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PostPosted: Wed May 01, 2013 6:59 pm 
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Joined: Wed Oct 03, 2012 11:47 pm
Posts: 68
Location: UK/Industry
Have recently installed the following combos;

695sr, zed crank, 52/36, 6700 chain
Bianchi Oltre xr, DA 7900 crank, 52/36, praxis bb, 6700 chain
Neil Pryde Alize, Ultegra 6700 crank, 52/36, praxis bb, 6700 chain

On all of these I've had issues with the chain dropping either off the inside or outside, or the chain riding up onto the tops of the teeth. On both the Oltre and 695, when in small/small, it also tries to upshift without any shifter input. I'm inclined to think it relates to chainline but I can't see how that could be resolved easily and when I put the shimano rings back on (albeit in 50/34) there are no issues whatsoever. I am certain the installation is spot on in all cases. Has anyone else encountered these issues with praxis and if so what solution was offered? My local praxis agent (I'm outside the US) isn't all that clued up on the product.


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PostPosted: Wed May 01, 2013 8:12 pm 
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Joined: Tue Feb 05, 2013 8:29 pm
Posts: 236
The solution is simply to not cross chain. Once you get to the 7th sprocket, upshift the front ring and downhift the back three times. That's usually equivalent to one upshift, and keeps your chainline where it should be. There's really no reason to be in small/small or large/large unless you're doing some insane climbing and can't afford trying to change rings.

IIRC, Praxis rings tend to have pretty aggressive pins/ramps, so it makes sense that it's trying to cross-chain-shift when your Shimano rings don't.


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PostPosted: Wed May 01, 2013 8:39 pm 
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Joined: Wed Oct 03, 2012 11:47 pm
Posts: 68
Location: UK/Industry
That was just one small issue(that I'd expect on bikes with short chainstays). Not cross chaining will not solve the other issues as they happen in various circumstances, for example the top gear(52/12) on the Alize was the worst culprit for the chain riding onto the tops of the teeth(and trying to jump off the outside).


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PostPosted: Wed May 01, 2013 9:05 pm 
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Joined: Tue Feb 05, 2013 8:29 pm
Posts: 236
Gotcha. If it's falling inside of the small ring or outside of the large ring, are you sure the FD is set up properly? Make sure there's about 1mm between the teeth of the big ring and the bottom of the cage, then set your limit screws so that you're a half turn-ish away from little-big and big-little chain rub. There shouldn't be enough physical space to let the chain drop without significant load. I know that you said you're sure the installation is spot-on, but it's worth giving it a double check especially if you're switching rings like you mention.


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PostPosted: Wed May 01, 2013 9:40 pm 
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Joined: Wed Oct 03, 2012 11:47 pm
Posts: 68
Location: UK/Industry
I'm sure everything is set up correctly, I'm a full time wrench ;) I've checked and double checked that everything is installed and set up spot on. Besides the problems with the chain riding up on the teeth in certain combinations happens without any fd rub.


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PostPosted: Wed May 01, 2013 9:45 pm 
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Joined: Tue Feb 05, 2013 8:29 pm
Posts: 236
Very good, just gotta cover all the bases you know? There's another thread going on about a guy with Ui2 and Praxis rings having trouble, so it might be worthwhile reading through it.

viewtopic.php?f=3&t=115434&start=15


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PostPosted: Wed May 01, 2013 9:53 pm 
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Joined: Wed Oct 03, 2012 11:47 pm
Posts: 68
Location: UK/Industry
I appreciate the suggestions, I saw that thread right after I posted this one, seems he's having the same problem I had on the Oltre. I'm really stumped as to the cause, it's all brand new kit with no apparent flaws in the praxis rings, yet they work fine with shimano rings or the look zed rings on the 695.


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PostPosted: Wed May 01, 2013 11:11 pm 
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Joined: Fri Mar 09, 2007 1:26 am
Posts: 547
Location: USA
I recently installed a set of Praxis rings (52X36) on a 9070 group and the shifting is flawless here.


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PostPosted: Thu May 02, 2013 2:52 am 
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Joined: Sat Jun 13, 2009 4:02 am
Posts: 1980
Location: NoVA/DC
If you email Praxis, they may say it's a flawed ring set and send you another one. They have very good customer service, and it's the only true solution to your problem.
Inner ring is facing the correct direction, right? just checking...


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PostPosted: Thu May 02, 2013 3:53 am 
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Joined: Wed Mar 06, 2013 4:23 pm
Posts: 614
Location: Austin, TX
On that note your rings are lined up properly, with the little tab and all?

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