wrote:

I am not convinced by that argument. Are you suggesting that people should simultaneously buy a premium product and a budget product, to verify whether the budget product does its job?

How was I or anyone to know that the Decathlon tool would be so inaccurate? I had my suspicions after using it, as described in my original post, but chains are standardised. If you decide to design a checker that is going to fit between a number of links with the value x , then you get y, which is a precise figure based on the standard lengths of links and gaps in a chain. Your checker then needs to be 0.75y long on one side and 0.5y long on the other. Not exactly a difficult engineering and manufacturing challenge, so one just assumed the tool must have been right, even though chain life was so short.

I can only be faulted for not trusting my own judgement and buying a different tool earlier. Decathlon are to blame for a dud design, which they did not bother to test or compare to other similar tools to assess real-world performance.

Sorry for the whooosh!

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roadbikepilgrim replied to andystow | 3 years ago
4 likes

There is no need for your apology, but you might remember that it always pays to check your forum comment against a good forum comment before saving it...

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Flintshire Boy replied to roadbikepilgrim | 3 years ago
0 likes

Chill a bit! Don't take EVERYTHING completely seriously!

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Rendel Harris | 3 years ago
3 likes

Really poor from Decathlon, whose products are generally excellent for the price - email their customer services, they are excellent and quick to make amends and offer compensation when they make a mistake in my experience. 

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roadbikepilgrim | 3 years ago
2 likes

Here is the photo of the Park Tool chain checker showing the same KMC X11 chain as hardly worn after between 1000 and 1250 miles!

Even when allowance is made for the different length of the two tools (i.e. they are measuring different parts of the chain, though both starting from the same link), the inaccuracy of the Decathlon tool in the photo in the other comment is clear to see.

 

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roadbikepilgrim | 3 years ago
2 likes

Here is the photo of the Decathlon chain checker showing a KMC X11 chain as shot after between 1000 and 1250 miles.

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andystow | 3 years ago
1 like

Thanks for the warning.

You can upload photos, one per comment, you just can't have photos in the original post.

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hawkinspeter replied to andystow | 3 years ago
1 like

andystow wrote:

Thanks for the warning.

You can upload photos, one per comment, you just can't have photos in the original post.

If you're prepared to host the file externally (e.g. on Imgur) then you can put a link to the JPG between a couple of IMG tags and that way you can put images into the original post and comments. Slightly more work than just uploading it, though.

I'm amazed at the Decathlon chain "checker" - how could they have got it that wrong?

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