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Old 07-05-12, 03:25 PM   #1
bjorke
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Bike Friday Mechanical Wisdom Sought

(Posting here before wandering to the Mechanics Section...)

So: my 12-year-old Pocket Rocket is skipping gears, both up and down, and not only under load.

My LBS swapped the (worn) chain, and the 8speed cluster looked worn too -- it was a Shimano HG-70, but (after calling BF to confirm) it started life as a NINE-speed set, which had the largest ring removed so that it would fit into the Sachs 3x7 gear hub. The LBS said that these days those gear sets are usually welded together, so just unscrewing one wasn't an option -- so we switched to a SRAM mtn-bike gearset that could be modified in this way (did I mention that my shifters and derailleur are Campy?).

But: it still skips around! Quite badly and randomly, even on flat roads.

So before I go back to my LBS (who are not, by default, Campagnolo dealers...), I'm pinging the wisdom here, in hopes of enlightenment.

The Ergo levers and derailleur are Campagnolo "Daytona" (now called "Centaur"). Is this likely to be an issue of weakened springs? Can these be swapped out, or am I looking at tracking down a new (old) derailleur? Can a new (new) one be used? Am I right in thinking that this is the old old style Daytona, rather than the new old style Daytona derailleur? This 2000-era bike is right on the "cusp" of a Campy design change...




Thanks for all insights!
kb
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Old 07-05-12, 03:40 PM   #2
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Can it be adjusted so that there is at least one gear where it does not skip around?

Pull out the derailer inner cable, squirt in WD-40, soak, blow out with compressed air, wipe the inner squeaky cleanwith WD-40, re-install. Like new. Dirty cables are always the reason why mine start skipping.
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Old 07-05-12, 09:13 PM   #3
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Quote:
Originally Posted by jur View Post
Can it be adjusted so that there is at least one gear where it does not skip around?

Pull out the derailer inner cable, squirt in WD-40, soak, blow out with compressed air, wipe the inner squeaky cleanwith WD-40, re-install. Like new. Dirty cables are always the reason why mine start skipping.
That is my question too. Assuming you clean it out and only a subset of gears skip, I'd check whether the derailer/derailer hanger is bent.

You have a 8 of 9 on 7 setup ...
http://sheldonbrown.com/k7.html#up7
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Old 07-06-12, 10:08 PM   #4
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Jur and IH both asked the same question, so they must be getting at something, but I don`t see what that is. What am I missing?

Sorry, Bjorke- I have nothing to offer except well wishes. I am curious, though.
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Old 07-06-12, 11:10 PM   #5
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Quote:
Originally Posted by bjorke View Post
(Posting here before wandering to the Mechanics Section...)

So: my 12-year-old Pocket Rocket is skipping gears, both up and down, and not only under load.

My LBS swapped the (worn) chain, and the 8speed cluster looked worn too -- it was a Shimano HG-70, but (after calling BF to confirm) it started life as a NINE-speed set, which had the largest ring removed so that it would fit into the Sachs 3x7 gear hub. The LBS said that these days those gear sets are usually welded together, so just unscrewing one wasn't an option -- so we switched to a SRAM mtn-bike gearset that could be modified in this way (did I mention that my shifters and derailleur are Campy?).

But: it still skips around! Quite badly and randomly, even on flat roads.

So before I go back to my LBS (who are not, by default, Campagnolo dealers...), I'm pinging the wisdom here, in hopes of enlightenment.

The Ergo levers and derailleur are Campagnolo "Daytona" (now called "Centaur"). Is this likely to be an issue of weakened springs? Can these be swapped out, or am I looking at tracking down a new (old) derailleur? Can a new (new) one be used? Am I right in thinking that this is the old old style Daytona, rather than the new old style Daytona derailleur? This 2000-era bike is right on the "cusp" of a Campy design change...




Thanks for all insights!
kb
Did you buy this bike used either from someone or pre-loved?!? I think I know what it is..

Thanks!
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Old 07-07-12, 01:29 AM   #6
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cant get an H cassette any more?. the 13~34t 7 set was perfect..
b screw is just to preload the top spring so quite pulley does not sit hard on the big cog

Components are normal , go to a bike shop, and get it looked at live and in person.
blind guesses for free are worth what you paid for them,..
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Old 07-07-12, 02:50 AM   #7
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Quote:
Originally Posted by rodar y rodar View Post
Jur and IH both asked the same question, so they must be getting at something, but I don`t see what that is. What am I missing?

