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Discussion Starter · #1 ·
I changed the front sprocket from 15 to 14 teeth and here is my thought.

Personal information:
2021 390 adventure with aluminium top box and side cases;
220lbs man often riding 2up.
70% city riding and 30% motorway riding (50-75mph, usually 60mph cruising)

First of all, Gas Mileage is not affected, if you are bothered by 1mpg difference, go get a 125cc scooter.
Stock gearing is OK, dont change if you dont want.
Here is just my opinion.

Q: why changing from 15 to 14?
A: stock 1st gear is too tall and I feel the clutch is over stressed at stop and go traffic.

Q: is 14 teeth solve the problem?
A: kind of, 14 provides 7.1% lower gearing/torque. it is noticeable at start up but the RPM at highway is increased significantly. (the mpg is not affected much, not noticeable.)

Q: pros of 14-45 setup?
A: 1.better startups. 2. a lot fun when riding wide open throttle and in moutain area. 3. can changed to 6th gear at speed of 45mph (a usually speed of chinese expressway, 15 45 is terrible at 45 mph because 5th is too low and jerky and 6th gear is too tall and engine runs rough below 4000rpm)

Q: cons of 14-45 setup?
A: 1.too much gear changing,25 mph at 4th gear intead of 3th, 40mph at 6th gear.

Q: RPM difference?
A: THE SPREAD SHEET IS BASED ON MY PERSONAL BIKE DATA AND THE SPEED IS NOT GPS SPEED. (1 MILE DIFFERENCE)!

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Q: if 14-45 is too much of upgrade, what about 15-46/ 15-47?
A: 15-46 is not noticeable of change.
Highway tourer, 90% highway riding:
1.one person with luggage, stock ratio.
2.2up with luggage,15/47
2.2up racer? 1290 R instead

Mixed rider, 50-50 city and highway
1.one person with luggage, stock ratio or 15/47.
2.2up with luggage, 15/47 or 14/45.

City rider, 90-10 city and highway
1.one person with luggage, stock ratio or 15/47 or 14/45.
2.2up with luggage, 14/45 or 14/46.

Q: 14-49 setup?
A: U R Nuts. I believe if the bike is geared too low, you will feel when you twist the throttle, the engine waste all the energy reving up instead of pulling the bike forward.
 

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16T front for me, stock 45T sprocket on rear. I wanted better 6th gear performance, cruising capability on highway. ~120 km/h here on the local highways.
 
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Discussion Starter · #6 ·
16T front for me, stock 45T sprocket on rear. I wanted better 6th gear performance, cruising capability on highway. ~120 km/h here on the local highways.
16 45 setup is good as long as the traffic is less busy, otherwise, downshifting is a must. 14 45 setup requires no down shifting when passing gentley. I guess Canada is a great place for cruising.
 

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Ah yes, the wheel/tire sizes are different I've realized. So the gearing is likewise not the same.
 
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Gearing Commander and similar sites are great tools for liter bikes and big V Twin cruisers where torque is readily available throughout the rev range. Not really so useful in small capacity bikes with peaky torque curves.
 

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I also only go up in the front to relieve the chain a little and went down in the rear to ride at the same speeds in lower revs.
I hardly ever ride in towns/cities and mostly longer distances in a row, 350 - 450 km/day so no need for me to lift the front wheel.


16T front for me, stock 45T sprocket on rear. I wanted better 6th gear performance, cruising capability on highway. ~120 km/h here on the local highways.
 

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Discussion Starter · #13 ·
I also only go up in the front to relieve the chain a little and went down in the rear to ride at the same speeds in lower revs.
I hardly ever ride in towns/cities and mostly longer distances in a row, 350 - 450 km/day so no need for me to lift the front wheel.

300km/day on a duke? man you have a titanium butt:cautious:
 

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Discussion Starter · #16 ·
Gearing Commander and similar sites are great tools for liter bikes and big V Twin cruisers where torque is readily available throughout the rev range. Not really so useful in small capacity bikes with peaky torque curves.
I do think though this is a high rev engine, it only gives up sub 5000 rpm completely, from 6000-10000rpm, the torque is guite nice and flat.
 

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In Australia at the moment there are no 14 tooth sprockets
I’m trying to find at 47T rear to go with a 15T front. This would give me a final drive close to 45Tr 14Tf but not sacrifice so much Top end
But I can’t find a sprocke that any retailer can confIrm will fit
Where are these nuts getting 49T rears
 

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In Australia at the moment there are no 14 tooth sprockets
I’m trying to find at 47T rear to go with a 15T front. This would give me a final drive close to 45Tr 14Tf but not sacrifice so much Top end
But I can’t find a sprocke that any retailer can confIrm will fit
Where are these nuts getting 49T rears
www.sprocketcenter.com had 47t rears in stock last I checked…
I am currently waiting on super sprockets to finish up my 48t for the Duke.
 
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