How y'all doing. I am seventeen years old and a upcoming designer and builder and I needs some opinions. I started building my when I was sixteen years old for various reasons. I only had 30 dollars and a thrift store down the street. I brought two bikes, cut them up and went to war. And now here is my progress. Oh yeah my name is James
modern board track racer, special design by me
- Thread starter jj256
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seconded. Good work, might wanna brace that up some.AKB said:
It looks like you're using a Predator 212cc? Nice motor choice. One bit of advice though while you can still easily make changes, it looks like your head tube angle is way too steep in relation to how much forward offset your fork provides. From the pictures it looks like you will have a lot of negative trail which at speed (and that motor is capable of a lot) you will have a hard time controlling the bike. You might want to lean the head tube back some and maybe make the suspension arm on your fork shorter.
Is anyone going to bring up the subject of trail before this guy hurts himself ? jj256, please read the page on this link and the few that follow. The rake and trail (or lack of it) you're building into this project is potentially very dangerous. Pedal powered bicycles might get away with it, but this one isn't pedal powered.
We would all like to see you stay alive and healthy so do yourself a favor and reconsider your design.
http://motorbicycling.com/showthread.php?t=32428&highlight=trail&page=30
MHF
We would all like to see you stay alive and healthy so do yourself a favor and reconsider your design.
http://motorbicycling.com/showthread.php?t=32428&highlight=trail&page=30
MHF
This brings up a good point for this site.
I have seen some pretty shady looking bikes getting 3hp+ engines put on them. Most of them never get finished so it's OK, but if one of the death traps does start running, it's going to hurt someone.
It's fine by me if you hurt yourself, but if your hurt anyone else riding that bike, that won't be good.
Your fork and the rear triangle/suspension will not work. First, the bicycle hub lower pivot is going to break. Second off, the pivot needs to be at the same height as the output shaft (and as close as possible) to keep your chain from changing lengths throughout the stroke. You will have severe chain tension issues. There will also be way to much flex in the rear end without a ton of bracing.
Keep it up, do some research, and get back at it. But, it would be wise to listen to pointers and to build it safe.
I have seen some pretty shady looking bikes getting 3hp+ engines put on them. Most of them never get finished so it's OK, but if one of the death traps does start running, it's going to hurt someone.
It's fine by me if you hurt yourself, but if your hurt anyone else riding that bike, that won't be good.
Your fork and the rear triangle/suspension will not work. First, the bicycle hub lower pivot is going to break. Second off, the pivot needs to be at the same height as the output shaft (and as close as possible) to keep your chain from changing lengths throughout the stroke. You will have severe chain tension issues. There will also be way to much flex in the rear end without a ton of bracing.
Keep it up, do some research, and get back at it. But, it would be wise to listen to pointers and to build it safe.
You're best bet is to weld the rear end solid (along with a lot more gussets and bracing).
Engineers have spent YEARS trying to get pivot points and chain lengths spot on. If you run it the way you have it set up, when you accelerate it's going to compress the rear spring (that's not a shock). That means chain slack, and the need for a tensioner.
If you are set on running a rear pogo stick (since you have no damping in the rear) you might as well cut the pivot out of another department store "full suspension" bike. But you are going to want to mount it up higher (inline with the output shaft) and as close to the output shaft as possible.
Engineers have spent YEARS trying to get pivot points and chain lengths spot on. If you run it the way you have it set up, when you accelerate it's going to compress the rear spring (that's not a shock). That means chain slack, and the need for a tensioner.
If you are set on running a rear pogo stick (since you have no damping in the rear) you might as well cut the pivot out of another department store "full suspension" bike. But you are going to want to mount it up higher (inline with the output shaft) and as close to the output shaft as possible.
