[pwork]

I've been chasing a ghost shifting problem on my wifes bike for some time now and may have found the issue. I was adjusting her rear brake, when spinning the wheel, I noticed that here cassett had a bit of runout (guessing .020-.050") which indicates to me that the freewheel is not spining on the same axis as the hub (~2001 Bonty disc wheel set not sure what model). I did this also with my wheel set and the runout was there but not as bad (2008 bonty select).

~2001 Bonty disc wheel set (not sure what model)

I poped the axel out and couldn't tell it had any bend. I've never taken apart a rear hub, are there going to tons of little pieces that fall out? Is it worth taking the freewheel off? Any hope for this hub or do I just upgrade? Any insight would be helpful.

 

[Mike T.]

Lots of hubs suffer from the Wobbling Cassette Syndrome and many of them are way more expensive than yours. I doubt it is the cause of the problem.

Please explain your ghost shifting - just when does it happen?

Can you swap her wheel for another wheel to see if this cures the problem?
Can you put her wheel in another bike to see if it brings the problem?

Ghost shifting that I have experienced was due to frame flex - standing and powering out of the saddle flexed the frame and pulled on the downtube mounted shift cable.

Make sure your wife's cassette lockring is tight.

 

[pwork]

LOL @ WCS, well that's good to know that it is a fairly common problem. As a mech eng, I would have never guessed that there would be that much wobbling in the system. I figured that with the 9 speed spacing that amount of lateral movement compared to the upper jocky it was the cause of the derailment.

The ghost shifting issue has largely been resolved by new cables (including full length to the rear), upgraded shifter, rear der and cassett. I had originally tried to build her a bike from hand me downs, when I couldn't get that package to work, I upgraded and with fine tuning it is acceptable. However, it still acts up randomly...and I hear about it! Good thing is (if there is a silver lining) that she can't lay down power in a high gear due to some torn cartilidge in her knee so she only uses a few gears when moderate power is required.

Obviously, I haven't done all steps you've recommended, I'll try that as weather permits. When I popped the axil out, the ball bearings were dry so I'm going to lube them up and see if I can get the freewheel off to get to that side. Since I've never seen a freewheel off I'm not sure what to expect.

 

[Mike T.]

It could be a bent derailer hanger. You mention 'cassette' and 'freewheel' in the same post so it's tough to tell you what you'll see when it's off. No matter as Park Tool has repair info for all this on their site. You'll be able to see what you've got.

You still didn't say exactly when it does the ghost shift or what actually happens. Does it actually shift up or down a gear? And the derailer indexing it set to a gnat's whisker?

 

[pwork]

Sorry for the confusion, I mistook freewheel to mean the same as a freehub/cassette hub according to Park (btw thanks, hadn't been to their site). I first noticed the runout when the cassette was installed. When I took it off the hub, the freehub had a lot of lateral play. I got the axel out, but didn't have an allen wrench bigger than a 10mm to take the freehub off. Looks to be a 11 or 12 and access is gained from the non drive side (disc brake side).

To be honest, I'm not sure if it ghost shifts up or down, as my wife's descripters are worse than mine. I assume that it is going down the cassette (skipping into a harder gear). I can't get the bike to reproduce the symptoms as it is very random now. But yes, I have the indexing set right on. Our schedules don't mesh well so I only ride with her 1 out of 3 times she goes to the trail...after watching her bash her bike on rocks during hike-a-bike I now understand why I spend so much time working on it!

 

[Mike T.]

Sorry for the confusion, I mistook freewheel to mean the same as a freehub/cassette hub according to Park (btw thanks, hadn't been to their site). I first noticed the runout when the cassette was installed. When I took it off the hub, the freehub had a lot of lateral play. I got the axel out, but didn't have an allen wrench bigger than a 10mm to take the freehub off. Looks to be a 11 or 12 and access is gained from the non drive side (disc brake side).

It should be a 10mm I think. And the wrench goes in the drive side after the axle is out.

To be honest, I'm not sure if it ghost shifts up or down, as my wife's descripters are worse than mine. I assume that it is going down the cassette (skipping into a harder gear). I can't get the bike to reproduce the symptoms as it is very random now. But yes, I have the indexing set right on. Our schedules don't mesh well so I only ride with her 1 out of 3 times she goes to the trail...after watching her bash her bike on rocks during hike-a-bike I now understand why I spend so much time working on it!

There's so many things that can cause bad shifts (gummy cables, bent hanger, bent derailer, flexy frames, bad indexing, pooched shifter and maybe a few others) it's tough to say wha the problem is without seeing it. Just buy her a new bike for xmas eh. :thumbsup:

 

[davep]

I got the axel out, but didn't have an allen wrench bigger than a 10mm to take the freehub off. Looks to be a 11 or 12 and access is gained from the non drive side (disc brake side).

It is a 12mm wrench that you need to remove a 'shimano compatible' freehub. Problem is that it is a sealed mechanism and cannot be serviced.....

Good thing that if it is indeed a shimano compatible unit (this defines the freehub to hub interface, and a LOT of lower priced and OEM hub mfg use these parts), you can just bolt a new one on and they are fairly inexpensive. see here: http://www.jensonusa.com/store/product/HU408Z14-Shimano+8+Speed+Hg+Freehub+Body.aspx as an example. If you have a local bike shop, they should be able to help as well...

 

[PlasticBike]

You may want to make sure (if you haven't already) that the hub itself is adjusted correctly. I was chasing a similar ghost-shifting issue on a bike. At first, I was just working it in the stand, and couldn't get the problem to happen. I was inclined to tell the owner to come back when it was misbehaving regularly enough to be caught. Instead, I decided to ride it around the block, and sure engouh: shifting of its own volition, up AND down. But what was really weird was how squirrely the rear wheel was. I adjusted the bearings, and rode it again - shifting was fine. Apparently, the hub had enough slop in it that, combined with a moderately loose freehup body, the whole cassette was wobbling under load, and this is what was causing the ghost shifting.