Rear Sprocket Change

[Dreamtool]

Hi, I'm currently searching for a new smaller rear sprocket with higher drive ratio than original (I belive original is 16 front 46 back) I think it would be easier to change the rear than front and was wondering how much dirrerence a few tooth will do in the rpm? I know a few people here have changed their sprockets in the other directions, how much difference was that? In standard driving ratio it's ~5000rpm@110km/h if I dont remember wrong, and I'm aiming for something like 3000-3500rpm@110km/h

What do you think about changing it to 40-44T at rear?

The reason for changing is cause I'm going on a Motorcycle trip around europe after winter and dont want to stress the engine with such high revs for such long time.

 

[JeffSez59]

Going down one tooth on the front I believe is equal to going down three on the rear. I went down two teeth on another bike and suggest if you really want a significant rpm drop you atleast go down three on the rear or 1 on the front whichever you find easier. Though some chain modification will be in order

Sent from my HTC6435LVW using Tapatalk

 

[greg]

tbh I would be worried about the engine labouring and not revving high enough if you changed the gearing that much, I'd be worried about it not charging properly too

the engines are designed to rev quite high, going at the speed limit is around 7k, which is half the maximum, and not really stressing the engine at all.


also going up on the front is like going down on the rear, it increases top speed at the expense of torque

personally i'd just give the bike a service before I went away, and not worry about the gearing. just how far do you plan on travelling?

 

[Dreamtool]

Yeah shorten/replacing the chain will be needed but that i think will be manageable.

Yeah I know that its prob. less than half way to what the engine can rev, and that it is built for high revs, but lower revs provide more smooth driving and should be more fuel economical when i'm not interested in driving fast. The charging problem gotta be noted though, gotta check it out...

A full service will be done in spring, all the things you need from tires and suspention to valve adjustments and clutch replace. Right now I'm planing a trip from sweden to norway, england, france, maby northern spain, or just switzerland, germany and back to Sweden again.

Edit. btw. correct me if i'm wrong but if the charging would be a problem it would just be to change down a gear. I.e drive like with a higher final ratio but lower gear? right? not so fun if you are 1000km from home and realize that xD

 

[Kenfz6]

I went up 1 on the front

1. Lowers highway cruising rpm by 500
2. Speedometer error is essentially corrected
3. No changes to chain length
4. Works well as a commuting setup, plenty of room between shift points. The bike still wakes up after 8k rpm.

Been like this for most of the bikes life (47k miles so far) with no issues with charging, that shows up under 3k rpm anyway.

On the s1 version, the rear chainwheel bolt torque settings are wrong, way too high. Good and snug is plenty.

 

[greg]

The generator provides maximum power when the engine is at 5000rpm, though 3500-4000 is usually sufficient. I can't say for sure if you'd have problems, you might get away with it, but if you run lots of powered devices then you may get problems.

FWIW I geared mine down (-1 at the front), and I still get around 60mpg (3.6l/100km)

 

[Nelly]

Yeah shorten/replacing the chain will be needed but that i think will be manageable.

Yeah I know that its prob. less than half way to what the engine can rev, and that it is built for high revs, but lower revs provide more smooth driving and should be more fuel economical when i'm not interested in driving fast. The charging problem gotta be noted though, gotta check it out...

A full service will be done in spring, all the things you need from tires and suspention to valve adjustments and clutch replace. Right now I'm planing a trip from sweden to norway, england, france, maby northern spain, or just switzerland, germany and back to Sweden again.

Edit. btw. correct me if i'm wrong but if the charging would be a problem it would just be to change down a gear. I.e drive like with a higher final ratio but lower gear? right? not so fun if you are 1000km from home and realize that xD

I have dropped mine by one tooth in the rear (46t to 45t) which has dropped the revs by about 1000rpm in every gear. I have not had any real world riding issues with loss of torque. Dropping one tooth in the front is roughly equivalent to dropping two in the rear.
Next time around I am going to drop two in the rear to 44t. If you don't have a speedo healer this will also correct the speedo error.

Nelly

 

[iSteve]

Most road bikes use a ratio around 1:3 our stock ratio is very close to that. So it is close to 3 teeth in the rear is almost equal to 1 in the front.

IMO it's best to change the front sprocket instead of the rear. First fronts are usually cheaper, easier to change, they wear faster and if the rear sprocket gets too small the chain will rub more on the swing arm pivot chain guide.

 

[Dreamtool]

Ok this is great! So it seams like i will change the one in the front by one tooth will be enough and try it from there. If I'm not satestied i might drop one in the back too before the trip.
I ran the gear ratio in a simulator and it seamed quite a lot better. (its for cars so the max rev calculated was 6500) The standard drive ratio is 2.875 (16T to 46T) With a 17T to 46T it will reach 2,705 wich i think will make a nice difference when crusing.
Just have to figure out how to change the one in the front though, but i guess it isn't rocket science.

Speedo-healer is alredy insalled on the bike so just some adjustments and i think it will be fine.

I will get back with a result and accurate rpm difference test if i get the items before winter and all snow we'll see, right now my fuel tank is at the painter and getting a remake custom paint so I might not make it for this season.

Tnx for all the good responses so far!

