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Discussion Starter · #1 ·
Some of you may have overlooked how complex it is to design a working chassis for a MotoGP bike on a slot car circuit. There is another thread where yet again reference is made to the bikes leaning abilities (or rather lack thereof) when ultimately I suspect that the bikes in the form that they are would provide a much more satisfying racing experiance on a slot car circuit.

The bikes don't lean but if they did then the following issues are encountered:-

1) position of magnet changes relative to power rail as a bike swings into a corner. This reduces downforce when cornering. The answer possibly is to have a U shaped bar magnet but it is still a tticky one to work out.

2) the running line of the tyres change relative to the groove and the guide. The tyres have a compound optimised for running on metal (glass like/wood like in its grip qualities). As the bike leans relative to the guide then the tyres will start to run on the plexy material, with possible having lower grip coificients. The answer is to have a guide that moves from left to right as the bike leans keeping the tyres on the metal.

3) the ride height of the bike relative to the guide is fixed. This height would change as the bike leans into a corner. Therefore the guide would have to move up and down as well as right and left if the bike was to lean.

4) the tyre rubber compound would have to be two part. One part in the middle to optimise grip on the metal, and two parts on the outer edges to optimise grip on the plexy, given that the wheels move onto this sufrface when leaning into the corners.

5) The rear wheel has suspension. This would compress as the bike leans into a corner further altering the clearance of the bike relative to the track and the position of the bike relative to the guide. Damping may resolve this but to the detriment of the performance of the MotoGP bike on track that is not pool table smooth.

I could go on with a few more points but I will stop here for the moment.

It is not a simple excercise and those that say it is should think again!



Moped
 

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QUOTE (moped rider @ 3 May 2004, 19:57)4) the tyre rubber compound would have to be two part. One part in the middle to optimise grip on the metal, and two parts on the outer edges to optimise grip on the plexy, given that the wheels move onto this sufrface when leaning into the corners.

5) The rear wheel has suspension. This would compress as the bike leans into a corner further altering the clearance of the bike relative to the track and the position of the bike relative to the guide. Damping may resolve this but to the detriment of the performance of the MotoGP bike on track that is not pool table smooth.
Interestingly, these two points certainly apply to 1:1 bikes.


I can't remember the tyre manufacturer, but I've seen adverts for dual compound tyres - hard wearing centre with softer sides offering more grip when cranked over.

1:1 bikes have suspension! All the variable clearance nightmares manifest themselves on a ride down most UK roads
Couple that with a changing coefficient of friction of the road's surface



Mark.
 

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Hey Diff,

I think it was the Bridgestoe BT-020 for sports-touring use. Hard wearing compound in the middle for longitivity on those motorway miles; softer side compound for a bit of naughty tarmac scratching!!


Actually I think a lot of tyres these days are dual/multiple compound, but the Bridgestone sprung to mind because I think they started making a fuss first..
 

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Cars deal with the rubber stuff hitting the metal and the plastic.

I think that people just really wanted a good model of a bike, and resent Scalextric from nicking all the licensing (and probably a few patents) if they weren't gonna do a good job of it. Leave it to someone who can do it all.

However, we all realise just how difficult it is to make them lean (no-one else has come up with any realistic ideas yet (that I've heard)). It's just that they are gonna look silly going round bolt upright, and I don't think anyone can deny that.

The banked track will make them seem a bit more attractive, but I think having every corner banked, and no oppertunity for esses, will just dissapoint more people. It's a shame they couldn't have come up with a way of banking the rails inside the track, and springloading the stabelisers.

Well, I know that most of this has been said before, but not by me. I also wanted to point out why everyone is disappointed with Scalextric. It may be hard to make them lean, so if you can't do it, don't just make them half-assed.

Saying all this, I think it's a terrific achievement that Hornby have made, making the bikes look so good, and making something run on two wheels at all.

Lotus

PS. Wow, a post wihtout Scalextric or moped bashing...
 

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QUOTE 1) position of magnet changes relative to power rail as a bike swings into a corner. This reduces downforce when cornering. The answer possibly is to have a U shaped bar magnet but it is still a tticky one to work out.
Not necessarily so - it depends on HOW the lean would be achieved and on how the magnet mounted. Even if it were so, it is no different from the situation with cars.

QUOTE 2) the running line of the tyres change relative to the groove and the guide. The tyres have a compound optimised for running on metal (glass like/wood like in its grip qualities). As the bike leans relative to the guide then the tyres will start to run on the plexy material, with possible having lower grip coificients. The answer is to have a guide that moves from left to right as the bike leans keeping the tyres on the metal.
Again, no different from using cars. Added to which it ain't necessarily so that the rear wheel would run off the metal and onto plastic. It would depend entirely on the design.

QUOTE 3) the ride height of the bike relative to the guide is fixed. This height would change as the bike leans into a corner. Therefore the guide would have to move up and down as well as right and left if the bike was to lean.
Again, not necessarily -it depends on HOW the lean would be achieved.

QUOTE 4) the tyre rubber compound would have to be two part. One part in the middle to optimise grip on the metal, and two parts on the outer edges to optimise grip on the plexy, given that the wheels move onto this sufrface when leaning into the corners.
Isn't this really just a repeat of point 2?
Two part rubber is NOT going to happen.

