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Something is a little odd here...

Started by mr72, August 16, 2018, 10:52:28 AM

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cbrfxr67

#1
Maybe they kept the back wheel and the outer two are basically training wheel style mounted?  :dunno_black:

I had to look cause was wondering more and more,..interesting,...

"Its something you take apart in 2-3 days and takes 10 years to go back together."
-buddha

mr72

Well, once I got through repeating "why... why?" over and over, it occurs to me that this is a great way to double the weight of a scooter and prevent it from cornering.

qcbaker

I've seen one of these things on the road before. At first, I was like "Huh, I've never seen a trike like that..." but then once I noticed the wheel in the middle and was extremely confused. The kit thing looked pretty professional, so my best guess was that some manufacturer sells a trike conversion kit for the Bergman. Looks like I may have been correct. Why anyone would buy one is beyond me though, because you''re right: all it does is add weight and make the scooter corner worse... I guess it adds stability (in a straight line) but if that's what they wanted, why not just buy a miata?

mr72

Quote from: qcbaker on August 16, 2018, 12:56:31 PM
I guess it adds stability (in a straight line) but if that's what they wanted, why not just buy a miata?

Well, a Miata can corner.

In this case, you get the worst of all worlds: a vehicle that's too heavy for the drivetrain, has far too little braking, which is really a bummer since you will be plowing headlong into things you'd really like to avoid by braking, since it will understeer like a top fuel dragster.

I think this is only stable when you are getting on and off of it. But it looks like a death trap to me.

If someone wants a "motorcycle" but is terrified of leaning or for whatever reason cannot balance a two-wheel machine, then the right solution is a Can-Am Spyder. Unfortunately that's 5x the cost or more of a four-wheel-ized scooter. But at least that puts two wheels at the correct end of the vehicle.

Shocks me that the seller of this Burgman suggests it will go 90 mph. Well, it won't, but if it would, that would be a one way ticket to the ICU.

cbrfxr67

"this is only stable when you are getting on and off of it"

"once I got through repeating "why... why?" over and over"

great lines in this thread
"Its something you take apart in 2-3 days and takes 10 years to go back together."
-buddha

Kilted1

I can hardly think of a faster way to ruin everything good about a motorcycle.  Maybe if you're a member of the Flat Earth Society but where I am there are hills and corners and the roads have a crown to them.

qcbaker

Quote from: mr72 on August 16, 2018, 01:10:30 PM
Well, a Miata can corner.

True, but not as well as a bike lol. Really I just meant a small vehicle where you're exposed to the wind

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In this case, you get the worst of all worlds: a vehicle that's too heavy for the drivetrain, has far too little braking, which is really a bummer since you will be plowing headlong into things you'd really like to avoid by braking, since it will understeer like a top fuel dragster.

Understeer and rollover in turns are problems for all trikes that have 2 rear wheels. As for the braking, are those extra wheels just free spinning or do they have brakes like a trailer?

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I think this is only stable when you are getting on and off of it. But it looks like a death trap to me.

If someone wants a "motorcycle" but is terrified of leaning or for whatever reason cannot balance a two-wheel machine, then the right solution is a Can-Am Spyder. Unfortunately that's 5x the cost or more of a four-wheel-ized scooter. But at least that puts two wheels at the correct end of the vehicle.

Shocks me that the seller of this Burgman suggests it will go 90 mph. Well, it won't, but if it would, that would be a one way ticket to the ICU.

The Bergman 650 will easily do 90, so I could imagine the 400 getting up to that speed, but the extra weight from the training wheels would make that a tall order I think.

mr72

Quote from: qcbaker on August 17, 2018, 03:58:03 AM
Quote from: mr72 on August 16, 2018, 01:10:30 PM
Well, a Miata can corner.

True, but not as well as a bike lol. Really I just meant a small vehicle where you're exposed to the wind


Well now. My Miata would out-corner most street motorcycles, and would certainly run off and leave pretty much any scooter on any road, corners or not.

But my point was in this case the mod essentially ruins cornering capability which on any 2-wheel vehicle is dependent nearly entirely on the ability for it to lean.

