My French Run report (longish)

It means he's geared it down, that's all. So it's turning higher revs at
a given road speed. Makes it snappier. Probably uses a bit more fuel in
the process, mind.

Put it back to standard.

 

Like a 'busa really needs to be made "snappier"..... or is it just a
lardy old tourer?

 

It means it'll accelerate a bit faster, & be going slightly slower for
a given RPM. If you don't care about MPG & never want to go above say
150mph, gearing it down to hit the rev limiter in top at 150 will make
for a very lively bike!

 

Slower, surely?

But have a lower top speed.

 

It's a wonder you don't capsize every time you change gear.

 

Sorry, got you two ladies of this parish mixed up

 

Or just use a lower gear.

I have to admit I'm a bit mistified as to why people gear down road
bikes: they're pretty tractable aren't they? I can see if absolute top
speed is a priority and top's a fraction overgeared and fifth's a
fraction undergeared then do it, or first's a bit tall for comfort,
but why else fit a larger rear sprocket?

For racing it's a different ball game, of course.

 

That's not the same thing at all.

Because if you never use the top 40/50/60mph available with the
standard gearing, but want as much acceleration as you can get, it's
the sensible thing to do.

 

See my comment below about bikes being pretty tractable.

 

They also handle pretty well, stop pretty well, grip pretty well etc
etc. Doesn't stop people changing the suspension, brakes & tyres to
suit their own needs.

 

Well, my point was that revving up through the gears to hit the rev
limiter with a larger rear sprocket might make the bike *seem* more
lively but it's mostly an illusion.

Sure, each individual gear will be lower and you'll get more
acceleration for that particular gear, but you'll also be upshifting
to a higher gear sooner and at a lower road speed.

The more frequent upshifts, faster rising exhaust note and even
possibly the faster swinging tacho between them might help give an
illusion of greater acceleration too, irrespective of what the bike's
chassis is actually doing.

Finally, just to achieve the same vehicle acceleration with lower
gearing would require a proportionally higher engine acceleration, so
the inertia of the roundy-roundy-uppy-downy bits becomes a more
significant part of the engine's load, though admittedly a tiny part.

The only real benefit I can see is if the bike's gears were originally
widely spaced enough that it was noticeably dropping off the cam on an
upshift - which is why I mentioned tractability. Otherwise you'll only
truly tell any advantage with a stopwatch or in first gear, where you
can't go any lower without a sprocket change.

 

Which is why it feels more lively. Go & stick a 3 tooth bigger back
sprocket on then come back & tell me it doesn't.

My MV sprocket collection ranges from 15F/37R (95mph in 1st, 180+ in
top) to 14F/43R (rev limiter at 140ish in top). I can assure you it's
no illusion when one combination gets the front up on the throttle in
2nd & another doesn't get it close to coming up in 1st. Similar things
happen when I switch between the two front sizes I've got for the Tiger.

 

Do you do anything to keep the speedo accurate?

 

I do on the MV, one of these - http://www.yellr.com/

 

Pip Luscher took a blunt brush and painted...

So if you are correct then I can gear my bike for a top speed of 1,000,000
mph and it'll still accelerate just as fast as it does now?

Coo!

I wonder why BMW and Merc and others are moving from 3 speed auto boxes, to
4, then 5, 6, 7 and even 8 gears. They're all wrong. We just need one.

Might it be something to do with keeping the engine in the optimal RPM range?

 

Heh. No.

Yes: the magic word "tractable" I used a couple of times.

 

....which brings us back to using a lower gear.

 

Pip Luscher took a blunt brush and painted...

Yup but there isn't an engine in the world that has a flat bhp plot which is
what you'd need for gears to not make a difference.

I can understand people gearing modern hyper sports bikes down.

My ZX10 does 110 in 1st gear, which basically means I never get to play with
high RPMs. The 9R was a lot lower geared and I could play with high RPMs on
the short dual carriageways round MK (and cook the brakes!)

Actually instead of thinking about it I'll do it. Anyone know what are good
sprocket sizes for the 10R for more fun at lower speeds? Neal?

 

Oh good grief!

<gives up>

 

I'm not sure of in full, but it's been a common approach with the 06
to swap the front sporcket to the Z1000 one, which takes it from a 17
to a 16 and makes a greater difference than changing the back sprocket
by a couple of teeth..

I've been thinking of doing this, but it also means fucking about with
the speedo signal to keep the right mph and odometer settings.