How weak is Your weakest link?

Discussion in 'Motorized Bicycle General Discussion' started by Going2Hell, Mar 21, 2014.

  1. Going2Hell

    Going2Hell Member

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    Okay, everyone asks how fast can it go?

    Well, I'm not everyone? I pose a new challenge to all who wish to accept...

    How much weight have you pulled? Was it uphill or flat? What is the setup you use or have used that you are most proud of?

    I know that like speed, this can be changed by gearing and tire sizes and such. This is to target other such factors as stress temperatures and heavy braking ability.

    How weak is your weakest link? (TIP: The chain is a major factor in this too!)
     
    #1 Going2Hell, Mar 21, 2014
    Last edited: Mar 21, 2014
  2. Powertool

    Powertool Member

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    This should prove to be interesting , members with trailers and payloads attached to their bikes . How much can a china girl pull ?
     
  3. mapbike

    mapbike Active Member

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    A high compression well tuned chine girl driving a 60-72T sprocket on a 24" wheel should produce some serious pulling power with a 10-12 mph top speed......lol!

    Map
    .wee.
     
  4. Going2Hell

    Going2Hell Member

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    Im about to take a trip to Leadville at 10,500ft from 5000ft over a 150 mile trip. I'll be towing 100lbs behind with 80lbs on the bike and 60lbs on me. I weigh 160lbs and the bike itself is about 80lbs. Approximately 500lbs total. The bike is a Huasheng chosen for torque on a 26" Huffy. Stock T-belt trans with a 48 tooth Grubee HD Freewheel, not sure of the ratio yet. Just to answer anyone who asks, I mine for gold in the mountains.

    I tested a chinagirl with unknown ratios and a broken frame at 200 additional pounds on a Arbor longboard on flat roads.
     
  5. ocho ninja

    ocho ninja New Member

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    Me ~ 280lbs + bike ~ 90-100 lbsn+ 15lbs school gear. On my 99cc predator can reach high 30 low 40s mile per hour on flat ground... Only thing that limits me is valve float
    I forgot the ratio but it handle hills pretty good.
     
  6. BarelyAWake

    BarelyAWake New Member

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    21 speed (jackshafted) four stroke Lifan CRF50 clone, 36v hub hybrid - built specifically for long distance heavy hauling. A test load nearing 500lbs (myself & cargo) strained it so little I didn't bother shifting.

    The only "weak link" I've found so far is the front brakes under cargo load in hilly terrain, I'll be swapping the 160mm rotors for 203s for a touch more grip.

    [​IMG] [​IMG] [​IMG] [​IMG]
     
  7. Going2Hell

    Going2Hell Member

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    Yeah, I was looking into a jackshaft for this bike. When I was putting together my parts list, the jackshaft for the Huasheng was a questionable part to me. I've seen the modifications required to get some to work with a Chinese shaft. A few months later SBP came out with it.

    How does your jackshaft do? On a scale of 1 - 10 where would you put it in reliability and helpfulness in pulling a load?

    Looking forward to seeing more of this Hybrid tech in the future. As soon as you can charge your batteries from the motor, I'm in too. When I get further into my light system from a dynohub, I'll post some great electronics tips and some electrical theory behind self-sustained travel.
     
  8. CTripps

    CTripps Active Member

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    Sometimes we pull a trailer with my wife's bike.. hers gets to do the job because it has a 48T sprocket for more torque, vs the 36T on my beast or the 44T on the cruiser.

    We've hauled home a $100+ worth of groceries more than a few times and hauled out close to $30 in assorted empties several times over.

    The only real problems that have come up have been from cagers not realising the bike has a trailer (crowding when followed, one nearly hit it when he treated the cross-street's stop light like a starting tree.. he was a hair early when he hit the gas, she was almost clear of the intersection) and a little bit of a problem with sharp right turns causing the wheel to hit the trailer arm.

