|
|
Thread Tools | Display Modes |
#41
|
|||
|
|||
Freeing up stuck derailleur pantogram
Frank Krygowski wrote:
On 2/9/2021 8:44 AM, Roger Merriman wrote: Frank Krygowski wrote: On 2/4/2021 8:08 PM, News 2021 wrote: Use a spring enough, and it will weaken. Not necessarily, for any practical definition of "enough." In fact, I'd say not usually. I’d agree but I’ve certainly had bikes that the derailleur has become sluggish, one was a old road bike with original kit and though it went though the gears it was slow to do so. And on the other end on my older MTB that is my commute bike that clocks up the miles, And is rather a grandfather’s axe/brush I’ve also had to replace the rear Derailleur few years back that just became sluggish. In both cases where clean with fresh cables etc. I think there may be many explanations for a "sluggish" derailleur performance besides weakening springs. The first thing I'd check is friction at the many moving points. In addition to the obvious hinges and pivots, there can be less obvious, hidden friction points. I mentioned the sliding contact between one derailleur's spring and an inside surface of the derailleur. And I've dismantled old derailleurs and found substances that were once grease, but now had the consistency of wax. In addition, cables can certainly have a dragging effect, sometimes from hard-to-spot locations. I imagine changing a derailleur might inadvertently improve alignment of the rear dropout's cable housing loop, causing the new derailleur to be credited for something it didn't do. Chain and sprocket condition can make a difference too. In both cases all but the derailleur was changed, ie had fresh inner and outers, due to the commute and the fact it’s a outside pet, cables don’t last that long, maybe a year or so before they get sticky which can’t be flushed out. They seem to shift fine covered in muck as is the habit with uk winters, so I don’t really see the hinges being it. I'm open to specific information on how a spring might weaken without fracturing or partially cracking. (I mentioned the potential analogy with vibrational stress relief.) But thinking about it in terms of stress levels within the spring, material properties, metallurgical structure etc. I don't know of a way it should happen, barring a design that permits gross overload. Thinking about it, I also have a old air pistol which is rather weak now, it’s spring rather than air really, and after 70 or so years of plinking cans it’s got a profile of a very fat pig jumping a big log! Have you not sat on a old bed with sagging springs etc, nothing lasts for ever. Roger Merriman |
Ads |
#42
|
|||
|
|||
Freeing up stuck derailleur pantogram
On 2021-02-05, Jeff Liebermann wrote:
snip https://www.ebay.co.uk/itm/Vintage-S...Cycle-Oil-Can- 227cc/274672630577?hash=item3ff3c3bb31:g:z-4AAOSw2w5gHUn4 Sewing machine and clock oils are usually based on common mineral oil. The polymers in the oil are cracked into smaller lengths to give it a lower viscosity. However, all petroleum based oils have the irritating habit of attacking rubber seals and plastic parts. You won't find that in a clock or sewing machine, both of which are mostly metal on metal. So, the synthetic sewing machine substitutes are used for those situations where the oil needs to touch rubber or plastic (or possibly paint). What I like about all of them is that they act the same whether hot, cold, wet, or dry. For things with tight clearances which are stuck, try Rock-N-Roll. It's unearthly in its penetration. I know this sounds like a tout but it really is exceptional. https://www.rocklube.com I'll give it a try. Ummm... which version? https://www.rocklube.com/products.html I'll look at the MSDS sheet later. My guess(tm) is that it's mostly mineral oil or a silicon based synthetic. My favorite penetrating oil is Kroil, which is banned in the Peoples Republic of California. I was somewhat involved in this mess: https://ww2.arb.ca.gov/kano-laboratories-inc-settlement I guess I shouldn't mention that I have a few unmarked cans of ozone depleting Kroil left in my secret stash. No, you can't have any. https://www.kroil.com Hi Jeff. I found a can of Kroil at my Mom's house. Man, it is odiferous and really likes to travel. I had to break my chain to get the derailleur off--had hoped I could avoid that. Suntour XCD 7000. All bad as new, now. Thanks for the tips Note to Frank: This one had a cylindrical spring with a tang at each end, no sliding part. pH |
#43
|
|||
|
|||
Freeing up stuck derailleur pantogram
On 2/9/2021 10:45 PM, pH wrote:
On 2021-02-05, Jeff Liebermann wrote: snip https://www.ebay.co.uk/itm/Vintage-S...Cycle-Oil-Can- 227cc/274672630577?hash=item3ff3c3bb31:g:z-4AAOSw2w5gHUn4 Sewing machine and clock oils are usually based on common mineral oil. The polymers in the oil are cracked into smaller lengths to give it a lower viscosity. However, all petroleum based oils have the irritating habit of attacking rubber seals and plastic parts. You won't find that in a clock or sewing machine, both of which are mostly metal on metal. So, the synthetic sewing machine substitutes are used for those situations where the oil needs to touch rubber or plastic (or possibly paint). What I like about all of them is that they act the same whether hot, cold, wet, or dry. For things with tight clearances which are stuck, try Rock-N-Roll. It's unearthly in its penetration. I know this sounds like a tout but it really is exceptional. https://www.rocklube.com I'll give it a try. Ummm... which version? https://www.rocklube.com/products.html I'll look at the MSDS sheet later. My guess(tm) is that it's mostly mineral oil or a silicon based synthetic. My favorite penetrating oil is Kroil, which is banned in the Peoples Republic of California. I was somewhat involved in this mess: https://ww2.arb.ca.gov/kano-laboratories-inc-settlement I guess I shouldn't mention that I have a few unmarked cans of ozone depleting Kroil left in my secret stash. No, you can't have any. https://www.kroil.com Hi Jeff. I found a can of Kroil at my Mom's house. Man, it is odiferous and really likes to travel. I had to break my chain to get the derailleur off--had hoped I could avoid that. Suntour XCD 7000. All bad as new, now. Thanks for the tips Note to Frank: This one had a cylindrical spring with a tang at each end, no sliding part. pH Suntour XCD rear changer? Just remove the lower pulley and rotate the inner cage plate. Yes, the pivot springs are cylindrical as you described. Frank meant the body return spring. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
On Topic! FD-7200 derailleur and RD-7400 derailleur the same group? | Sir Ridesalot | Techniques | 4 | May 22nd 20 03:24 PM |
Suntour rear derailleur that has no derailleur hanger | Postman Delivers[_3_] | Techniques | 19 | March 25th 12 09:47 PM |
FA: SRAM X9 SHIFTERS & REAR DERAILLEUR W SHIMANO DEORE XT FRONT DERAILLEUR | ottodog | Marketplace | 0 | August 27th 06 02:45 AM |
stuck QR skewer | Bryan | UK | 1 | August 17th 06 08:26 PM |
Stuck again | Paul R | Mountain Biking | 14 | July 20th 05 01:05 AM |