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Understeer and rollover in turns are problems for all trikes that have 2 rear wheels. As for the braking, are those extra wheels just free spinning or do they have brakes like a trailer?
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Who knows but it hardly matters because under virtually all braking the weight is transferred to the front so the front brake will do 90% of the braking. You've doubled the weight of the vehicle without increasing the braking either in terms of tire adhesion or actual brakes. If those rear wheels were hooked up to the brakes, assuming you also fitted a brake booster and whatever, they'd just lock up.

Imagine trying to brake at all in a curve on this thing. You'd understeer and skid straight out of the apex of the corner off the road.

qcbaker

#9
Quote from: mr72 on August 17, 2018, 10:36:48 AM
Well now. My Miata would out-corner most street motorcycles

What do you consider a "street motorcycle"? Stock vs. stock, I would imagine that basically any 600+cc sportbike would be able to carry more speed through any given corner. The Miata can pull lateral G of ~.9G right? A GSX-R600 can pull something like 1.4 IIRC.

Not trying to start a Miata vs sportbike argument or discount the Miata, btw. I just bought an FR-S, so its not like I don't appreciate a car that's focused on handling rather than power lol.

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and would certainly run off and leave pretty much any scooter on any road, corners or not.

You're almost certainly right about that lol.


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Who knows but it hardly matters because under virtually all braking the weight is transferred to the front so the front brake will do 90% of the braking. You've doubled the weight of the vehicle without increasing the braking either in terms of tire adhesion or actual brakes. If those rear wheels were hooked up to the brakes, assuming you also fitted a brake booster and whatever, they'd just lock up.

Imagine trying to brake at all in a curve on this thing. You'd understeer and skid straight out of the apex of the corner off the road.

You're not wrong, but certainly some amount of rear wheel braking would be better than none at all, right? Though, I say that but I almost never use the rear brake on my bike, so... :dunno_black:

mr72

Quote from: qcbaker on August 17, 2018, 11:17:40 AM
Quote from: mr72 on August 17, 2018, 10:36:48 AM
Well now. My Miata would out-corner most street motorcycles

What do you consider a "street motorcycle"?

A third of all street motorcycles in the us are Harleys. Among the rest, a sizable portion are either metric cruisers, old style standards, dual sports and a small number of sport bikes.

I'd guess a stock Miata will probably outcorner all but sport bikes. Mine wasn't stock.

qcbaker

Quote from: mr72 on August 17, 2018, 03:11:16 PM
A third of all street motorcycles in the us are Harleys. Among the rest, a sizable portion are either metric cruisers, old style standards, dual sports and a small number of sport bikes.

I'd guess a stock Miata will probably outcorner all but sport bikes. Mine wasn't stock.

I guess I forget that most people don't ride sportbikes lol. You're probably right that a Mitata will outcorner any bike that isn't a sportbike.

If you don't mind the thread drift, what all did you modify on yours?

mr72

Quote from: qcbaker on August 20, 2018, 06:04:22 AM
If you don't mind the thread drift, what all did you modify on yours?

This is an odds-n-ends thread... drift is what it's all about :)

My Miata was my first new car, I bought it in 2000. I totally loved that car, so when it came time to either replace it because it was getting old and was beginning to need work or to rebuild it, I chose to rebuild.

In my case I did a near complete restoration of the car with the idea being the eventual result to be somewhere between a track car and a regular roadster. I replaced the engine block with a later model and had the head redone, winding up with +-0.5 compression ratio in the process and probably 10+ hp and mostly more torque, ss headers, open intake with a gigantic "cone" type filter, removed the EGR and any non-essential emissions stuff, removed the carpet and built a shorty console for it, reupholstered the seats and painted the car after doing whatever bodywork needed doing. I fabricated the exhaust system myself, two stainless-steel "glass-pack" type mufflers and 2.25" tubing straight back. It was loud and quick. Being an early NB it was maybe 2250 lb and with the slight engine warming over it had maybe 160hp so it would get 0-60 in right around 6 seconds and screamed at you while it was doing it.

