Gearing change with ABS

[Lucas]

I'll try and make a long story short.

I bought a 2011 monster 796 back in may. ABS was an 800 dollar option that I said no thanks to for my own reasons. When I went to pick up my bike they said Ducati sent all the M796s over to the US with ABS at no extra charge. Can't argue with that right?

I love everything about the bike exept the ridiculous
tall gearing. Have to feather the clutch in anything under 10mph. Never use 5th or 6th even on the highway. Easy enough, I'll drop a tooth in the front and I'll be good to go!

Not so fast.

Apparently the ABS is tied into the ECU and if you change the gearing it will hit a soft rev limiter and the ABS can engage sooner than it normally would because of the change. (I'm not sure I explained that best)

Some guys on the monster forums changed it
anyways. They say it works just fine. Tested the ABS in a parking lot and that also works as it should.

Ducati says no until there is some type of ECU remap to go along with it but who knows how long that would take? Cost?

What would you do? I'm tired of waiting!

[OreoGaborio]

A front sprocket is what, around 20 bucks? Not a very expensive experiment if you ask me

[Lucas]

A front sprocket is what, around 20 bucks? Not a very expensive experiment if you ask me

And risk messing up the ABS/ECU not to mention voiding my warranty?

Decisions. . .

[OreoGaborio]

So the possible side effect on the ABS is permanent?

[Lucas]

No idea. Not sure if my safety will be at risk. Damn electronics. I'll try to copy paste one of the letters a number of monster owners received back from Ducati.

[gadget]

I do not doubt the ABS system works with the ECU but shouldn't it be flexible enough to deal with a variety of conditions including slightly different sized tires and inflation, road surfaces etc?
Would changing the front sprocket screw it up that much?
I have read about people changing it on Triumph Tigers with ABS all the time with no effect to the ABS and I have been considering it as one of the winter mods I was going to put on my list.

[Lucas]

Here's the definitive reply from Ducati North America.

Thank you for contacting Ducati North America.



The ABS system uses both speed and RPM in its computations, two things directly affected by changes made to the gearing ratio. The ECU that governs the ABS system is programmed to work with the stock gearing on the bike only.



We hope this provides you with the information you were after.

Regards,

Customer Service



10443 Bandley Drive

Cupertino, CA 95014






Phone: 408.253.0499

www.ducatiusa.com

[Honclfibr]

Brakes are one of those things you don't really appreciate until they're not there.

[Lucas]

Bump.

[NobodySpecific]

I changed the front sprocket on my Sprint with ABS and it didn't make any difference in regards to the ABS system, but obviously there is no relationship between ECUs Unless they programmed it into the ECU that x mph = y RPM for each gear, then it shouldn't make much of a difference, as that really is the only thing that a gearing change does. I don't see why RPM really has any role in an ABS system, but that's a different topic.

[Paul_E_D]

I'm baffled. How can they be related? ABS kicks in when the tire stops right? What could RPM have to do with that?

[Lucas]

I'm baffled. How can they be related? ABS kicks in when the tire stops right? What could RPM have to do with that?

That's what I don't get but the letter from Ducati say it does rely on RPMs.

[Paul_E_D]

Just change the sprocket. Ducati is pretty good about honoring warranties. I don't think the bike is going to apply the brakes on you suddenly, or take them away. That would be legal suicide.

[BSR6]

Maybe it has something to do with the connection between the front and rear wheel in the ABS system? By that I mean, maybe they have programmed it not only to keep each wheel from locking up, but also so the system can know what both wheels are doing in relation to one another and make corrections based on that as well.

[Kurlon]

I'll have to check but I believe the 796 uses the same wheel speed sensor on the front and rear wheels for ABS so it doesn't need to do any RPM x Gear math to determine what should be going on... wierd

[nhbubba]

Edit: BSR6 has my guess. I should have just read his post.

That's my guess too: They're taking vehicle speed off the trans output, before the sprockets. Then using this VSS reading to calculate a delta in wheels speed, front to back. Then inferring wheel spin and potentially pulsing the ABS system.

Also may be used for traction control. Does this bike have traction control? Wiki says some Monsters (newer? 1100's?!) do.

[NobodySpecific]

Edit: BSR6 has my guess. I should have just read his post.

That's my guess too: They're taking vehicle speed off the trans output, before the sprockets. Then using this VSS reading to calculate a delta in wheels speed, front to back. Then inferring wheel spin and potentially pulsing the ABS system.

Also may be used for traction control. Does this bike have traction control? Wiki says some Monsters (newer? 1100's?!) do.

For traction control I understand the usefulness, but for ABS? They would be making the assumption that the speed of the engine determines the speed of the wheels, which is completely false in a lot of braking situations. If they did it in an attempt to improve the ABS system, then maybe I understand it, but it's still a pretty weird thing to look at. If changing the gearing caused my ABS to not work I would be looking for a different bike, as they should be calculating each wheel's speed independently and directly, and that information is more than adequate to satisfy all ABS system requirements.

[dankatz]

I have the 14T sprocket on my Monster 696 which makes it easy to ride in the city. I don't have ABS, but agree with other people and don't see why the ABS won't work well. Traction control became standard on the 1100EVO

[nhbubba]

They would be making the assumption that the speed of the engine determines the speed of the wheels, which is completely false in a lot of braking situations.

The assumption is that the final output shaft of the transmission (which the front sprocket is attached to) is directly related to the rear wheel speed. Which is absolutely true in all circumstances, assuming the drive chain is not broken or skipping teeth.

The exact ratio between the shaft speed and wheel speed is dictated by the sprocket combination. Which Lucas here wants to change. Potentially putting the bike in a situation where the ECU *thinks* the rear wheel is going faster or slower than it actually is.

If there is no ABS sensor on the rear wheel itself, the computer must be getting this information somewhere else.

If they did it in an attempt to improve the ABS system, then maybe I understand it, but it's still a pretty weird thing to look at. If changing the gearing caused my ABS to not work I would be looking for a different bike, as they should be calculating each wheel's speed independently and directly, and that information is more than adequate to satisfy all ABS system requirements.

We're all talking out of our asses here, as we don't know anything about how the system is designed or implemented.

The Duc literature on the website says "Unlike the majority of motorcycle ABS set-ups, this system has the advantage of ensuring a more natural braking ‘feel' for the rider."

Sounds to me like Ducati has done something unique to their ABS system in the name of "a more natural braking feel".

Me, I'd still try the new sprocket. Worst case you find it unridable and put it back to stock. I definitely would not "be looking for a different bike" over an issue like this. Talk about throwing the (damned sexy, Italian) baby out with the bathwater.

[NobodySpecific]

Me, I'd still try the new sprocket. Worst case you find it unridable and put it back to stock. I definitely would not "be looking for a different bike" over an issue like this. Talk about throwing the (damned sexy, Italian) baby out with the bathwater.

I didn't say I would be looking for another bike in this case, I said I would look for another bike if it caused ABS to stop functioning, which I don't believe is the case here.

Good point about using countershaft speed (not RPMs as I had assumed) to measure rear wheel speed. It just seems a little more complicated than it really needs to be, but if it works then