Reenforcing down tube?

[Trokair36]

I hope this is the right place for this and if this has been talked about before just send me in the right direction. Thanks

I was just wondering if it would be possible to reenforce the down tube so that it won't crack after a hole has been drilled in it. I did this to mount my HT engine and I would like to ride it to school but I'm a little worried that it will break while I'm on the road. The frame is from a Raleigh m20 mountain bike and it's made from alluminum idk if it's strong enough for the stress of daily rides with that hole in it. Any thought would be greatly appreciated.

 

[DougC]

I hope this is the right place for this and if this has been talked about before just send me in the right direction. Thanks

I was just wondering if it would be possible to reenforce the down tube so that it won't crack after a hole has been drilled in it. I did this to mount my HT engine and I would like to ride it to school but I'm a little worried that it will break while I'm on the road. The frame is from a Raleigh m20 mountain bike and it's made from alluminum idk if it's strong enough for the stress of daily rides with that hole in it. Any thought would be greatly appreciated.

Ride it carefully until you can find a steel frame.

The problem with trying to reinforce the aluminum frame is that you would likely need to weld (or have welding done) on it. Aluminum softens a lot from welding, and must be re-heat-treated to restore its original stiffness.

A steel frame on the other hand can be welded on, and won't require re-heat-treating afterward.

Also--steel tends to bend quite a bit before cracking--unlike aluminum, which tends to be much stiffer but cracks much easier as well.

 

[Al.Fisherman]

I hope this is the right place for this and if this has been talked about before just send me in the right direction. Thanks

I was just wondering if it would be possible to reenforce the down tube so that it won't crack after a hole has been drilled in it. I did this to mount my HT engine and I would like to ride it to school but I'm a little worried that it will break while I'm on the road. The frame is from a Raleigh m20 mountain bike and it's made from alluminum idk if it's strong enough for the stress of daily rides with that hole in it. Any thought would be greatly appreciated.

First for all that read this, I don't recommend a hole drilled in any tubes, especially for mounting a engine. Why...this was a steel tube.


A very small hole was drilled (where a water bottle attaches), to run wires through it. I only drilled out the anchor for the screw.

The bike can be repaired, but at what cost? I repaired the crack in mine but I chose to use a different frame. Me the cost was none as I have the equipment, but safety was the reason.

 

[double trouble]

get a magnet

The monocoque frame appears to have lasted a single year (1996) and is gone. The aluminum frames continue on with the M800, M600, M400 and M200. Steel bikes are the M80, M60, M3000 (cheap full suspension), M55, M50, M40, M30 and M20.

You have a steel frame. should be fine...

 

[Al.Fisherman]

Just to make sure..test it with a magnet. A refrigerator magnet will do.

 

[oneninesixnine]

Be a man of your word.

Do right by me, FarRider.

 

[retromike3]

don't drill you will be sorry

On my bike I drilled the seat tube and It looked like somebody had cut it with a hacksaw. The vibrations coupled with the stress risers inherent in that type of mounting will go though steel quick. Sick Bike Parts make a frame mount that really worked for me when I had the tubes to large on my seat tube.

Its gone OK for me for half a year, but I did have a bolt get loose after a while because I intentionally did not put a double bolt on one of the mounts gust to see if they would rattle loose. It did but in a strange way, it only exhibited problems in a certain RPM range. So when I got home I checked it out and sure enough I had two blots that needed tightening.

So I double bolted them (with a little blue lock-tight thrown in for good measure) and it been going grate since then.

Those guys really know there stuff. I am thinking of getting a shift kit but I think I will have to build a new frame and maybe get a morri engine for that project.

mike

 

[jeffuehrer]

Crack in my tube!

I recently spotted a very fine crack in my down tube originating from what appears to be the stock water bottle cage threaded hole. The frame is Atomic 13 Aluminum (whatever that means) - (if interested you can see the full specs here "http://www.bikepedia.com/quickbike/BikeSpecs.aspx?Year=2006&Brand=Raleigh&Model=Venture+3.0&Type=bike". Anyway, I was wondering if it is still safe to ride? I cruise at 20mph-22mph (90% of the time) and burst no more than 30mph (10% of the time). Also, would I be able to repair this type of problem on my balcony? I've included pics for more accurate assessments. Thanks team!

"If it ain't broke yet, keep on ridin' that thang!"

 

[double trouble]

keep riding , but

I would buy some alumaweld or similar rod and eventually grind off the paint and fill that crack line in. Just so that crack does not expand. You will have to move or remove the motor , but I can get one off in 15 minutes. A $15 4 inch grinder and metal wheel from harbor freight should take off the paint and feather the crack line in a couple minutes. If i am looking at the bike corectly you should turn it upside down and use mapp gas or propane torch to melt the rod in.

 

[BigBlue]

Is it still safe to ride? I would probably say not. Why take a chance of injury. At minimum, I would recommend having it welded. Best bet would be to switch to a steel frame. Others on this forum can attest to the durability of aluminum frames. If possible, look on Craigslist for a mobile welder and/or a steel frame.

Good Luck,

Chris
AKA: BigBlue