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gearing 15-42(boldor spec)vs 15-45(gibbo spec)vs 14-45(recon spec)vs 16-40vs15-40

98K views 208 replies 80 participants last post by  Sito73  
#1 ·
42t rear sprocket

Me wanna get one :yes:

Any suggestions on brands / suppliers ?
 
#7 ·
This is available free shipping in the lower 48 but this deal runs out 12/29/14 after that it will be in one part of the country and I will be in another part of the country for several months so won't be able to ship it.
 
#6 · (Edited)
Enlighten me here fellas. With the 15-42 combo, how is the gearing for riding at higher speeds?

Has it cured the Dukie's inability to get it up in 3rd gear? (Or is that just a personal problem on my end?) Hate having so slam her down into 2nd to get my "phat minga" on

Sorry to thread jack...
 
#8 ·
It'll suck I did -1 in the front and the highest I've hit is 115 mph from 125-6mph.

I could get it up in third with stock gearing just had to be clutched up at the perfect RPM or if have to put my left foot on the passenger peg while I cover the brake with my right. Even easier now to do it that I have an exhuast, cam and airbox. Use your weight to your advantage and preload it right before clutching it up and lean back you should be able to get it up if you use your weight and toss it back.
 
#9 ·
Larso, I am going to boldly claim to be the pioneer for this bike with regards to fugg'n with the ratios. My issue was that I could not find a happy gear for 60 km/h. 60km/h was right in between 3rd and 4th for where I reckon the engine should rev.


I went down a couple of teeth first on the rear (38) to try and make first more useful and also make third taller for cruisin' at 60km/h. It worked for the lower gears but "stretched" the taller gears too far apart. 6th became a waste of time.

So then I went up two teeth on the rear (42) to try and make 4th my 60km/h gear and I preferred the 16/42 ratio to the 16/38, but it still wasn't tip-top. So I dropped a tooth on the front (15). 60km/h is still a little "choked" in 4th but on the flat it goes ok.

As for top speed, I don't think I did an ounce of harm. These bikes are not 200km/h plus machines, rather the motors aren't. Even if you got the perfect set up to challenge the 200km/h barrier, I just don't think it'd be a fun trip: get a better suited bike for that schit. Therefore, if you are willing to accept a usable top speed of 170km/h (it'll go a bit faster than that) everything is going to be apples. In the real world, even at track days, 170km/h plus is bullschit territory anyway, except on the main straight. If you get pinched doing 170km/h in my neck of the woods it's all over red rover - go directly to gaol - do not pass go - and deffo do not collect 200 sovs.
 
#10 ·
Larso, I am going to boldly claim to be the pioneer for this bike with regards to fugg'n with the ratios.
Boldor I'm going to boldly take your advice and get dat 42t, should be sweet out on the ice as well! Closest thing to a track my poor duke will have ever seen, assuming we get something plowed...
 
#17 ·
I could make a motza here. You guys are paying more second hand than I pay new.

PUBLIC NOTICE TO ALL SPROCKET SHOPPERS

ALL (each and every!) single cylinder KTM's have the same sprocket mount. Go to your dirt bike man and getz yourselves some sprockets over the counter.

The only KTM sprocket mounts that differ in dimensions are the two-cylinder machines.
 
#19 ·
#25 ·
So beating this poor horse again.
From my understanding 15-42 gearing is what everybody loves to run, which makes sense.
But from what I've read, 16-45 gearing is almost exactly the same compared to 15-42.
So, the big and simple question, is why does everybody buy a 15 tooth front and a 42 tooth rear, instead of just buying a 45 tooth rear and only change one sprocket?
More teeth on the front, one less sprocket to buy and switch out, I don't see the downside?
Is the chain not long enough to fit over a 16-45?


Enlighten me duke friends.



And yes this deserved another entirely new thread about gearing.
 
#27 ·
I was the Bloke who takes credit for first messing with final ratios on this forum.

When gearing down, my first step was to buy a 15 front because it was cheaper than a bigger rear. I liked the initial result but wanted more gearing down so I was forced to buy a bigger rear because putting a 14 on the front bothered me. If I did it again, I would just have bought a 44 or even a 45 for the rear. I have suggested that this is the way to go, but the 15/42 concept has kinda stuck.
 
#30 ·
I am not sure that NJD has the right end of the stick there. But I cannot refute him because I don't run the stock chain any longer - it's gone. Either way, if you get the 45 and you have to later buy the 15 front, it's no biggie. The 15 is as cheap-as-chips even here in Australia. I guess you'll be running 15/45 which is lower gearing again, but if the bulk of your riding is about town, you'll like it even more too!
 
