Chain jump only when pedaling backwards (on stand)
08-01-21, 10:41 AM
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Chain jump only when pedaling backwards (on stand)
I have a freehub drag issue on a road bike with the latest Ultegra. I have the bike on a stand, and when I slowly spin the pedal backward the chain skips down to a smaller gear. When I pedal forward, the chain goes back up to the correct gear. The bike shifts perfectly otherwise: normal shifting, pedaling forward. I only see this when pedaling backwards.
To clarify, I don't think freehub drag has anything to do with this. That is the reason I happen to have the bike on a stand and pedaling backwards.
What is going on here??
To clarify, I don't think freehub drag has anything to do with this. That is the reason I happen to have the bike on a stand and pedaling backwards.
What is going on here??
Last edited by ronopolis; 08-01-21 at 10:49 AM.
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08-01-21, 11:47 AM
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I'll second that this is normal behavior. The system is not designed to be pedaled backwards. The rear derailleur controls the lower run of chain and guides it onto the selected cog when pedaling forward. When you pedal backwards, there is nothing guiding the top run of chain onto the selected cog, so it tries to take the straightest path from the chainring to the cassette.
08-01-21, 11:49 AM
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OK, thanks guys. I've had many bikes that do not do this. But I'm all good
08-01-21, 11:53 AM
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Does the chain jump to another sprocket in all gears or only the ones where you are cross chained? Also, bicycles with short chainstays are much more prone to this than bikes with longer chainstays
08-01-21, 01:39 PM
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I don't think quite normal my bike spins backwards easily although cross chaining does not make it so great but it still has no issue. Something is a bit off and my guess is check B tension screw and go through a complete re-indexing. What shifters and speed/groupset do you have?
08-01-21, 02:21 PM
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Causing the chain to approach the cassette at an angle is precisely the principle on which derailleur systems are based. Some bikes, particularly bikes with longer chainstays and modern flexible chains, can be pedaled backward in most or even (maybe) all gear combinations without derailing the chain, but that's a matter of happenstance, not a design goal.
I doubt that any of my short-wheelbase racing-geometry bikes can be pedaled backward in the various extreme gear combinations. I'll probably never know.
08-01-21, 02:32 PM
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Really? Including in the big chainring/big sprocket combination?
Causing the chain to approach the cassette at an angle is precisely the principle on which derailleur systems are based. Some bikes, particularly bikes with longer chainstays and modern flexible chains, can be pedaled backward in most or even (maybe) all gear combinations without derailing the chain, but that's a matter of happenstance, not a design goal.
I doubt that any of my short-wheelbase racing-geometry bikes can be pedaled backward in the various extreme gear combinations. I'll probably never know.
Causing the chain to approach the cassette at an angle is precisely the principle on which derailleur systems are based. Some bikes, particularly bikes with longer chainstays and modern flexible chains, can be pedaled backward in most or even (maybe) all gear combinations without derailing the chain, but that's a matter of happenstance, not a design goal.
I doubt that any of my short-wheelbase racing-geometry bikes can be pedaled backward in the various extreme gear combinations. I'll probably never know.
