Tandem timing chain adjustment

[Dustbin Dog]

I have the problem where the chain is fairly new and I have already run out of adjustment.  If I had to remove a complete link the chain isn?t long enough to go round with the eccentric adjuster at it?s closest.  It seems that the maximum adjustment range you get is less than one link of the chain, so as the chain stretches you will always end up in the situation of a slack chain until it stretches enough to get a link out.  I have measured the chain stretch using both the Park tool and the trusty steel ruler and it?s about 0.5% so would not need replacing.  Is this normal for timing chains? 

 

Does the statement below hold any water? 

 

"If your frame was properly designed, tightening the eccentric won't cause you to need to remove a link. If you do find yourself removing links on fairly-new timing chains, you can correct the original design error by changing both timing rings from an even to odd number of teeth or vice-versa." 

[AndreZA]

Look for half link. On the one side it connects to the inner link and the other side to an outer link.

 

http://www.bikepartsplace.com/images/P/31186210.jpg

 

 

[TiBones]

Dunno what pitch a tandem timing chain is! Is it the same as the drive chain. I don't know if offset links are available for this chain but bear in mind that using an offset link will REDUCE THE STRENGTH OF YOUR CHAIN BY ABOUT 30%. Chain can stretch to about 2% before it needs to be replaced so, on a 3/8" pitch chain, when 10 links measure anything over 97 mm, the chain needs to be replaced. When you count links, remember to count the PINS, not the plates.

[Johan Bornman]

Dunno what pitch a tandem timing chain is! Is it the same as the drive chain. I don't know if offset links are available for this chain but bear in mind that using an offset link will REDUCE THE STRENGTH OF YOUR CHAIN BY ABOUT 30%. Chain can stretch to about 2% before it needs to be replaced so' date=' on a 3/8" pitch chain, when 10 links measure anything over 97 mm, the chain needs to be replaced. When you count links, remember to count the PINS, not the plates. [/quote']

 

Your statement is riddled with errors to the point that nothing in here is true. Unfortunately someone is going to remember every word you said and like weeds in my garden, it will come back and back and back and back.

 

1) A statement that claims a single link will reduce a chain's strength by X percent is pure nonsense. A weak link is a weak link and a strong chain is a strong chain. By putting one weak link in you have one weak spot. I don't know how you got the statistics worked into all this.

 

2) Chains can't stretch.

 

3) Bicycle chain pitch is 1/2 inch.

 

4) 2% elongation is 100% over the allowable limit. Chains should never elongate beyond 1% otherwise the sprockets will be damaged. 1% approximates 1/16th of an inch elongation over 24 links.

 

5) Counting pins vs plates. Your formula holds for counting more than one link. But when counting one link you'll end up with a count of 2. Very confusing. Refer  to inner and outer links instead.

 

 

PS - What is an offset link?

[Johan Bornman]

I have the problem where the chain is fairly new and I have already run out of adjustment.  If I had to remove a complete link the chain isn?t long enough to go round with the eccentric adjuster at it?s closest.  It seems that the maximum adjustment range you get is less than one link of the chain' date=' so as the chain stretches you will always end up in the situation of a slack chain until it stretches enough to get a link out.  I have measured the chain stretch using both the Park tool and the trusty steel ruler and it?s about 0.5% so would not need replacing.  Is this normal for timing chains? 

 

Does the statement below hold any water? 

 

"If your frame was properly designed, tightening the eccentric won't cause you to need to remove a link. If you do find yourself removing links on fairly-new timing chains, you can correct the original design error by changing both timing rings from an even to odd number of teeth or vice-versa." 

[/quote']

Your problem is typical and the only way out is a supply of half-links or hybrid in/out links like Mampara showed.

 

My experience is that this happens to expensive and cheap tandems.

 

The quoted statement doesn't hold water. The cam cannot take up as much slack as allowable chain elongation.

 

Thow away the ParkTool measurement goody. It makes a nice keyring, but that's about all it is good for.

 

If I were a tandem owner I'd use 8-speed chain for the timing chain. It lasts noticeably longer than 9-speed, is much cheaper and half links are readily available.

[Dustbin Dog]

Thanks Guys for all your input.  I really appreciate your effort.

[Speed Devil]

Look for half link. On the one side it connects to the inner link and the other side to an outer link.

 

http://www.bikepartsplace.com/images/P/31186210.jpg

 

 

 

 

Ok, wait for it...I'm about to ask the inevitable question......

 

Where can a person buy these halflinks? 

 

 

Speed Devil2009-02-18 01:54:29

[TiBones]

Oooh, Ouch Eina, flamed in a tech thread - Johan, I defer to you in all tech aspects on cycling, I respect your opinion and even enjoy your overly opinionated writings.

As far as my post is concerned, I contend that:

 

1) Have a look at this url. Tsubaki have been making chain for years and, in the Power Transmission Industry, are considered amongst the leaders in research and development of chain. - http://tsubaki.eu/chain/faq/. Refer to Q2.

2) You and I are aware that sideplate elongation and pin wear result in what lay people would call "stretch". I was addressing the post to a lay person

3) As I have said, both in this thread and in previous threads, my speciality is not bikes and my knowledge of things cycling comes from the likes of you, Mampara and the other techies on this forum. However, I stand corrected and offer the following:

 

10 links of half inch chain should then, by calculation measure 127 mm

A 2% ELONGATION of the chain would result in a length of 129.54. If your 10 links of chain is longer than that, it needs replacing. The more links you use to assess the chain, the more accurate your result will be. 2% is and industry standard acceptable elongation.

