Shaft drive vs Chain drive - benefits or drawbacks?

Worked for that former cop who beat the speeding ticket rap in court.
Claimed he was accelerating to avoid an accident somewhere near/in
Mansfield IIRC, and the judge agreed.
- sanbar

 

In aus.motorcycles on Thu, 29 Jan 2004 12:22:30 +1100

I get 17-18km/l on the daily commute on the Guzzi, and 20+ on long
highway runs.

I don't often fang it, when I did I found that spending heaps of time at
or near redline didn't make the consumption drop below the normal
commuting amount.

What it did do was drop the normal commuting consumption! I went from
low 17s to high 18s.

If you want a big bike with good fuel consumption, a square-slide
Dellorto soft cam T/SP series Guzzi is a very good candidate. You get
bugger all performance really, but those squareslides are misers for
fuel.

Zebee

 

Kleenex to pit no 3 please ...

Cheers
Goaty

 

TPG's farking news service ditched your post, Smee, so I have to reply to
Zebee's.

But,.....

For starters, my GPX250 accelerates quite acceptably at highway speeds, but
what do I need to "get away" from?

Secondly, what I'm getting at is that "powering out of trouble" means that
to avoid one potential danger, you are increasing your speed, (and, as you
are powering away from the danger, putting yourself in a situation where you
can't brake if another danger arrives).

If you leave appropriate gaps, keep up your concentration etc, you will
never need to power out of trouble.

That having been said, everyone does make mistakes, and there are times when
having that power is useful for getting you out of trouble that you have put
yourself in. But from my experience, in traffic, I'd rather better brakes
than more power anyday. The GPX (RII model, with the twin discs with 2-pot
callipers up front) I find to be a better mount around town than the ZX10
(similar brakes (although a little larger, and with semi-floating discs),
but a lot heavier), despite the ZX10 having heaps more power.

To be fair, I used to "believe" in the powering out of trouble thing, but to
be honest, a lot of it was just an excuse to ride fast. Since I've had my
license back (after an 18 month absence which was entirely my fault) I don't
ride as fast, but I'm a lot safer. I haven't been in a single situation
where I've even thought about "powering" out of trouble in the last 2 years.
I use the brakes with a fair bit of force every week or so though.

Besides, all that power isn't going to help when the traffic is chockers.
Being small, light, and nimble might.

 

I thought it was a 17" front, vs 16".

 

Getting away from what?

Besides, if you want to increase the distance between yourself and
someone else, judicious use of the brake can be just as effective as a
twist of the throttle.

There are SOME times when having power is handy, but it's use to 'get
out of trouble' is ,IMHO, highly over-rated.

That said, I love KNOWING that on the highway I can just twist the grip
on the K and be around that road train in a flash. If I was on the GS, I
probably wouldn't attempt it; and THAT is another way of getting out of
trouble - by not getting into it in the first place.

---
Cheers

PeterC [aka MildThing]
'81 Suzuki GS450-s
'87 BMW K100RT

www.dmcsc.org.au

 

When that car in the next lane that's about to come across and flatten
you and hauling on the chocks will just get the car behind you up your arse.

 

Pity someone else bought the bastards before I could.

DaZZa

--
People can be divided into three classes.
The few who make things happen
The many who watch things happen
And the overwhelming majority who have no idea what has happened

Picked up from a web site, author unknown

Address in header is spamblocked. ROT13 the following for email replies

 

I get 16km/l on my 1000cc sidecar. Make you feel better?

Al

 

I remember noticing it on a loaner z1000(?) Kwaka years ago, but never
noticed on any Bimmer I took for a ride, so probably depends on how
well the rear suspension is set up. The Kwaka had a quite noticeable
rear end lift and slightly sideways under power.

Also rode an XJ900 for a week or so in the late 80s and didn't notice
the effect there either.

Cheers



-------------
Kevin Gleeson
Technical Director
Blue Rocket Productions
Hobart, Tasmania, Australia
www.blue-rocket.com.au

 

Swingarm length has a lot to do with it, shorter swingarms lift more than
longer swingarms. My XJ750 it was very noticeable. The only reason I
noticed it at all on my K100RS is because I took the Paralever rear off and
replaced it with a standard K100 Monolever (strength issues for sidecar
use), it was very noticable then. Shafts dont handle badly anyway, the only
downside they have is extra unsprung weight (diff/driveshaft weighs more
than chain and sprockets).