QUOTE 5) The rear wheel has suspension. This would compress as the bike leans into a corner further altering the clearance of the bike relative to the track and the position of the bike relative to the guide. Damping may resolve this but to the detriment of the performance of the MotoGP bike on track that is not pool table smooth.
This contradicts point 3 where it states that the guide/bike distance is fixed. Either way, yet again, this is no different from the situation with cars. Whatever the vehicle, however many wheels it has, it must cope with track irregularities.
It is extremely unlikely that the suspension would compress significantly , given the low grip levels on either metal or plastic.

QUOTE I could go on with a few more points but I will stop here for the moment.
Hmmm . . . no comment!
 

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Jim Moyes
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Now would seem to be a good time to relate something I have heard about but admit that I have never seen myself. Though the "info" comes from 2 people who I consider to be "straight up", one has seen this only static, yet the other has had the thing run around his club track.

Basically it is a 2 wheeled motorbike that not only leans realistically when cornering but also has weighted joints in the knee and elbow of the rider. So that as the bike leans into the bend, the riders knee drops toward the track! That part wouldn't be too hard when you think about it, but what something like this would cost at the market place I wouldn't like to guess. I suspect it would have to be considerably more than the £30 that Hornby's bikes will be.

As I say this is just something I have heard about and I have no more details than I have given here, but the people who told me have been into slot racing a lot longer than the 12 years that I have.

I am not interested in bikes myself and I assume that MotoGP is just one branch of the sport, so another concern could produce these without treading on Hornby's toes. Whether that will ever happen is another thing!

Mr.M
 

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DT
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How and why does a real bike lean into a bend?

By the intention and action of the rider. Else the bike would note make it and fly off.

How could this be achieved on a 1:18 scale?

A pendulum action wouldn't look good unless it was housed internally. But it defeats the purpose as it the G-Force of going around the bend that initiates the lean.

A mechanical trigger attached to the guide would be a solution, but would be complicated and perhaps prone to busting. Would the guide turn enough to actuate a mechanism that would cause the bike to lean.



Would the leaning bike eliminate the need for a sled that the MotoGP bikes have?
 

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Discussion Starter · #9 ·
I have seen such a two wheeled MotoGP bike in the RC world with a rider that has pivoted joints and a bike that leans.

But the bike is much bigger than 1:18 scale, heavier with on board batteries, with a centre of gravity that may well be much lower, and with wheels that have enough mass to impart a centrifugal force.

The laws of physics on the model therefore match those of its 1:1 counterpart. And of course the pivoting ability of the driver to lean into the corner string puppet like adds fuel to the leaning fire.

Hornby therefore would need to place all these traits in their version of the MotoGP bike to at least give the bike the physical properties required to induce a lean naturally.

Therefore much heavier wheels (die-cast metal), a lower centre of gravity (lead weight lower chassis, and a MotoGP driver model that has weighted legs that pivot out would clearly be a requirement for a bike to have natural leaning abilities. You then have some sort of damped spring fixed to the paddle to prevent the bike from falling right over.

As the bike enters the straight then nature agin takes its course and the bike sits upright.

The real issue is with the guide as all this takes place.

And you are going to have to have one almighty level of skill to have perfect cornering speed with the MotoGP bike else you clearly are in an off situation.

To fast and over you go. To slow and you come to a halt as the bike falls inwards on its side. In fact the level of skill required for this would be much higher than for any slot car!



Moped
 

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To clarify:

When steering an RC bike, the rider is moved by a servo. The handlebars do turn everso slightly, but it's mainly just a leaning rider. When steering is released, the driver returns to normal position, but it's the inbuilt gyroscope that makes the bike return to it's upright, 'straight line', position.

So, to work like this, the scalextric bikes would have to be able to predict corners (or use the guide movement, and lean in too late). They would also require a gyroscope. Hopefully no one needs it explained just how hard it would be to incorporate one into the little things.

So using RC bike principles is out, and the only other way is using the pendulum effect, or the guide as a mechanical trigger. The problem is that as moped says, you would need to perfect cornering speeds, and this would be very hard, as I suspect the window would be quite small. This isn't something that you average Joe Homie wants, as RTR is the key to the home drivers market.

Another point. If they leaned, just imagine how hard they would be to marshall. Not only would you need to throw them forward with enough velocity to keep them upright, but when you pick them up, they would go all floppy in your hand. Impossible...

Lotus
 

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you would know all about floppy things in ya hand eh lotus!


yeah, tis all good but what is the chance of scalex doing this? not a lot I dont think.

now what else can i argue about?
 

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I think they should make trikes and sidecars etc - then they would not need to lean so much would they?
and we could argue about wether the front wheel is in the way for the slot or not - or something ....


//peter
 

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I loved the old Scalextric sidecars, favourite mag 'thing' ever driven. Bring them back.

Speaking of, has anyone got any that they would like to swap/sell?

Lotus
 

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It seems to me that the only time motorcycles EVER become 'desirable' on a slot track is when they are no longer readily available and the nostalgia buffs wind up the mechanism of their yearning for the good old days machinery.

For those who haven't seen it, I commend you to this thread - there is little or nothing new under the sun.

Speaking of . . .
 

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QUOTE I think they should make trikes and sidecars etc - then they would not need to lean so much would they?

Excellent. I laughed out loud and drew the attention of my governor!
 

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Russell Sheldon
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Given that the Scalextric bikes don't lean, I really wish that they had rather made them in 1/32nd scale rather than 1/18th scale.

I'm almost convinced that Polistil made a 1/24th'ish' bike that leaned, making use of an elaborate guide system....

Kind regards

Russell

 

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So how long did these guys remain in the range for, Thomas?
 

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...app. 8 years - but not very well sold! So these are really rare collector items! The only reason why Scalex started Moto GP?
 
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