Chain And Sprocket Thread - HUGE Read But Worth It

[Monstaman]

Ok, you asked for it ... grab a crate, some sausages and a pillow :D

This is from an engineer and NOT me, I am not that cleva to work this shit out, the ultimate info from this is you are better to run uneven numbered sprockets front and rear and a larger front sprocket places a lot less anger on your chain.

read on.....

14-Tooth vs. 15-Tooth Front Sprocket Wear
For (say) a 96-link chain ...
A 15-tooth front sprocket will contact the same chain link every 32 revolutions. 15 x 32 = 480 links ÷96 = every 5 chain revolutions.
A 14-tooth front sprocket will contact the same chain link every 48 revolutions. 14 x 48 = 672 ÷96 = every 7 chain revolutions.
With the same rear sprocket and at the same road speed, the 14-tooth sprocket and the 15-tooth sprocket both contact the same number of chain links per unit time.
So for example, for every 35 chain revolutions, the 15 tooth sprocket contacts the same link 7 times and the 14-tooth sprocket contacts the same link 5 times.
If we assume that there is a defect on one of the front sprocket teeth (or a particular chain link) that can cause abnormal wear to the same chain link (or sprocket tooth) when contacted over and over again, the 14-tooth sprocket would actually result in (7-5)/7 = 29% LESS defect-related wear than a 15-tooth sprocket.
However, for the same 35 chain revolutions, the 15-tooth sprocket rotates 224 times and the 14-tooth sprocket rotates 240 times so the 14 tooth sprocket (and the chain) would see (240-224)/240 = 7% MORE continuous wear than a 15-tooth sprocket.

Odd vs. Even Sprocket Teeth Wear Pattern
For reduced wear to the sides of the sprocket teeth, it’s better to run odd-numbered tooth sprockets, front and rear. Here’s why.
A chain alternates its links inside-outside such that side-to-side chain positioning is controlled by contact between a sprocket's teeth and the inside links. Because a chain always has an even number of links, each tooth on an even number-tooth sprocket will always contact either an inside link or an outside link. Each tooth on an odd number-tooth sprocket will alternate between inside and outside links that gives a uniform wear pattern to the sides of the sprocket.
Of course, this really isn't a significant problem with steel sprockets, so Ducati uses a 14-tooth front sprocket on some models. Even-tooth rear sprockets are standard on a number of models. However, if you intend to replace your sprockets with aluminum which is a lighter, but softer material, accelerated sprocket wear will be a consideration.
But who cares? A little wear on the sides of a sprocket doesn't significantly affect chain engagement.
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Wear to the face of the tooth is the reason for using a hunting tooth when meshing two gears. When you have a chain-driven sprocket instead of gear-to-gear contact, the wear issue becomes avoiding the same teeth on the sprockets repeatedly meshing with the same links on the chain.

