1st build is to fast

[avery08]

I built a cranbrook with a kit from bikemotorkit.com it's a lot of fun.I built it for my 14 year old son.Is it possible to lower the top speed.I'd like to slow it down a bit while he gets used to it.He's a teenager so I'm sure he'll go as fast as he can.Thanks.......

 

[mapbike]

I built a cranbrook with a kit from bikemotorkit.com it's a lot of fun.I built it for my 14 year old son.Is it possible to lower the top speed.I'd like to slow it down a bit while he gets used to it.He's a teenager so I'm sure he'll go as fast as he can.Thanks.......

you can put a larger rear sprocket on the lower gear ratio, that is the best thing I know of, you will need a longer chain if you go with a larger sprocket, I would just get another chain and a couple master links so I could ad the extra length needed for the larger sprocket and then if you wanted to gear it back up some for more speed later on you could just reverse engineer the chain by removing the extra length and bingo... right back the way it was.

Here is a link that will take you to a forum members parts page, scroll down and you will see the sprockets he sells, a 48T is about $12 + shipping and he has a larger 56T also, but I think the 48T would be best, a 59T will have that thing at a very low top speed with crazy torque on the bottom end, a 48T will have it running at what he can likely peddle the bike at top speed at.

http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_2.html

Map
.wee,

 

[avery08]

I was hoping maybe I could adjust the throttle,throttle cable or carb to slow it down some.Thanks for the link and suggestion...

 

[crassius]

feed the throttle cable thru a good-sized nut after the spring & before the slide - this will limit slide travel to about half way or so

 

[avery08]

That carb trick sounds like just the ticket......

 

[mapbike]

Problem with limiting throttle is that it will not have enough power to do much, its worth a try but throttle limiting isn't a good idea in my opinion with these little engines that need a good amount of throttle to get going, if the boy is a very light weight kid then it might be ok as long as he never goes on grass or ever goes up any type of an incline, if he goes off road or encounters a hill the bike will not likely have enough power to get it done at half throttle.

The larger sprocket will have the opposite effect, bike will be slower but pulling power at low speed will increase, now that is the right way to go so the boy can have plenty of power for off road or hills but he cant go to fast.

Map

 

[avery08]

Hey thanks I think I'll leave everything alone for now.This is the perfect excuse for a 2nd build for me.That way I can ride beside him to make sure he doesn't get out of control right lol.I bookmarked the workmans bicycle site recently.I've been meaning to see if they have a 24" cruiser model for a build.I'm short like my kids only 5'5" so I like the 24" the best.

 

[mapbike]

Hey thanks I think I'll leave everything alone for now.This is the perfect excuse for a 2nd build for me.That way I can ride beside him to make sure he doesn't get out of control right lol.I bookmarked the workmans bicycle site recently.I've been meaning to see if they have a 24" cruiser model for a build.I'm short like my kids only 5'5" so I like the 24" the best.

Sounds like a great plan, I actually built myself a 24" cruiser out of a 1963 26" bike frame, put some suspension forks off of a 24" bime on it and bought some heavy duty 24" wheels for it, the bike is still in the process, but rides nice and fast with a 30T sprocket on the 24" rear wheel, a 26" frame makes a nice 24" bike, it low and a bit longer so it handles really nice.

Best wishes on your personal build and I look forward to seeing it come together.

Map

 

[MotorBicycleRacing]

I built a cranbrook with a kit from bikemotorkit.com it's a lot of fun.I built it for my 14 year old son.Is it possible to lower the top speed.I'd like to slow it down a bit while he gets used to it.He's a teenager so I'm sure he'll go as fast as he can.Thanks.......

How about brakes?
Do you have a decent front wheel brake?
I remember being 14 so I trust that he wears a helmet?

Rear mirror is a safety feature I wouldn't ride without too.

 

[maniac57]

The drawback to limiting top speed with a larger sprocket, is that every single teenage boy I ever saw will scream it's guts out trying for more. Limiting the throttle is MUCH safer for your engine lifespan.
Just sayin'

 

[mapbike]

The drawback to limiting top speed with a larger sprocket, is that every single teenage boy I ever saw will scream it's guts out trying for more. Limiting the throttle is MUCH safer for your engine lifespan.
Just sayin'

Good point....

maybe if it were so that only about 3/4 throttle could be used it would still have enough power and limit speed????

something to tinker with to get it just right probably.

map

 

[avery08]

Thanks for all the info this site and users are great.I haven't messed with bikes in 35+ years so I didn't realize a 24" bike fork would fit a 26" frame.I'm quite the rookie on this project....

 

[2door]

As for your concern about your son riding too fast; install a digital speedometer that retains the recorded top speed. Tell your son not to exceed 25mph. When he gets home from a ride check the speedo to see how fast he went. If he exceeded 25 tell him he gets one more chance and then the bike is yours, not his

Serously, I know how difficult it can be dealing with a teen. I built a bike for my nephew and gave him instructions on how to take care of it. I told him if he abused the bike I would take it back. He ran it without oil, seized the engine then left the bike laying on its side in his back yard. He doesn't have a bike anymore.

Tom

 

[mapbike]

avery08

Here is a pic of my old 1963 Western Flyer bike, it was a full 26' bike when I got it and now I have put some 24" mountain bike forks on it I got off of an old girls bike, and I bought the 24" wheels at my local bike shop, rear wheel has Shimano coaster hub and I have a good V brake on the front, this bike is fast it is running better now than it was when I GPS'd it at 45.8 MPH today I rode it 12 miles and actually registered 51.5 MPH as my top speed, I was going down a slight hill with the wind to my back and I'm not sure if my speedo is 100% on this bike yet because I haven't compared it to my GPS since I installed it today.

I'm sure you're not looking to go real fast like that....LOL! but the main purpose for this post is to show that a 26" frame can make a nice little 24" build.

By the way that is a good idea from Tom/2door about the digital speedo, if you want to go that route here is a link to the wired type digital speedometer I have on two of my bikes now, cheap and works great, easy to install.
http://www.ebay.com/itm/360738780783?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649



Map