[Rider2022]

Hi,

My duke 390 currently has the stock gearing and chain (15T front, 45T rear).

Being my duke is for commuting to work and not really for fun, my aim is to get to work n back cheap as I can, thus fuel economy is key for me.
I am interested to know people experiance on the gearing your running and the effect of the RPM at say 70 MPH of before and after the gearing swap out.
I am considering to swap mine out after the stock gears are worn out to 16T front. 42T rear to allow for better cruising RPM at duel carriageway roads (my main run to work type of roads)

How have people found the drivability when making the gearing much taller ?

 

[DukeofSeven]

mileage doesn't change, but the reduction of engine rpm definitely has its pluses.

i think the reason the mileage doesn't really alter at all is because of how the MAP sensor in the throttle body senses the increased load on the engine [with my 16x43 gearing] and offsets any presumed advantage you might gain from fewer injector pulses per minute at reduced rpm.
then again, at 75 mpg no matter how i drive it, what am i really looking for that i don't already have?

but because I always seemed to be trying to grab another gear, in the type of driving i do, i opted for the gearing i settled with, and i also find that it calms the whole package down, once i set it in top gear, as long as i'm then above 5500 rpm.
it does not have any difficulty pulling the taller gearing...
and as long as i'm not pushing against a headwind, i can cruise it in 6th, comfortably, if i choose to, as long as i'm moving at 50 mph (roughly 4500 rpm) or higher.

looked at another way, my gearing is running the engine at 89.6% rpm, compared to stock...
your proposed gearing would run your engine at 87.5% rpm.

So if our bikes were both running 7000 rpm at 70 mph with stock gearing...
mine is now running 6272 rpm at 70, and yours would be running 6125 with your preferred gearing.

those projected rpms do sorta lay right in that flat spot in the torque and hp curve... but of course, it perks right back up as you get closer to 6800 rpm. to pass around, i always drop a gear anyway.

 

[troop]

Load up this app and enter the KTM/390/Duke info. Stock gearing info will pop up and allow you to see gearing changes with different sprockets. I swapped out the front 15t cs sprocket for a 16t over the winter, but haven't had the chance to try it yet here in WI. Gear commander shows 400 rpm lower .

Gearing Commander - Motorcycle Speed and Drive Train Calculator v7

Motorcycle speed and sprocket calculator with bike database for gearing, sprockets, tires and chains of over 1750 bikes. Request yours to be added as well.

www.gearingcommander.com

 

[Oblivionlord]

I've already swapped out my rear 45 for a 42 and it makes a nice difference in the topend. I see no reason why the bike came stock with 45 in the back when it operates just fine with a 42t considering this is a street bike not an enduro bike. If even this were an enduro bike then I wouldn't be happy with a 45, I would have gone even higher. Even for stunts you'd want to change it for a larger ring.
I'm now in the process of changing out the front to 16t to give it even more topend since it still requires quite an excessive amount of shifting through gears using 42t.

 

[Oblivionlord]

I've just swapped out the front 15t for 16t and kept the rear at 42t. The bike now feels great on the road even more so than the 42t change at the rear. The 6th gear is only usable on the highway or anytime you are in the 70s whereas before 6th was at 67mph at 6k rpm which was just a bit too high for me. It required me to go through the gears more often compared to now at 16t/42t, I travel less through the gears.

The only thing I really do not like is that the 16t does not have the rubber dampener for the chain. It is just a bare sprocket which makes it a little noisier and adds vibration in the foot peg area when you are riding slow.

 

[DukeofSeven]

and adds vibration in the foot peg area when you are riding slow.

See # 13... grease it. It feeds chain drag/oscillations directly into the footpeg. Jus sayin'.

 

[troop]

I've just swapped out the front 15t for 16t and kept the rear at 42t. The bike now feels great on the road even more so than the 42t change at the rear. The 6th gear is only usable on the highway or anytime you are in the 70s whereas before 6th was at 67mph at 6k rpm which was just a bit too high for me. It required me to go through the gears more often compared to now at 16t/42t, I travel less through the gears.

