Changing sprockets - Advice required
Discussion
Right, so I am looking at ordering new Renthal sprockets for the R6.
The standard sizes are as follows:
Front - 285-525-16
Rear - 210-525-45
The way I understand it is that if I want improved acceleration, I either a) drop a tooth off the front, ie. go to 15 teeth, or b) increase the teeth on the rear. Right ?
So.... the options are as follows:
I either order a 285-525-15 front for £14.38 or order a 285-525-46 (or 47) for the rear at £29.66 (£31.77).
Which would be better ?
I was going to replace front/rear & also the chain, however the standard chain is a high quality D.I.D one & so seems a bit pointless to do so.
I understand that taking a tooth off the front is like adding 3 to the rear, so in theory changing the front seems the best option. But what do I know.
Finally, what is the difference with the race spec sprockets ? They all seem to be 520 instead of 525. What does this give you ?
Cheers again.
The standard sizes are as follows:
Front - 285-525-16
Rear - 210-525-45
The way I understand it is that if I want improved acceleration, I either a) drop a tooth off the front, ie. go to 15 teeth, or b) increase the teeth on the rear. Right ?
So.... the options are as follows:
I either order a 285-525-15 front for £14.38 or order a 285-525-46 (or 47) for the rear at £29.66 (£31.77).
Which would be better ?
I was going to replace front/rear & also the chain, however the standard chain is a high quality D.I.D one & so seems a bit pointless to do so.
I understand that taking a tooth off the front is like adding 3 to the rear, so in theory changing the front seems the best option. But what do I know.
Finally, what is the difference with the race spec sprockets ? They all seem to be 520 instead of 525. What does this give you ?
Cheers again.
Your assumption is pretty much spot on.
Things to be aware of, A smaller front may lower the chain onto your swing arm, and cut a groove in it.
A higher rear may increase the length of chain required unless you can shorten the wheel enough- which might effect handling. (shorter wheelbase)
your speedo may be gearbox fed, and hence read incorrectly, a "yellow box" can re-calibrate it.
You may improve MPG!
or decrease it 
depends how much the motor struggled before.
top speed decreased but acceleration improved.
525/520 - narrower, need narrower cogs and chain. unsprung weight reduced (the best weight to get rid off) wear/life reduced.
its recommended to change chain and sprockets together as the "settle in" together, and the older item may increase wear on newer items as they dont "match" wear.
Things to be aware of, A smaller front may lower the chain onto your swing arm, and cut a groove in it.
A higher rear may increase the length of chain required unless you can shorten the wheel enough- which might effect handling. (shorter wheelbase)
your speedo may be gearbox fed, and hence read incorrectly, a "yellow box" can re-calibrate it.
You may improve MPG!
or decrease it depends how much the motor struggled before. top speed decreased but acceleration improved.
525/520 - narrower, need narrower cogs and chain. unsprung weight reduced (the best weight to get rid off) wear/life reduced.
its recommended to change chain and sprockets together as the "settle in" together, and the older item may increase wear on newer items as they dont "match" wear.
So in theory it would be better to change sprockets & chain to the Race type to a) increase acceleration & b) reduce weight.
This would probably cost around £175 + fitting (as I ain't gonna try doing it myself).
Still a lot cheaper way of increasing acceleration than putting a new exhaust/power commander, etc, on the bike, which would probably be nearer 2k.
Cool. Off to the bike shop I go.
This would probably cost around £175 + fitting (as I ain't gonna try doing it myself).
Still a lot cheaper way of increasing acceleration than putting a new exhaust/power commander, etc, on the bike, which would probably be nearer 2k.
Cool. Off to the bike shop I go.
Right then. Assuming I go down the new sprocket/s & chain root which would be a decent mix to go for ?
Standard, as mentioned earlier, are as follows:
Front - 285-525-16
Rear - 210-525-45
Options available to me, using Renthal are as follows:
Front:
455U-520-14 through to 455U-520-16
Rear:
210-520-43 right through to 210-520-52
Obviously I am after quicker acceleration, but don't want the thing to max out at less than 140ish.