5) no problem

6)An offset link is the same as a half link.Same thing different industry term.

Thank you for your enlightening posts (in all sincerity) but allow others who have a working knowledge of the item in question to also offer advice and information, much as you do, without getting uptight.

[Johan Bornman]

Oooh' date=' Ouch Eina, flamed in a tech thread - Johan, I defer to you in all tech aspects on cycling, I respect your opinion and even enjoy your overly opinionated writings.

 

 

Don't cry. I don't know you so it can't be personal. It is just that misleading posts should be corrected and/or debated in public and not in private. Besides, you are anonymous, so no-one really knows who got corrected.

 

[/quote']

 

 

As far as my post is concerned' date=' I contend that:

1) Have a look at this url. Tsubaki have been making chain for years and, in the Power Transmission Industry, are considered amongst the leaders in research and development of chain. - http://tsubaki.eu/chain/faq/. Refer to Q2.

[/quote']

You made a few mistakes in transcribing this information. Tsubaki clearly stated that the link is weaker than the rest of the chain. You said the chain becomes 35% weaker. There is a difference and it is significant. Further, motorbike chains are laterally weak. Bicycle chains are laterally strong. Motorbike chains don't change gears, that's why. A half-link (off-set link - I learnt something new today) is weak because tension on that link has a lateral component on the two sideplates from the vector of the forces. The sideplates want to pull inwards and thus tend to pop the rivet under high tension. Bicycle riders aren't that strong and bicycle chains have relative small forces on them unless you are shifting badly. Then things change and lateral strength is paramount.

 

A half-link is fine for a timing chain as it only deals with one set of legs.

 

Quoting Tsubaki's credentials as backup was a red herring. I go straight for the facts and ignore certificates, degrees, accolades, marketing hype and reputation.

 

2) You and I are aware that sideplate elongation and pin wear result in what lay people would call "stretch". I was addressing the post to a lay person

 

I had an inkling that you did that' date=' yet it doesn't help the lay person. He will understand elongation. Stretch just gives the wrong impression and forms wrong perceptions of what really happens in a chain.

Chains on conveyor belts stretch under load - enough to cause a bounce in the belt that could wreck the system if not designed to cope with the chain's elasticity. However, even those chains don't stretch beyond yield. In other words, that stretch is not permanent. On bicycles it is the same, except there is no noticeable stretch under load and certainly no permanent stretch with use.

 

Use the right terms and we'll root out confusion.

 

 

3) As I have said, both in this thread and in previous threads, my speciality is not bikes and my knowledge of things cycling comes from the likes of you, Mampara and the other techies on this forum. However, I stand corrected and offer the following:

10 links of half inch chain should then, by calculation measure 127 mm
A 2% ELONGATION of the chain would result in a length of 129.54. If your 10 links of chain is longer than that, it needs replacing. The more links you use to assess the chain, the more accurate your result will be. 2% is and industry standard acceptable elongation.

 

 

This is too complicated and shouldn't be converted to metric. Stay Imperial. 24 links (i.e. 24 half links or 12 double links) should measure 12 inches. A 1/16th inch elongation after use is the maximum wear limit. Replace at or just before 1/16th elongation. Use the full 12 inch section in order to reduce the overall error in measurement. No use trying to measure one link.

 

 

5) no problem

 

No problem then.

 

6)An offset link is the same as a half link.Same thing different industry term.

I learnt something new today.

 

Thank you for your enlightening posts (in all sincerity) but allow others who have a working knowledge of the item in question to also offer advice and information' date=' much as you do, without getting uptight.
[/quote']

 

I'm not as uptight as you may think. I talk straight but it doesn't mean I am insensitive.  I also don't as a rule offer advice if it is already there and correct and complete. I don't however tolerate MAS, BS and feeble guesswork arse-covered with a "just my 2c worth".

 

Chains are fascinating and dominate our troubles on the bike. Let's stick to facts.

 

 

[Johan Bornman]

 

Ok' date=' wait for it...I'm about to ask the inevitable question......

 

Where can a person buy these halflinks? 

 

 

[/quote']

 

Last time I fixed a problem tandem for a friend, I got it from Harris Cyclery in Boston. They run a fine online shop and don't balk at requests for odd or hard to find parts.

 

I tried my local bike shop in those days and got the "this oke is still nuts" look from the proprietor.

 

Also, I mentioned that timing chains should best be 8-speed and if you can get it, track chain. Track chain is made for a perfect chainline but offers incredible reliability and durability. Half-links are readily availble for track chain since track bikes suffer the same adjustment problem.

 

[Guest Big H]

I am going through the same process. My package with my half links arrived in South AFrica las week. I should get them when I visit at the end of the month. I ordered mine from St John Street Cycles in Great Britain ( http://www.sjscycles.com/store/vIndex.htm )

 

How many teeth does your chainrings have???? We have 33 teeth ring currently. I ordered two 39 teeth chainrings. 39 teeth rings worked perfectly on a previous crankset on the same tandem. My logic is that at any one time there are 22 teeth on each ring occupied by chain, thus again 44 teeth in total. If you use an odd size it will be a total, in my case of 39 teeth. A chain link spans two teeth and a link is 1 inch long. There....... you have "gained" half a inch and that is exactly what you will gain with the half link. My problem was that I have a Sugino crankset with 110 BCD five hole cranks. I could not get chainrings in SA. I ordered new chainrings as well from St John Street Cycles.