How Fast are You going? - I wana know

Discussion in 'Motorized Bicycle General Discussion' started by T-lo, Mar 19, 2012.

Tags:
  1. hwybikedon

    hwybikedon New Member

    Joined:
    Mar 25, 2012
    Messages:
    61
    Likes Received:
    0
    28" Skinnie mini tire 49cc stocker did 31mph on the Tom Tom after brake in. Very slow set up

    Same bike 66/80 Air filter, Carb re-jetting, Intake porting, Head shaved, Exhaust porting, Pipe, Kings sprocket 31 tooth.

    Now I have broken three old school speedo's, like in the video I posted a couple days ago. So I took the old trusty Tom Tom for a ride. I had some questions about the speed of the ones I use. They were off around 6mph at top speed seem to be closer down around 30mph.

    Topping out I hit 50mph on Tom Tom, did this a few times and parked it, shew.
     
  2. moonerdizzle

    moonerdizzle New Member

    Joined:
    Jun 28, 2009
    Messages:
    874
    Likes Received:
    0
    clocked by my phones gps and confirmed with my boss pacing me in his car, but my high compression 66cc with 40 tooth sprocket maxed out at 35mph. not a pleasant feeling between the motor screaming and the hellish vibrations. motor is mounting on a road bike with 27in front wheel and a 700c rear wheel. both tires are 34mm wide.
     
  3. bikeman8

    bikeman8 New Member

    Joined:
    Mar 12, 2012
    Messages:
    18
    Likes Received:
    0
    brnoti have a stock mega motors on a 26 inch huffy cranbrook.

    the back wheel is a 26 inch mountain bike wheel, everything else is stock, 44 tooth 66cc im 225 bik is about 50

    i do 42 on flats and cruise around 28-34
     
  4. darkhawk22

    darkhawk22 New Member

    Joined:
    Aug 17, 2010
    Messages:
    733
    Likes Received:
    0
    My phone GPS app shows 29-31 on flats depending on the area. Downhill is faster but the motor is screaming pretty good so I usually let off and pull the clutch, I live in a fairly hilly area. The bike will cruise along very nicely at 22-25 mph.
     
  5. biknut

    biknut Active Member

    Joined:
    Sep 28, 2010
    Messages:
    6,378
    Likes Received:
    5
    I doubt anyone's bike is as fast as they said in a 20 mph headwind lol. I've noticed wind is harder to overcome than hills.

    The Cadillac will 37 mph in a crosswind. With a tailwind about 39. In a strong headwind it struggles to do 30.

    It's got skinny 1.95 tires which I'm about to change to some 2.3 fattys, so after that I expect a couple more mph.

    Cadillac AV Sport
    36T sprocket
    26x1.95 tire 80.25" circumference


    RPM MPH
    1000 5.2
    1200 6.2
    1400 7.2
    1600 8.3
    1800 9.3
    2000 10.3
    2200 11.4
    2400 12.4
    2600 13.4
    2800 14.5
    3000 15.5
    3200 16.5
    3400 17.6
    3600 18.6
    3800 19.6
    4000 20.7
    4200 21.7
    4400 22.7
    4600 23.8
    4800 24.8
    5000 25.8
    5200 26.9
    5400 27.9
    5600 28.9
    5800 30.0
    6000 31.0
    6200 32.0
    6400 33.1
    6600 34.1
    6800 35.1
    7000 36.2
     
  6. mapbike

    mapbike Active Member

    Joined:
    Mar 14, 2010
    Messages:
    5,380
    Likes Received:
    1
    Please correct me if I'm wrong here but I always thought that using a wider tire would increase rolling resistance + more wind resistance and possibly lower speed a bit rather than increase it........shrug????

    Please explain where I'm wrong in this thinking if I am.

    Peace, Map




     
  7. The_Aleman

    The_Aleman New Member

    Joined:
    Jul 31, 2008
    Messages:
    2,658
    Likes Received:
    1
    Yeah, wider tires definitely increase resistance. He probably means he expects more speed due to the increased overall diameter.

    Personally, I doubt the speed gain will be anything but minimal going to a wider tire. The increase in overall diameter would be offset by the increased resistance.
     
  8. Ibedayank

    Ibedayank New Member

    Joined:
    Oct 29, 2011
    Messages:
    1,171
    Likes Received:
    0
    depends on the tire
    go from a 40psi BIG lugged MTB tire to a 80-100 psi slick the slick will roll much easier then the lugged mtb tire on pavement
     
  9. The_Aleman

    The_Aleman New Member

    Joined:
    Jul 31, 2008
    Messages:
    2,658
    Likes Received:
    1
    Of course the tire type matters. Changing from a ~70psi 1.95 slick to a ~70psi 2.3 slick tho, top speed isn't likely to increase much if at all.

