Hanging over my desk, for many years now, was my first 2WS/2WD experimental electric recumbent bike. While leaning back in my chair and staring up at it recently, I wondered why a video wasn't produced as soon as it was done. Then it hit me: It was built and ridden about 3 years before YouTube was launched! It was designed and built almost a quarter century ago! It also hasn't been ridden in 8 years - time to take it down, dust it off, and give it a fresh set of tires and batteries! The paint exhibits some wear and tear, but, well, so do I:
Sunday, October 22, 2023
Monday, May 29, 2023
The 2WS/2WD system for the next racer is assembled and on the bench! This is the first bike project of mine where the frame wasn't built first. Now the frame designs itself and gets built next.
Saturday, June 25, 2022
When the decision was made to build the last racer, the first 3 thoughts went through my head:
- This is going to be a lot of work.
- This is going to be a lot of fun to ride.
- This is going to generate a lot of stupid comments.
2) It was. More fun than anybody else knows!!
3) Far less than I expected in the real world - virtually none, really!!!
- That's just a copy of the Gurney Alligator!
- You'll die if you crash or run into something!
- All those ball joints and rods kill steering feel!
- Can't see where you're going on the track!
- Can't steer properly if you can't move your body!
- Can't stand on the pegs while riding over bumps!
- Why don't I see them racing in GP or the IoM TT?
- Low CG motorcycles are hard to balance!
- Driving a steered wheel requires negative trail!
- Two wheel steering is pointless and stupid!
- It's just a two wheeled car!
- There's no rake at the front end!
2) Considering the liquid cooled twin cylinder engine, 2 wheel steering, no steering head, virtual hub center steering front suspension, remote mount handlebar, and reclined seat and rider position, there are more differences than similarities. That said, comparisons are understandable; the 'Gator was the only recumbent motorcycle to get any decent coverage in this country from the legacy motorcycle media this century.
Front end feel comes from changes in the steering load - a little change means a lot. NOTHING kills that feel more than having the rider's weight on the handlebars while trail braking. With a recumbent motorcycle, the handlebars are just that - bars for the hands - the level of feedback from the front end is amazing if there is enough trail to provide it. Hub center steered front ends often need less trail for stability, which also makes the steering lighter, but that also reduces front end feel - something too often blamed on "All those linkages".
Speaking of feel: Nothing else provides a better level of feedback than a riding position that spans the wheelbase - any change in traction and/or yaw shift is immediately felt.
No, you won't read or hear any of that from the moto-infotainment outlets. They have no experience with the subject, nor do they want any.
Saturday, December 4, 2021
The racer has spent almost 3 years stuck in the workshop, welcoming me every time I walked in the door. While it still is an unusually amusing sight, it isn't otherwise doing me a whole lot of good. The original plan of parking it in our living room seemed like an increasingly bad idea - a split level mid-century house, oddly enough, isn't optimized for motorsports displays. What about loaning it to a museum, so others can marvel/point and laugh at it? A call was made to That Big Motorcycle Museum in Alabama - the word "Loaning" didn't get finished before the other end of the line snapped back a snotty "We only accept donations - on OUR terms - NO LOANED MOTORCYCLES!". Oh, really: Not at my current net worth.
So the next call went out to the nearby St. Francis Motorcycle Museum. I asked if they were interested in displaying an experimental homebuilt roadracer. They said they would be interested - if it is something different. This sure sounds like the right place!
Last night, the racer was loaded up in the van and rolled in through their front door this morning. Would the spot between the ELR and unmolested R90/6 be OK? Oh, yes.
In the mean time, the next racer is in that stage where lots of work has been done, but it doesn't look that way - just an increasing spread of small parts waiting to become one big part. Boring, indeed.
Saturday, July 31, 2021
One of the big challenges for the next racer was building an engine with my own crankcase. The built and fully developed engine was expected to weigh under 100 lbs and produce over 100 hp. The initial engine build is the relatively quick, cheap, and easy part - the development is where time, money, and work can be severely challenging. All of that isn't entirely necessary any more - the recent KTM 890 engine fills that requirement reasonably well. A KTM Duke 890 has just rolled in the shop, and a lot of the previous donor engines and parts have been sold to help pay for it. This project was about a year behind schedule - this moves things forward quite a bit! Absolutely no changes are required for the rest of the motorcycle. A 4-stroke twin also provides greater opportunities for racing in clubs that accommodate real purpose-built race bikes.
Unlike the EX500 engine in the last racer, the 890 engine has a very advanced ECU. A lot of learning and work lies ahead getting that to work in a racing application with different dynamics and no ABS. At this point, I don't know how well the stock ECU will work with the next racer. Or if it'll need a race ECU, like the one on the just released KTM RC 8C. Should know a bit more about the subject when this is done...
Building and running the 2-stroke engine design that I had in mind would have made for a good story. While lap times and all that don't care about "The Story", the most intriguing racing motorcycles have a good story behind them beyond the race results. I don't believe that racing is strictly about the racer and not the motorcycle, otherwise we could just discard those unnecessary machines and just race unburdened the purest way imaginable: Running barefoot and naked! No, that's really not my idea of fun, either. But a finished story is always better than an unfinished one - right now, the 890 engine is the fastest and easiest way to get the happy ending I'm expecting.
In the mean time, work is still in progress. Ever wonder what a 2WD motorcycle differential looks like? The inner (Rear wheel) pulley is solidly mounted to the spool - the outer (Front wheel) pulley is mounted to the spool with a one way clutch bearing. The spool itself mounts in the drive arm and is chain driven by the engine.