Sorry, Bjorke- I have nothing to offer except well wishes. I am curious, though.
We also need to know now: is it a bent der hanger- or maybe the butler that is to blame? Hope you find the answer, and that we get to hear about it. I vote for a bent hanger.

Edit: http://www.bing.com/search?q=Bent+de...=0-0&sp=-1&sk=

Last edited by badmother; 07-07-12 at 02:54 AM.
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Old 07-07-12, 07:16 AM   #8
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Quote:
Originally Posted by bjorke View Post
(Posting here before wandering to the Mechanics Section...)

So: my 12-year-old Pocket Rocket is skipping gears, both up and down, and not only under load.

My LBS swapped the (worn) chain, and the 8speed cluster looked worn too -- it was a Shimano HG-70, but (after calling BF to confirm) it started life as a NINE-speed set, which had the largest ring removed so that it would fit into the Sachs 3x7 gear hub. The LBS said that these days those gear sets are usually welded together, so just unscrewing one wasn't an option -- so we switched to a SRAM mtn-bike gearset that could be modified in this way (did I mention that my shifters and derailleur are Campy?).

But: it still skips around! Quite badly and randomly, even on flat roads.

So before I go back to my LBS (who are not, by default, Campagnolo dealers...), I'm pinging the wisdom here, in hopes of enlightenment.

The Ergo levers and derailleur are Campagnolo "Daytona" (now called "Centaur"). Is this likely to be an issue of weakened springs? Can these be swapped out, or am I looking at tracking down a new (old) derailleur? Can a new (new) one be used? Am I right in thinking that this is the old old style Daytona, rather than the new old style Daytona derailleur? This 2000-era bike is right on the "cusp" of a Campy design change...




Thanks for all insights!
kb
I won't have internet where I'm going for a couple of days, so here's my thoughts as I used to run the same setup as yours.

First of all, I am assuming you are running the older Campagnolo 8 speed Ergo shifter (pre 2001 and later 2009; Campy used index in between except Chorus and up) with a Campy derailleur on a Shimano cassette. This system is known as "Shimergo". The only problem is that, the cassette pitch of the Shimano 8 speed cassette is "different" than the cassette pitch of the Campy 8 speed cassette. However, you can shift a Shimano OEM cassette 7 speed cassette with a Campy 8 speed Ergo and I suspect your bike first came to life as a 7 speed with 1 speed taken out. Since the cassette pitch difference between a Shimano OEM cassette and a Campy cassette is only 0.2mm (Campy 5mm and Shimano is 4.8mm), there were 2 ways to approach this. Buy the original Shimano OEM cassette since the tolerance is much higher than aftermarket or use the HubBub modification to change cable routing to clamp on a sharp acute angle inducing significant cable friction. Bike Friday chose the OEM cassette route with a Campy derailleur and provide so so shifting.
In the past, we used a device called the Avid Rollamajig (like a travel agent) to improve shifting a bit. Unfortunately, you are not using an OEM cassette anymore and aftermarket cassette is not that great (hence they are cheaper than Shimano), so without a cable pull ratio converter, you are simply out of luck. To complete this, you need to purchase a Jtek Shiftmate #1 which will solve your problem and you can use any kind of cassette, but ofcourse the OEM cassette if you can find one to allow the modification will shift much better than without it! I know as I used to have a Campy Ergo Mirage with the Sachs 3x7 hub and an 8 speed cassette mod from 9.

All bikes that came out of the factory after 2003 or 2004 should have the Shiftmate installed. I don't see any cable pull ratio converter on your derailleur, so I suspect somewhere along the line, someone modified this to work with Shimano cassette with so so shifting and now, when you replaced with a SRAM cassette, nothing will work.

Hope this helps..

http://jtekengineering.com/shiftmate.php (This gives you an idea of the conversion chart)

Last edited by pacificcyclist; 07-07-12 at 07:21 AM.
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Old 07-07-12, 11:42 AM   #9
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Quote:
Originally Posted by pacificcyclist View Post
I won't have internet where I'm going for a couple of days, so here's my thoughts as I used to run the same setup as yours.

