Power Thrust Curves

Half crazy said: "Thought maybe it would spark a conversation about gearing and RPM...."

Rpm RANGE?

An extensive rpm range should mean a lower gear is possible, for any given road speed. Maybe translating what appears to be a less torquey machine into a higher effective rear wheel torque.

There's a good chance such a machine would weigh considerably less, further helping to even out the balance when it comes to rates of acceleration.

Meaning? Never underestimate ANYTHING which happens to pull alongside at the lights and you won't go far wrong.

Pure speculation!

Idle is between 1000 and 1100 rpm (it hunts a bit because of the cams).

Primary gearing is 1.50:1
1st = 3.20:1
2nd = 2.19:1
3rd = 1.53:1
4th = 1.24:1
5th = 1:1
6th = .92:1
Final drive is 2.26:1 (actual with the present gearing)

Rear tire diameter is 25.8"

I cannot tell you speed at max RPM in top gear. It doubt it would go that fast.

Shift to 2nd comes well after 60', more like 85'. Like I said, it will do 60-ish MPH in 1st gear. You may be correct on the 44 mph in 60' but the top speed in 1st is higher.

I'll spin it to 6200 rpm in 1st tonight and let you know...

Here, you'll love this. I raced my friend in the final. I have him by 10 or more HP so I know I can run him down and win, so I figured I'd take my time, being sure not to red-light, and use the motor to power past him. I was WRONG. I ran 11.68 and he ran 11.97... AND HE BEAT ME to the finish line by 21 thousandths of a second. I was just a bit overconfident.

http://www.youtube.com/watch?v=RATiqMk_QDI&list=UU4mClI1oSNrmlIIOn2Wq6-A...

Yes, but once you shift 2nd, that same thrust is no longer a waste... or in 3rd... etc.

Jag said: " but if one has a lot more linear thrust available in first gear than one can possibly use, is this not a waste? Maybe with less potential maximum linear thrust available under 50 MPH in first gear, you could then use first gear to say 60 + MPH"

You would have to say yes. I can't help thinking that this bike is a bit under geared. Raising the gearing would lower the enormous first gear torque (and therefore thrust) and raise the road speed attainable in first gear. We all seem to agree that what happens in first gear is vital to the final ET. It would make the top gear more of an overdrive again.

Half crazy said: "Rear tire is actually 25.84" Making the circumference 81.14" if that changes anything"

The rolling circle (which is not the tyre outside diameter) is almost impossible to measure. We're near enough already I reckon. With your recent test run and allowing for speedo error, everything is clicking into place, with three of us ending up with the same answer. That's encouraging! Hope you enjoyed your run out.

Half crazy said: "Yes, but once you shift 2nd, that same thrust is no longer a waste... or in 3rd... etc."

That's because it's not the same thrust. With each click of the gear lever less maximum torque is available. You take the max engine torque and multiply it by all the overall ratio to the rear wheel. As higher gear ratios are actually numerically "lower" there is less torque at the rear rear wheel.

Like I commented much higher up this same thread, it is cruel of science to make it that the faster we go the less torque we have, which is when we most need it. And when are going very slow we have too much. It's that damned torque/power thang again.

When we consider the speedometer and tach accuracy (or lack thereof), we're pretty close.

That would probably hurt this old man. JAG, thank you again for your efforts on this. It has been interesting. I learned so much here.

We need to talk Kevin into some 1/4 mile testing of the bikes he reviews. Seeing the ET and 60' numbers would be a nice tool for comparison. Reviewers often list 0-60 mph, 0-100 mph, and 1/4 mile ET, but never 60' time.

Yes, a purpose-built drag bike would be a crappy daily driver. Too many compromises for the track at the cost of practicality. Going to the track is maybe a once a year event at most for me. Right now, this is my only motorcycle, so practicality is far more important.

That's what we're here for, right? Interesting discussion with our peers? Many things discussed here and on the belt drive thread were things I had never given any thought to previously.

Not sure how unique it is, but it works well for me and what I do on a motorcycle. The offspring resulting from Ducati's Diavel raping Harley's Road King. Could be seen as the ultimate compromise between the two, or as an abomination... depends on your perspective.

The R1200R is such a 'standard' bike. I like that too. I test rode all the BMWs and they are really nice bikes, but they don't make me giggle like a schoolgirl. I think the Diavel would make me giggle. The V-Max is too heavy and gawdy like oversized costume jewelry.

Naked SV-1000?
Ducati Monster?
Griso 8V?
Speed Triple?

One of these days I'll get something along those lines from the used bike market for cheap thrills.

Half crazy said: "It seems like traction would be more of an issue in 1st, but that's not the case. Doesn't make sense to me at all."

Doesn't appear to make sense, so let's try to eliminate the easy explanations first.

For the comparison from first gear to second gear to be accurate you would have to be applying full throttle at max torque revs in both gears. Is that the case?

Are you dropping the clutch during the second gear wheelie?

Is body position identical in both cases?

Max torque comes at 4300 rpm. I'm talking about 2800 rpm.

Same technique in either case. No touching the clutch.