Park Tools are an American company manufacturing bike tools for the home and professional mechanic. They claim to be the largest bike tool manufacturer in the world.
From personal experience I have found that while Park Tools are more expensive, they tend to be of higher quality than their competitors. Despite being an American company, most of their tools are actually manufactured in the far east.
Why would you want a Chain Checker?
Chains are said to stretch with use. The chain doesn't actually stretch. What happens is that the pins and bushings are worn away by use, creating play. A worn chain under tension will elongate further than a new one. Once the chain has elongated by 1% or more it is considered worn. This level of wear is not visually obvious. Chain checkers provide an accurate and reliable method of measuring chain elongation.
When new, the rollers of the chain sit close to the bottom of the sprocket. As the chain wears and elongates the rollers sit higher and higher on the tooth, wearing the sprocket teeth away. On the rear sprocket this wear changes the pitch of the sprocket, meaning that a new chain will no longer fit. On the front chain rings, this wear causes hooking of the teeth.
Excessive wear can cause a whole host of problems including difficulty changing gear both front and back, skipping of the chain on the rear sprocket, and dreaded chain suck on the front chain rings. Chainsuck occurs when the chain does not drop smoothly off of the bottom of the chain ring. Instead the chain ends up being "sucked" up around the back of the chain ring, where it meets the chain running across the top. This will typically lock the transmission.
Put simply changing your chain regularly will help reduce wear on chainrings, and rear sprockets. It will also keep your gear systems sweet, and help to reduce the number of failures out on your ride. Chainsuck can cause nasty accidents as well as destroy bicycle transmission systems.
For my off-road bike, I renew my chain and rear sprockets together. Some people claim that a sprocket will last 2 chains, but I haven't had much success doing this. I change the chainrings every other chain renewal. They might last longer than this, but it prevents me getting too many problems with chain suck.
What about the Park Tool Chain Checker?
The tool is simple to use. Position the concave semi-circular end around the roller, and then let the tool drop onto the chain. If the tab on the other end slots inside the roller, then the chain is worn to the limit marked on the tool.
The Park tools chain checker allows you to check for both 1.0% and 0.75% wear. The 0.75% marking allows you to plan chain/sprocket/chainring replacement.
Quality wise the tool appears to be made from stainless steel. No particularly sharp or rough edges, and fits nicely in the hand. The paint used for the graduation marks is tough and shows no sign of wearing off despite being regularly thrown in the bottom of my tool box.
Overall
It's cheap, it won't break, and it does the job
More details
Price
£7
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