First of all, I am assuming you are running the older Campagnolo 8 speed Ergo shifter (pre 2001 and later 2009; Campy used index in between except Chorus and up) with a Campy derailleur on a Shimano cassette. This system is known as "Shimergo". The only problem is that, the cassette pitch of the Shimano 8 speed cassette is "different" than the cassette pitch of the Campy 8 speed cassette. However, you can shift a Shimano OEM cassette 7 speed cassette with a Campy 8 speed Ergo and I suspect your bike first came to life as a 7 speed with 1 speed taken out. Since the cassette pitch difference between a Shimano OEM cassette and a Campy cassette is only 0.2mm (Campy 5mm and Shimano is 4.8mm), there were 2 ways to approach this. Buy the original Shimano OEM cassette since the tolerance is much higher than aftermarket or use the HubBub modification to change cable routing to clamp on a sharp acute angle inducing significant cable friction. Bike Friday chose the OEM cassette route with a Campy derailleur and provide so so shifting.
In the past, we used a device called the Avid Rollamajig (like a travel agent) to improve shifting a bit. Unfortunately, you are not using an OEM cassette anymore and aftermarket cassette is not that great (hence they are cheaper than Shimano), so without a cable pull ratio converter, you are simply out of luck. To complete this, you need to purchase a Jtek Shiftmate #1 which will solve your problem and you can use any kind of cassette, but ofcourse the OEM cassette if you can find one to allow the modification will shift much better than without it! I know as I used to have a Campy Ergo Mirage with the Sachs 3x7 hub and an 8 speed cassette mod from 9.

All bikes that came out of the factory after 2003 or 2004 should have the Shiftmate installed. I don't see any cable pull ratio converter on your derailleur, so I suspect somewhere along the line, someone modified this to work with Shimano cassette with so so shifting and now, when you replaced with a SRAM cassette, nothing will work.

Hope this helps..

http://jtekengineering.com/shiftmate.php (This gives you an idea of the conversion chart)
You just reminded me of why I like hubgears..
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Old 07-07-12, 04:10 PM   #10
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Zowie! Thanks for all the detailed replies.

In looking over the parts, I realized that the LBS put an 8-speed chain onto the (formerly) 9-speed cassette. I can see this guy mis-feeed on the stand ever at hand-crawling speeds -- a miss every 5 or 7 pins on the gear! So bringing it back to them (and see if they think the hanger is bent -- I've had that in the past on other bikes, but this one *seems* okay...) to see what can be done about that obvious gaffe first.

I have 9-speed ergo's being used as 8. BF shipped it in October 2000. There have been some changes, like swapping-out the original 406's for 451's (but keeping the campy & sachs hubs).

Thanks again, will report back!
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Old 07-07-12, 07:36 PM   #11
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...I realized that the LBS put an 8-speed chain onto the (formerly) 9-speed cassette...
They promptly corrected it -- rides much, much better in an initial trial around the neighborhood. Crossing fingers!
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Old 07-13-12, 01:25 PM   #12
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Yeah, funny how a chain too wide for the gear spacing will mess you up

Everything great now!

I am really really curious about the shiftmate now, too
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Old 07-13-12, 03:07 PM   #13
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Yeah, funny how a chain too wide for the gear spacing will mess you up

Everything great now!

I am really really curious about the shiftmate now, too
It will definitely shift better with shiftmate and also extend the wear of both your chain and cassette. That's my impression when I had it dialed in with the Daytona shifter I had on my NWT.
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Old 07-14-12, 12:54 PM   #14
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We had a bike with Campy Shifters and Shimano cassette. LBS took apart the cassette and applied different spacers that solved the problem. Don't know if this is done anymore. Also Tandems Limited sells a "Shimangolo" adapter that should fix the incompatibility of the gear spacing.
http://www.tandemsltd.com/
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Old 07-18-12, 07:25 PM   #15
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Disclaimer: I am not a mechanic.
Assumption: 9 speed groupsets had a narrower chain profile than 8-speed (pretty sure, too tired to check).
Assumption: You are using the original front chainrings from the 9sp groupset.
Assumption: Chainrings for 9sp/8sp groupsets are profiled to match the width of the chain.
Assumption: You have never changed your chainrings on this bike.

Maybe your chainrings are worn, and that wear paired with them being slimmer in profile than your 8sp chain is causing skipping. 12 years of pedaling will wear down any chainring, especially if a lot of grit got into the chain (which, judging by your rear der perhaps it did). Not judging lack of fender use, I don't use a front fender on my commuter/beater.

Why not try to post this question in the mechanics subforum? There isn't anything here that is really specific to a folding bike.
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