 

[Dreamtool]

Quick question, is the original chain size 530 or 520? I have currently found both alternetives marked as "Original"

 

[DeepBlueRider]

Dropping one tooth in the front is roughly equivalent to dropping two in the rear.

Isn't that dropping one in a front is almost equal to adding two in a back ?

Here is my math:

46/16 = 2.875
46/15 (-1 front) = 3.0666666
48/16 (+2 rear) = 3
44/16 (-2 rear) = 2.75

 

[DeepBlueRider]

You can use Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator to see estimates how gearing change will change crusing speeds, rpms etc.

Pretty useful and pretty accurate as far as I can tell (roughly matched my experience with my wife's ER6N).

 

[Sigg79]

The original chain size is 530.

When are you going on your motorcycle trip? Sounds like a blast!

 

[Nelly]

Isn't that dropping one in a front is almost equal to adding two in a back ?

Here is my math:

46/16 = 2.875
46/15 (-1 front) = 3.0666666
48/16 (+2 rear) = 3
44/16 (-2 rear) = 2.75

yes that's about right, changes on the rear by one tooth are slightly more subtle than changes on the front by one tooth.

Nelly

 

[Dreamtool]

The gearing commander i can say is a bit off on my yamaha fz6 but it's a decent measurement. I't seams according to that that i can go up one at front and down one at rear. But think it will quite a difference with just the front sprocket accoring to you guise. But i will order a 17 front and 45 back and try it out, make my own opinion whats good else change back to 46 back. I think that would be the best since i dont have to modify the chain anyting if i go down at rear too.

As for the trip, i will try to make it sometime in late May to maby catch some action of Isle of man TT outside England. I have always wanted to see it live before it gets banned. But it depends much on my work and if i can take a vacation... fingers crossed!

 

[major tom]

The TT banned?!!!!??? I don't think so. They shoot lawyers over there if they propose banning the island's main tourist attraction and end over a century of tradition. I'm jealous, enjoy the trip, Maybe one day, sigh.

 

[Carlos840]

I recently went one less in front and kept stock in the rear.

I am now doing 120 km/h at 7000rpm and 140km/h at 8000. I was a bit worried that it would be hard to deal with on long trips but rode Brussels-Paris and back (320km each way) and honestly it was fine!
The bike was happy staying at 8000rpm for extended periods of time, even did quite a large chunk of the return trip at 10000rpm and up and it never even go warm.
No extra vibrations, nothing uncomfortable.

Performance wise it really makes the bike a lot more fun to ride if you enjoy keeping the rpm high... It feels like you don't have to try as hard to keep it over 8000rpm, it just happens on it own! It just feels a lot happier and revs better. If you are the kind of guy that always shifts at 5000rpm don't do it!
I did see a small drop in fuel mileage but nothing dramatic.

I have not been able to see if the top speed was influenced, as didn't have a speedo healer before the sprocket swap and the stock speedo is pretty optimistic.
All i can say is that i have done 219km/h with it at 12500rpm and still had something to give.
According to some you lose top speed, according to others you dont because the stock top speed is limited by lack of power, not by the gearing.

One thing to watch out for is that the bike now has a tendency to lift the front wheel easier... If i am cruising around in 1st or 2nd at 5000 rpm and open wide the front wheel shoots straight up. That never happened to me with the stock 16t sprocket.

All in all this is probably my favourite mod with the FZ1 bar and the aluminium foot pegs, and i would really recommend it!

I don't really see the point of going 17T front and 45 back, that would be the equivalent of going half a tooth down at the front i think and would probably be pretty meaningless!

Wooops, just realised you were actually trying to lower the revs! My bad....
I would not worry about stressing the engine though, it was built to deal with 16000rpm and i really don't think keeping it at 7000, 8000 or even 10000rpm for an extended period of time will hurt it.
As i said earlier, i rode mine for 320km keeping between 8000 and 12000rpm and it didn't even get warm!

 

[Dreamtool]

The TT banned?!!!!??? I don't think so. They shoot lawyers over there if they propose banning the island's main tourist attraction and end over a century of tradition. I'm jealous, enjoy the trip, Maybe one day, sigh.

I know it will be difficult but sooner or later the TT will get banned, cause face it it's really dangerous... A few people get injured or killed every year for one race... Take the nürburgring for example, it was a good racetrack but got banned because it was too fast and dangerous for most official races...

So thats why i want to see it before anyone mess with it

 

[FinalImpact]

More votes for NOT lugging the crap out of it. Lugging drops vacuum, adds MORE fuel and it not saving MPGs if gone too far. The added fuel for the increased load also washes the cylinder of oil.

Engine = HAPPY pulling RPM, more oil flow/splash for cooling, more oil to vital parts, charging = good, cooling system = good. No good comes from lugging an engine. More deposits internally, higher stress on piston, connecting rod, wrist pin which equals more wear...

JMO

 

[Cali rider]

I went to a 17/44 sprocket combo when I did my final chain replacement. I went about 25,000 miles on this setup and really didn't notice an appreciable change in MPG or acceleration. But it did correct the speedometer error (although the odometer was now off by 10%) and made it smoother at a true 65-75 mph cruising speed.