How often the same tooth meshes with the same link can be calculated by comparing the number of teeth on each sprocket to the number of links in the chain.
The first step is to factor the number of teeth and links into prime numbers. Here’s some common results:
Front Sprockets
14 tooth - factors: 7x2
15 tooth - factors: 5x3
Rear Sprockets
36 tooth - factors: 3x3x2x2
37 tooth - factors: 37
38 tooth - factors: 19x2
39 tooth - factors: 39
40 tooth - factors: 5x2x2x2
41 tooth - factors: 41
42 tooth - factors: 7x3x2
43 tooth - factors: 43
44 tooth - factors: 11x2x2
45 tooth - factors: 5x3x3
Chain Links
94 links - factors: 47x2
96 links - factors: 3x2x2x2x2x2
98 links - factors: 7x7x2
Two numbers are defined as relatively prime if they have no common factors. The front sprocket/chain combinations from above that are relatively prime are:
15 tooth front - 94 link chain, 98 link chain
The sprocket and chain will meet at the same spot every 15 turns of the chain and 94 or 98 turns of the sprocket respectively.
14 Tooth front - none of the combinations are relatively prime. If the two numbers aren't relatively prime, then the number of turns will be divided by the common factors. For example:
14 tooth front - 94 link chain
Here, 14 (7x2) and 94 (47x2) have the common factor of 2. Consequently, the sprocket and chain will meet at the same spot every 7 turns of the chain and 47 turns of the sprocket.
14 tooth front - 96 link chain
Here, 14 (7x2) and 96 (48x2) have the common factor of 2. Consequently, the sprocket and chain will meet at the same spot every 7 turns of the chain and 3 turns of the sprocket.
14 tooth front - 98 link chain
Here, 14 (7x2) and 98 (7x7x2) have the common factors of 2 and 7. Consequently, the sprocket and chain will meet at the same spot every turn of the chain and 7 turns of the sprocket. Not very good for wear.
The rear sprocket/chain combinations are computed separately, the same way as for the front. Here’s the result for combinations that are commonly used:
36 tooth rear (18x2) - 94 link chain (47x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 18 turns of the chain and 47 turns of the sprocket.
38 tooth rear (19x2) - 94 link chain (47x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 19 turns of the chain and 47 turns of the sprocket.
38 tooth rear (19x2) - 96 link chain (48x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 19 turns of the chain and 48 turns of the sprocket.
40 tooth rear (5x2x2x2) - 96 link chain (12x2x2x2)
Here, the common factor is 2x2x2. Consequently, the sprocket and chain will meet at the same spot every 5 turns of the chain and 12 turns of the sprocket.
42 tooth rear (21x2) - 96 link chain (48x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 21 turns of the chain and 48 turns of the sprocket.
42 tooth rear (21x2) - 98 link chain (49x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 21 turns of the chain and 49 turns of the sprocket.
44 tooth rear (22x2) - 98 link chain (49x2)
Here, the common factor is 2. Consequently, the sprocket and chain will meet at the same spot every 22 turns of the chain and 49 turns of the sprocket.
45 tooth rear (5x3x3) - 98 link chain (49x2)
No common factors. Consequently, the sprocket and chain will meet at the same spot every 98 turns of the chain and 45 turns of the sprocket.

[NordieBoy]

Good reading.

It's not tooth wear that worries me with my bikes.
Yes they're worn but it's chain roller/pin wear/chain stretch type issues.

[Taz]

A 15-tooth front sprocket will contact the same chain link every 32 revolutions. 15 x 32 = 480 links ÷96 = every 5 chain revolutions.
A 14-tooth front sprocket will contact the same chain link every 48 revolutions. 14 x 48 = 672 ÷96 = every 7 chain revolutions.
Every link of my chain contacts the sprocket every revolution. None get missed at all?

[98tls]

Interesting read although sprocket wear is a thing of the past really since fitting Supersprox ones,damn things just dont wear out.

[NordieBoy]

Interesting read although sprocket wear is a thing of the past really since fitting Supersprox ones,damn things just dont wear out.

Wonder if they do any for the DR650?

[98tls]

Wonder if they do any for the DR650? Have a read through here mate,i posted a link to there site with listings,if theres one for a DR find the Aussie distributor.http://www.kiwibiker.co.nz/forums/showthread.php?t=101859&highlight=supersprox

[Eddieb]

Every link of my chain contacts the sprocket every revolution. None get missed at all?

Yes, but the same tooth only goes through the same link every x times.

E.g the 14th tooth on the sprocket only goes through the 100th link in the chain every 7th revolution, the other 6 revolutions the 14th tooth goes through a different link.

[Sidewinder]

yea and what? who cares if you need to go fast you pay the price

[Taz]

Yeah I know but I've never had sprocket with just one damaged tooth in over a hundred thousand k's or more of riding. It's easy to look after and inspect a chain and sprockets and replace them before the wear gets too great.

[Sidewinder]

Yeah I know but I've never had sprocket with just one damaged tooth in over a hundred thousand k's or more of riding. It's easy to look after and inspect a chain and sprockets and replace them before the wear gets too great.

but if you race you need to have the perfect gearing and not worry about the wear life, thats why you use a 520 chain

[Taz]

but if you race you need to have the perfect gearing and not worry about the wear life, thats why you use a 520 chain

If you race you'd replace your sponsored chain very frequently. Proper race chains while strong and light don't last.

[Sidewinder]

If you race you'd replace your sponsored chain very frequently. Proper race chains while strong and light don't last.

bro hardly anyone gets free anything,
they all say there sponsered but its realy only suport, and thats from the wholesalers and anyone can get that

[Taz]

bro hardly anyone gets free anything,
they all say there sponsered but its realy only suport, and thats from the wholesalers and anyone can get that

I didn't say free, I said sponsored. Sponsored does not equal free. Still a serious racer will not race with a fucked chain or sprockets. Comes down to preparation.