As far as problems in cornering with shafts most of the horror stories come
from older Boxers or Guzzis where it is the along the frame crank that is
the problem, not the shaft. On one of these bikes with a heavy flywheel you
get a large torque effect throwing the bike to the left or right when you
accelerate or backoff the throttle suddenly, it can in some circumstances
throw the bike down into the corner. But the deal is that you dont ride
like that, you shouldn't be shutting down hard in the middle of a corner
anyway. Ridden appropriately (and many people can, it's no black art) they
handle well. It doesn't happen on K-series BMWs (also an along the frame
crank) as the flywheel/clutch spins in the opposite direction to the engine,
negating the torque effect.

Al

 

"James Mayfield" wrote

KH100?

I commute 55 kms each way on an 1100 Guzzi. I don't do this to save
money on fuel. It actually increases my fuel cost as the fuel for the
company ute is very cheap indeed. I do it because I want to.

Theo

 

Yeah, the XLV is quite short and has a very noticeable shaft
reaction, the rear noticeably climbs under acceleration.
I don't think it's a problem, though -- it's just one of
those things you automatically compensate for.

Yeah, the CX650 used to jitter sideways when idling. When it
was cold and misfiring it used to look like it was about to
throw itself off the sidestand! Again, it never seemed to
make a difference above walking pace ...

-----sharks

 

That can go onto the "Why didn't somebody think of it sooner?" list.

I've though about this for three minutes, and can already envisage what
seems like a solution; I humbly submit it here to be drawn, quartered and
condescended.

Taking a Guzzi-style longitudinal-vee engine, you could separate the
flywheel from the crank and replace it with a drive gear, such as modern
inline-fours have on one of their webs. You then lower the crank in the
cases, and raise the flywheel-clutch basket-gearbox input shaft assembly.
Next, make the flywheel a gear to engage with the drive gear fitted to the
end of the crank, like the clutch basket on an inline four. The crank and
the flywheel will now spin in opposite directions, negating the torque
reaction, but retaining the rotational inertia necessary to stop the thing
stalling every third attempted takeoff from a set of lights.

To keep the engine compact and lined up with the drive to the back wheel,
you'd have the gearbox output shaft bolt somewhat underneath the input shaft
instead of directly beside it, and there'd probably be no need to dry-sump
the engine because there'd be room for a sump under the gearbox (lowering
the crank without removing the sump from underneath it would bring the motor
much closer to the ground).

Trying this on a Boxer would be more difficult. You'd have to_raise_the
crank- the cylinders would be unacceptably close to the ground otherwise,
making it impossible to achieve the sort of thing Al got up to on the
weekend, lower the flywheel-clutch-input shaft and then stick the output
shaft where required.

If you really tried, though, you could possibly even make an extremely short
engine in which the gearbox shafts sit directly underneath the crank.
Probably not achievable with a flat twin ( the cylinders would stick out too
far for the height they'd have to be at then) or a v-twin (the engine would
end up being too tall), but a short-stroke flat-four or a v-four...

Waddayasthink?

 

"Alan Pennykid" wrote

IMHO that's a load of crap Alan. If this was an effect that you can
feel you should be able to notice it when you accelerate or decelerate
sharply when travelling in a straight line. It doesn't happen and,
believe me, my bike has a massive flywheel.

Theo

 

Clem,

Why did you drive to 3 GP's in the mid 90's?

Steve

 

Theo,

That calc gets thrown out if it's a choice of spend $10 or $20k on
either a car or a bike.

Steve

 

X-No-archive: yes
sharkey wrote in message ...
~

~
Probably just caught it's own reflection in the window and was shuddering in
horror.....
Clem
[....as you would.]

 

X-No-archive: yes
Theo Bekkers wrote in message ...

Eh? Surely you jest!
I've only ever ridden one 'Guzzi but I could hardly overtake on the bloody
thing 'cause as I'd accelerate it'd try and turn left!
I never noticed the effect as pronounced on the one BMW I've ridden though..
(Maybe I'm a larger percentage of total weight these days!).
I'm sure though that, like shaft-reaction, it's something you don't even
notice after 100km-or-so.
Clem

 

In aus.motorcycles on Fri, 30 Jan 2004 13:49:14 +1000

Bizarre.

My GT has The Flywheel That Ate Mandello, and the T's is not much
smaller. I haven't noticed a problem.

I did have a stonkingly light flywheel on the T for a while, an epicycle
racing item that was a lot of holes held together by some alloy more or
less.

The difference is marked in engine behaviour between the two flywheels
but not in handling.

Zebee