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The chain on my bike has started to slip a lot -- every couple of seconds when riding. It happens, as far as I can tell, in every gear, and is unrelated to shifting.

The precise nature of the problem is hard to diagnose because I can not make it happen when the bike is on a stand, it happens only on the road.

What kind of chain/derailleur problem would manifest only on the road and never when the bike is on a stand?

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    A bike on the road flexes due to your load -- weight, pedal stroke, etc. A bike on the stand doesn't. – Batman Apr 15 '16 at 13:55
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    You may have a stiff link on your chain. With the bike on the stand, spin the pedals backwards so all the mech is spinning but the wheels are not. See if as any particular point on the chain passes through the derailleur the derailleur gets pulled forward, this would show where the stiff link is. Try this in multiple gears. I've had this cause slipping under heavy load. – renesis Apr 15 '16 at 18:35
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You likely have a problem with worn drivetrain components. You only really notice the jumping under load is my experience.

It's either a worn chain or a worn cassette in most cases. If you replace the cassette, replace the chain too.

Surprisingly enough, a worn chain and a worn cassette may work well together till one of the two parts are replaced.

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If the problem was worse in some gears, I'd say you have worn-out cogs. But you say that it doesn't depend on the gear... So I'm going to guess that your freewheel mechanism is failing, and the pawls are slipping when they're under heavy load.

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When all drivetrain parts serviced and in good repair, this problem doesn't happen. Couple of things you can check: Front and Rear derailleur adjusted properly. Check the chain stretch. How worn out is the cassette?

I don't presume to tell people what to pay for; but bringing your bike into a good local bike shop for a tune is the fastest way to get this fixed. They may also notice if you have other unnoticed issues, parts in need of replacement or grease can make for a more enjoyable riding experience. Bike tunes can range from $50-$300 in my area, all depending on the level of work to be done. The $50 tune is the most basic, pump tires, clean and oil chain, adjust gears (minor adjustments no extra parts like cables), adjust brakes. Where the $300 tune is a full breakdown of the bike. Everything get's put into the part wash, new cables (shifters and breaks) so on and on... Thank should cover it, Good luck.

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  • The problem started only after I brought the bike in for a tune-up. I think I need to bring it back to them. – Michael Stern Apr 15 '16 at 14:44
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    @MichaelStern Definitely. I'd drop a bike shop if they didn't investigate an issue that appeared after a service. Of course, they can disagree on if it was an issue caused by them. – SGR Apr 15 '16 at 14:57
  • the answer -- The bike had a new chain and cassette, which revealed some slightly bent and/or chipped teeth on both old chainrings. I guess the previous chain had been more forgiving. Anyway, we straightened the bent teeth and all was well. – Michael Stern Apr 26 '16 at 10:48
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Similar thing happened to me before but not in that amount that chain would slip completely. I was also using bike stand and after adjusting gears (while bike was on bike stand), my chain was slipping a little on every cog during ride.

I think, there is a slight possibility if you use this kind of bike stand, that when you place your bike on the stand, clamp that holds frame in place, tightens the gear cables. That could be the reason why some things work on bike stand and fail when you ride your bike. It is always best option to attach bike stand clamp to seat post (beneath the seat) and not on some other part of bike frame (where center of gravity is) where you can accidentally stretch cables.

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As Mike answered, mostly the chain slips when the cogs are worn, thou, as he pointed, it's common to start with some gears, not all of them. Only one time I saw a cassette worn out so it was slipping on all the cogs.
Second thing to check is the chain. When the chain is worn (or not proper length) it can slip also.
But if it happened after only after a service in bike shop, I'd guess, it's bad tuning they done. But yet maybe you had the problem with components a little bit worn, and now you just feeling it more.

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It happens when you put pressure on the chain, not when switching gears, right?

If it's a more recent issue, usually this happens due to wear & tear on Chain/Cogs/Chain ring. (Chain rings wear off and become less able to grip the chain.

I had to replace my chain ring a few months ago when that happened. Replacing chain rings doesn't mean replacing the whole crank. For Cogs sometimes you can swap out just the bottom most worn cogs. Chains have to be replaced every 2000k or so on a MTB, probably less often on a road bike.

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I will describe my bike 'problem' so you can see whether it fits with your problem. I know what the reasons are and how to solve them, so it is not an 'I also have this problem' answer.

I have the problem of a slipping chain and on my bike it is clearly a tension wheel that moves out of its place, so in fact the chain is not tensioned enough.

The slippage starts when there is stress on the chain, like when riding away from the traffic lights and on the steep parts of hills. When the wheel moves a bit more/the chain becomes a bit longer compared to what is should be, the slipping becomes more general, if still worse when trying to increase speed.

In the last stage, the chain jumps in every stroke of the pedals and cycling becomes impossible. (Then I take out the tools and fight the system so the tension wheel will be in the proper position for a while.)

Unless your bike is in the 'last stage' you will not be able to copy it on the stand as you do not put the same amount of power on the chain, so do not get the same stresses on it.

This is on my recumbent bike, which has a long chain and is designed for lots of adjustments for different riders.

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