#125 · (Edited)
Old dead thread I know, but after doing a few longer rides on my '17 690 Duke I decided to with HIGHER gearing. The original owner has lowered the gearing to the common 15/42 gearing combo. Still on original chain as only 3K miles on the bike.

I see that 90% of posters here want LOWER gearing. Maybe these guys never have to ride long highway sections? Or just track ride their Dukes?

As a few point out, in USA we don't have 45 mph speed limits and a cop with a radar gun on every corner like Oz.

Also, my Duke (for the time being) will be used to follow along on multi day sport touring rides with guys riding big GS's, KTM 11 and 1290's, Vstroms, Kawi Versys 1000 and Duc Multi's.

Out on open roads or freeway sections we average 80 to 90 mph. My Duke, with it's 15/42 gearing is spinning just a bit too fast at 80 mph. Yet, if I slow to 70 mph indicated, it's really pretty smooth, doesn't feel stressed in the least. :thumbup1:

I don't know true speeds here, just indicated, so probably subtract at least 10% quoted speeds ... and with my 15/42 gearing ... even further off I suspect.

I have original OEM sprockets so plan to re-fit them before our Spring group rides. The current gearing would be great if our routes were all very tight, back road twisty roads ... or short course Race tracks like Chuckawalla, Streets of Willow ... or even Sear's Point. But I'm not doing that any time soon. Maybe in Summer I'll try a track day on the DUKE. But even at Sear's you need 120 mph plus top speed on the two short straights.

IMO, if I need more boost in the twisties ... I use a very old and novel technique ... it's called DOWN SHIFTING! :laugh2:
 
#39 ·
I let this go for awhile, but, KM or MPH, math is math, other than, apparently, Australian math. Gearing calculations are quite simple so the speeds at the stock rev limiter are pretty easy to calculate. Per my observations, the speedometer on my 2015 690 Duke is darned accurate and its top speed at the rev limiter is 112 mph true (~180 kmh, if I have the notation correct at all). Since the stock gearing is 2.5, and 15/42 is 2.8 and 16/45 is 2.8125, 16/45 should also top out at about 112 MPH, or 180 kmh. 15/45, which is 3:1 would hit the limiter at 104.5 mph, or 167 kmh.

I would not have commented on this gearing discussion but about a week ago I was out for a battery charging cruise, running the posted 55 mph speed limit, and behaving myself very maturely and properly. As I headed toward home I turned onto a back way that is sort of curvy but also fairly high speed and I noticed two motorcycles on the same route that had turned in front of me and were headed the same direction. Well, after weeks of behaving, something sort of snapped and I decided to unlease the 690 a bit and catch up to the others. So, I did, but, to my surprise, I did not close in on them. Seems that they were on a mission and that they were stepping rignt along. I then, I am ashamed to say, went deep into the red haze and I bumped the rev limiter a few times in top gear. I did close the gap quite a bit, but, then, we came to a long straight section that is miles long and the two bikes jetted away from me even as I once again bounced off the limiter at 112. Of course, taller gears would not have helped at that point since four cylinder sports bikes can go a lot faster on a long straight than a 690 single, but, 15/42 gearing does have its limitations. Anything shorter, except for possible serious stunting work, would be overkill.

One final thought is that I now have a nice selection of gears that all work with my stock chain as I can do 15/40 and 15/42 and 16/40 and 16/42. And, in fact, after the lack of top end that I had to deal with the other day, I seriously considered putting the 16T front back on the bike. That would give me 119 mph (190 km) at the rev limiter, and the way my bike pulls to 112, it should be able to do that. But, I would miss that 15/42 grunt at legal speeds and around town. And, 119 would still have been dropped by the sports bikes which hit 150 without even breathing hard.

I guess that the KTM answer is a 1290R, but, my buddy got one and he has dropped 1T on the counter sprocket as the stock bike is geared too tall. So, apparently. all KTM's are geared too tall for sure as delivered. And, his 1290R is hidden under blankets in his garage in the hopes that the police will give up looking for him at some point, as absolute power corrupts absolutely.
 
#40 ·
And, his 1290R is hidden under blankets in his garage in the hopes that the police will give up looking for him at some point, as absolute power corrupts absolutely.
LOL, too awesome
 
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#41 ·
+1. The difference between the 690 and 1290 is how easily it goes fast. They are both fast. I prefer longer gears at the sacrifice of take off. I had 16/42 on my 690 and thought it was great. Hit 112 once. The wind was nuts. I do 112 on the SDR effortlessly. Just roll it on in 4th.