Identify This Stretch Suspension For Tall People Up To 6'5"

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atombikes

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Feb 14, 2010
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Unless you place a jackshaft directly on the rear suspension pivot point, this bike will suffer from a "pogo-ing" effect when you feed the throttle. It should squat, which translates to loss of power. The power being put into the chain will just compress the rear shock.
 

DaveC

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Jul 14, 2010
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Unless you place a jackshaft directly on the rear suspension pivot point, this bike will suffer from a "pogo-ing" effect when you feed the throttle. It should squat, which translates to loss of power. The power being put into the chain will just compress the rear shock.
Looking at it in hindsite your right. Not only that it would pogo just rideing it. You'd have to turn the spring up to uselessness so that it wouldn't. Would work fine with a solid link, though. I know the spring is a "design feature" but your better off with a springer seat or post.
 

killercanuck

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Dec 17, 2009
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yea, jackshaft, or super-heavy-duty spring on a swivel tensioner. I found another bike with a similar design over at JustBicycles.com JBM:Micargi Cheetah NX3, but starting to think again because of the chain issue. Would make a nice E-bike though, lots of room in front of the back tire for batts... hmm.
 

atombikes

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Feb 14, 2010
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The designer said the shock is a m/c shock; I think that means it'd have the resiliency to handle a small engine... I feel my Honda Nighthawk compress, when I hit the throttle, happens to every bike, doesn't it?
Being strong enough isn't really the concern; if it is so stiff that it will counteract the forces from the chain, then it really won't act like much of a shock absorber, nor will it reduce road induced vibration (because it is so stiff).

With a real motorcycle, this isn't as much of a concern since there is adequate HP; the losses associated with squat are negligible.

But, as I previously stated, a jackshaft placed at the rear suspension pivot point will solve this problem for the subject bike. If this is done, the shock absorber can be tuned to suit real suspension needs, not to resist pedaling and/or engine chain forces.

When I see designs like this I wonder exactly how much experience these designers have designing these types of vehicles?
 
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killercanuck

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Gotta remember they're designed for "pedal power" too. Once we slap on an engine, that changes everything. Could put in a stiffer spring/shock, but like atom says, that'll negate the usefulness of the suspension if its so stiff to counter the "squat"...

I think we crashed the JustBikes site too, lol. We love a new design or what, eh? :p
 
I'm not disagreeing with you; but I'm in horizontal Lifan (z50) 50cc Honda clone, (with E-start, and auto shift; it's the only way to get it recognized in many states as a moped/motorized bicycle, and that varies from state to state), no jackshaft req. Many places have chains (420), and sprockets (bolt on type, to single speed freewheel (worksman), fitted to the hub). Personally, I feel Alan's bike is a beautiful bike; but I'd like to have seen it a bit longer, maybe 5" on the bottom tube. I do like how he's got the BB so far forward, I need to stretch my legs, (first, to get maximum power, when needed. Second; my legs were busted up in the Army, and I can't have them all bent up for long).

As far as the power loss goes, as with a m/c, I think it'd be negligible also... Do you think it would be better with dual shocks? If I designed that bike, I'd have made the bottom tube, a bit longer, to allow for the 18" or so, needed for the horizontal push, 4 cycle engines, as previously mentioned.