[NordieBoy]

yea and what? who cares if you need to go fast you pay the price

I just want a chain to last longer than the 8,500km and 19,000km I got from my last 2.

The big singles are hard on chains.
The DR650 is the only(?) one that comes with a 525 however as the rest use 520.

[Monstaman]

At the end of the day for me, an average joe rider, to elongate the chain and sprocket life through better combos can only be good, also not really mentioned here is the benefit of larger front sprocket which will introduce a lot less heat into the chain again helping the life again.

All good fun and my sponsor who looks very much like me is dutchie when it come to making things last.

[bart]

Interesting read. I almost made some sense of it.

However, chain and sprockets aren't really that expensive in the scheme of things.

edit. Would be worth considering if doing a REAL adventure type ride of thousands of km.

[Woodman]

Is there any advantage in using bigger sprockets in the sense of leverage on the wheel and leverage from the front sprocket to the rear etc.

E.g using a bigger front (1 tooth) and rear (3 teeth) to achieve the same gearing, would the leverage be a noticeable advantage.

possibly overlooked some basic physics but still curious.

[Monstaman]

That is exactly what I am doing Woodman, 15/43, take some heat and tightness of turning out of the chain and proven to be better and particularly for adventure bike chains getting covered in crap and run dry etc.

[warewolf]

Interesting read although sprocket wear is a thing of the past really since fitting Supersprox ones,damn things just dont wear out.Yes they do. KTM sell them as OEM. The rivets holding the steel tooth ring to the alloy centre carrier have been known to fall apart occasionally. Even if those rivets last, from what I could gather the whole thing doesn't last as long as a Chain Gang (http://www.chaingang.com.au/) sprocket. Chain Gang are not cheap but stealths are worse, although they are marginally lighter. I've never found any complaints about chain gang except the price - can't say the same thing about stealth.

It's been said 90% of competitors in the Aussie Safari use Chain Gang sprockets (comment made by a journo prepping his own & Kevin Schwantz' bikes). That's a fairly strong endorsement.

[98tls]

Yes they do. KTM sell them as OEM. The rivets holding the steel tooth ring to the alloy centre carrier have been known to fall apart occasionally. Even if those rivets last, from what I could gather the whole thing doesn't last as long as a Chain Gang (http://www.chaingang.com.au/) sprocket. Chain Gang are not cheap but stealths are worse, although they are marginally lighter. I've never found any complaints about chain gang except the price - can't say the same thing about stealth.

It's been said 90% of competitors in the Aussie Safari use Chain Gang sprockets (comment made by a journo prepping his own & Kevin Schwantz' bikes). That's a fairly strong endorsement. Yea nice,thing is i can only comment on what ive used and so far so good,TLs though old are hard on chains/sprockets and i give my old girl shite when i bother to ride it and have only praise for there product.As for the Aussie Safari endorsement that to is wonderful (though ive never heard of it) though doesnt sway my opinion on what i use.

[Howie]

I found this web site a while ago, which has a excellent gear calculator on it which also shows how many revolutions of the chain before you get same tooth, same link combination. http://www.gearingcommander.com/

this page has a bit of info on it about why the same tooth same link is not good for chain life. http://www.gearingcommander.com/base/gc_howto27.htm

Cheers

Paul

[warewolf]

Is there any advantage in using bigger sprockets in the sense of leverage on the wheel and leverage from the front sprocket to the rear etc.It changes the suspension squat & push, ie the way the suspension extends (or not), forcing the rear wheel into the ground under power, unweighting the front making the bike run wide. Fairly esoteric stuff for an adventure bike, but you'll find it discussed in suspension threads, tied in to the swingarm angle (pivot vs rear axle height), possibly swingarm length (remember how all the marketing depts at the moment are banging on about lengthened swingarms for better traction?).

Bigger sprockets add gyroscopic forces to your drive train (heavier sprockets) and you may have to run a longer (heavier) chain, too. Any marginal wear improvements are likely more than offset by increased load, reduced fuel economy etc. We're talking poofteeths all round, here. Probably not worth chasing in and of itself.

