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#71
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THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute
Looks like your bendibeam with balloon tyres will give you everything
you want in a trike -- though I can't say I'm equally impressed with your willingness to consider an unstable delta on equal terms with a stable tadpole. Big moneysaver and complication-saver if the bendibeam works as well for bikes as it works the rear of hatchbacks. -- Andre Jute On Jun 9, 12:58*pm, Bernhard Agthe wrote: Hi, Andre Jute wrote: On Jun 8, 1:57 pm, Bernhard Agthe wrote: (leaning car vs leaning trike) No, unfortunately not. It is apples and oranges. Compare a non-leaning car and a leaning car. The non-leaning car has wide flat tires; the suspension is designed to keep them upright; the car gets its stability from its track width. (Ever ask why Lotus made such great big wide sports cars -- they weren't incompetent and they weren't Don't need to tell me why fast cars are low *and* wide. Look at a Formula-1 racer... But if you want a fast HPV, I'd rather refer you to two-wheeled lowracers... Or would you use your Ferrari to pull a camping trailer?! looking for extra space for luxuries, I assure you.) The leaning car, by contrast, is narrower, and has narrow roundshouldered tyres; it gets its stability from leaning over effectively to make its contact patch (eventually!) as wide as that of the fat tire on the "upright" car. You know, I cannot say anything to that, because I have never seen a leaning car (especially not a successful commercially sold one). My theory is, if "leaning" was so essential in cars, why aren't there any leaning cars to buy? So I figure "leaning" is not necessary on a vehicle that runs in more than one track - which a trike is... It might be a nice feature, but I wouldn't spend money for it, because I don't consider it necessary... From my reading, I suspect that the rear suspension is important on all tripods, as is a well-suspended seat. Front suspension is apparently much less valuable (and you too said so after your trial As said before, I cannot say how it feels to ride a bike without rear suspension, but I've been comfortable without front suspension. Looking at the weight distribution, I'd guess that front and rear "axle" each carry roughly half of the total weight (depending on the actual design). While there are two front wheels, there is only one rear wheel, so any effort in terms of suspension has about twice the effect... ride). So I see the chassis as running from the seat past the bottom bracket (I still like my feet inside the wheelbase! to the front axle. The rest of the chassis is the swing arm for the suspended rear wheel, and the crossarm which acts as an axle for the front wheels. By putting the front axle that much forward, you actually "produce" the problem that needs "leaning" as a solution. We agreed that the triangle between the contact patches of the tires is essential for stability. By putting the front wheel so far forward, you put the COG at the narrow part which is bad. By putting the front axle "below your knees", you lessen the problem so much, it's not worth the bother of tilting... Also, a trike with such a long wheelbase would likely have an excessively large turning radius... As said above, if you're afraid about your feet, just put a "T"-shaped extension on the bottom bracket beam, that will have the same effect. (a) both front wheels connected by a single, straight beam that is allowed to bend just a little to absorb a little part of road bump (compare leaf spring). Use a standard steering linkage. Yes, no problemo. It could be a U-shape (as on a truck-chassis) but turned open-side down. VW-Audio have been very successful with this sort of controlled-flexure rear axle. Mount it on rubber straight out of a Ford (or a Renault) exhaust hanger, and you have a certain amount of damping and isolation too. As Tom Sherman warns - you need to clear the rider's feet and legs... Apart from that - yes. (b) trapezoid front wheel linkage with little or no springiness as described above (corner outside wheel moves backward a bit). Clever baggins, you. I hate it! It is all unsprung weight whereas my Actually I was more afraid of the bearings sticking because the beams flex just so much... parallel, equal lengths arms, forming a rectangle perpendicular to the centreline of the car is hallowed by tradition, only half unsuspended Use Big-Apple or similar tires and dump the front wheel suspension (with suspension applying purely to the spring-and-damper component, I don't want to connect the front wheels with magnetic forces ;-) But even then I'm sure you can work out the whole front wheel suspension and linkage thing like I described it, I just simply cannot imagine how that would look like. And then we're again at a point where I don't see the need to bother with something so complicated... There are many problems to solve that are more serious (see my comment about semi-automated shifting)... weight, and can be built with parts bought off the shelf at any hot- rodder or ultralight racing supplier, so a minimum of custom manufacture. However, your idea, if it can be made light enough, will work though i find it hard to visualize it working better than tilting wheels. Build the whole thing three-dimensional and you get your tilting wheels for free. You'll have some seriously diagonal linkage then, though... You might need a lot of two-or three-dimensional bearings, though... I'm not so certain any of the sporting tadpole we're considering will have good luggage capacity or handling. Even that suggestive big Are you trying to pull your camping trailer with a Ferrari? So don't try to