Gearing - trying a 42T.

[BrammoBrian]

I always get ansy in the winter when I can't ride and the race season is over, so I start thinking about ways to modify my bike.  I worked on my Ducati a few winters ago, my BMW S1KRR last winter, so now it's time to mess around with my Empulse R.  I realize that most are pretty pleased with the off-the-line acceleration from the stock gearing, but I'm going to try a 42 tooth on the rear to see what I get.  I kind-of already know, because that was one of the first mods done to the TTX bike for racing and resulted in this video...



I'll let you know how it goes if we can get a couple of days of decent riding weather.

[Shinysideup]

Cool! I was thinking of playing around with the rear sprocket when it comes time to change out the chain, probably in another 20K miles, since I have 11K on her now.

With the 42, how hard is it to accelerate to the max and NOT pop a wheelie by shifting the body weight forward? I love me some hole shot power, but I don't like constant wheelies. Mostly I'm interested in making 6th gear more useful to me on the freeways, as well as nudging the motor's rpm's up into a more efficient zone when traveling slowly around the city in 1st gear, especially climbing hills slowly in San Francisco.

Of the top of my head (or outta my a**) I was considering going to a 40T for just an incremental change. But if 42T can be fitted without affecting the chain line under the chain guard and over the chain alignment plastic add-on goodie, and if I can easily control the wheelie capability, I'll try the larger sprocket.

Looking forward to your report, weather permitting.

[00049 (AKA SopFu)]

I'd be curious as to what happens to top speed with the bigger sprockets.

[Brammofan]

Any chance that it will affect the accuracy of the speedometer?

[BrammoBrian]

It should not as we use a rear wheel speed sensor.  We can't use motor rpm to gauge vehicle speed as we do on the Enertia as the Empulse is not direct drive. 

[ttxgpfan]

After my interview with Jeff I've been curious about the opposite.  He told me how the 0-30 was there the Empulse R was fast.  I wonder if a (slightly?) taller gear might help keep the bike in 1st gear longer and improve the 0-60 time while sacrificing the 0-30 time.

[Jeff]

Welp, I'll let you all know myself!  Thanks Brian for continuing to insert terrible ideas into my head.

I picked up one of these and one of these. 

(note: if you want to do this, the Empulse chain is absurdly short.  The shortest size they sold (96) was plenty long)


Goodbye old chain, you fulfilled your duty well (and probably would've lasted PLENTY longer)


HellOOOOOOOO sexy!


Aw yiss.  The sprocket actually appears to be every so slightly kind of an olive drab?  Looks nice, whatever.

In any case, I think I solved California's drought problem:  as soon I as install a badass rear sprocket, we actually get rain for the first time in months.  It's gravely needed, so I ain't gonna complain, but hahaha I am going to wait to try out any wheelie madness.  Will definitely report back!

[7racer]

Lol.  Install looks great!  Can't wait for it to dry out and give us a report!

[Shinysideup]

You call THAT rain??

Anyway, it's dry today and we NEED that report! (But no pressure).

Nice-looking bits you found: wouldn't expect anything less from you!

[BrammoBrian]

Oops... I guess I forgot to comment on this change on my bike. 

The good:

It definitely makes a difference on acceleration.  It pulls hard enough in sport mode to lift the front tire for about 10 feet off the line.  Stock gearing provides 882Nm at the rear wheel in 1st gear, this change will put you at 975Nm (720 lb-ft)!   

You can find yourself at 90+ mph very quickly.  I'm not sure the difference versus stock gearing, but it feels much quicker. 

The bad:

You have to shift through 1-2-3 very quickly.  You can hit 60mph in 2nd, but you've got to over-rev the motor a little bit past peak power. 

It makes a steady throttle hand a necessity when exiting slow speed corners or in wet conditions. 

It also makes the regen feel stronger.  I'm not a big fan of the regen level in Sport mode, so this kind of bugs me.  Good thing I can have it turned down though... 

[BrammoBrian]

Thanks Brian for continuing to insert terrible ideas into my head.

I knew I was good for something...

Nice chain selection BTW.

[7racer]

...
It also makes the regen feel stronger.  I'm not a big fan of the regen level in Sport mode, so this kind of bugs me.  Good thing I can have it turned down though... 

whoop sneaky 6pt font post!  Can I make a request for selectable regen modes please!

[Gavin]

I have a way to remove all regen...park at work for 9 hours in 30 degree weather and presto, no regen for the ride home

Only works in winter...

G

[7racer]

I have a way to remove all regen...park at work for 9 hours in 30 degree weather and presto, no regen for the ride home

Only works in winter...

G

Lol. I'll see how that works as it heats up here in Dallas!

[BrammoBrian]

FYI... you can find the Empulse in the gearing commander database now...

http://www.gearingcommander.com/