Bicycle Mechanics - Jamis Aurora Ghost Shifting When Standing on Pedals

I've been having some trouble with my 2009 Jamis Aurora, which I love.

It's been ghost-shifting (up to a higher gear) when I stand on the pedals going uphill. I like to be able to stand and stretch my legs sometimes on long climbs and increasingly the bike jumps to a smaller cog, at which point I MF the poor drivetrain out loud.

Here are some things I've ruled out:

1. Chain and cassette. Relatively new and properly installed.
2. Cable and housings. Recently replaced and properly installed.
3. Cable tension--oft-adjusted. Works fine on stand and when I'm not hammering.

Here's what the tech at my LBS (whom I trust) said:

There's a mismatch between the Tiagra shifters and the Deore derailleur, a road-mountain combo necessitated by the fact that Shimano makes no touring group. Jamis addressed this problem on more recent models of the Aurora and Aurora Elite by replacing the Tiagra STI shifters with bar-end shifters which would not have been a solution for me, as I don't much like bar-ends (no offense to them that do!).

I'm told there isn't much I can do about this other than switching to a Tiagra rear derailleur, but then I have to go from an 11-32 to an 11-28 cassette, and while that would probably be okay commuting (though I live in hilly Pittsburgh and certainly do spin in the granny gear from time to time), if I decided to do even a light loaded tour and hit some real hills, I could be unhappy. I'm not paying hundreds of dollars to replace my whole drivetrain with a Sram Apex--I don't know that I even could.

I like the triple crankset and the big range in the back. Anybody else encountered this problem and have any bright ideas, or do I just have to live with the occasional involuntary upshift until I decide to replace this otherwise worthy bike?

Thanks,

Matt

PS--I think the problem has been there off and on since I bought the bike, but has gotten worse of late. I've owned the bike for about a year and have probably put about 2500-3000 miles on it.

I don't know enough about the shifters in question to know if the mechanic is right or feeding you a line. What I can say with confidence is that I recently had a similar problem and it was caused by my derailleur hanger being slightly bent.

I don't know enough about the shifters in question to know if the mechanic is right or feeding you a line. What I can say with confidence is that I recently had a similar problem and it was caused by my derailleur hanger being slightly bent.

Thanks, woodway. As it turns out, the bike toppled over recently when the wind blew it off its kickstand. The hanger did get bent and I did straighten it so it's good now. When it was bent (and it was only for the rest of the ride until I could get it on the stand), it was just jumping around like crazy. When that was fixed, the crazy shifting was gone, but the ghost upshifting on hills was still there.

As for the tech feeding me a line, I really don't think so. He has treated me extremely well and has a great rep in town. I have never heard anybody say a bad thing about him, and he said this problem drove them crazy because they liked selling the Aurora. He said they tried a number of fixes to try to get it to stop, including taking out the barrel adjusters on the rear shift lever in hopes of removing unhelpful flex from the cable, but this didn't do any noticeable good.

But he may not know everything, so I'm not as concerned about the shop's honesty (although they did sell me the bike and presumably this had already come up, so there is that) as I am hopeful that somebody out there has solved this.

Thanks.

I don't know enough about the shifters in question to know if the mechanic is right or feeding you a line. What I can say with confidence is that I recently had a similar problem and it was caused by my derailleur hanger being slightly bent.

That said, I will check the hanger again.

That said, I will check the hanger again.

are you checking it with the derailleur alignment tool, or just eyeballing?

are you checking it with the derailleur alignment tool, or just eyeballing?

With the tool. Same distance to rim all the way 'round (90 degree intervals).

assuming it's 9 or 10 speed - is there a spacer behind the cassette on the hub?

Perhaps a little off-the-wall, but a thought: you say you suspect the problem has been present to some extent since new? If so, and if you are a bigger and/or stronger rider, you might be flexing the (steel) frame quite a bit (i.e. excessive twist at the b/b putting everything momentarily out of alignment) when you stand/pedal. This can be a cause of 'ghost shifting'. Do you have the problem at all when in the saddle, even when hammering? Remote, but it is a possibility if everything else is newish/within spec.

Here's what the tech at my LBS (whom I trust) said:

There's a mismatch between the Tiagra shifters and the Deore derailleur, a road-mountain combo necessitated by the fact that Shimano makes no touring group.

This is false. The cable actuation ratio is a perfect match between your Tiagra rear shifter and your Deore rear derailleur, they should work perfectly together despite the fact that Tiagra is from the road lineup and Deore is from the mountain lineup. Makes absolutely no difference in this case, the cable actuation ratio is the key, and it matches with those parts.

We sell a lot of Auroras at our shop, and the only inherent shifting problem we've found with bikes from the time period of your '09 bike is that the stock shift cable housings are prone to collapse at the ends of the housings prematurely. That's the first thing we check when there's a shifting problem with one of those bikes; you say you've already re-cabled the bike (including new housings), and you've also checked the derailleur hanger alignment. Those would be the two most likely suspects in my mind. One other thing that comes to mind, based on the what you describe and the pedaling uphill out of the saddle when the problem occurs, is that the rear triangle may be flexing enough when you do this to cause the ghost shifting. I've not seen this with an Aurora that I can remember, but it's certainly possible that it could be happening if you're REALLY torquing the drivetrain. The bike has relatively long chainstays, which would be a contributing factor to rear end flex.

