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Motorized Bicycle General Discussion All topics regarding bicycles with engines.

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  #3501  
Old 04-15-2012, 05:51 PM
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breno breno is offline
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Default Re: what did you do to your motor bike today?

What A ktm clone will do to a bike in roughly 5-10 hrs of riding, not jumping off gutters or anything either

Im so lucky I picked this up before going out for another fang.
This could have killed me!!

Anyways so I just bought another frame which is the same size, just going to weld a gusset in each corner for some added stength and maybe weld in some strengthening at the rear wheel fixing point.
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File Type: jpg crack in bike frame.JPG (113.1 KB, 430 views)
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  #3502  
Old 04-15-2012, 05:58 PM
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Default Re: what did you do to your motor bike today?

if you think about it, B, giant gets full points for welding.

As you say, a gusset will probably fix it.
Probly need less carbon in the chrome moly tube, huh?

I might be tempted to braze this one up, add the gusset, and run it hard while keeping an eye on it.

but I'm a real cheapskate.

Good luck
rc
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  #3503  
Old 04-15-2012, 06:14 PM
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Default Re: what did you do to your motor bike today?

Brutal Breno, eep! Could've been messy, for sure.

Like RC says, just weld'r up, save the new frame for another day.

You guys remember seeing that motorized bicycle with the cut up skillsaw blades for gussets? That'd be slick, eh?
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  #3504  
Old 04-15-2012, 09:11 PM
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Default Re: what did you do to your motor bike today?

Quote:
Originally Posted by breno View Post
What A ktm clone will do to a bike in roughly 5-10 hrs of riding, not jumping off gutters or anything either

Im so lucky I picked this up before going out for another fang.
This could have killed me!!

Anyways so I just bought another frame which is the same size, just going to weld a gusset in each corner for some added stength and maybe weld in some strengthening at the rear wheel fixing point.
Oh man real sorry to hear Breno! You may have just gotton a fluke.
Is this frame aluminum? I do get to wondering about the average department store type bike these days? They'll say on the bike tags that it is a alloy type metal. My personal complaint is that the tubing is often too thin walled. i also wounder how consistent the mix is in the melting pot so to speak in places where these come from like China and Taiwan?
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  #3505  
Old 04-16-2012, 12:03 AM
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Default Re: what did you do to your motor bike today?

I'd throw that frame in the scrap bin, that is scary! But welding gussets on another frame is probably a good idea.

If you can weld, why not construct your own frame?
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  #3506  
Old 04-16-2012, 12:23 AM
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Default Re: what did you do to your motor bike today?

Quote:
just going to weld a gusset in each corner
I remember back in the mid 80's I think, could of been earlier, when the BMX style bikes came out the head tubes were the weak link on cheaper bikes. A lot of those bikes would crack just like that at or around the head tube.

So the first thought of manufaturers was to gusset the tubes together that joined the head tube. Unfortunately, all that did was shift the stress point to the ends of the gusset and breaks were common at those points. That in fact made them more dangerous or subject to catastrophic failure.

Just throwing that out there for you to consider. Ultimately a good BMX bike could not be made cheaply and simply corrected by adding a gusset. It just may be the wrong material to depend on is my thought.
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  #3507  
Old 04-16-2012, 12:28 AM
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Default Re: what did you do to your motor bike today?

Vibration is a powerful force. Is there any slack in the chain (any tensioner device or something to give a little)? Could this crack be the result of torque affecting the frame so severely as to fracture it there?
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  #3508  
Old 04-16-2012, 01:21 AM
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Default Re: what did you do to your motor bike today?

finished wiring up my headlight, and turn signals to the bike. just need to wire the horn in, and a brake light, and she'll be fully functional.

not looking to get her registered, but figured i'd be much safer if it was built like it could be.
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  #3509  
Old 04-16-2012, 03:47 AM
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Default Re: what did you do to your motor bike today?

thanks for the thought out commets guys.

I may just give the frame design the benefit of the doubt and just go with the material being daggy.
I will use the "new" frame and see how it goes.
Hopefully the other one was just a dud.

I kind of get what you mean with the gussets being an issue fugit so I might just leave the gusset idea for my next bike if it so happens to be.

HSC im far too lazy to make up my own frame but in saying that if there was a pipe bender laying around here it would def. be worth a shot.
Only my problem is I overkill everything so my power to weight would end up worse than a HT powered bike me thinks..LOL!

There is a fair bit of vibration when I back off. I'm not sure if I can really stop it though as it appears to be the outer bell of the clutch vibrating from the shoes touching it slightly. If I make them tighter its still there.

The bell has probly 1-2mm of in out movement though so that could be it.

Anyways for how cheap ya can pick up frames these days off ebay I'll probly just stick with the lazy route for now and just replace them as they break.
Possibly more freq. checks may be on the cards instead of going hard out making a tank.

I will try to work on reducing vibration might even give the dreaded rubber mounting ago

In the end of the day this could be an ongoing problem as I weigh 100kgs and ride the bike like I stole it everywhere + these bikes I'm using atm just aren't designed for this much torque, weight, vibration, harmonics and speed.

May need to look at buying a HD cruiser style bike if this ends up being a consistant pita.

Thanx guys.
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  #3510  
Old 04-16-2012, 05:25 PM
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Default Re: what did you do to your motor bike today?

You can get whole bikes off Craigslist for $50-100, 90s mountain bikes. Sometimes you find one missing a front wheel or sold without wheels for that, but with better components.
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