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I am almost positive. The AT has a 2 channel system, meaning it can turn off the rear and they work independently, but they rely on input from both WSS when rear abs is turned on. Also when you remove the front WSS, it completely disables all ABS function, not just the front. (this could be a safety feature, because it verifies both WSS are working before turning it on too, but more than likely both WSS are used for calibration).

You are correct, that if you lock up the rear of the bike, and brake hard on, the front ABS will kick in and still function. This is because it uses a calibration and sensor ring based on the 21in wheel and rotation speed. With a 19in wheel, it will kick in just a bit later. Looking at the spreadsheet above, the biggest gap between rev/mi is only 6%. This is such a small amount, that it would be pretty hard to perceive under normal riding scenarios, and ABS and traction control will still function but with a 6% delay.

Here is a pretty solid video of the 2 channel system:

I still don't think a 19 will have any major negative affects at all, and I plan on running one in the next few months.
 

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Do you even know for sure that the ABS computer compares front/rear rotational speeds?
My assumption is that it does not. It only calculates changes in wheel speed at each wheel independently.
Lets say I'm riding on gravel and I have turned off the rear ABS. Going a little hot into a corner I lock up the rear. I'm pretty sure the front ABS still works in that situation.

For what it's worth, running a 19" front wheel on my KTM990 Adventure did not have any effect on the ABS of that bike.

I know most automotive ABS systems compare wheel speeds but cars do not have independently operated front and rear brakes.
I think thats the way I am leaning as well, I dont know if it compares front to back or is just looking for when the front OR back are about to stop turning/or stop turning. The system diagram in the shop manual does talk about inputs for Motorcycle speed from both Front/Back then feeding down to Front/Rear tire slipping rate, then going down to Hydraulic brake control pressure for Front/Rear based on the setting map in the ABS controller.
The 21 inch to 19 inch tire size examples above have a difference of 5.3% and 6.4% difference in sizing I often get close to that now just changing from a road tire to a knob tire 2.1% front and 4.9% rear.
TC is fairly easy to do just of the rear sensor as well, so not sure if they would want or need to compare to front wheel speed but there is not much in the shop manual on TC.
So I would still be guessing how it works so thats why I was looking for a bit of in the wild testing.
 

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I had the 19" 17" fitted at Rally Raid this week with Bartubeless option on my DCT - happy bunny so far (I am mostly road user) on the 120 mile ride home - I want to do more - but it is snowing again this weekend. I will pen a few note shere when I have done a few hundred more.
John
 

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I had the 19" 17" fitted at Rally Raid this week with Bartubeless option on my DCT - happy bunny so far (I am mostly road user) on the 120 mile ride home - I want to do more - but it is snowing again this weekend. I will pen a few note shere when I have done a few hundred more.
John

How about some photos, nice see how it’s turned out. What about front mudguard, did you have to modify it?:grin2:
 

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Skip - the tyres were already on the bartubless wheels and are 150/70 R17 and 110/80 R19 - so wanting tubeless and already having lowered the bike to a degree I was very happy to be a guinea pig for the 17/19 combo as Rally Raid offered me a good deal. I have only done some 300 miles or so and will do a little write up when I have done a few more - but so far I am very happy - for my riding which is almost all road. On the road the front end definately feels more planted - but I do not feel qualified to offer any comment on how it would be off road.
John
 

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Skip - the tyres were already on the bartubless wheels and are 150/70 R17 and 110/80 R19 - so wanting tubeless and already having lowered the bike to a degree I was very happy to be a guinea pig for the 17/19 combo as Rally Raid offered me a good deal. I have only done some 300 miles or so and will do a little write up when I have done a few more - but so far I am very happy - for my riding which is almost all road. On the road the front end definately feels more planted - but I do not feel qualified to offer any comment on how it would be off road.
John

didn't the 17/19 conversion change the geometry of the bike, by lowering the front more than the rear? Did you compensate by adjusting preload (+ front or - rear) ?
Thanks.
 

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Yes indeed it did, I have not at this point compensated in any way - so far I prefer the feel at the front. There is of course a slightly chunkier tyre too. I need to do more miles to fully evaluate more, but the little bit of skittery feeling I might have at the front in certain situations is much improved. I was sometimes feeling I needed a steering damper with the 21 inch, but not so far with the new set up.
John
 

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didn't the 17/19 conversion change the geometry of the bike, by lowering the front more than the rear? Did you compensate by adjusting preload (+ front or - rear) ?
Thanks.
It doesn't make all that much of a change. By the numbers the 150/70-17 lowers the rear by 13mm and the 110/80-19 lowers the front by 18mm. So only a difference of 5mm lower in the front. Probably not enough to need any compensation and if anything dropping the front 5mm probably improves handling a little bit.
 

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I have now done some 1200 miles on the 19/17 Bartubeless and am very happy indeed with them. Not a great deal to add to previous comments, the front end to me feels more stable and planted, the bike overall feels solid and stable at high speed - but I am not a scratcher anymore.

The tyre pressures have barely moved at all in that time and mileage.

The experience at Rally Raid was great, John and I put the world to rights while he was swapping the wheels over.

Just the speedo to sort - I haven't tried it with GPS yet - John mentioned fabricating a fix for that but I have not as yet followed that one up.

John
 

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I've been running the 19/17 RR Wheel Set since a few weeks ago.
My AT has the DCT option.
The initial choice of tires were Anakee3 since I do 50/50 riding.
For the off pavement tours, there is no problem with the 19" front
unless you are trying to jump 19" logs.

I'd say there is some improvement due to the wider footprint (110 vs 90)
So far, have been more interested in performance on road
and the initial results are very good:
 

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I, too, recently added the 19/17 Rally-raid tubeless wheels. I'm running Metzeler Tourances on them. I find the bike has a dramatic improvement on pavement, especially grooved, cracked, etc. I hated the way the skinny 21-inch front would track on grooves and especially cracks running in the direction of travel. Now , the bike just rolls right over them. It is also more stable at higher speeds. Feels a lot like my previous bike - v-strom 1k.
I bought a second set of rotors and abs rings so I can easily swap wheels. I'll keep some knobby-ish tires on the oem wheels and swap them on when I want to do some more serious off-roading. Two bikes in one!

Oh, and btw, the RR wheels are awesome. Way better quality than oem wheels. You can also get them in the 21/18 size (and tubeless).
 

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Did you change sprocket sizes? Does the side stand need modification? Is there anything else needed to purchase to do the switch besides tires and smaller rear sprocket?
 
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