I've seen the detailed maths on how much extra wear is created by small front sprockets and it is much less significant than urban myth would indicate. Basically it's not considerable until about 11T, IIRC. That's on a typical dirt bike 520 size chain.


Monstaman you are on the money; the idea about spreading the load is a good one and fairly well known. A little bit of wear everywhere, with differences offsetting one another, is much better overall for longevity than digging a deep hole in one spot. I get very visible wear on the 640 running 16/42 (oem) or 16/44: the sideplates wear their own patterns in the sprocket sides, and every second tooth has a different shape. And also lots of tight links in the chain. Note to self: convert to odd numbers next set of sprockets. Ditto the 200, with 14/46 and 14/48 and sometimes 14/44.

[ajturbo]

ok...

where would.. or what would my 11 tooth/ 43 tooth go?

apart from a great take off!!! woo hoo.................

[NordieBoy]

ok...

where would.. or what would my 11 tooth/ 43 tooth go?

apart from a great take off!!! woo hoo.................

Depends on which bike but on a DR650 it'd go through the slider and swingarm in a couple of hours :D

[cooneyr]

I just want a chain to last longer than the 8,500km and 19,000km I got from my last 2.

The big singles are hard on chains.
The DR650 is the only(?) one that comes with a 525 however as the rest use 520.

You did well - I was killing JT CS sprockets in 2k kms on the DR. Adv riding has to be about the harshest conditions for any chain to be exposed too. Lots of grit and crap like a dirt bike but also lots of long high speed kms covered in grit and crap. Therefor anything we can do to extend chain life is a good thing.

+1 on the chain gang sprockets - good stuff. Also a good point about the odd number teeth on the sprokects. Will keep that in mind for pending gearing changes (can only use 6th on the 950 above about 110kph or it is lugging too much).

[warewolf]

where would.. or what would my 11 tooth/ 43 tooth go?

apart from a great take off!!! woo hoo.................On your MX bike, where you want a great take off! :yes:

[Monstaman]

ok...

where would.. or what would my 11 tooth/ 43 tooth go?


That's a hellova tight wrap for a chain, at any amount of speed that will be generating a lot more heat within the pins, also smaller no of teeth = more likely to break teeth off.

[Taz]

You did well - I was killing JT CS sprockets in 2k kms on the DR.

Only changed the CS sprocket once on my XT600E in 43000kms. Used a loobman on that bike though. My VFR750FL did 45000kms on a chain and sprockets with a scottoiler.

[cooneyr]

Only changed the CS sprocket once on my XT600E in 43000kms. Used a loobman on that bike though. My VFR750FL did 45000kms on a chain and sprockets with a scottoiler.

I recon it was the scotty that I could never get to run without blocking with grit that was my problem. Never enough oil to keep flushing the crap off but just enough to make grinding paste. Manual oiling each time I hit the seal for any length of time seems to be far better for chain life.

[warewolf]

Yeah I reckon I prematurely destroyed some chains & sprockets while trying to get my Motrax AutoLuber to work properly. Main issue was getting the oil to go on to the chain. Ended up setting the delivery nozzle to rest against the side of the rear sprocket.

I was getting 27-30,000km from a set on the Triumph using Maxima Chain Wax. Fitted the autoluber and it killed the chain in 19,000km, but the replacement did 49,000km on the old sprockets, taking them to 68,000km. The next set did well over 50,000km using a Scottoiler, despite engine mods increasing the power by 50%. I'd expect the ChainGang sprockets and Scottoiler combo to deliver 100,000km.

Which reminds me, I really must get that Autoluber installed on the 640. Front sprockets last 6-9000km, changing them 2-3 times per chain and steel rear. All have been 16T matched to even T rears. Hmmm, looking at my gearing chart, I can go 15:43 for adventure use, and 17:43 for road use. Done!

[NordieBoy]

I'm looking at 14/44 for off road and 15/44 for road use.

[Monstaman]

My bike came on 14/48 :eek5:, so I am going to run 15/43 for road, for any more dedicated trails I will bang the 14 back on, good to have a play.

[XF650]

The Freewind is 15/43 std but nowdays I run 14/43 for adv riding. For long distance road trips (god forbid), I have a 16th to go on the front.