Bending 6061 T6 Tubing

No you can't bend it unless it is annealed.

Look on the net for annealing tips. 775F 3 hours, then cool to 500 for 3hours then cool to room temp.

Or go buy some 2024 or 5052.

Then fill it up with water and freeze it before bending.This is only based on my meager knowledge of the metal, I have never done this myself.

For $13 why not just buy one...

http://www.ebay.com/itm/like/371690956350?lpid=82&chn=ps&ul_noapp=true

...or go all out $150...

http://www.ebay.com/itm/Thomson-Masterpiece-Bicycle-Seatpost-330mm-27-2mm-Black-16-mm-Offset-Bike-Post-/311660968275?

I don't know about your particular alloy but I have bent many aluminum pipes over the years simply by filling them with hard packed fine sand before putting them in my old tubing bender.

The sand helps keep them from kinking but there is a limit to how tight of radius most aluminum alloy tubing will take before they rip on the backside of the bend doing it that way.

Best guess is that a 15 - 20 degree bend on the diameter of tube you have over a 4- 6" length should have a fair chance to work. If not you will know exactly why it didn't!

Thanks for the tip with the sand I'll have to try that

Do you work at the same place as buffalocrossing?

Not that I know of..

@solar eagle, sure if I could find one for $13 I'd order it but I think that's a bmx part where this is for a road bike. The $150 would work but making stuff is more fun anyway..

I'm fairly confident I can hot work the part as I need to, so the question is now this: when I'm all done, what will the strength be like? will it harden back to at least partially what it was originally? can I bake it in my kitchen oven to get up to T4? or would it naturally get there? I don't have means to bake much over 500 (kitchen oven)

Bend it. It won't break off. I've comprmized each and every part of a bike to and past the point of failure.

frightening thought? Then buy one. It won't break off either.

Just a comment - my son had a handlebar on his bike break. Biking in north London. Of course he fell off and got a few grazes. Cars stopped and people picked him up and dusted him off, but it could have been a lot worse, eg under a lorry.

A 3/4" rigid electrical conduit bender should be able to do this with no trouble. The bend portion will occupy about 2" of arc length. Bend about 2º past where you want; it will spring back to about right.

I would agree with Tornado on this. We use 6061-T6 aluminum tubing for electrical substation buswork. Usually larger bends are done using welded or swaged fittings, but small bends & offsets can be done using a conduit bender. In olden days, lots more bending of this tubing was done in the field. If you are trying to get just 15^o - 20^o of bend, it should be possible.

Can't allow a pipe bending thread to pass without mentioning eutectic alloys, for example cerrolow 117

http://www.ebay.co.uk/itm/Cerrolow-117-aka-Bolton-117-1-2-lb-ingot-226-grams-Blocking-Alloy-/291214944764

melts in hot water at 117°F (47°C).

So: melt it; fill the part of the pipe which needs bending; cool it; bend it, and, remove the alloy again with hot water.

Hi - I live to rebuild bikes and see a better route if you can spend some money. Unless this is a seat post like we used in the 60's with the clamp a separate unit from the post, and the 27.2mm size makes that questionable, you may have a problem getting the saddle level again.The modern post with attached clamp does not adjust the tilt angle over a very wide range. Why not use a Thomson Elite Setback, since this in the very common size of 27.2mm, I know there are several lengths available up to 300mm. Then add the Selle Anatomica Titanico saddle which has rails that are about 1.5 times as long as other saddles allowing a very easy adjustment fore and aft, plus it is leather, and much easier to sit on than the plastic gadgets they call saddles these days. ALL my bikes (15 of them) are equipped with Thomsons except for one restored bike where I kept the old fashioned straight post with swaged neck for the separate clamp. Have to restore to original you know.

You're correct in thinking it's a modern post with the integrated clamp. My goal here is to end up with the seatpost vertical, rather than angled back like the seat tube. I may also spin the seatpost 180 degrees so the clamping mechanism would be on the front, pushing the seat even further front. I think that would work as long as the seatpost is vertical.

But that's a good point, I need to confirm the seat will be able to be tilted in the way I need it to before bending away on my seatpost..

Ultimately this project is turning my old '03 Giant OCR2 road bike into a time trial bike (as cheaply as possible!) to use for sprint triathlons. Seat location is a big part of getting the geometry right to be able to properly use aerobars. It's been a pretty fun project so far..

Ohhhh...I thought you wanted a set back, not moving the saddle forward. Forget the Thomson - they're meant to set the saddle back, and the clamp, strangely enough, is directional on them. The clamp should handle the vertical position - it is too far back that can become a problem. If you can't get the post bent, then the saddle I mentioned will slide forward a couple of inches beyond any other saddle. After we (collectively the cycling community) found out that being a bit forward of the pedals is not bad on your knees as thought for years, I have used that saddle to get a bit closer to the handle bar to take the load off a separated shoulder joint. A bit cheaper than playing the what length of stem game. Yeah - I have dense bones, so I don't break my bones in wrecks - just tear the shoulder joint and rib cartilage apart.

