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Thread: The ElMoto Dream Bike

              
   
   
  1. #151
    Moderator Nuts & Volts's Avatar
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    Quote Originally Posted by teddillard View Post
    That's a new one on me. I never heard of screwing up the handling with additional rigidity... can you say a little more?

    Thanks for chiming in, Mike! Looking forward to seeing your build...

    OK Kyle. If you guys are indulging my personal penchant for YELLOW then I figure it's only fair to indulge you on the NO ANDERSONS thang...
    I can give you one example. When your bike is leaned over in corner, your suspension can no longer function to its full capabilities due to stiction. Well if you have no suspension and go over a bump in the turn you increase the risk of losing traction which is bad . So the big OEMs use the spring rate/elasticity of the frame/engine material (all materials have some sort of spring action) to act as the suspension to maintain maximum traction. They actually tune the bikes to do this. Remove the engine and you have messed up that optimal/optimized spring rate and compromised handling. This is with modern bikes.

    I have no way to quantify the difference (well actually I know the equations needed, just don't feel like figuring out the variables. In my opinion you can get pretty good performance, by replacing the engine with something that has similiar properties (elasticity, weight, modulus, etc.).

    The center of gravity and overall weight are also factors that come into play, but are easier to tune with the suspension settings available.


    Ted, there are alternatives to Andersons, but most of the time they are really expensive. Tyco electronics has some, but I don't know them off the top of my head.
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  2. #152
    Seņor Member podolefsky's Avatar
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    Quote Originally Posted by Nuts & Volts View Post
    It's mostly a personal thing. I have used some of the larger ones before and they were such a pain in my ass to try to disconnect. It had a bit to do with where they were on the bike. They are large and do not fit well on a bike which is already cramped with things. I think they're ugly too.

    I have no science to say why I don't like them. I have just used appropriately sized ones and hated them every second. I love them for lower current charger connections thou.
    I don't like them either. They're actually really well designed, if you're not pulling things apart that often. There's a lot of pressure between the pins, so they might have a bit more surface resistance than screwing things together, but probably not much. But this is also why I don't like them...they're too hard to pull apart. I always feel like I'm going to smack my knuckles on something or yank the wires out with how hard I have to pull on them. They make a special handle so you can get better grip, but that just makes them bigger.

    What I wish they had was a little lever that opened them up without having to brute force yank them apart. Or just a clip to keep them connected, that you press to release, like almost every other connector out there.

    They do come in different colors, which is neat. I got red ones. (what's weird is that the red ones and the grey ones aren't compatible )
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  3. #153
    Seņor Member podolefsky's Avatar
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    Quote Originally Posted by Nuts & Volts View Post
    I can give you one example. When your bike is leaned over in corner, your suspension can no longer function to its full capabilities due to stiction. Well if you have no suspension and go over a bump in the turn you increase the risk of losing traction which is bad . So the big OEMs use the spring rate/elasticity of the frame/engine material (all materials have some sort of spring action) to act as the suspension to maintain maximum traction. They actually tune the bikes to do this. Remove the engine and you have messed up that optimal/optimized spring rate and compromised handling. This is with modern bikes.
    There was an article about this Cycle World (or Motor Cyclist?) a few months back. What they said is that in addition to the stiction issue, there's also the fact that when leaned over the forces get close to perpendicular to the suspension travel. To soak up bumps, the wheels need to be able to move sideways (relative to the bike), so they engineer some flex into parts of the chassis. It's not a perfect solution because a flexing frame isn't very well damped, but it's better than nothing. Overly rigid bikes are prone to more chatter when cornering hard.
    - Noah Podolefsky -
    The GSX-E

  4. #154
    Senior Member Skeezmour's Avatar
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    Check out the MotoCzysz front suspension to see how they work with the handling while leaned over.

  5. #155
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    Quote Originally Posted by teddillard View Post
    That's a new one on me. I never heard of screwing up the handling with additional rigidity... can you say a little more?

    Thanks for chiming in, Mike! Looking forward to seeing your build...

    OK Kyle. If you guys are indulging my personal penchant for YELLOW then I figure it's only fair to indulge you on the NO ANDERSONS thang...

