Gearing Ratio's for SDGT's

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Aussie Dave
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Gearing Ratio's for SDGT's

Post by Aussie Dave » Fri Jul 05, 2019 6:43 am

G'day all,

I have been experimenting with my 17SDGT final gearing ratio's and here is some info if anyone has been thinking of making some changes.

17/38 = OEM sprockets = awful - too tall geared for Aussie roads and speed limits.... struggles in 5th at 100kph and 6th cannot be used without being caught for speeding and locked away in jail.

17/40 = 15min rear sprox change, good results, probably all that's needed..... GT still struggles in 5th at 100kph in hilly terrain with touring luggage (I used 4th and let it sing). Not quite right for our Oxley Hwy corners but pretty damn close. Adds 250rpms to oem gearing.

16/38 = 1 tooth smaller front sprox takes the abruptness away and adds 500rpms to oem gearing. Ok but seemed like it had less torque. I was surprised I didn't like it as much as I thought I would. Might try it again.

16/40 = Initially I thought it was too much, but then I felt quite happy with it..... 4000rpms in 6th = 100kph, and 60kph is fine in either 3rd or 4th. adds 750rpms to oem gearing. Excellent in traffic & around town. Feels like it has more torque than the 16/38 combo....... so it tames the beast for busy traffic duties, but retains the acceleration when asked...... for our Aussie conditions ;) ...... no unlimited Autobarns/Motorways, speed cameras and unmarked cars/bikes anywhere/anytime, tight potholed corners, narrow mountain roads etc etc.(might even be the solution for those still stalling at traffic lights etc?).

For the real world of road riding (not track days) it may well be the best setup...... the internal gearbox ratios are the problem but they are not easily changed. So 16/40 sprox's gives me all 6 gears to play with and no chuggy/luggy sensations at awkward times in busy traffic while trying to indicate and dice with d-heads.

Weather gone sour this weekend, need more riding in faster corners than Beechmont/Tamborine to be sure.

If I don't stay with 16/40, I'll happily return to 17/40...... all the above combo's do not require longer chains, but I do wonder if a 17/42 at new (longer) chain & sprox time might be the better option....... :idea:

:mrgreen:
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Prev loves...Capo1200TP-014, CBR11xx-002, 2xFZR1000genisis-94, FJ1200-89, FJ1100-84, XS1100P, VF1000F-83, CX500, VF750S, KZ1000J1-81, KZ1000ST-79, CB750F2-77, CB360T-74, CB175.. started it all in 1974 ;)

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Re: Gearing Ratio's for SDGT's

Post by jjscsix » Mon Jul 08, 2019 2:00 am

Good information Dave. I'm still stock, but I do think I might try a bigger rear sprocket. Just hasn't risen to the top of my to-do list yet.
2017 KTM Superduke GT, 2017 Yamaha FJR1300, 2012 Ducati 1199 Panigale

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Re: Gearing Ratio's for SDGT's

Post by mick shere » Mon Jul 08, 2019 6:04 pm

As always great write up Dave thank you mate
We have just got back from a 2000 mile round trio to the south of France, 6th gear just about hangs in 2 up with full panniers at the speed limit of 130km (80 mph) on the motorways :)

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Re: Gearing Ratio's for SDGT's

Post by pk1 » Mon Jul 08, 2019 9:02 pm

Good info Dave, I run 16/38 and it’s perfect for me on my own but when 2 up and loaded I find it wants to lift the front on any sort of acceleration. Which when trying to quickly get bye traffic on a back rd gets me a few digs in the back from the wife as it’s hard to keep the front wheel down even short shifting.
I think 16/ 40 would be mad and fun but way too much when fully loaded.
It’s possibly due to my other mods also and a combination of both.

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Re: Gearing Ratio's for SDGT's

Post by Clogan » Mon Jul 08, 2019 10:52 pm

Guess I'm in the minority, but I love the OEM gearing. I find that I spend most of my riding in either 3rd or 4th, (covers 40 - 70mph) so not much time is spent shifting gears. On the rare day I get to the interstate, I'll go to 5th, but it's rarely needed. Sixth gear? Never need it.

I just don't see the logic in spending time and money changing gear ratios just so I can shift gears more often.

(Flame suit on)

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Re: Gearing Ratio's for SDGT's

Post by GarrCano » Sun Jul 21, 2019 6:02 pm

On the SD1290GT the speed is taken from the ABS-sensor on the front wheel.

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Re: Gearing Ratio's for SDGT's

Post by Aussie Dave » Mon Jul 22, 2019 6:49 am

Speedy14 wrote:
Sun Jul 21, 2019 2:57 pm
How do you guys that change the gear ratios correct the speedometer readings? It will certainly throw off the speedometer from the stock ratios.

(My previous Ducati 1299 Panigale had a auto correction feature in the electronics for correcting changes in tire sizes or gearing) .. From my experience, when you start changing the ratios it also throws off the Traction control...

Just wondering..?
Speedy

Hi Speedy14, No changes to speedo with sprocket changes on the KTM. I checked with my Garmin sat nav..... as mentioned above, the readings are taken from the ABS sensor, not the gearbox, so only tyre size & profile will alter the speedo reading.

For info, my SDGT runs with 1-2% speedo error regardless of which sprockets I have installed and the SDGT doesn't require any reset for TC.....(no mention in the manual, nor from my KTM dealership who installed the 16t) . I have changed to Michelin PR5 tyres now (same 120/70 & 190/55) and the speedo error is the same as the oem Angel GT's the bike had from new.

