Shaft Effect and Technique

[barbagris]

I have been riding in-line engined shaft drive bikes most of my life - I have never been without one. Hell I have had my current Guzzi since 1982. So I actually find it all normal.

Shaft drives with a single pivot (i.e. R3) will climb the pinion esp if they have thrust - UNTIL the forward inertia is enough to lift the front suspension. I find, generally, that shaft drivelines prefer to be set up for a corner and run through at a constant speed. Shafts with a second pivot can be very very neutral. But these can be expensive and a PITA to maintain.

The R3 ime will lift its head quite fast (so go wide) if accelerated out of bends too hard. Esp if you are near the peak of the torque curve. You can drift an R3 - into bends with some ease. I avoid doing so in the wet though. This ime helps more than throttling out - ON THE R3. And as has been mentioned I believe a lot of the R3 cornering characteristics has to do with the disparity in sizing of front-rear tyres.

This constant revs thing is allied to the rotating mass which generates a gyroscopic effect which CAN screw up axial rotations. Look up Gyroscopic precession.

Trail braking - works well. But with Classic footboards and the monstrously overpowered rear on R3's it's tricky. I am always very gentle with the R3 rear - maybe overly so - but it can lock up even with a CT on. Early Buells were infamous for having really poor rears - but were designed for trailbraking. And were bloody wonderful for powering out.

Also important to note (Rob) - Having decent suspension makes this more evident.

 

[1olbull]

Rob, "Running wide after apex, I’ve always felt that power on helps me tighten my line on the rocket and I am able to really roll on quite early in the corner."
Power on while leaned into a corner will always stand the bike up, increasing your radius. It will not "tighten" your radius unless you increase your lean angle.

Scott, front trail braking does improve cornering time; however, because it requires a higher level skill set and my reactions are not what they used to be, I use it very judiciously, kinda like when I was maintaining the gap between us up the 92 near Montrose CO - and you were riding TWO-UP!

 

[Steel]

Front trail braking gives a couple of benefits. It lowers the front end, giving better geometry going into the turn, and flattening the front tire a bit, giving a larger contact patch. But like @1olbull said, it's a delicate balance of letting off the brake, and applying throttle in a balanced manner to maximise the exit in a controlled way. It goes against everything I learned as a young rider, and a bit nerve wracking the first few times. But it becomes second nature after a while.

 

[barbagris]

Power on while leaned into a corner will always stand the bike up, increasing your radius. It will not "tighten" your radius unless you increase your lean angle.

Or you drift the tail out. Rob has the extra horsies to do so.

 

[Bedifferent]

Shaft effect is way overrated unless you are a technical and aggressive rider. I'm on my 3rd shaft drive and like most average riders I never give it a thought. It's kind of like when I bought my Fatboy and I read how the solid rims were a problem in a crosswind. I worried about it until I rode in a big crosswind. I couldn't notice anything different than any other bike I have had. All technical hype like rotational inertia of the engine.

Sometimes it's just best not to overthink things. Then again, what do I know...maybe I'm just use to it.

 

[scot in exile]

Shaft effect is way overrated unless you are a technical and aggressive rider. I'm on my 3rd shaft drive and like most average riders I never give it a thought. It's kind of like when I bought my Fatboy and I read how the solid rims were a problem in a crosswind. I worried about it until I rode in a big crosswind. I couldn't notice anything different than any other bike I have had. All technical hype like rotational inertia of the engine.

Sometimes it's just best not to overthink things. Then again, what do I know...maybe I'm just use to it.

Have to agree with you I doubt very much that anyone on this site has the skill level to feel the effects but like you what do I know. not saying we have bad riders but the level for these factors to start getting used is extremely high.

 

[Claviger]

Well said all. I should clarify what I said I guess.

When i roll on hard in corners two things happen automatically with my body position that i don’t even think about, but do because of how and what I learned to ride on. It may be why I feel like the bike never runs wide.

I transfer most of my weight forward, basically tucking my man parts right up against the tank, one ass cheek off the seat, and my upper body is in the air on inside of the tank and I use he power to hold the line I was in during steady state even though I’ve now shift all the weight possible inwards. This is why I find pegs kicking up so disturbing, most ( probably 80%) of my weight is on the inside peg in that position.