    Perhaps screw up is a little harsh but the whole bike is designed to flex under load. It is a careful balance of weight, power and flexibility to maximise the handling. Of course road bikes are a trade off but, for example, you have 50 hp in a chassis designed for 150 hp the the bike will handle differently than was intended. On the road this may not be noticeable, even something like the Isle of Man TT course may let you get away with things you wouldn't otherwise but on a short circuit there will definitely be a difference.

    If you look at the Aprilia RSV4 road bke and compare it to the World Superbike you will notice they don't use the centre engine mount to allow the frame to flex more. On the Aprilia CRT bikes in MotoGP that whole spar isn't there at all.

    When we built out last British SuperBike we had the stock swing arm tested by a friend of mine that designs MotoGP bikes and WSB swing arms. His conclusion was that the torsional stiffness was fine but the lateral stiffness was too much. Bizarrely on an aftermarket swing arm hw would have chosen to run more torsion stiffness but only if he could reduce the lateral.

    Clearly it can be a black art, or at least something reserved for those looking for the absolute limit of traction but that is our goal which is why he'll be designing our bike and making sure the carbon fibre flexes as intended.

  6. #156
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    Quote Originally Posted by Skeezmour View Post
    Check out the MotoCzysz front suspension to see how they work with the handling while leaned over.
    This is where Michael Czysz and I disagree.The traditional suspension design works really, really well these days and whilst engineering improvements have minimised the tolerance in the hub centred approach favoured by Czysz there will always be a degree of slack in the steering right at the point where you need the optimum amount of feel.

    This may only be at 99.99% of optimum and it may be superb up until that point but it will never, ever beat the system in use in MotoGP and pretty much everywhere else where optimum performance is the goal.

  7. #157
    teddillard
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    Quote Originally Posted by Mike Edwards View Post
    This is where Michael Czysz and I disagree.The traditional suspension design works really, really well these days and whilst engineering improvements have minimised the tolerance in the hub centred approach favoured by Czysz there will always be a degree of slack in the steering right at the point where you need the optimum amount of feel.

    This may only be at 99.99% of optimum and it may be superb up until that point but it will never, ever beat the system in use in MotoGP and pretty much everywhere else where optimum performance is the goal.
    So. You guys are pretty much laughing your asses off at me and my '70s vintage steel tube frames, huh?

  8. #158
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    It seems to me that Ted's bike is right up to date. It has all the flex it needs to corner smoothly. Who needs suspension when you have frame-flex.

    Personally, I don't think designing frame flex is a very big engineering concern for most production street bikes made by the major manufacturers. I doubt there are too many production motorcycles that wouldn't benefit from a more rigid frame. I think a too-rigid frame is only a consideration under high speed cornering racing conditions and not when riding on the street. I think the manufacturers make frames as rigid as possible within the constraints of their budget and styling concept.
    Richard - Current bikes: 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2011 Royal Enfield 500, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior.

  9. #159
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    I always wondered if Ducati flex tuned their frames by evidence of the smaller diameter diagonal tubes(than the other diagonal tubes) next to the steering head:




    http://www.ducati.ms/forums/attachme...ainted-043.jpg
    Last edited by Fab man; 16 February 2013 at 2242.

  10. #160
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    Quote Originally Posted by Fab man View Post
    I always wondered if Ducati flex tuned their frames by evidence of the smaller diameter diagonal tubes(than the other diagonal tubes) next to the steering head:

    They may not have fully understood the amount of flex they were introducing but the steel lattice style frames Ducati used for years worked well but they clearly weren't thinking when they moved to the extremely stiff carbon MotoGP frames that relied on the engine as a stressed member.

    Richard230 is right though. On the street it is debatable whether the frame flex issue is even noticeable over the additional 100 lbs+ weight from the batteries.

    It may even be barely discernible on the track when your bike weighs over 500 lbs but it will be a factor, especially with the swing arm. Hopefully we will be able to find a way of securing the battery pack so the frame can flex without trying to pass on that flex by twisting the battery pack under high loads.

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