:D
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Prev loves...Capo1200TP-014, CBR11xx-002, 2xFZR1000genisis-94, FJ1200-89, FJ1100-84, XS1100P, VF1000F-83, CX500, VF750S, KZ1000J1-81, KZ1000ST-79, CB750F2-77, CB360T-74, CB175.. started it all in 1974 ;)

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Re: Gearing Ratio's for SDGT's

Post by Aussie Dave » Sat Jul 27, 2019 7:20 am

Cheers Troppo...... I think I saw your post on the other forum..... with a pic at the Beechmont hang glider launch site cafe....... ;) .

The 17/40 is good, and will make Aussie speed limits nicer. It is only an extra 250rpms in 5th at 100kph, but it takes away most of the judder the motor gets when the revs are just that little bit to low. The other options require more surgery than simply squeezing a +2 teeth sprocket in at the back...... and probably don't yield as much bang for buck as the 40T sprocket. Be sure to read the thread on here about correct install.

I'll keep an eye out for your Black GT..... that's my coffee run - Canungra Outpost or beechmont or Binnaburra.

;)
2017 1290GT 27,484km, 05 CBR1100XX 130k kms

Prev loves...Capo1200TP-014, CBR11xx-002, 2xFZR1000genisis-94, FJ1200-89, FJ1100-84, XS1100P, VF1000F-83, CX500, VF750S, KZ1000J1-81, KZ1000ST-79, CB750F2-77, CB360T-74, CB175.. started it all in 1974 ;)

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Re: Gearing Ratio's for SDGT's

Post by Carolina SDGT » Tue Feb 04, 2020 8:05 pm

I know this post has been 'round for awhile but just my $0.02 in USD, one tooth off the front is roughly equivalent to three larger on the rear but harder on the gearbox output shaft and chain. I've played around with this on my vintage Norton 750 and finding the "right" final gear ratio is total dependent on your riding style (usage) and environment. I will probably wait until the chain or countershaft sprocket starts to show some wear and go with a 17/42 combo. It's going to be tough not lubing the chain so it will wear faster :lol:
Steve
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Re: Gearing Ratio's for SDGT's

Post by Aussie Dave » Wed Feb 05, 2020 8:15 am

Cheers CarolinaSDGT,

You are on the right pathway...... I agree, after 27,000kms I am thinking the same, and will likely fit 17/42 or 17/43 when my chain needs replacing..... but the chain hasn't been affected by the -1 front sprocket at all, and isn't wearing...... so it will be another 12 months/20,000kms before I even think about buying a new longer chain and fitting new 17/42 or 43 (or maybe even 44) sprockets....... These new x-ring super chains are so much better than all the older o-ring chains and light years better than the old style un sealed chains ;) .

The 16t front isn't totally perfect as it feels like it reduces the sensation of torque that the 17 gives, but it does allow for a better spread of ratios to speeds (unless you have wide open traffic free roads - with almost no police around).

I am still very happy with the 16/40 combo on the oem chain, though I just recently removed my O2 dongles (again) and reinstalled the O2 sensors while fitting a 'Booster Plug' module to the air box temp sensor. That seems to make my bike feel super strong on acceleration at any rev and yet retain fuel economy and touring range in excess of 400kms.

I was never unhappy with the stock fueling, but everybody else seemed to want O2 dongles, so I tried them a couple of times, with ordinary results. They worked, but their benefit wasn't that clear to me on my SDGT.

However I'm now in the process of converting to an MiVV can (beautiful sound) and maybe even doing a de-cat and SAS delete in the near future, so it's all a state of flux for me at the moment......... but the SDGT sure is brilliant :D .

Once a hoon, always a hoon......
Carbon Fibre with 55mm main  tube vs oem mufflers 60 main and 42 dB restrictor. So it's got more of a V2 note but not anti social..jpg
Carbon Fibre with 55mm main tube vs oem mufflers 60 main and 42 dB restrictor. So it's got more of a V2 note but not anti social..jpg (55.04 KiB) Viewed 394 times
2017 1290GT 27,484km, 05 CBR1100XX 130k kms

Prev loves...Capo1200TP-014, CBR11xx-002, 2xFZR1000genisis-94, FJ1200-89, FJ1100-84, XS1100P, VF1000F-83, CX500, VF750S, KZ1000J1-81, KZ1000ST-79, CB750F2-77, CB360T-74, CB175.. started it all in 1974 ;)

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Re: Gearing Ratio's for SDGT's

Post by DaveNZ » Wed Feb 05, 2020 7:25 pm

I replaced my chain and front sprocket at 30,000kms mainly because i had a big bike tour ahead and didn't want to risk a stretched worn chain ruining my ride. But i made a little mistake of ordering a DID chain in the stock length, (114 links) so i couldn't fit my 41 rear tooth sprocket on, so had to revert back to the stock 38. But with the engine running so much smoother due to de-cat Booster etc, in the low revs i found the stock gearing ok, even in 6th at 100kms the bike ran smooth. So I've left it stock geared for now, I'm picking now the chain has travelled 6000kms the 41 sprocket may fit again, but I'm happy for now with the taller 38, i love big torque driving tall gears, get to feel the torque biting and driving the bike forward, and acceleration is there to match the 1290Rs and V4 Tuono Factories.
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Re: Gearing Ratio's for SDGT's

Post by Carolina SDGT » Wed Feb 05, 2020 10:29 pm

I agree 100% on the new chain (and sprocket/chain wheel) technology being just amazing. Hard to argue with the miles some of the “iron butt” folks are getting out of the modern bits and pieces. I also agree the smaller front sprockets don’t seem to damage the gearbox on modern bikes like back in the 60s and 70s. Modern fueling maps and sensing of key parameters sure do mask changes that would be more apparent with a vintage machine like my old Norton.
Steve
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