Would dropping a tooth off the front be adequate or should I also add a tooth or two to the back as well ?
Just how much difference does each tooth make is what I need to know.
Standard, as mentioned earlier, are as follows:
Front - 285-525-16
Rear - 210-525-45
Options available to me, using Renthal are as follows:
Front:
455U-520-14 through to 455U-520-16
Rear:
210-520-43 right through to 210-520-52
Obviously I am after quicker acceleration, but don't want the thing to max out at less than 140ish.
Would dropping a tooth off the front be adequate or should I also add a tooth or two to the back as well ?
Just how much difference does each tooth make is what I need to know.
Hobo,
I have an Excel spreadsheet which gives road speed in each gear at different engine revs and allows you to see the effect of changing sprockets and tires on a variety of bikes (including the 06 Yam R6) PM me if you would like a copy.
BTW. the industrial roller chain (which is what a bike chain is) numbering system is one of those wonderful engineering anachronisms.
The first number is the pitch or distance between each roller in 1/8ths of an inch, the second pair of numbers is the space between the side plates in 1/80ths of an inch
For example a 525 chain has a pitch of 5/8th of an inch and a width of 25/80 or 5/16th of an inch, whereas the 520 has the same pitch but the width is 20/80 or 1/4 inch.
As S2ooZ said; narrower and therefore lighter. (but not really worth it for the road)
M
I have an Excel spreadsheet which gives road speed in each gear at different engine revs and allows you to see the effect of changing sprockets and tires on a variety of bikes (including the 06 Yam R6) PM me if you would like a copy.
BTW. the industrial roller chain (which is what a bike chain is) numbering system is one of those wonderful engineering anachronisms.
The first number is the pitch or distance between each roller in 1/8ths of an inch, the second pair of numbers is the space between the side plates in 1/80ths of an inch
For example a 525 chain has a pitch of 5/8th of an inch and a width of 25/80 or 5/16th of an inch, whereas the 520 has the same pitch but the width is 20/80 or 1/4 inch.
As S2ooZ said; narrower and therefore lighter. (but not really worth it for the road)
M
Try this website - has an online ratio calculator with some presets already loaded - very useful 
www.xs4all.nl/~ator0437/gc/
www.xs4all.nl/~ator0437/gc/
hobo said:
… The way I understand it is that if I want improved acceleration, I either a) drop a tooth off the front, ie. go to 15 teeth, or b) increase the teeth on the rear. Right ? …
Technically correct but …… as with so many things in life ….. it all depends!
While doing the adjustments above does lower the overall gearing of the bike, you also need to consider how and where you ride the bike and where you want the extra acceleration. For example, in 0 to 60 times, a large contribution to the times is the gear change and if reducing the overall gearing causes an extra gear change then any gains from the lower gearing are likely to be lost in having to change gear. Likewise. with modern sports bikes, it is often very difficult (almost impossible for us mere mortals) to get ALL the power down in 1st or even 2nd gear without spinning the wheel/risking a “turn turtle” wheelie. Thus, lowering the gearing will simply make it even more difficult to get the power down.
Also, if you don’t ride your bike pretty much at the red line almost all of the time, then reducing the gearing is going to have a detrimental effect as all you will do is make the engine rev higher to attain the same road speed. Remember, bikes on the track are ridden pretty much flat out all the time where riding your sports bike on the road like that all the time would be approaching suicidal.
I actually found that raising the gearing on my Firestorm gave me the improved acceleration I wanted. That’s because it allowed me to use and hold second and third gear for more overtakes (where I actually wanted the extra acceleration) and also had the added advantage of slightly improving fuel consumption. My off the line acceleration may be slightly slower and while my top speed may technically be slightly up, reality is that the slightest up hill/head wind now knocks the top speed back. Both of these “disadvantages” are so rarely noticed that I am more than happy to live with them.
