Chain slipping under load

robbiepapenfus
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Chain slipping under load

Postby robbiepapenfus » Mon Feb 26, 2018 12:09 pm

Hi All,

I have a Trek hybrid road bike which I bought new about 5 years ago and used it for my daily commute.

I noticed that the chain keeps slipping on the 2nd chain ring (the one which was most used). The slipping is only noticed when I push hard on the peddlers on harder gears. On the light gears, there is no slipping.

Functionally, everything is fine in terms of changing gears etc.

Any ideas what could be required to fixed the slipping on of the chain?

Cheers,
Robbie

eeksll
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Re: Chain slipping under load

Postby eeksll » Mon Feb 26, 2018 12:32 pm

worn chain or worn chainrings.

the cassette has probably worn too, have you changed any of that stuff in the 5 years?

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AUbicycles
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Re: Chain slipping under load

Postby AUbicycles » Tue Feb 27, 2018 8:09 am

There are a few things.

If you haven't regularly cleaned the chain and drivetrain, all of the tiny grit works like sandpaper and slowly grinds away. While cleaning can be a chore - it will increase the lifespan of your parts. Non-the less, a clean and lube can help it run better but if it is worn, then is really needs new equipment.

Firstly is the chain - these stretch over time and if it is no longer sitting nicely, then it would be more prone to slipping (which in turn wears out the chain ring as well. A new chain can also help and I would certainly get it checked for stretch.. after five years and a good lease of life, it may be due for a replacement anyway. On a commuter, these are generally not too pricey.

Secondly is the chain ring. This sounds like it is worn (due to the above). An image below provides an example, the teeth are shorter and more curved for the worn chain so it doesn't lock the chain in as nicely and it can slip over under heavy load.

Image

In summary, the chain ring (just one one) can usually be replaced and it is probably worthwhile replacing the chain. For an even more complete overhaul, check the rear cassette for wear. A new cassette can make it feel like a new bike again :)

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Duck!
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Re: Chain slipping under load

Postby Duck! » Tue Feb 27, 2018 8:56 am

The progression of wear is chain -> cassette -> chainrings. The chain is the most heavily loaded part of the drivetrain, so will wear out first. Depending on conditions of use and maintenance a chain could be worn out in as little a 3000km or as much as 8000km. The cassette will normally need to be replaced with every second chain, but again, depending on conditions of use & maintenance can be made to last for a third chain. Chainrings typically see out two cassettes.

So if your chainrings look like the above example, everything else will be well and truly worn out too.
I had a thought, but it got run over as it crossed my mind.

robbiepapenfus
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Re: Chain slipping under load

Postby robbiepapenfus » Tue Feb 27, 2018 9:11 am

Thanks for all the advice. Up until now, in terms of maintenance, all I have been doing it greasing the chain every 1-2 weeks and wiping down the chain from excess dirt.

This weekend I'm going to give both my bikes a good clean!

dunamis
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Re: Chain slipping under load

Postby dunamis » Tue Feb 27, 2018 2:07 pm

Was out riding yesterday with my son and his chain slipped under load. It was because I took it off to clean and wax and had put it back on with a joining pin and the link was tight. A tight link will skip over the cassette in the small sprockets.

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ValleyForge
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Re: Chain slipping under load

Postby ValleyForge » Thu Mar 01, 2018 5:29 pm

robbiepapenfus wrote:Thanks for all the advice. Up until now, in terms of maintenance, all I have been doing it greasing the chain every 1-2 weeks and wiping down the chain from excess dirt.

This weekend I'm going to give both my bikes a good clean!

But I think you'll not notice any improvement with a clean. Me thinks a trip to the LBS or a dive into the deep blue of DIY bike repairs.

We're here to help.
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Thoglette
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Re: Chain slipping under load

Postby Thoglette » Thu Mar 01, 2018 6:14 pm

Here's a worn chain next to a new chain. 116 links, half a link or so of "stretch" or 0.5%. It's stuffed.
Image

As it was the third chain on some of the franken-cassette, the new chain slipped in all gears. even the bits with only two chains worth of wear.
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hoffo
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Re: Chain slipping under load

Postby hoffo » Tue Mar 06, 2018 9:25 pm

Hi, my chain jumps off the cassette when under load, like the OP. See this slo-mo video on youtube, only 15 seconds and chain jumps twice.
https://youtu.be/lC_XqWHF-Ig
Its a hacked together pub bike, converted to a fixie by the previous owner. I didn't like the gear ratio so I replaced chain ring and the chain (its now a BMX-type chain). It then started jumping.
I think the previous responses answer my question too, ie I need to replace the cassette, right?

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Re: Chain slipping under load

Postby AUbicycles » Tue Mar 06, 2018 10:45 pm

Hi hoffo, if that is a single speed, based on the info here you would go for a new chain and the single cog (or cassette). Good news is that if is is a single speed, a replacement cog is fairly inexpensive.

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Duck!
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Re: Chain slipping under load

Postby Duck! » Tue Mar 06, 2018 11:02 pm

If it has only started jumping/slipping after replacing the chain and chainring, that can only mean the sprocket on the rear is worn and not meshing with the new chain.
I had a thought, but it got run over as it crossed my mind.

hoffo
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Re: Chain slipping under load

Postby hoffo » Wed Mar 07, 2018 9:58 am

Thanks AUbicycles and Duck. Yes sounds like I need a replacement cog/sprocket. Kinda obvious i guess, its the only old bit left :)

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