Suspension-wise, I stuck to 15" lightweight wheels (mini-lite knockoffs) with 205/50R15 BFG Comp 2s which were among the best tires I had on the car. Funny thing with a car like this, it's light enough that a lot of tires, especially really big tires, won't get hot enough to grip unless you are literally on the racetrack, and if you drive in the winter at all they are deadly. So getting the "right" tires was not easy. I think in the 15 years I had the car I went through 11 sets of tires so I got a pretty good idea of what worked and what didn't. Anyway, I pulled the rear sway bar and put a set of very stiff adjustable coilovers on it. Car had a Torsen LSD which with a rear sway bar and soft rear springs made for very interesting right-hand turns, but it was steer-by-throttle with the hard springs and no rear bar. I never really got the suspension totally dialed. It was maybe 1-1.5" lower than stock but being a 100% street car I needed the ground clearance and suspension travel to stay up there. On the road it had the feeling of driving a not-quite-road car, like this car was just a barely too insane to really drive on the road, but it was very livable as long as you could tolerate a hard ride and real loud exhaust.

Anyway, it was totaled in 2015 when a driver made a left turn in front of me while I was commuting to work, I hit the front right fender of that car going probably 50 mph. May she rest in peace.


Cal Price

I never "got" trikes unless you really want to get the worst bits of motoring and motorcycling.
Black Beemer  - F800ST.
In Cricket the testicular guard, or Box, was introduced in 1874. The helmet was introduced in 1974. Is there a message??

qcbaker

Quote from: mr72 on August 20, 2018, 08:02:13 AM
*Miata Stuff*

Sounds like you basically had a racecar that was still technically street legal lol. You ever do any track days or AutoX or anything with it? I wanna try out some AutoX at some point, I think it would be a ton of fun, even if my times aren't anywhere near competitive lol.

mr72

Quote from: qcbaker on August 21, 2018, 07:07:20 AM
Quote from: mr72 on August 20, 2018, 08:02:13 AM
*Miata Stuff*

Sounds like you basically had a racecar that was still technically street legal lol.

Almost. The "feel" I was going for was more like a vintage race car. I wanted the car to have the vibe kind of like you're driving a 240Z race car on the street, which is pretty close to what it was. But with air conditioning and a radio.

Oh yeah I also built flat/plain door cards for it with straps. And it had twin center stripes like a Cobra and gumballs on the doors with the number '21'.

Actually it was kind of like the Miata version of a '73-74 911 RS.

This wasn't my first "race car for the road" type of car. But this was style points and the visceral feeling of a bonzo car, not real performance. I'm sure the car handled better earlier in its life with stock suspension and the 14" stock (super light) wheels with the Proxes T1-S tires, which were literally designed for Miata track cars. But it didn't feel as sharp and immediate with those tires and suspension.

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You ever do any track days or AutoX or anything with it? I wanna try out some AutoX at some point, I think it would be a ton of fun, even if my times aren't anywhere near competitive lol.

That always sounded like fun but I went to a number of AutoX when I was younger and saw just how easy it is to break things. Since this was my daily driver and sole transportation, I couldn't afford to smoke the clutch or crack a wheel or bend a control arm going rear end first into a curb. I saw this happen too many times. I think AutoX makes the most sense in a car that comes in on a trailer.

I did work with a guy with a similar car to mine who was the national champion in B-stock. The amount of money he put into the shocks alone, which was just revalving of the stock/original shocks since the rules don't allow swapping, was mind blowing.

qcbaker

Quote from: mr72 on August 21, 2018, 12:47:04 PM
That always sounded like fun but I went to a number of AutoX when I was younger and saw just how easy it is to break things. Since this was my daily driver and sole transportation, I couldn't afford to smoke the clutch or crack a wheel or bend a control arm going rear end first into a curb. I saw this happen too many times. I think AutoX makes the most sense in a car that comes in on a trailer.

I can understand burning out a clutch at an AutoX event if you try to drive harder than you're actually able, but I've never seen an event that had damaging obstacles near it. Most of the stuff I've seen is in wide open parking lots and the only thing that you can hit are cones. I agree that busting up your DD is definitely a bad idea, but I wouldn't have put AutoX as something that was that risky. I'll probably try to attend some events to get a feel for it, then if I think the risk-reward equation balances out, I'll try my hand at it lol.

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I did work with a guy with a similar car to mine who was the national champion in B-stock. The amount of money he put into the shocks alone, which was just revalving of the stock/original shocks since the rules don't allow swapping, was mind blowing.