There are a couple of things you mention @barbagris that probably contribute:

- Suspension, it lets me cheat and grab a handful, if and when it does break loose I just leave the throttle steady state and ride it out, it smoothly breaks and regains traction. It’s super easy to drift, but I don’t do it intentionally as I like my bike . The extra confidence and capability probably has me riding and using more of the bikes potential than those I ride with get from their bikes.

- Extra torque, this is what I’m trying to wrap my head around. At what point does the chassis stop lifting and instead start squatting? Doubly so, at what point does this occur mid corner?

When on hard power and the forks are full extension but just barely kissing the ground, essentially I’m riding the back tire and fronts just along for the ride. Is that the point it crosses from rising to sinking as you feed more in?

When I get it just right it’s a weird but amazing feeling, you can feel every squirm wiggle and dance of the rear tire. I never felt it until I put on the Wilber’s, but you can actually feel the amount the tire deflects from the load.

I don’t often get it to these points when I’m out lately as I’ve been riding a lot of roads I don’t know so use a little more restraint. I think I need to put a couple of cameras looking at front and rear suspension one day and really see what’s going vs what my inner ear is telling me.

I do know, with the new power I find 1st gear power ups a bit challenging, the bike unloads the front and then instead of lifting the front, nownit just winds up the back tire, exactly what happened the other day Steve when we were heading out, I went for a little mono after you did and it spun it’s ass off lol.

 

[Jeremy]

I would be curious to read some of the writings and see a couple videos. If someone could put a link or two up I would appreciate it. I have a specific rider that is in my core group of friends that just cannot corner at all. I have worked with him and maybe this would help.

I come from a long time habit from riding and racing motorcross from a young age, so cornering and the use of the front brake and back brake comes a little more natural to the feel of how the bike is in the corner in relation to my speed and conditions of the road. I will not say that motorcross did not give me any "bad habits" either, but the readings and video I would be interested to check out.

 

[Claviger]

Here’s the video

It’s old at this point but 100% relevant still.

I know my biggest obstacle learning to corner hard was trusting the tires to not just slip. There’s a theory about the 20% number. Humans tend to be tolerant of up to 20% leans, past that and most people start to get a little panicky feeling until they’ve trained on it.

 

[Claviger]

I have been riding in-line engined shaft drive bikes most of my life - I have never been without one. Hell I have had my current Guzzi since 1982. So I actually find it all normal.

Shaft drives with a single pivot (i.e. R3) will climb the pinion esp if they have thrust - UNTIL the forward inertia is enough to lift the front suspension. I find, generally, that shaft drivelines prefer to be set up for a corner and run through at a constant speed. Shafts with a second pivot can be very very neutral. But these can be expensive and a PITA to maintain.

The R3 ime will lift its head quite fast (so go wide) if accelerated out of bends too hard. Esp if you are near the peak of the torque curve. You can drift an R3 - into bends with some ease. I avoid doing so in the wet though. This ime helps more than throttling out - ON THE R3. And as has been mentioned I believe a lot of the R3 cornering characteristics has to do with the disparity in sizing of front-rear tyres.

This constant revs thing is allied to the rotating mass which generates a gyroscopic effect which CAN screw up axial rotations. Look up Gyroscopic precession.

Trail braking - works well. But with Classic footboards and the monstrously overpowered rear on R3's it's tricky. I am always very gentle with the R3 rear - maybe overly so - but it can lock up even with a CT on. Early Buells were infamous for having really poor rears - but were designed for trailbraking. And were bloody wonderful for powering out.

Also important to note (Rob) - Having decent suspension makes this more evident.

Looking at Gyroscopic precession, I definitively don’t mentally notice a difference in right/left turn feel, but my tires tell a different story. I corner harder right than left, while there are a number of rider caused reasons besides gyroscopic precession for this, it could be a intuitive reaction to the effect. I wonder if other R3 riders notice a difference in left/right wear at the outer edges of their tires.