    You'd see much better results going from a knobby <40psi 1.95 to a 2.5" Hookworm with 65+ psi in it tho.
     
  10. mapbike

    mapbike Active Member

    Joined:
    Mar 14, 2010
    Messages:
    5,380
    Likes Received:
    1
    An apples to apples comparison as far as tire type and inflation pressure would increase rolling resistance but a wider tire that has smoother tread and can be inflated to a higher psi could create less resistance........ Yep makes sense to me.

    Thanks Guys, good explanations.

    Peace, Map
     
  11. mapbike

    mapbike Active Member

    Joined:
    Mar 14, 2010
    Messages:
    5,380
    Likes Received:
    1
    My fastest bike has MTB knobby tires on it, I have the Kenda cross tires and another type that is very smooth tread pattern, for me on my bikes I cant see any benefit in the smoother tires, they just make things more tricky when I'm on the dirt roads, all my bikes do 38-40mph on the dirt road or on pavement, could be a slight difference that I just don't notice, but if so it's very small

    Map
     
  12. NormO

    NormO New Member

    Joined:
    Jun 15, 2011
    Messages:
    197
    Likes Received:
    0
    My last known speed was 34.6 mph in fourth. WOT on fairly level ground. I've made quite a few changes in the gearing. Don't know what the top speed is now. Gear ratio calculator say 50 mph @ 8000 rpm, but i doubt it. A little too cold to find out. Not a typical kit. I'm using a 42cc saw engine. Made a quick and easy mod to the exhaust (just removed the spark arrestor screen). Helped it all around. Will see how it does when things get a little warmer.
     
  13. lowracer

    lowracer New Member

    Joined:
    Oct 17, 2008
    Messages:
    1,319
    Likes Received:
    1
    I have 3 MB's.
    - 'The Beast' has a max speed of 53 mph (Cag stage2 w/pipe)
    - 'Wimpy' has a max speed of 34 mph (Subaru Robin EH035)
    - 'No Name Yet' has a max speed of 40 mph (Tanaka PF3300 w/pipe)
    (all speed tests done at sea level in an aero tuck w/no wind using a tachometer, gear calculator w/ rollout measuring & extra verification using wife's minivan).
    -Lowracer-
     
  14. Easy Rider

    Easy Rider Santa Cruz Scooter Works

    Joined:
    Jan 15, 2008
    Messages:
    2,148
    Likes Received:
    4
    I have a bone stock 50cc h2o cooled Morini with a 50 tooth rear sprocket. I weigh 185lbs and the bike is roughly 85 lbs. I was clocked at Grange at 41mph. I have it geared for the track.
     
  15. halfevil333

    halfevil333 New Member

    Joined:
    May 18, 2010
    Messages:
    307
    Likes Received:
    0
    Bgf "z-80" engine (with the larger mounts, and stock high comp' head) ported, polished, plug and wire, expansion chamber, yadda yadda.....clocked at 45 last time I was pulled over by a curious copper...
    Can we trust his radar?!?
    Figure I trust the radar more than the man....
    ...oh yeah, 28t. Sprocket...figured I should mention.
     
  16. 2door

    2door Moderator
    Staff Member

    Joined:
    Sep 15, 2008
    Messages:
    16,308
    Likes Received:
    30
    Really proud of you guys. 3 pages of discussion about 'speed' and not one argument or poo-pooing on anyone. I knew you could do it. :)
    Tom
     
  17. bairdco

    bairdco a guy who makes cool bikes

    Joined:
    Aug 18, 2009
    Messages:
    6,375
    Likes Received:
    36
    i was thinking the same thing, tom. what happened to all the guys with 46t sprockets on stock engines doing 50?

    i mean just today i went 78mph down a sidestreet with my mom pacing me in her mini van. backwards...:)
     
  18. Greg58

    Greg58 Well-Known Member

    Joined:
    May 1, 2011
    Messages:
    2,923
    Likes Received:
    87
    My 48cc grubee gt2b will hit 30.8 on flat ground with a 44 t sprocket, mild porting, tuned cns2 carb and moded exhaust. Have hit 35.1 downhill but that thing was screaming, aluminum frame 26 inch beach cruiser and I weigh 210.
     
  19. DFlanagan

    DFlanagan New Member

    Joined:
    May 23, 2011
    Messages:
    63
    Likes Received:
    0
    Yea 41mph....... What your not saying is it's like a rocket when that clutch engages! What diameter rim?
     
  20. Easy Rider

    Easy Rider Santa Cruz Scooter Works

    Joined:
    Jan 15, 2008
    Messages:
    2,148
    Likes Received:
    4
    Yeah, it's good coming out of the corners and off the line.
    I'm using 24" wheels with extra wide rims.
     

Share This Page