Yeah depending on the class, people go crazy tweaking their builds just to get another thousandth of a second off their time.

mr72

In the stock class in SCCA [back then, IDK now] the rules allowed you to run any combination of parts that would have come on the car from the factory, which meant epic hunts for just the right oddball combinations of bin parts plus allowable rebuilding of stock parts within limits, such as switching stock shocks from gas to oil like in my friend's case because it can lower the car 1/2". And the thing is, EVERYONE is doing this to the limits, so you basically have to start there. Most of the B-stock Miata guys would start out by stripping the entire car on a rotisserie, media-blast off all of the sound deadening just to get the weight reduction, then bolt in the cage, paint it, and build the entire "stock" car from the frame up using every choice part the factory ever made in any combination to get that edge. Oh yeah and blueprint everything. Insane. That's how you turn a $10K used car into a $100K race car project.

Anyway, I saw my share of failures on the AutoX courses. In Austin they have a parking lot greenspace ordinance that requires islands with trees and grass, and curbs, to be sprinkled liberally throughout the pavement, so it's pretty difficult to put together an AutoX course that doesn't get close to a curb here and there. And once the car gets away from you because you lift mid-corner it can go tail-first into a curb 50 ft away pretty easily.

The Buddha

Quote from: qcbaker on August 17, 2018, 11:17:40 AM

What do you consider a "street motorcycle"? Stock vs. stock, I would imagine that basically any 600+cc sportbike would be able to carry more speed through any given corner. The Miata can pull lateral G of ~.9G right? A GSX-R600 can pull something like 1.4 IIRC.


This isn't quite as simple as that. Let me try to explain as best as I can. A stock miata going through a specific corner at a specific speed is at lets say .9g. If you took that same miata and slapped on a longer set of axles and put the same wheels and tires on making it say 1' wider, run it in the same corner at the same speed it will pull less than .9g. In other words more width = less g's as is measured and published.
A GSXR's essentially got no reliable comparison to a miata or any other car in this regard, cos the width (track) on a bike is basically 0. Only comparisons between cars, or between bikes make for apples to apples comparison.
You can compare average corner speeds in race tracks where they race carbs and bikes and make some conclusions if you like, or just ride the same set of corners and see where you break traction in car vs bike but IMHO, carbs and bikes are very close in max corner speeds.
The only reason you outrun cars is that in most real world situations with a max 90 highway speed, lots of stop/slow and go and people never come close to breaking traction anywhere in a car while a lot of bikers do when braking and some even while accelerating - Bikes accelerate harder, and bikers enjoy that, so they let it rip. So in town and in traffic lights we leave all the cars in the dust, get on the highway and the GS especially starts wheezing @90, where all the cars catch up and stay with you.

Cool.
Buddha.
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mr72

Quote from: The Buddha on August 30, 2018, 02:06:26 AM
Quote from: qcbaker on August 17, 2018, 11:17:40 AM

What do you consider a "street motorcycle"? Stock vs. stock, I would imagine that basically any 600+cc sportbike would be able to carry more speed through any given corner. The Miata can pull lateral G of ~.9G right? A GSX-R600 can pull something like 1.4 IIRC.


This isn't quite as simple as that. Let me try to explain as best as I can. A stock miata going through a specific corner at a specific speed is at lets say .9g. If you took that same miata and slapped on a longer set of axles and put the same wheels and tires on making it say 1' wider, run it in the same corner at the same speed it will pull less than .9g. In other words more width = less g's as is measured and published.

I agree it's not nearly as simple as that, but it's also not as you suggest.

lateral G force can be calculated purely with speed and turn radius. It has nothing to do with the car really. It's easier to measure in-car with a meter.

But of course this whole "out-handle" statement I made before can't be fully equated to lateral G-force measurement. In a Miata, you can (and often would) perform a cornering maneuver that exceeds the lateral grip of the car. You can intentionally break the rear loose and get the car to oversteer and tighten a corner, making the turn faster than it would be if you stayed within the limits of adhesion. On a motorcycle this would result in a crash.

But also "handling" is much more than simply how fast you can make a given corner. It's also about how controllable the vehicle is when going over the limit, how it transitions, how much braking you can apply especially while turning, how it can lay down power during a turn exit and etc. So a car with 4 tires on the ground and the ability to control camber in turns and vary roll stiffness front to rear really has a huge advantage, not to mention the fact that the driver is more physically capable of operating the car when it is over the limit. I mean, in a car you can recover from coming into a turn too hot or if it gets away at least part of the time.

It's an apples to oranges comparison anyway.

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