Chain suck

[Chrisjvv]

I’m experiencing chain suck on my Specialized Diverge on every ride. I have to replace my chain now again for the second time after the last ride because it got twisted up between the bottom bracket and the chain ring.

Ultegra all round, praxis crank and chain rings. Smoove chain lube.

 

It happens in all configurations, small ring to big ring - big ring to small ring - rear derailleur clutch engaged or disengaged - tar road or gravel road - it just happens.

 

I suspect I’ll have to change the crank to shimano to sort the problem out.

 

Any advice, spell, magic potion or old dark art of bicycle maintenance to help me finish a ride without oily hands and fingers?

Edited January 3, 2021 by Chrisjvv

[DR ◣◢]

Have you replaced the chainrings yet?

[Chrisjvv]

Not yet. Bike has not even done a thousand km

[SwissVan]

Not yet. Bike has not even done a thousand km

 

New bike then, take it back to the shop and tell them to maak reg

[RobertWhitehead]

Sounds to me like your freebody is the issue, does it happen the moment you stop pedaling?

[MrJacques]

Don't shift

 

Could be a couple of things.

 

- Dirty or worn chain. Stiff link(s)

- Worn chainring (unlikely, but possible. maybe a bent tooth?)

- New chain on old chainring

- Chain too long (not enough tension)

- Front derailleur set at incorrectly (wrong angle?)

- Freehub drag

- Frame flex (if it only happens when shifting under load)

Edited January 4, 2021 by MrJacques

[MrJacques]

Looks a bit hacky and it's better to solve the actual issue, but apparently a zip tie 'peeler' can help if it happens.

 

[TheoG]

Looks a bit hacky and it's better to solve the actual issue, but apparently a zip tie 'peeler' can help if it happens.

 

 

Nice easy fix to treat the symptom, it should not happen in the first place though ...

[Jewbacca]

I'm going with freehub issue.

 

That or you are constantly shifting under load. 

 

My take would be to take it to an LBS to check. That way, if it happens again there is recourse.

[MrJacques]

Praxis chainrings and Ultegra chain... it may be the issue. Shimano designs their drivetrain as a system for everything to work together. The Praxis' tooth profile might not be 100% compatible.

[Chrisjvv]

Praxis chainrings and Ultegra chain... it may be the issue. Shimano designs their drivetrain as a system for everything to work together. The Praxis' tooth profile might not be 100% compatible.

This is what I’m thinking as well.

[Jewbacca]

Praxis chainrings and Ultegra chain... it may be the issue. Shimano designs their drivetrain as a system for everything to work together. The Praxis' tooth profile might not be 100% compatible.

No.. Plenty of bikes were specced with Praxis cranksets and Shimano shifting. The 12 speed MTB stuff is pretty specific, but the rest not so much.

 

Loads of pre GRX gravel bikes were specced like that. The issue is more ikely to be a too long chain or an issue with the free hub

[MudLark]

Usually caused by putting a new chain on a worn chainring, The pitch difference has the result that the chain weight is insufficient to cause it to drop off the teeth of the ring. In this case because everything is new, you've either got a poor chain (unlikely if its Shimano) or the chainring teeth are not accurately stamped. The only quick solution without fiddling around and trying this and that is to replace the Praxis chainring with something Shimano and make the sure the chain is Shimano and then you shouldn't have a problem.

[MudLark]

No.. Plenty of bikes were specced with Praxis cranksets and Shimano shifting. The 12 speed MTB stuff is pretty specific, but the rest not so much.

 

Loads of pre GRX gravel bikes were specced like that. The issue is more ikely to be a too long chain or an issue with the free hub

 

Yes. But something's wrong here. Maybe just this specific chainring. Maybe somebody dropped it before fitting it or something. Could try just replacing the offending chainring - and if that doesn't fix it then the chain too. Chain may well be twisted now anyway. Dunno. Only way is to try or just all new Shimano bits to be sure to be sure.

[Chrisjvv]

No.. Plenty of bikes were specced with Praxis cranksets and Shimano shifting. The 12 speed MTB stuff is pretty specific, but the rest not so much.

 

Loads of pre GRX gravel bikes were specced like that. The issue is more ikely to be a too long chain or an issue with the free hub

Awesome. Then I’ll keep the praxis crank.

Going to get the chain replaced today, hope it solves my problem.

Please explain what problem the free hub should have to cause chain suck that I can look out for that problem

[DieselnDust]

if the freehub is sticking i.e is not disengaging momentarily when you stop pedalling it will throw the chain or cause chain suck.

This could be because the freehub is too dry or because there's the wrong grease in there that's too tacky, causing the pawls to stay open and engaged just a fraction too long.

 

The only way your chainring is the issue is if the teeth in the power zone are worn to the extent the extent that it does not release the chain. This is highly unlikely on a bike with a 1000km even if the crank is a Praxxis

Edited January 4, 2021 by DieselnDust