Before tearing down the KTM, it'll require some break-in mileage. It is the first "Normal" motorcycle I've ridden since race school, early 2012. It seems like a shame to take apart a perfectly good bike (And I really like the Duke 890 an awful lot!), but the next racer should be faster, more fun, and have a pretty good story behind it when it is done...
Thursday, December 24, 2020
According to the social media techno-gossipers, I'm doing everything wrong! They don't know what I'm doing, so clearly I must not know what I'm doing...
Roadracing motorcycle design has evolved itself into a dead end - they can't accelerate or decelerate any harder without flipping, or corner any harder without running out of clearance. Any changes to one or more areas to improve one aspect will result in an overall loss of performance. Tires are optimized to accelerate or brake, not both, leading to cooling/overheating events. Suspension has to be optimized for load transfer extremes. All the above leads to both slow roll response and high polar inertia about the roll axis. And that results in terrible aerodynamics. ALL of the above problems can be successfully addressed IF you discard the old configuration and derive a functionally superior new configuration.
Here are those problems (And causes):
- Stoppies (High CG, short WB)
- Wheelies (High CG, short WB)
- Lean angle limitations (Oversized rear tires)
- Roll rate limitations (High roll axis, high polar moment)
- Suspension sub-optimization (High CG, short WB)
- Tire sub-optimization (High CG, short WB)
- Aerodynamic sub-optimization (High CG, short WB)
- Long WB, low CG, linked brakes
- Long WB, low CG, 2WD
- 2WS, appropriate tire selection
- 2WS, low roll axis, low CG
- Long WB, low CG
- 2WD, 2WS, linked brakes, long WB
- Long WB, low CG
2. Also pretty obvious. Same as the above, but from the opposite direction - just a lot more difficult to implement. Doing it beats complaining about it. The ultimate solution to that problem is addressed near the end of this post.
3. Not obvious, at least with the 2WS part. The tire part ought to be obvious: With 2WD and linked brakes, a big fat rear tire is no longer necessary or even desirable. A narrow tire at both ends provides enough footprint area - more about that in #6, below.
With 2WS, cornering force deviates from perpendicular to the roll axis, thus reducing lean angle (Simple trigonometry, if you must). If 2WS is taken to an extreme, a single track vehicle dynamically transforms into a purely 2-tracked vehicle known as a "Di-cycle": NO lean angle required at all for cornering. That isn't practical for obvious reasons, but steering the rear wheel in the same direction of the turn at any proportion much over 25% (Ideally over 33%) contributes to the same effect, thus significantly reducing lean angle.
6. With 2WD, linked brakes, 2WS, low CG, and long WB, both tires are working all the time - a relatively constant load should result in a relatively constant tire temperature - tire cooling/overheating shouldn't be such a major source of drama anymore. And since extreme load transfer isn't happening anymore, much lower tire pressures (With the obvious benefit of a larger footprint) are both possible and desirable without developing stability and control issues. Having interchangeable front and rear wheels and tires is a welcome benefit. I doubt that existing tires are close to optimized for such implementation, but the choice of racing slick tires with different compounds and carcass stiffness is a huge help.
The rationale (And obvious physics) behind all 7 points guided the design of my next racer. All 7 points are necessary, however inconvenient, to work. No, I don't expect said techno-gossipers to grasp any/all of those points. Nothing in the real world depends on their comprehension or consent.
In the mean time, work is progressing nicely if not quickly on the next racer.
Monday, June 22, 2020
Monday, December 9, 2019
The engine casting will have to work well with the 2WD final drive arm, so those get designed and built together - after that, the frame and 2WS system pretty much fall into place. The big plan for the bodywork is to have as little as possible, as simple as possible, and as cheap and easy to replace, vinyl wrap, and install as possible - wasting time and money on dysfunctional over-styled plastic that gets vinyl wrapped anyway seems really stupid on a racer, where bodywork is considered a consumable item, like tires, safety wire, cash, collarbones, etc...
So where does a home built supercharged single cylinder 2 stroke 2WS 2WD motorcycle race? Obviously not any of the "Professional" OEM-centric racing organizations. The local club's rulebook is very helpful - since I'm making my own racer, the supercharger isn't aftermarket:
Saturday, April 13, 2019
And that's the end of that project - on with the next one.
Sunday, January 13, 2019
My favorite thrill is pinning the throttle after the apex of T3 at HPR, especially with an untested bike. My second favorite thrill is getting an idea out of my head and turning it into a design before making it real, loading it into the van, and taking it to the track. The next racer is into that "Second favorite" stage. The details are a lot different than the first racer, with a few exceptions. The shocks will end up in the same area, and the upper A-arms and single sided steered upright will return at both ends (With vastly lighter and better looking design and fabrication). I'm really excited about the design of the lower suspension arm - it is VERY exotic and unique (One arm for both wheels) - it solves all of my prior 2WS/2WD design nuisances and headaches.
Another good thrill is having a photo pass for MRA events and shooting video. While nothing beats the view of the race from a race bike, being able to wander around the track and scout out vantage points for capturing the action is about as close as anyone else can get. A lot of my footage made it into the MRA's Award Banquet video - thanks for the credit!
Getting the shop together and tooled up is still in progress. All of the lighting and outlets were removed and replaced. A heater should be installed very soon. Real machine tools have been moved in. As always, good help is necessary for rigging heavy machines!
There's a LOT of work in the shop to be done in 2019. And MRA racing action to shoot at HPR with a new camera this upcoming season well.
Top video: Jeremy Alexander