14/42 (1:3 ratio) gearing harmonics, integer gear ratios, etc...

[victor441]

changed my front cog to 14 soon after I bought my M800 and didn't know at the time that integer "hunting"  gear ratios are not desirable for the final drive due to harmonics and uneven wear on the countershaft sprocket...changed the cogs and chain recently and went with 15/44 and a 104 link chain this time which gives nearly the same ratio (15/45 would not be good, also an even ratio...15/46 would be OK, etc)   Anyway, from what I've read and experienced the common 14t mod is not a good idea for bikes with 42t in back (Monster 695 and 800 and some other Ducatis), especially since the number of chain links (102) is also divisible by 3...the same teeth and links will mesh regularly

[Speeddog]

Did you notice a difference with the 15/44 over the 14/42?

[Howie]

Were you having a vibration problem?  in theory hunting is better, in practice maintenance and riding conditions make more of a difference.  If your set up is truly non hunting do any work that affects the chain/sprocket theoretically you should mark the chain and sprockets to avoid noise and vibration problems. The good news is the chain turns the set up into partial hunting so you still have a random pattern.  OOPS!  I was thinking 104 links which would make it partial hunting.

[battlecry]

You can rotate the front 14 sprocket one tooth every 3000 miles to even the wear.

[Howie]

You can rotate the front 14 sprocket one tooth every 3000 miles to even the wear.

 

[victor441]

Did you notice a difference with the 15/44 over the 14/42?

definitely quieter and smoother than 14/42 was, but everything is brand new now so I can't say for sure that tht is due to the new ratio and longer chain.....but the wear differnces from chain sideplates are obvious looking at my old 15 and 14 cogs that ran with the original 42.  It may well be that the mumber of links (102 = 34x3) combined with the integer ratio is more of a factor, but a bad overall combination in any case

[victor441]

found a web site recently http://www.gearingcommander.com/ that confirms what I experienced and gives some numbers on tooth/chain contact too....14/42/102 really is a bad combination
here are the numbers for 15/42/102, 14/42/102, and 15/44/104   Anyway, an interesting site to check out various gearing/chain setups prior to buying parts, well worth a look

[bigiain]

... in theory hunting is better, in practice maintenance and riding conditions make more of a difference.

+1

I've run 14/42 gearing on my Monster for two sets of sprockets (and 4 chains), and wasn't able to detect any increase in wear or vibration.

I understand the argument and the idea behind it, but I've got at least a little bit of real world experience that says if there is any effect that that theory predicts, it's clearly small enough to be completely overshadowed by other factors...

I'd avoid integer ratios if it;s easy at the time, but if the shop's only got 42t rear sprockets, I'll just say "OK, gimme one of them this time" rather that wait for a 43 or 41...

big

[bikepilot]

Another, probably larger effect is that the 15T gets the chain further away from the swinger and spreads the load over more teeth.  I've found that larger sprockets tend to last longer and run smoother than smaller ones even when you don't have the integer issue.

[bigiain]

Another, probably larger effect is that the 15T gets the chain further away from the swinger and spreads the load over more teeth.  I've found that larger sprockets tend to last longer and run smoother than smaller ones even when you don't have the integer issue.

That's a good point, there's certainly some people who've experienced undue chain guide wear with a 14t  front sprocket, often people with raised rear ride height, but at least some people have chimed in wi the problem wi stock ride heights.

If you've got a voice between, say, 14/43 and 15/46, the 15t combo is probably a bettere choice. I think the 14t option is suggested so often is because it can be done without changing the chain or rear sprocket, and that makes it super inexpensive to try.

Big

[victor441]

+1

I've run 14/42 gearing on my Monster for two sets of sprockets (and 4 chains), and wasn't able to detect any increase in wear or vibration.

I understand the argument and the idea behind it, but I've got at least a little bit of real world experience that says if there is any effect that that theory predicts, it's clearly small enough to be completely overshadowed by other factors...

I'd avoid integer ratios if it;s easy at the time, but if the shop's only got 42t rear sprockets, I'll just say "OK, gimme one of them this time" rather that wait for a 43 or 41...

big

In my case the stock chain length (102) was a big factor also, 14/42 (1:3) is not as bad w/ a length that is not a multiple of 3....this shows 14/42 w/ 102, 100, and 104 chains

[stopintime]

Two examples of even number sprockets. 14/40 

[He Man]

from my experience runing odd and even, there is no difference...on a steel sprocket.

that image looks like an aluminum sprocket, which wears considerably faster. (much much much faster) than a steel.

ive got (on oem sprocket) about 17k with even wear running stock 15/41, and a steel aftermarket sprocket running 15/42 from 17k to now 30k.

[victor441]

from my experience runing odd and even, there is no difference...on a steel sprocket.

that image looks like an aluminum sprocket, which wears considerably faster. (much much much faster) than a steel.

ive got (on oem sprocket) about 17k with even wear running stock 15/41, and a steel aftermarket sprocket running 15/42 from 17k to now 30k.

one even sprocket is no problem....wear problems can occur (on steel or aluminum sprockets) when BOTH are even and especially if the chain length is also an integer multiple
check out www.gearingcommander.com/base/gc_howto27.htm
this is how the CS sprocket wore with the 14/42/102 combination, similar to the photos above...

[dbran1949]

something I did a while ago, different sprocket combos sorted by ratio

Front   Rear   Ratio
15   38   2.533
15   39   2.600
15   40   2.667
14   38   2.714
15   41   2.733
14   39   2.786
15   42   2.800
14   40   2.857
15   43   2.867
14   41   2.929
15   44   2.933
15   45   3.000
14   42   3.000
15   46   3.067
14   43   3.071
15   47   3.133
14   44   3.143
15   48   3.200
14   45   3.214
15   49   3.267
14   46   3.286
15   50   3.333
14   47   3.357
14   48   3.429
14   49   3.500
14   50   3.571