use a luggage-cart-style-bicycle for racing ;-) They simply don't match... basket that the Anthrotech can be fitted with is in the wrong place for putting anything heavy in it: as little as ten kilo in there would unbalance the handling of the bike at speeds easily attained on the hill on which I live; IIRC the rating is 30kg of luggage and that would be lethal on the sharp corners at the speed the trike seems likely to attain on some of my better hills. For good handling of Oh come on, the Anthrotech is not known for flipping over. And you can still get the "narrow" rack and use either Ortlieb bags or even mount hard-shell containers. They'll be low enough to work well... luggage on a trike, it should be under your legs. The Culty that Chalo referred us to the other day has the luggage in the right place but the wheels in the wrong place. Most of the others you and I are likely to consider are too low to put anything under the legs. Chalo seems to like his Culty, so *for him* the wheels are in the right place. Apart from that, why not consider a delta trike - look at the ones mady by Hase-Bikes. You can build it so that you have a large cargo-carrying space just between the seat and the rear wheels. Actually you can even have the front wheel in front of your feet and have full suspension easily. The more I think about it, the more interesting they seem... And they have a community of enthusiast fans... So, why rule that design out up front? I see no problem with building your bendibeam. The transperse axle beam can be bolted onto the longitudinal "frame" beam with U-bolts over a hard rubber pad for both isolation and the small amount of play you want. At an all-up weight of say 150kg (loaded for your world tour) and human pedal-power, you're never going to wear it out, so the assembly is maintenance-free. Saves on front suspension. I'm very So by building a "bendibeam" trike, I would get sufficient and reliable "suspension" at no additional cost (just use the different material). You'll laugh, but I think that's the way trike design should go: use materials smartly and put them to multiple use, in this case one part for both wheel attachment and suspension. Saves weight, cost and maintenance... impressed with Schwalbe's Big Apple balloons, which are available in 406 rim diameter too. You see, I wouldn't consider them on an upright bike (I love my narrow tires), but I would prefer them to a "fully" sprung bike anytime: use one single component for multiple purpose (again)... Ciao.. . |
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#72
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THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute
On Jun 9, 2:30*pm, Bernhard Agthe wrote:
Hi, Andre Jute wrote: However, what is wrong with a single arm that mounts rear wheel, crank and pivot, pivoting at the junction of a trident with a long central arm, the two short side arms reaching back to the front wheels from as far in front of the notional axle line as is necessary, the central arm carrying all the payload of rider and luggage, the rider's feet then ending up inside the "structure" and the chainline being straightly unarticulated and not requiring idlers when hub gears are used. Probably semi-recumbent to keep the wheelbase from growing too long, but that is where I started anyway, with seat comfortable to sit down in and from which it is possible to rise with grace. That's a lot of tech talk in very little space ;-) The ideas are now firming up in my mind. Thanks for help in working them out. Actually I'd agree at once, but I do see the danger of the trike actually leaning towards the outside of a corner if there is too much flex in the frame. That's why I would connect the front wheels with a straight (or almost straight) beam... Too much of anything is not good ;-) The beam itself could be solid with a little play in the mounting. However, I remember driving a Bugati when I was young which was said to have had a solid front axle with small articulation from the factory, which was soldered up because it never worked. I had a good description from the engineer who owned and rebuilt it of the purpose of the articulation, and also why it dinna work, but the details are long gone. So, for myself, I conclude that a trike should have the "leaning" feature, if it has significant suspension on the two-wheeled axle. If it has no or very little suspension on that axle, it would be better to have no leaning, just to keep it simple ;-) Leaning depends on the geometry of the axle mounting. It is not tied to suspension. However, suspension-type links are the easiest by which to arrange a tilting trike. So, we now have the sporty-trikes with cool suspension and leaning and we have the more-utility-trikes with "bendibeam" and/or Big-Tire technology and no extra leaning ;-) We might not be able to find a "one-for-all" design, but that's fine with me ;-) I never set out to persuade anyone my idea was "best". Only building all the ideas and racing them will prove which is best -- and then some of us will argue that a little sacrifice of speed for a more upright seat is well worth it! Super thread! Andre Jute Down with the spoilsport Telemachus! |
#73
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THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute
Bernhard Agthe wrote:
Andre Jute wrote: luggage on a trike, it should be under your legs. The Culty that Chalo referred us to the other day has the luggage in the right place but the wheels in the wrong place. Most of the others you and I are likely to consider are too low to put anything under the legs. Chalo seems to like his Culty, so *for him* the wheels are in the right place. I don't ride a Culty. I simply pointed it out as a leaning, high- riding trike when Andre complained that other leaning trikes were too low. I expect that the idiosyncrasies of tilting and rear steering trump all generic concerns about delta versus tadpole layout-- whether good or bad, there is no other machine to compare to the Culty from a functional standpoint. I think that Andre's case against delta trikes is circumstantial; the few that carry their riders low and between the rear wheels (e.g. the Hase Lepus and Kettwiesel trikes you have already mentioned) are good handlers on a par with similarly low-slung tadpoles. The practical drawback to these is that the best place for carrying loads is occupied with the rider, but that is the tadpole trike's predicament as well. Chalo |
#74
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THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute
Hi,
Andre Jute wrote: The beam itself could be solid with a little play in the mounting. However, I remember driving a Bugati when I was young which was said to have had a solid front axle with small articulation from the factory, which was soldered up because it never worked. I had a good description from the engineer who owned and rebuilt it of the purpose of the articulation, and also why it dinna work, but the details are long gone. Sorry, but I cannot picture this :-( Well, as you stated, I have "my" trike (at least the idea of it), so it probably doesn't matter ;-) Leaning depends on the geometry of the axle mounting. It is not tied to suspension. However, suspension-type links are the easiest by which to arrange a tilting trike. Sure... But as I stated elsewhere, it is likely not worth the bother to build a tilting mech into an unsprung trike... But if you want lots of suspension, you'll end up with either "anti-roll" or a leaning mechanism, so it might be a good idea to combine suspension and leaning. I'll agree with you, if you have to counter unwanted outward-tilt, you can build the suspension to provide leaning right away ;-) You convinced me ;-) I never set out to persuade anyone my idea was "best". Only building all the ideas and racing them will prove which is best -- and then some of us will argue that a little sacrifice of speed for a more upright seat is well worth it! Well, I wouldn't want to race them - I'd end up last with my complete camping gear on the "bendibeam" trike... But it might still be the best trike for carrying half a household ;-) At least for me. So I'd rather build (and advertise) a bike for the utility factor ("carry a month's groceries without strain"), while you would probably talk UCI into letting you take part in the Tour de France for advertisement reasons ;-) You win the race while I watch before going on in my world camping trip ;-) So now we have wishlists for two A.R.B.R.-trikes, one sporty with all the latest features, supple suspension and leaning, and one looking like a shopping cart on three wheels (with a lawnchair attached)... Does anyone have an idea, where I could go to have my frame built (as stated, I don't have the resources)? Ciao ;-) .. |
#75
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THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute
On 10 June, 11:09, Bernhard Agthe wrote:
Hi, Andre Jute wrote: The beam itself could be solid with a little play in the mounting. However, I remember driving a Bugati when I was young which was said to have had a solid front axle with small articulation from the factory, which was soldered up because it never worked. I had a good description from the engineer who owned and rebuilt it of the purpose of the articulation, and also why it dinna work, but the details are long gone. Sorry, but I cannot picture this :-( Well, as you stated, I have "my" trike (at least the idea of it), so it probably doesn't matter ;-) Leaning depends on the geometry of the axle mounting. It is not tied to suspension. However, suspension-type links are the easiest by which to arrange a tilting trike. Sure... But as I stated elsewhere, it is likely not worth the bother to build a tilting mech into an unsprung trike... But if you want lots of suspension, you'll end up with either "anti-roll" or a leaning mechanism, so it might be a good idea to combine suspension and leaning. I'll agree with you, if you have to counter unwanted outward-tilt, you can build the suspension to provide leaning right away ;-) You convinced me ;-) I never set out to persuade anyone my idea was "best". Only building all the ideas and racing them will prove which is best -- and then some of us will argue that a little sacrifice of speed for a more upright seat is well worth it! Well, I wouldn't want to race them - I'd end up last with my complete camping gear on the "bendibeam" trike... But it might still be the best trike for carrying half a household ;-) At least for me. So I'd rather build (and advertise) a bike for the utility factor ("carry a month's groceries without strain"), while you would probably talk UCI into letting you take part in the Tour de France for advertisement reasons ;-) You win the race while I watch before going on in my world camping trip ;-) So now we have wishlists for two A.R.B.R.-trikes, one sporty with all the latest features, supple suspension and leaning, and one looking like a shopping cart on three wheels (with a lawnchair attached)... Does anyone have an idea, where I could go to have my frame built (as stated, I don't have the resources)? Ciao ;-) . Dexion (drilled and slotted steel angle for shelving system) will make up a frame in double quick time. For your basic requirements it may even survive as a finished working model. Use the shelves to make a luggage box/seat. |
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