    [​IMG]
     
  9. BarelyAWake

    BarelyAWake New Member

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    On a scale of 1 - 10 I'd put this jackshaft square on "null vote" in that you've inadvertently asked a trick question, it's not actually needful with this particular build. Due to the torque characteristics of both a four stroke & an electric assist I hardly ever shift the thing at all & if I do, it's with the Lifan's primary 3sp autoclutched gearbox, a real internal transmission known for durability & longevity - designed by Honda & copied by Lifan, I can't take any credit lol

    This particular jackshaft setup is specifically for fine ratio adjustments to maximize efficiency - but not like you'd shift a car or motorcycle. It's for either setting up for major changes beforehand like trails vs street, high speed vs low speed cruise and trailer & cargo vs unladen (3sp primary) or extremely minor "in flight" adjustments in ratio to decrease cruise RPM (7sp final).

    Here's a quick vid of the jackshaft itself: http://youtu.be/U10xLqTekOw

    [​IMG]

    So the Lifan's 3sp is like the high/low range in a 4x4, the final seven gears of the rear cassette only to set cruise RPM, at most I may shift those twice on any particular run, to fine tune cruise or to adjust for extremely hilly terrain & back again - but usually as it's already set in the cruise ratio from a previous trip, so I'll pedal assist some on take off & just leave it be. Having the jackshaft also allows me to use any 26" rim w/cassette as a replacement rear wheel should the hub fail or I taco the rim, unlikely but I've also left the rim brake bosses on the stays when I converted to disc, also enabling me to use just about any wheel & brake combo I can find.

    The components are nevertheless still being used all the time whether actually shifted or not yet they've proven quite reliable, some of the critical differences between this DIY jackshaft & the commercially offered shiftkits are also with this in mind. With this all the components are inexpensive & commonplace, for example the pedal chain freewheel is a BMX part, responsible only for the pedal drive and on a round 5/8" keyed shaft, sealed bearings pressed into the cylinder of a bottom bracket, all assuring proper centering. I had no end of difficulty with the long-term reliability of the commercial shiftkit's pedal crank freewheel, expensive with limited availability when it fails you've no drive at all, pedal or engine. This DIY jackshaft was also designed so all chains are properly & automatically tensioned regardless of suspension compression or chain wear, so there's little to no maintenance and no adjustment required. As the jackshaft is housed in what used to be the bottom bracket for the rear stays, it's so rigid & sound there's no movement at all, the side plate flex of the aftermarket shiftkits another issue I experienced, the fatigue & strain causing additional long-term reliability issues.

    Don't get me wrong, the "shiftkits" are fun & an easy way to get gears, they're just fine for many bikes - but for this build the demands are greater in torque & cargo weight and given it's for long distance use, reliability & redundancy is of paramount importance. Should there be a failure I also need to be able to get a replacement part easily from the local bike shop or hardware store, I don't wish to wait two weeks or more for shipping at some random rest stop somewhere lol


    This build does trickle charge the batteries both from the Lifan's lighting & charging coil as well as regenerative from the rear hub - while still technically a "plug in" hybrid, I've not managed to run the batteries dead yet, even during a three day camping trip & associated use without external power. I'm sure it's possible as all I'd have to do is not use the four stroke & run around on electric only - I sometimes do this anyway, but not till the batteries are dead lol

    The Lifan has a tiny 12v SLA (starter) & the hub drive's batteries aren't particularly huge, it's just a 36v 10ah LiFePO4 pack in one of the two front trays (other tray has chargers, converters & associated electronics) but both the charging systems & batteries (12 & 36v) maintain each other's charges if they've the voltage to spare, this also means my lighting will work even if a battery fails as it's all through the 12/36v converters anyway. The converters haven't enough amperage for the Lifan's starter motor, but I've also a kick start and I can pedal start... so yea, that redundancy thing "again" heh ;)

    LiFePO4 pack;
    [​IMG]
     
  10. BarelyAWake

    BarelyAWake New Member

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