It is good to hear someone else is actually concerned about fit on the cycle - many pains occur in the knees and hip until you finally realize how important good fit is. Age makes it even more important.

Good luck and keep pedaling.

Thanks will do!

I recommend against bending your existing seat post for a number of reasons.

First, aluminum may fail catastrophically. Increasing the risk of having a jagged giant hypodermic needle aimed up your butt in any bike accidents would seem like something worth avoiding. If this were something like 4130 chromoly, you'd have a lot more leeway.

That would suggest avoiding home heat treatments (including annealing) as well as adding significant stress to 6061 t6 through plastic deformation.

I concur with Phys on the possibility of the seat post not working with the sea tube angle, though some would. The seat will be seeing the seat tube at somewhere around either a 93 or 53 degree angle (assuming 20 degree change and 73 degree initial) to horizontal which in either case is pretty far off anything typical.

What are you trying to achieve? Do you want the seat further forward or back? Are you trying to take pressure off an injury to your back or knee, or perhaps trying to gain a more efficient pedaling position?

Have you moved your seat as far as you can on the rails? The bend you are describing will change your position forward or back only a very small amount, probably less than 2 inches total (with a 15 degree bend over the length of seat post exposed) at the top of the seat depending on the distance above the top of the bet section the seat lies and the length of the section you bend.

How is the position of your handlebars as it relates to how you desire your position to change?

Ultimately what I'm doing is turning a road bike into a time trial bike.

Step one is add aerobars.

Step two, assuming you started out with a properly fitted road bike, now your seat is too far back and you have to really reach to get on the aerobars. So the seat has to come forward. I slid the seat the whole way front on the rails but I need a little more. Hence bending my seatpost so it comes out of the frame then turns vertical.

I already have a shorter handlebar stem on the bike than the one it came with (90mm maybe?), but perhaps I could go a little shorter there instead. I definitely don't want to take an aluminum shard up the backend....

Was thinking if I can hot-work the material, it should easily bend 15 degrees without major stress fracturing, and worst case I end up with soft metal that might bend but probably not explode when I go over a bump right?

Ductile would certainly be better than brittle. Temperature control and rate of cooling isn't that easy without proper equiment.

Fatigue life is another factor. Aluminum alloys typically don't show a fatigue limit. This means there is no known stress sufficiently small that it doesn't contribute to material fatigue/reduce the remaining fatigue life of the material. Failing to annealing properly or completely and then bending could cause significantly lower number of cycles to failure.

I've run 50mm stems in winter when sitting close to up right, which, here in heavy drifting/lake effects country, is very advisable. Seeing is everything on a snow covered road. No Chris Froome riding style (looking straight down half the time) at that time of the year. A 50 mm looks all wrong, but they do what they should.

Considering all of the problems you might encounter, as well as the investment of your time, why not go with SE's recommendation (Post #2) to just buy one?

I've always been a fan of doing things myself just for the fun of it, for the sake of learning something new, etc. And some form of heat treating and then working a slight bend onto an existing aluminum seatpost doesn't seem like that much work. Not saying it won't be a challenge, just able to be attempted without a big investment of money or time. And if it fails to turn out like I expect then I'll just go buy one like everyone else.

Realize that if your bend is not well aligned with the seat centerline, that you will have to choose between having some portion of your seat centered or having your seat facing straight forward.

Consider another option that avoids the heat treatment issue (proper temp control really important), most of the increase in fatigue/catastrophic failure risk, as well as problems with seat alignment likely to be introduced by less than perfect post bending.....

Remove your seat post from bike frame and seat. Look at how the lower portion of the part that clamps to the seat is attached to the post. Could you remove the top inch of the post along with that bottom portion of the clamp and have a modified bottom clamp portion machined out of aluminum that you could epoxy into the post? This new piece would work with the remaining top portion and bolt that clamps to the seat, yet position the seat the inch or two forward that you desire.

You are suggesting he tries glue to hold on a seat clamp??? Are you crazy? I've had a seat clamp fail on me once and that is enough. This is not the old cruiser bike of the mid 20th century, with high mounted handle bar, where standing up for miles is an option. Pedaling standing up for more than 1 mile on a road bike with standard geometry is very difficult. The position of the handle bar in relation to the pedals is such that you are in a very tiring position on a flat stretch of road after about 1 mile of trying. I've tried it on a less radical, geometry wise, cyclocross bike, and it is not fun. You eventually give in and try to sit on that stump - ouch.The exception is on steep inclines going upwards, where you are leaning forward. You'll get him stuck out away from home looking for a ride.

I'm suggesting a new piece be machined and well attached. I am not detailing specifics but a robust seat clamp machined for an interference fit inside the original seat tube press fit in with epoxy is one possibility that wouldn't be anything new or radical to bike seatposts.

I'm actually on exactly the opposite side of the concern scale from what you imagine/accuse. I also have work experience in this exact field.

Working by building and attaching a new seat clamp to the post gives a very good chance of resulting in a reliably robust final product that can be used with confidence. Bending a used 6061 T6 aluminum seat post that may already have crack nucleation, using imprecise annealing and heat treatment regimes is going to result in something for which confidence is never really warranted. When is it going to break off and shish kabob you in the keister?