Like all things, the gearing of a bike is a compromise. In this case between performance, economy, comfort and engine longevity. Think carefully about what you are trying to achieve, what your are willing to sacrifice to achieve it and what benefits will come as a result.
Ride safe and enjoy
Also raising (or is that lowering?) the overall ratio to get better acceleration does not always lower top speed;
In the case of my Ducati 916 I fitted a 14t front sprocket (-1) which is the poor man's way of doing it (to go up on the rear meant buying a new, expensive, rear sprocket and a longer chain instead of a cheap front sprocket) and I have not noticed any drop in max speed (theoretically of course
) but it gets there quicker, this is due to the fact that it, like all Ducatis was massively over-geared in the first place.
According to the gear calculator www.xs4all.nl/~ator0437/gc/ in standard trim at the rev limiter (10,400rpm) in 6th gear and with a 180/55 tyre it should do 186mph, however it doesn't have enough power to even get near this. Using the same calculator with a 14t front sprocket it should do 174mph but the top speed is effectively 'limited' to 160 - 165 by the BHP/aerodynamics anyway, I could gear it for even better acceleration without losing any top end by going larger on the rear, something which I intend to try when next changing the chain/rear sprocket, in fact according to the calculator I could fit a standard 15t front with a +5 on the rear and still get the same top speed, although I think +3 is a better option for controllability - a mate of mine had a 900ss with a +3 rear which would 'easily' lift the front in 2cnd gear.
BTW it is theoretically 'better' to have an odd number of teeth on at least one sprocket as this causes the chain wear to be spread more evenly, also not to go too small on the front as the radius being smaller also wears the chain faster - mine being 14/36 (15/36 standard) is not best practice and 15/39 would be a more satisfactory setup.
In the case of my Ducati 916 I fitted a 14t front sprocket (-1) which is the poor man's way of doing it (to go up on the rear meant buying a new, expensive, rear sprocket and a longer chain instead of a cheap front sprocket) and I have not noticed any drop in max speed (theoretically of course
) but it gets there quicker, this is due to the fact that it, like all Ducatis was massively over-geared in the first place. According to the gear calculator www.xs4all.nl/~ator0437/gc/ in standard trim at the rev limiter (10,400rpm) in 6th gear and with a 180/55 tyre it should do 186mph, however it doesn't have enough power to even get near this. Using the same calculator with a 14t front sprocket it should do 174mph but the top speed is effectively 'limited' to 160 - 165 by the BHP/aerodynamics anyway, I could gear it for even better acceleration without losing any top end by going larger on the rear, something which I intend to try when next changing the chain/rear sprocket, in fact according to the calculator I could fit a standard 15t front with a +5 on the rear and still get the same top speed, although I think +3 is a better option for controllability - a mate of mine had a 900ss with a +3 rear which would 'easily' lift the front in 2cnd gear.
BTW it is theoretically 'better' to have an odd number of teeth on at least one sprocket as this causes the chain wear to be spread more evenly, also not to go too small on the front as the radius being smaller also wears the chain faster - mine being 14/36 (15/36 standard) is not best practice and 15/39 would be a more satisfactory setup.
Edited by catso on Tuesday 27th June 13:05
Just been to the bike shop & as mtbr advised me yesterday, they said to first just drop a tooth off the front but keep the same rear & chain. This will only cost around £30 fitted. If after this I still want a bit more then its to start adding to the rear.
Again, as mentioned by mtbr to me in a mail yesterday, they reckon they can play around with the fuelling a bit (not a huge amount) without the need for a power commander. Obviously as & when I add a new exhaust system the power commander will be a necessity, however if I can get away with it for the moment all well & good.
Cheers again.
Cadwell Monday
Again, as mentioned by mtbr to me in a mail yesterday, they reckon they can play around with the fuelling a bit (not a huge amount) without the need for a power commander. Obviously as & when I add a new exhaust system the power commander will be a necessity, however if I can get away with it for the moment all well & good.
Cheers again.
Cadwell Monday
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