What exactly is "roll-on power"? (in reference to motorcycle or
automobile engine performance.)  I've seen the term used in a way that
appears as if it may be synonymous with acceleration, but I'm
interested to find if it's more nuanced than that.  A complete
definition of what it refers to is desired.

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Request for Question Clarification by sublime1-ga on 27 Nov 2006 16:13 PST

bluecrayon...

I couldn't find anyplace where the term is formally defined,
even on the Urban Dictionary, Wikipedia, and Nascar sites.

A Google search for the term puts it in context on a number
of pages:

"roll on power is"
://www.google.com/search?q=%22roll+on+power+is%22

Defining by context seems to suggest that it has to do with
the availability of *fast* acceleration, and this should be
available at any speed, in any gear, ideally. Having to 
downshift to obtain the needed torque disqualifies a vehicle
from having this quality at highway speeds, as can be seen
in this motorcycle review by Chuck Hawks:

"Power delivery is smooth, with most of the punch in the upper
 half of the RPM range. Magazine road tests credit the bike
 with a quarter mile time in the low 12-second range. Frankly,
 it does not feel that fast when ridden normally. The throttle
 response is good, but roll on power is only fair unless you
 keep the revs up. If you want to pass a slower moving vehicle
 on the highway when cruising in 6th gear, you will normally
 have to shift down a couple of cogs."
http://www.chuckhawks.com/triumph_thunderbird_sport.htm

Reading through this and the other results from the search
above, it seems to be essentially synonymous with power during 
acceleration, or torque, and would be ideally present at
low, medium and high RPMs in all gears.


If this satisfies your interests, let me know and I'll post
a formal answer...

sublime1-ga

---

Clarification of Question by bluecrayon-ga on 27 Nov 2006 19:24 PST

Hi sumblime1.  Thank you for your comments.

I've been trying to determine the term's meaning in the same way: by
context.  I guess my hope is that someone would just know what the
term is precisely, and could say: "Oh yeah, roll-on power is the
blah-de-blah..."  I need to use the term authoritatively and I think I
would feel more comfortable doing that if I understood what, in
particular "roll-on" was refering to.  Poking around a little bit, I
see as well that roll-on performance and roll-on acceleration are
other ways the term is used.

It feels to me that "roll-on" is probably a specific reference.  I
wonder if it's a racing term, as in "rolling start?"  If that's the
case, it could simply refer to acceleration that is available while in
motion(at whichever particular speed?)

Any additional light you can shed on this would be greatly
appreciated, but in any case I am happy with the work you've done and
will be happy with whatever you can provide for an answer.

Thank you.

Thanks!

---

Clarification of Question by bluecrayon-ga on 27 Nov 2006 19:32 PST

Hi again.

It looks like I've found it:

"The Performance Bike people analyse thrust, acceleration, and roll-on
performance. Roll-on performance is another thing you don't see in
import magazines. It's the performance of the car while it's already
moving and you upshift (like when you want to pass that 18 wheeler in
a 2 lane highway and have to pull out into the oncoming lane with a
short distance...your life and others may depend on it). They look at
40 mph to 150 mph time. So while you are moving at 40, how long does
it take you to get to 150? They saw a 1.6 sec. improvement in this
bike's roll-on performance."

Looks like we were pretty much in the ballpark.  Please go ahead and
post a formal answer!

Thanks again.

bluecrayon...

Thanks very much for accepting my work as your answer.
I'll repost it here for the sake of future readers.

----------------------------------------------------------

I couldn't find anyplace where the term is formally defined,
even on the Urban Dictionary, Wikipedia, and Nascar sites.

A Google search for the term puts it in context on a number
of pages:

"roll on power is"
://www.google.com/search?q=%22roll+on+power+is%22

Defining by context seems to suggest that it has to do with
the availability of *fast* acceleration, and this should be
available at any speed, in any gear, ideally. Having to 
downshift to obtain the needed torque disqualifies a vehicle
from having this quality at highway speeds, as can be seen
in this motorcycle review by Chuck Hawks:

"Power delivery is smooth, with most of the punch in the upper
 half of the RPM range. Magazine road tests credit the bike
 with a quarter mile time in the low 12-second range. Frankly,
 it does not feel that fast when ridden normally. The throttle
 response is good, but roll on power is only fair unless you
 keep the revs up. If you want to pass a slower moving vehicle
 on the highway when cruising in 6th gear, you will normally
 have to shift down a couple of cogs."
http://www.chuckhawks.com/triumph_thunderbird_sport.htm

Reading through this and the other results from the search
above, it seems to be essentially synonymous with power during 
acceleration, or torque, and would be ideally present at
low, medium and high RPMs in all gears.

----------------------------------------------------------

It looks like your burning curiosity just beat me to the punch.
I would have jumped on the terms you provided in your last
clarification, as apparently you did, and done a search like
this one:

"roll-on performance"
://www.google.com/search?q=%22roll-on+performance%22

So I would have quickly found sites like the one you found
(in addition to deodorant studies), such as this one Biking
Today, which confirms my association of roll-on power with
torque:

"...the CBF's development team concentrated on finding ways
 to maximise its value as a daily rider and an easily accessible
 fun machine, albeit a powerful and aggressive one, by maximising
 its engine's torque output, and thus roll-on performance."
http://www.mysporttoday.co.uk/ViewArticle2.aspx?SectionID=3974&ArticleID=1683355&sitecode=hccn&sportcode=bike


Best regards...

sublime1-ga