14 tooth g/box sprocket

[Bitza]

Hi All, so currently I run the heap (94 frame 851 type swinging arm) with a 15 tooth g/box sprocket and a 39 on the wheel, but have decided that it's really too high gearing, specifically around town bearing in mind that the flywheel is minus 1kg. So in the interest of minimising weight I'm considering swapping to a 14 tooth, rather than using a 42 on the back, i.e. 14/39.
Any thoughts or experiences you might want to share?

P.S. I've just edited this from 43 to 39 cos Dukedesmo response made me think, so I checked, whoops.

[Dukedesmo]

When I first got my 916 it had 15/36 gearing which was way too long - gearing for 190mph but power for only 160ish, making riding in traffic very kangaroo-ish.

Online search suggested 15/39 was probably the sweet spot but, obviously that requires a new rear sprocket and a new (longer) chain so, given that it was a new bike I opted for a 14t front instead as it was a much cheaper option and it gives, pretty much the same overall ratio.

Once the chain/sprockets required changing I swapped to a 15/39 as it is technically 'better' due to a larger front being under less load than the smaller meaning faster wear also, less bend of the chain but I doubt the load issue is really a worry except on, maybe a really powerful bike? and it certainly caused me no bother.

So, IMHO the 15/46 is 'better' but I doubt the 14/43 would cause any issues whatsoever and, as you say will weigh slightly less.

As an aside, I initially tried 15/41 on my Monster but found it too 'buzzy' so went to 15/39 which is still a little lumpy in city traffic (exaggerated by other factors) but as I live and (mostly) ride rural it suits me fine as it keeps it in the sweet spot at typical 'cruising' speeds.

You may already have seen the gearing commander website? https://www.gearingcommander.com/ which is very useful for 'experimenting' with different chain/sprocket combinations.

[Dukedesmo]

To add, whilst your suggested options are not so, an even number of teeth on both front and rear is best avoided for wear reasons.

[Luddite]

I've had pretty much the same experience as DD with my Evo. Standard gearing was 15/39, as with yours, and initially I just went down to a 14 front as it was quick, cheap and easy and the existing chain was still new so I didn't want to replace that unnecessarily.

And, like DD, when the time came to replace the chain, I took the opportunity to go down the 15/42 route with a longer chain. I did consider dropping from the standard 525 to a 520 but didn't bother in the end. I presume you're running a 520 as part of your weight loss regime?

I ran the smaller front sprocket for over 10,000 miles with no problems so, as you're top priority is lightness, that's probably your best option.

This is from my mods thread http://www.ukmonster.co.uk/monster/s...ad.php?t=55168

Originally Posted by Luddite

Well, it's been over a year but, yes, the Evo is still going strong! I thought it was about time that I treated it to some more goodies and a new chain was on the shopping list. Now, a new chain means new sprockets and that throws up the question of gearing.

From earlier posts, you may remember that I did what many other Evo owners have done in an effort to improve low speed running, I lowered the gearing.

I went down the cheap and cheerful route by just fitting a 14 tooth front sprocket - quick, easy and no need to fit a longer chain.

However, I had said that, when the time came to replace the chain, I would go back to the standard front sprocket (15t) and fit a larger 42 tooth rear (standard is 39t). This requires a longer chain at 106 links, rather than the standard 104, but this set up should, in theory, give both chain and sprockets an easier time. So that's what I did.

But why fit a boring standard style sprocket when there are natty CNC quick change versions on offer?

I've swapped the gold DID chain for a neat black and silver one and chosen an AEM Factory sprocket kit, which allows you to change the rear sprocket independently of the carrier. Saves about a kilo of weight too. The sprocket is hard anodised aluminium. I'd have preferred steel but we'll see how it wears...

No real problems in fitting; the gearbox sprocket at 186Nm whizzed straight off with my cordless impact wrench but the larger rear sprocket nut at a lower 156Nm wouldn't budge and needed a three foot long breaker bar before it would move

I'm pleased with the look but, as I haven't ridden it yet, can't comment on any change in the riding experience.



There have been some arguments that the smaller 14t front sprocket brings the chain too close to the swinging arm and can wear it away. However, I checked the plastic protector at the gearbox end and, although there is evidence of some rubbing, it is quite minor considering the smaller sprocket has been on there for over 10,000 miles. So, if you're currently running a 14t sprocket, I don't think you've got anything to worry about.

[Wasta]

I run a standard rear sprocket but have a 14t on the front. I really like it, the traffic light gp is an easy win but, gear changes come thick and fast and obvs the top speed has dropped a bit, although as an old monster I rarely go over 6,000 rpm.

[Dave G]

I have a 14t front on my S2r, and my SC1000, I also had a 14t on my old 916 and SS.
Always preferred the road manners with the smaller front sprocket, the effect on top speed is irrelevant on the roads.
I seem to remember the only reason for the 15t front was to do with noise emission measurements at certain road speeds, which is why Ducati passed them though seemingly still louder than most of the rival makes, though I could be wrong on that.