Does any one know anything about bending handlebars to add flair or sweep?
I'd like to take some Nitto Noodles and flare them out more right at the end of the ramp and beginning of the drop. Similar to the Midge. But I don't want to kill myself on the trail when my bars snap. They are heat treated. Would this severely weaken them. Do bar manufactures bend there bars and then heat treat them?
Heat treated bars should not be force to a different shape. I have some origin 8 copies and they seem pretty nice, though the shape turned out not to be what I wanted so I can't actually tell you how they work over the long haul.
For aluminium handlebars (and frames or any other component for that matter), manufacturers heat treat AFTER any type of forming is done.
Originally Posted by Eddie8
Drawing, tapering, butting, bending, folding and welding are usually done when the alloy is in "Zero-state." Then it is heat treated to an intermediate hardness (usually T4) so that precision machining can be done - like threading, facing, boring, reaming - anything that involves a final machine cut. Quality control checks and re-alignment (if necessary) are also done at this stage.
Then it's back to the ovens for the final heat treatment to hardness (T6). After this point it is NOT a good idea to make any physical alterations to aluminium components.
Steel handle bars (or frames) on the other hand are more forgiving... but I would leave the aluminium ones alone. A bent aluminium bar (or frame) after an accident is compromised, stressed and fatigued. Do not be tempted to bend those things back... they should be replaced.
So if a person wanted to mess around with various handlebar bends, what is the best course of action? Thinking hobbiest level, not custom or production level here.
Find a tube bender and go at it with stock that could be used for positioning, to nail down the bends, but which might not be strong enough for full time, finished use? Or, in the same vein, as OP suggested, bend extant AL bars, knowing that they will be weakened and should only be used for setup/prototype, not for production or actual use? Start with steel bars, which won't be weakened as much as aluminum?
Is there a simple way--like using a kitchen oven, propane torch, or similar--to draw the heat treatment out of the bars, bend at will, then re heat-treat them?
If you're developing a custom bend for a special reason, I would mess around with copper tube first (if you can get it cheap) just to explore various angles by trial and error. It's soft, easy to bend and can be done over and over. You can install it on the bike for the "feel of it" but it won't be strong enough for a proper ride tho. Once you get the shape you want, you have a "master" to copy off from. You could also use 1/8 - 1/4" steel rod to suss your angles out, but you can't pre-test it.
Originally Posted by mconlonx
For hobbyists, steel is the way to go but try to get "seam-less" tubing. High tensile would be my minimum for handle bars, and they can be cold-formed just fine. Just bent it, that's it. If you have access to chromoly-steel tube even better, but they can be tricky to bend without the right type of bender (the tube cross-section tends to crush or ovalize along the bend, more so than high-tensile tubing).
If you're building a handle bar for cruising around or commuting, that's cool... you can probably even adjust an existing steel handle bar by cold-forming as long as you don't alter the bends by too much. But for performance applications like BMX or Mountain Biking for example, safety becomes a real issue and I would advise against altering or building your own bars (think face-plant or sipping your lunch through a straw). If you must have it, maybe arrange to send your "copper master" to a handlebar fabricator to make one or two custom bars for you. I'd ship it in a small wooden crate or you might get a surprise when your custom bars arrive back.
This is exactly what the factories do when an aluminum "batch" goes a miss. They anneal it back, make the adjustments and then heat treat them back-up again. Different types of aluminum require different types of heat treatment (various temperatures, various durations of exposure, some types need to be dunked in water, some types need to be blasted with cool air, etc). I don't think we can do this with appliances we have around the house and garage. We would have no way of knowing if we compromised the bars along the way or even if we got it back up to standard.
Originally Posted by mconlonx
Last edited by Pocko; 12-23-08 at 04:18 PM.