A Taste Of A Race

[Racing Dave]

I caught up with two other bikes with very similar performance. One was a 50 cc Honda step through, old school, 70s kind of thing. Other was a home build with two wheels at the rear, motorcycle controls, pivot in the middle. The engine was above the rear axle.

As seen in front of RC...

[Dave-]

I was on a Yamaha Jog in my orange/black race leathers.

Drafting or reducing my profile seemed to make no difference at all.

I found the biggest contributors to speed were keeping the bike straight and riding the line of least resistance. A group of guys 'drafting' came up on me nearing cave stream, down the hill I zoomed away from them with a superior MotoGP line, they caught up to me and overtook me along the cragieburn straight, but again I got them all back again on the downhill. I wasn't tucked or anything, I was literally sitting on my scooter line an arm chair, one handed, cruising like.

If drafting really made any difference they would have had the run on me down the hill, but I think their bikes were all just faster and they were pussies who used the brake too much.

I actually found tucking down made my scooter more sensitive to input which meant that I'd spend more effort keeping the thing driving straight and lose speed to the tiny corrections I had to make to keep it straight.

On my race bike I notice a huge difference tucking under the fairing and drafting, but I really think the aerodynamics at sub 100kph contribute a negligible amount to your drag.

Whatever though eh, it was still an awesome day

[rastuscat]

I think we met, Dave.

Braking on a moped is such a waste of momentum. I have to work hard to gain momentum, I don't waste it by braking.

You sure learn a truck load about preserving momentum by riding smoothly. And that learning transfers to my touring bike, which is far nicer to ride since I got the moped.

[rastuscat]

As seen in front of RC...

Yes, that's the guy.

It was scary tucking in behind him, the back wheels are kind of sticky outy.

[Hobbyhorse]

Yes, I found the same thing, maintaining momentum became a big thing. Sit up straight and loose 5kph so hunched up it was. Also found that each scooter had a different sweet spot and I swapped places on a regular basis with other scoots as the grades changed and then flattened out. I have to say that the throttle slide did not get much wear as it was wide open most of the way.

[rastuscat]

I have to say that the throttle slide did not get much wear as it was wide open most of the way.

I had my Adly Silver Fox tapped out the whole time, and the actual speed was determined by the gradient, drafting, position, headwind etc.

Up Porters Pass was 20 kmh, down the speedo wound a longcway past the 80 kmh max indicated.

Happy days.

[Hobbyhorse]

Up Porters Pass was 20 kmh, down the speedo wound a longcway past the 80 kmh max indicated.

Happy days.

I was riding a 1988 Vespa 50S and I chickened out at 65kph on the downhill run.

[rastuscat]

I was riding a 1988 Vespa 50S and I chickened out at 65kph on the downhill run.

Turned out removing the cat convertor on my moped was the key. It allowed enough acceleration, and combined with quite tall CVT gearing it led to rapid down hills.

The loose grit on the the way down the Otira Viaduct was a challenge though.

[Racing Dave]

Up Porters Pass was 20 kmh, down the speedo wound a longcway past the 80 kmh max indicated.

Some poor sods were reduced to 5 km/h or less.

[Hobbyhorse]

Good photos. Do you think it was the lack of engine power or the CVT transmission that let those guys down?

I was in 2nd gear on the Vespa on the steepest part of climb at 25kph until I was checked by a couple of the struggling ones and had to drop into first gear.

[Racing Dave]

Good photos. Do you think it was the lack of engine power or the CVT transmission that let those guys down?

I was in 2nd gear on the Vespa on the steepest part of climb at 25kph until I was checked by a couple of the struggling ones and had to drop into first gear.

I reckon that it's a combination of both.

In 2012 I rode a Suzuki SJ50 and like most CVT scooters of that type, I held it pinned the whole way. The problem with the CVT is that it doesn't allow the engine to rev, and thus develop peak power, at low road speed, as this is a function of the pulley diameters. The standard centrifugal clutches also engage at low rpm, which hinders initial acceleration from a standstill.

The other issue is, of course, their utter lack of power (is it 2kW?) which makes hill-climbing a struggle anyway, but which also brings its own joys, as RC details above, when it comes to slipstreaming. I was definitely no faster than 20km/h at the top of Porters, but over-revving on the way down (thanks, gravity) saw 65km/h indicated, which it would never do on the flat.

In 2010 I rode a C50 step-thru, which was seriously worn out, but at least it had the advantage of the 3-speed gearbox, allowing me to unmercifully rev the poor thing up the three 1st gear climbs (top of Porters, the right hand bend just before Castle Hill, and the climb out of Arthurs Pass Village) but I think it was still down to around 20km/h.

In 2014 I rode a Honda Super Cub (one of the modern 110cc four-stroke injected ones) which comparatively has abundant torque, and that pulled up Porters in 3rd gear (at full throttle) never dropping below 50km/h. Torque, (more or less proportional to engine capacity) makes a huge difference.