The only thing I really do not like is that the 16t does not have the rubber dampener for the chain. It is just a bare sprocket which makes it a little noisier and adds vibration in the foot peg area when you are riding slow.

Does your bike pull top gear with this taller gearing?

 

[Oblivionlord]

See # 13... grease it. It feeds chain drag/oscillations directly into the footpeg. Jus sayin'.

View attachment 56102

That's not the cause of the vibrations. The vibrations is the chain making contact with the bare 16t sprocket vs the contact on the bushing that's present on the 15t sprocket. You can even feel this just by taking the bare sprocket by hand and contacting it with the chain. The feeling of that is amplified as the chain is being turned by the motor. Very similar to the vibration dampener ends on the handlebar.

 

[Oblivionlord]

Does your bike pull top gear with this taller gearing?

6th gear at this gearing has very little pull on the highway. You need to drop down into 5th to overtake anyone.

 

[JingalalaHoe]

Can anyone provide a link to purchase 16T front sprocket for the 390 in USA?

 

[DukeofSeven]

That's not the cause of the vibrations.

I was trying to indicate it would help.

Can anyone provide a link to purchase 16T front sprocket for the 390 in USA?

SUPERLITE (#73305R) 520 Pitch Chromoly-Steel Front Sprocket - KTM / HUSQVARNA - SprocketCenter.com

Made of chromoly-steel & drilled for lighter weight. Available in sizes 14 - 16. Sprocket Center is the #1 Superlite Sprocket dealer in the nation and we have more inventory than all other retailers combined. Unlike our competitors, we stock what we se

sprocketcenter.com

Drive Systems - 390 ADV/Duke/RC - Front Sprocket

Drive Systems Design and Produce the Lightest Sprockets with Durability that will outlast the Competition!

www.rottweilerperformance.com

same products, different source. if it helps.

 

[KTMasean]

You can order these from Super Sprox.

Can anyone provide a link to purchase 16T front sprocket for the 390 in USA?

 

[JingalalaHoe]

same products, different source. if it helps.

You can order these from Super Sprox.

I think I'll get a Duke 200 chain sprocket kit (14/42) and replace the front sprocket with one from a 390 - which coincidentally I have a brand new one. It will end up only slightly more expensive than the 16T front sprocket alone hehe

 

[troop]

I'm thinking I'll go with the 16/43 combo. Good thread !

 

[KTMasean]

Then why not only buy a 42 rear???
What will you do with the unused 14 front ???

I think I'll get a Duke 200 chain sprocket kit (14/42) and replace the front sprocket with one from a 390 - which coincidentally I have a brand new one. It will end up only slightly more expensive than the 16T front sprocket alone hehe

 

[JingalalaHoe]

Then why not only buy a 42 rear???

We dont get just sprockets or chains. It's always a set of 2 sprockets and the suitable chain. The front sprocket is an exception though and I managed to get a new one (15T) from KTM service center. Just the new 15T front sprocket was ~3.5USD, new chain and sprocket kit with x ring chain here is about 30USD

What will you do with the unused 14 front ???

Nothing, I guess. The Duke 200 has 110 links instead of 112 for the 390, thats because of the smaller sprockets too I reckon. Using a 42 in place of 45 with the standard chain might stretch it out too much

 

[Oblivionlord]

Can anyone provide a link to purchase 16T front sprocket for the 390 in USA?

We dont get just sprockets or chains. It's always a set of 2 sprockets and the suitable chain. The front sprocket is an exception though and I managed to get a new one (15T) from KTM service center. Just the new 15T front sprocket was ~3.5USD, new chain and sprocket kit with x ring chain here is about 30USD



Nothing, I guess. The Duke 200 has 110 links instead of 112 for the 390, thats because of the smaller sprockets too I reckon. Using a 42 in place of 45 with the standard chain might stretch it out too much

It worked fine when I used a 15/42 but ultimately I much preferred 16/42.