50 mph ?? (Down hill doesn't count)

shiloh0 · #1 10-14-2008, 07:09 AM

im wondering if anyone here has achieved 50 mph or more on a motorized bike. my top speed with a 26in mountain bike is 42 with a 27t sprocket. i want it to go 50. i might even buy a helmet if i can get it there. i m looking at that tuned pipe thinking it might help.

Jemma Hawtrey · #2 10-14-2008, 10:36 AM

BUY A HELMET ANYWAY!

flat out speed of 42mph is more than enough to kill you if you came off head first, that or reduce you to a dribbling wreck... either of which arent good.

As to top speed - you could probably eke out another 10% on top speed or maybe more with a pipe - depending on how the pipe is tuned (some are tuned for all top end and others for a mixture). More to the point the frame and wheels arent really designed to take that sort of stress and you may get serious breakages leading to the scenarios indicated above.

another point is that most police forces would have 50 fits if they are sitting in their panda car and someone sails past on a pushbike at 50mph and throw the book at you bigtime..

Jemma xx

velardejose · #3 10-14-2008, 11:43 AM

Hi
I drive to and from work at ~20-25 mph and I always use a helmet
Peace

shiloh0 · #4 10-14-2008, 02:22 PM

ya, a helmet is a safe idea. but kinda looks odd to wear on a bicycle going 15 mph while the motorcycle guys go by with no helmets. but this is not the safety section of the forum, it's the "high performance" section. and as far as the "going 42mph gonna kill me"
ya, but life is killing us all anyway but we still keep living it. it's my sincere belief that going faster (to an extent) is safer. this due to speed difference in CARS and bicycles.
a car going 60 not paying attn...and smashing into a 20 mph bike would kill quicker than
going 42 on the bike. my bikes are tuned, the wheels are true, the chains are properly tensioned and they feel solid.
i did see a cool looking helmet that i might get, but its not one of those court jester looking bicycle helmets. i would never wear one of those getups. i like the motorcyle half helmets and the race car helmets. prolly more protection too.

comfortableshoes · #5 10-14-2008, 05:23 PM

shiloh0 when you suddenly stop posting we will know why

I wear a real motorcycle half shell DOT approved helmet. I felt silly at first BUT when a motorcycle was cruising down a nearby street slowly was hit and rider very hurt I decided it was less silly than NOT wearing helmet. In MA where I am, I have to wear the helmet but I feel better with a lid on my head...

anyway. 50MPH on a soild bike should be doable in short bursts. I hit 33mph on a rough patch of road and it sucked more than i can tell you, hit the same speed on a smooth stretch and it was an exhilarating feeling... I don't maintain those speeds on my friction drives but can't wait to see what my HT will do.

Easy Rider · #6 10-14-2008, 07:04 PM

My bike could probably hit 50 if I threw a 44 or 36 tooth sprocket on it but I'm into more low and mid range power.
As for wearing a helmet, I wear one everytime I ride even if its a short test ride up and down the street. I've seen too many head injuries in my life to know how easy it is to crack your head open like a melon and that scares me. Plus, I still have young kids I want to see grow up.

Motormac · #7 10-14-2008, 08:25 PM

Don,t be STUPID shilohO, wear a helmet. you may not get lucky and get your deathwish but you may end up a drolling babbling vegetable.. Take a minute and think about it.

Saddletramp1200 · #8 10-14-2008, 08:41 PM

John Howard went 152 MPH on a bicycle. 5 MPH is enough to snap your neck. Helmet? always.

Saddletramp1200 · #9 10-14-2008, 08:59 PM

Five years or so back I was going to a friends house. I was riding a Honda Goldwing. Very powerful very heavy motorcycle. The idiots with the hiway dept. desided to dig a hole in the asphalt during the day and then cover it with dirt. No warning at way over the speed limit, in excess of a hundred I hit the 45 yard long hole. If not for my speed I would have died. I was wearing my cop like half helmet. Almost dumped it. The weight of the bike and momentum is all that saved me. Hiways in Texas are bad at best. 4 H4 halogen road lights and an H6 head light was not enough to see it in time. No construction sighs at all. I have never wanted to sue anyone, but I would sue Live Oak county for being Morons. The hiway was fine the day before.

Andyinchville1 · #10 10-14-2008, 11:03 PM

Hmmmm....safety issues aside (BUT Please do be safe and dress appropriately), I think you will need a smaller sprocket unless you are running an engine other than a HT capable of high RPM's....

A properly designed tuned pipe would no doubt help....probably a fair amount of power will be needed to overcome aero drag at those high speeds..

If you are hitting a true 42 MPH with the 27T (are you RPM limited or power limited at that point?.....I would guess RPM limited?)....A 19T or maybe 18T
would get you to 50 MPH IF you can get to those same RPM's on the engine
(A slight down hill would also help! A sprocket that small would require use of the disc hub mounting method....a 9 hole mount will not work (bolt circle is too large).

Good Luck on your speed run....Keep us posted!

Andrew

PS - Please be careful!