Frame Snapped

rockonp04

rockonp04

New Member
I was ridding along doing some minor adjustments with the tensioner and the whole frame snapped just above the lower frame mount. I'm going to get the bike repaired but I am getting a stronger bike next time. Does anyone know about this problem or had this happen to them?.bf.
 
What bike? Where exactly did it "Snap"? "lower frame mount" doesn't tell us much. We'd like more details and photos if possible.
Tom
 
Here are some frame snap pics. :(
 

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Not bad. I would definitely try a mountain bike or cruiser because they are typically built stronger than a lightweight road bike. The 26" wheels are generally stronger than the road wheels with the exception of really cheap 26" wheels and you can fit nice wide tires which gives you a more comfortable ride. I would personally lean toward a steel frame as steel is more forgiving when it comes to clamping the engine to it and usually has smaller frame tubes which fit the engine mounts better. It would ideally have a 1 -1/8" steer tube fork which are usually found on mountain bikes and are inherantly stronger and easier to find suspension forks for. If you prefer the classic look get a steel frame cruser. If you want ultimate strength and the possibilty of a suspension fork go with a steel frame mountain bike. Oh and disk brakes are nice, especially in the rain.
 
Rockon,

Your motor is "unevenly" anchored to the bike frame. You should adjust or "tilt" the motor until it is "cradled" to where it just rests in the "V" of the frame.
Make sure that both anchor points of the motor are making as much contact to the bicycle frame as possible.

You might have to take up some "slack" by putting a shim in to make full contact on the front frame mount. I had to. Don't use a "skimpy" piece of bicycle tube for this. The pressure of tightening the clamp to frame will eventually cut through it.

Some really good shim material is to take an old car tire and cut a chunk out of the side wall and fashion it in a way to fit perfectly taking up the slack. It also absorbs the vibrations and shock lessening the trauma to the frame.

RPM
 
The bike is going to be repaired and i am going to find a suitable bike for a "proper" build. This was a first time build and currently looking for a sturdy mountain bike that is steel and large enough to fit a 66 cc in.
 
Part of the problem was that the pedals were too close and would not fit without the pedals hitting the engine. I custom made a mount that was mcgyvered. my next build is going to be professional.
 
Your nishiki road bike was aluminum or steel. Your motor mount looks like it transferred vibration incorrectly. It got loose on you. Mounting these motors in a solid manner is the way to go.
 
aaron brother's art mart makes good frames...

sorry, kidding again.

repairing that frame is pretty much a lost cause. even if you do, it won't be strong enough for anything but pedaling it to the store. you could find an old bike on craigslist for cheaper than it would cost to be welded, with less hassle.
 
I strongly disagree with the suggestion to use rubber, or any reslient material between the engine and frame. You've already seen what can be the result. The engine needs to be mounted as solidly as you can get it with full contact with the inside curvature of the mounts and the frame tubes. Rubber mounting does not eliminate vibration but will transfer it to places you don't want it...like frames and fasteners. There are many aluminum bikes ridden by members here with very few structural failures, except those who soft mount the engine.
Tom
 
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