...if you are a bigger and/or stronger rider, you might be flexing the (steel) frame quite a bit (i.e. excessive twist at the b/b putting everything momentarily out of alignment) when you stand/pedal. This can be a cause of 'ghost shifting'......

+1. I mentioned that it my above post, and didn't read your post until just now.

^+1 on frame flex. But you don't necessarily need to be particularly big or strong to experience this.

With the exception of early Dura-Ace, Shimano STI is compatible with pre-2012 Deore RDs. The cable pull requirement is the same as it is with a Tiagra RD. For 2012, Shimano redesigned the Deore RD to be compatible with its previously released Dyna-Sis products. Dyna-Sis RDs require a different cable pull ratio and are not compatible with the old standard. There is no indexed road shifter that will work with the new pull ratio. Jamis' drivetrain change for 2012 was most likely due to it being less costly, not for being more compatible than the previous combination. Many bikes have been sold with factory-spec'd STI shifters and
Deore RDs over the years, including the Aurora since 2003.

Respect and trust that mechanic as you wish, but changing your RD and cassette isn't a remedy and will only result in a thinner wallet.

you might be flexing the (steel) frame quite a bit (i.e. excessive twist at the b/b putting everything momentarily out of alignment) when you stand/pedal. This can be a cause of 'ghost shifting'.

I agree. If you can't find any mechanical alignment issue as the cause, you might just consider changing your riding behavior during climbing. You've got a touring bike, you'll be able to spin in the saddle up those hill. =)

I agree. If you can't find any mechanical alignment issue as the cause, you might just consider changing your riding behavior during climbing. You've got a touring bike, you'll be able to spin in the saddle up those hill. =)
True, but the OP only stated that he prefers getting out of the saddle occasionally to stretch his legs, not that he needed to do so.

True, but the OP only stated that he prefers getting out of the saddle occasionally to stretch his legs, not that he needed to do so.

I think you guys have hit the nail on the head, and it's good to know the shifter and the derailleur should work together. By the way, the shop definitely did NOT recommend switching out the derailleur, so while I may now have some questions about their competence, I still don't think they're trying to upsell me. Like I said, they've been good to me. Everyone who buys a bike gets six months free maintenance and 15% off anything in the shop, and I've had mine for over a year and nobody's even hinted about ending that for me. In any case, I'll stop defending my LBS and address the frame flexing.

I know that the rear triangle is flexing. A week ago, it drizzled enough for my brakes to make some noise when they contacted the rim. I also, though, heard that noise when hammering the pedals, especially when I experimented and stood up in a high gear, even in the flats. Happened at the bottom of my pedal-stroke on the left side. Might have happened because of wheel flex, but I'm thinking the frame was definitely flexing and this could be the problem. Does steel flex more or less than aluminum or carbon (I know the answer to that question is probably infinitely complex. Materials engineers, bring it on!)

Thanks (sorta :)) for the climbing advice. Yeah, I definitely spin my way up hills, but like I said, sometimes it helps just to stand up for a little while and stretch it out, or I get impatient. Still would rather it didn't happen, but it's good to have a hypothesis and I might dry downshifting a bit even when I'm standing. No good for the knees if the resistance is too high, anyway.

Thanks all. I'll let you know if it helps. New wheel next week and I tuned up the bike today and had it running better than it has in months. Went up a short, not too steep hill out of the saddle just to test and it didn't ghost, so maybe there's hope.

This is false. The cable actuation ratio is a perfect match between your Tiagra rear shifter and your Deore rear derailleur, they should work perfectly together despite the fact that Tiagra is from the road lineup and Deore is from the mountain lineup. Makes absolutely no difference in this case, the cable actuation ratio is the key, and it matches with those parts.

We sell a lot of Auroras at our shop, and the only inherent shifting problem we've found with bikes from the time period of your '09 bike is that the stock shift cable housings are prone to collapse at the ends of the housings prematurely. That's the first thing we check when there's a shifting problem with one of those bikes; you say you've already re-cabled the bike (including new housings), and you've also checked the derailleur hanger alignment. Those would be the two most likely suspects in my mind. One other thing that comes to mind, based on the what you describe and the pedaling uphill out of the saddle when the problem occurs, is that the rear triangle may be flexing enough when you do this to cause the ghost shifting. I've not seen this with an Aurora that I can remember, but it's certainly possible that it could be happening if you're REALLY torquing the drivetrain. The bike has relatively long chainstays, which would be a contributing factor to rear end flex.

Thanks, that's all good info, and when I replaced the cable and housings, the condition you describe did exist in the housings for the rear shifter/derailleur.

I am bigger--198 lbs, and I think, as I described below, I am definitely flexing the rear triangle when I'm off the saddle and hammering the pedals. Good pickup.

Here's an update for all you helpful folks: The problem was, indeed, flexion, but not frame. It was wheel. My beleaguered stock wheel had been breaking spokes on the non-drive side for months and I was very tired of replacing them. Bought a new, better wheel and the problem is gone, presto.

Thanks for all the help.

I can't imagine how it could possibly be the wheel unless the spindle is made from al dente pasta; no amount of wheel flex should affect the positio of the cogs relative to the derailleur.

In fact, a stiffer wheel would be likely to exacerbate the problem, because you'd prolly get more frame flex instead.


Does steel flex more or less than aluminum or carbon

It depends more on design than material, but the answer is generally yes, because steel frames tend to use narrower tubes.

If the problem recurs, you might try a full length of housing between shifter and RD; if it instantly disappears, you know the answer is frame flex.