Sprocket advice

[StephenC]

I've read a few topics on this subject, but want to check I have the right take on the advice given. I have an 1100S and on the ride home from buying it found that at legal speeds (110kph) it was lumpy in top gear, below 4000rpm. To be honest, it felt OK a gear lower still. This makes me think I could get away with a sprocket change to give me more torque at low revs and won't miss top the loss in top speed. I may just have to start using the top gear on my rare freeway rides.
I gather that changing to a T14 on the front is easy and cheap but mechanically less sound than going up a few teeth on the rear. Presumably a bigger rear sprocket will need a longer chain?  Will making these changes affect the (already atrocious) accuracy of the speedo?  Are there any issues I should be aware of!  Any recommendations of brands?

Thanks

[Slide Panda]

Presumably a bigger rear sprocket will need a longer chain?  Will making these changes affect the (already atrocious) accuracy of the speedo?  Are there any issues I should be aware of!  Any recommendations of brands?

Thanks

Highly likely you'll need a longer chain if you mount a bigger rear sprocket. Not 100% guarantee, but probably.

No, will not effect the speedo. It's operation will remain the same. It's running from a sensor detecting wheel speed, not gearing + engine RPMs like many Japanese bikes (and triumph 675s)

Issues? Not really anything beyond the math - -1 in front is roughly the same as +3 in the rear. http://gearingcommander.com/ can help you hash math if you want.

Renthal makes nice hardedned AL ones. CA Cycleworks carrys some nice *lighter* steel ones (still heaver than AL thought), SuperSprox

[Howie]

On the older Monsters you could go +2 in the rear without adding a link, not sure about the new generation.  How many miles on the chain?  In theory the chain and sprockets should be changed as a set, but if fairly new...

[Estoma]

The 14-tooth Front Sprocket is obviously the easier, cheaper and hence more popular route.  However,  the smaller Front Sprocket also constitutes the Mechanically less sound option, as you have rightly pointed out.  Your Chain Links see more rotation over the Link Axis with a smaller Front Sprocket and your Chain itself spends more time on the Upper Chain Guard, adding additional Wear to the Rollers and Guard while depleting Chain Lubrication.

Your best bet is a 42-tooth Rear Sprocket with two additional Links on your new Chain. The added Links are necessary in order to preserve your current Ride Height and Wheel Base with the Eccentric Adjuster on the Rear Wheel.  These two Factors, Ride Height and Wheel Base, might seem more trivial than is actually the case.

[StephenC]

I've only got about 6000km on the bike so might wait until it is a bit more loved first.  I'm not sure if this is a job I would take on myself or sent to the mechanic.  In any case, I have a pile of other tasks that are a higher priority.  Thanks for the input.

[LA]

There is nothing bad/wrong at all with using a 14T front. It's a factory option and has no drawbacks at all as far as I'm concerned.  I put 40K miles on my S4r and have 44K miles on my S4RS now with no problems at all. It makes my bike run 60 mph at 4000 in 6th. I ran a 14/44 on the s4r and a 14/43 on the S4RS.

Ducatis should come with a 14T sprocket wired to the price tag.

[ungeheuer]

The 14-tooth Front Sprocket is obviously the easier, cheaper and hence more popular route.  However,  the smaller Front Sprocket also constitutes the Mechanically less sound option, as you have rightly pointed out.  Your Chain Links see more rotation over the Link Axis with a smaller Front Sprocket and your Chain itself spends more time on the Upper Chain Guard, adding additional Wear to the Rollers and Guard while depleting Chain Lubrication.

Your best bet is a 42-tooth Rear Sprocket with two additional Links on your new Chain. The added Links are necessary in order to preserve your current Ride Height and Wheel Base with the Eccentric Adjuster on the Rear Wheel.  These two Factors, Ride Height and Wheel Base, might seem more trivial than is actually the case.

^^  This.

More or less.

I finally settled on 15/43 on my M1100s as gearing perfection for me.  Yup, its more costly than the 14t option coz you're gonna need a new chain (or lengthen as Estoma says...  although adding links isnt my preferred option).  So maybe go the 14t with your existing chain to see how you like the lowered gearing first.... and come time for a new chain then go 15/42 or 15/43....

[StephenC]

I've spent too much on the bike already, so this will go on the back burner for now. When the time comes I think I will go for the longer chain and bigger rear sprocket. Thanks for all the input.

[Greg]

Go with the 14T, far cheaper and I've never seen a mechanical complaint on these forums from using one. When the chain wears out then you can swap around and go for the bigger rear.

[Curmudgeon]

Ducatis should come with a 14T sprocket wired to the price tag.

[StephenC]

Go with the 14T, far cheaper and I've never seen a mechanical complaint on these forums from using one. When the chain wears out then you can swap around and go for the bigger rear.

I guess that makes sense.  Is a sprocket change a DIY job (I'm mechanically incompetent, but can read!) or something I should let a mechanic do?

[brad black]

Go with the 14T, far cheaper and I've never seen a mechanical complaint on these forums from using one. When the chain wears out then you can swap around and go for the bigger rear.

what he said.  while the alleged perils of the 14 tooth front sprocket are true internet folklore, people forget that every 748 and 749 left the factory with one.  don't see too many of them with destroyed swingarms.

if you are replacing all, i say fit a 15 front.  but with the price of rear sprockets for the sss bikes and need for replacing the chain as well, 14 front is a no brainer for a simple gearing change.

[StephenC]

Which type of 14T do I want for my Monster 1100S?  Monsterparts lists two different sprockets and they both have a few different fitments: plate, nut etc..  I might get the mechanic to actually fit it as they told me there was a problem with the thread in the crankcase hole the rear-sets bolt on to so I am wary of taking them off myself.  Can anybody recommend an Australian distributor that sells the sprocket I need?

[MonsterDave]

I've been using a 15 front / 39 rear for the last couple years. Top end stinks but 0 to 100 is awesome. Would top out at 118. Just changed it to 15/40. Gained about 5-8 mph but who wants to go that fast on a naked? I'll take the low end torque anyday. 

[racingj]

Changing the final drive ratio on the current air cooled monsters should be a first for performance improvement. 1100EVO are geared way to tall to satisfy the emissions testing. This keeps the motor in the closed loop injection RPM at testing/road speed. Final drive ratio is easy math by dividing the rear sprocket by the front sprocket. Exp. 39/15 =2.6 This is the stock set up. 39/14=2.78 This is the ratio with the 14 tooth countershaft sprocket. On my 1100EVO with 14 tooth sprocket you still need about 70mph for sixth gear operation. I will add additional teeth to the rear when the current chain is worn out. I plan on a 41/14 =2.9 with replacement. This should give you excellent acceleration and good highway cruising. Monsters don't need gearing for 140 top speed, as with the stock set up. How many of us spend that much time at over 100mph on a naked monster ?