A word of caution using the 14t with a 112 link chain

Was just running some numbers through the gearing commander, and noticed something that should be shared.

http://www.gearingcommander.com/

Most of us look towards a 112 link chain when going with a bigger sprocket combo. When using a 13t front sprocket with a 112 link chain there is no reason to worry about undue wear and tear on the final drive, but when you go up to a 14t that changes.

The 14t sprocket hits the same tooth, on the same link, each time the chain cycles over the sprocket. Compare this to 13 chain revolutions required for the same link to touch the same tooth on a 13t sprocket.

This is easily mended, by dropping a link off the chain. 111 links creates an environment were we see a one revolution gain over the stock gearing... 14 revolutions..

I know this is getting very picky but I don't have a carb to fiddle with anymore so might aswell get the final drive dialed in :P

Say what?  

You can't drop just 1 link from this type of chain, you have to add/subtract 2 links at a time in order for the master link to connect both ends.  So you'll always have a chain with an even number of links.

Many have opined in earlier posts that the "same tooth, same link" issue is moot on dirt bikes, as the primary source of chain and sprocket wear is likely to be dirt and sand etc.

I'd like to apologize for my ignorance as a precaution, but.....isn't it actually an advantage if you always have the same tooth/link combination?
I mean, at least theoretically after some wear the possible surface contact between link and tooth will be 100%, force closure will be on this maximized surface and hence wear should be lower?
Where is my error in reasoning here?

Probably it's at the very bottom of the page is because it's at least that low of a priority -- if not lower ; }

SwissDude wrote:

I'd like to apologize for my ignorance as a precaution, but.....isn't it actually an advantage if you always have the same tooth/link combination?
I mean, at least theoretically after some wear the possible surface contact between link and tooth will be 100%, force closure will be on this maximized surface and hence wear should be lower?
Where is my error in reasoning here?

www.gearingcommander.com/base/gc_howto26.htm

www.gearingcommander.com/base/gc_howto27.htm

SwissDude wrote:

.....isn't it actually an advantage if you always have the same tooth/link combination?
I mean, at least theoretically after some wear the possible surface contact between link and tooth will be 100%, force closure will be on this maximized surface and hence wear should be lower?
Where is my error in reasoning here?

I would agree with this reasoning, especially given today's more uniform manufacturing processes. However, if one sprocket tooth gets damaged, it will do more sympathetic damage to fewer links ironing itself out, as opposed to symmetric imprinting distribution throughout more of the chain when non-repetitive arrangement is allowed. Since we are talking about high wear item(s) [chain and front sprocket] verging on sacrificial, I'd be inclined to settle on a link count that is optimal when new (before chain stretch), irrespective of further considerations with regard to repeat imprinting.

I do seem to recall seeing some bizarre chain wear photos on older/cheaper material endowed chains. If not mistaken this was attributed to the repetitive same tooth same link phenomenon. Worth considering.

wwguy wrote:

www.gearingcommander.com/base/gc_howto26.htm

www.gearingcommander.com/base/gc_howto27.htm

yup, seen that, but it lacks an explanation. Just saying does not really count  

well, geez. This is what happens when I try to be helpful. LOL you are right, 111 links won't work. It crossed my mind before I published the thread, but also kinda reckoned the clever among us would steer me straight.

This all comes from my recent upgrade to Heidenau K60 scout tires. With the larger tire, my recent regear to 13/47 turned into what amounts to a 13/45. Once I figured out my next move, (13/49, 14/49) I became concerned about the revolutions per same tooth etc. After a recent 750km trip, I wanted to get my road gearing back in order. I can't imagine how folks run short gearing on the highway...... would drive me mad (even with my earplugs)

I'm sure regular cleaning and maintenance (or lackthereof) has more weight on the life of my final drive than this calculation, but it's still worth knowing what is happening down there every revolution

I mostly just didn't want to chew through a brand new D.I.D. VX2 gold chain by being careless or uninformed. Thanks for putting my worries at ease.

CC_Rider it was a great topic.
Got me to thinking so I ran the numbers, and FWIW a 14/50 final drive hits the same tooth every 5 revolutions of the chain (if I did the math right for my 114 link chain). Not the 'optimum' attainable outcome, but significantly better than the worst case scenario the article warns against.
Thanks for posting this information.

Nothing wrong with this thread

But I'd still love to hear an explanation why "same tooth/link" should cause excessive wear

SwissDude wrote:

Nothing wrong with this thread

But I'd still love to hear an explanation why "same tooth/link" should cause excessive wear

Don't exactly know, but hazarding a guess, here's what I think would happen in a scenario which "proved" their point;

A weak link stretches. Its developing asymmetry begins to unfairly pick on the same front sprocket tooth each time around, steadily elongating that position until it can't be "normally mitigated" by adjacent teeth link alliances, since their duties are being skewed. Now the roller just ahead of the offending link starts getting crowded within its own dedicated tooth valley, having garnered unintentional advancement. This would appear to aggravate the forces that are already acting upon the marginal link, by incipient allocation of further real estate where-in the link opposite (trailing) the "weak-link" begins the unabated task of compensating for said "weak link" deficiencies in polar sympathetic response. Ultimately links on either side of this equation will continue to alternately bear inordinate burdens, deteriorating at an incremental, and eventual exponential rate (immediately prior to catastrophic failure)

Just a guess. I almost got paranoid while typing that conspiracy theory

I can see how this may help if you do a lot of street riding with your WRR/X.

But I am usually in the muck with mine and the sometimes using the bike to commute to work (even then I am hitting dirt roads). Basically in that environment the dirt and grit will take more out of chain life than the number of revolutions a tooth is hitting the same link.

Best thing I have found to keep a happy chain.

- Watch the tension.
- After playing in the muck clean and lube the chain.
- Lube the chain (when at home I use 90W grear lube, on the road Dupont Teflon Chain Saver, White Lithium grease, or WD40) after ever tank (4.7 gallon tank) or every other tank.
- Keep an eye on the front sprocket, once it starts to wear replace it.
- Set you sag