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To whomever down rated my previous comment, even there is disagreement; even if concerns were warranted, marking the comment 'off topic' is disingenuous. It is exactly 'on topic'.

Don't try to argue or express your disapproval by punching the 'off-topic' button. Use your words.

Okay - may work that way. I just don't want anyone stuck on a bike he can't pedal well anymore, and the seatpost is very critical.

I am the definition of an expert on bicycles - if it can go wrong, I've done it and learned not to do that anymore. (yeah - I have to try all the things they say not to do and tried a few they haven't thought of)

Good call, I think I even have a spare seatpost I can cut apart to get a look at.

Keep the forum posted on how things turn out.

Best of luck to you.

Not to put words in anyone's mouth, but if I was following him correctly I would still be inserting (probably tapping with a hammer) a modified clamp down into the seatpost. Obviously yeah, a very critical connection there

I find this to be a bit strange. How stretched out are you on this bicycle in the standard road set up? I know with any of my road bikes, I could put on a set of time trial clip ons on my road bar, and then be stretched out about right for time trialing. Maybe I ride too high in the road position because of my bad shoulders. I really can't recall anyone else having this problem. You must get down very low on the road bars.

I don't think my road geometry is overly aggressive, but I'm definitely not straight upright. Assume I'm riding a normal road bike, with my hands on the hoods, and my upper body leaning forward as much as is practical without sacrificing vision and comfort.. then I lean front until I can rest my forearms near the elbow on the top of the bar.. it's a pretty big change in position. You want your upper arms close to vertical so your upper body more or less rests without straining your arms, and to get there you end up sliding way front on your seat. For this reason time trial specific bikes have much steeper seat tubes (not angled back as far) as a traditional road bike. Hence me needing to get my seat as far front as possible to get a true time trialing position.

Forward positioning for TT bikes also related to maintaining a powerful sustainable/comfortable shoulder and hip angles.

Shoulder angle (elbow to AC to hip) around 90 degrees (some prefer a little less) and hip angle (AC to hip to bottom bracket center) around 100 degrees makes for a powerful comfortable efficient position.

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Hey, just a heads up, to be legal for UCI or USAC time trials or races, the front of your seat is required to be 5cm behind the verticals line up front the center of your bottom bracket. There are some other geometry specifications as well,l. Worth a look if that is something you are considering.

Okay - it is me. I can do that with my normal road set up, so I must have the bar/seat closer together to begin with, and at 66years of age, I no doubt have the bar at a higher position relative to the seat top, as well. I try for about 29" from seat center to handle bar, on either mountain/off road or road bikes, but I use a large sweep back off road bar (think Jones H bar and some knock offs by others) on my mountain bikes, so I get more up right when on the ends of the off road bar. On the Jones bar, I put my fore arms on the bar to hold the extensions, similar to what you are doing for the time trial bike, but probably closer to the wrists than you are trying for.

They used to make down hill saddles that were often called "sofas" - very long rails and saddle, to let you do the opposite - slide way back on the descent. I have a three of those, but have retired them. The Anatomica made them obsolete. Wouldn't look too good on a time trial bike, plus the rails were 1mm bigger in diameter.

Let us know how the post modification goes - I like to have all the tricks covered, and would try it just for fun, and to amuse the bike shop people, if it works.

I have formed aluminium ladder roof ridge hooks section 35mm by 25mm by 1.5mm wall by freezing it full of water.

I do not know the material or state but it worked well. The angle I believe was about 10deg over 200mm - no damage to the material obvious. The part is now used as a hand rail in the house.

This was just using clamps and hammers - a bending jig would help for a round tube.

http://www.bikefit.com/s-10-tri-bikestime-trial.aspx

That's cool, never saw the images overlayed like that but that's pretty much it. I'll post some pics when I'm all done, I did take some pics of me on the bike before I started for comparison sake. Also waiting on a new stem to arrive then I should have everything I need

Alright - bicycle geometry 101. Very good. Now for real fun, show a "fat" bike frame or a true downhill mountain bike.

Triathlon/time trial bikes do have a seat post a bit closer to vertical than I realized. (the one bike style I've never owned)

It still can be done with a road bike. ALL the charity/local races I've ever been too make it a point to let you know that putting clip on time trial bars is not allowed, and there were many racers with them 10 years ago before the over all banning of them caught on. Perhaps "teddyboy" is onto what the amateur road bike racers had to do to run them.

So now I have to wonder where "teddyboy" is going to use this modified bike.

Haha, just to be clear I'm not one of those freds who shows up at a group ride with a time trial bike. I like to do sprint triathlons (the shorter the better).. even though I'll be the first to admit I'm a totally average unspectacular athlete it's still a blast. To me the holy grail would be to average 20mph on the bike leg, and I'm kind of stuck around 18-19 on my commuting road bike, with treaded 28c tires, a luggage rack, heavier frame with comfortable geometry etc. All that to say, it's really nice to have a second bike I can tool around with just for racing and not worry about keeping it practical for anything else

My kind of bike owner. I don't really have a use for 10 of my 15 bikes - it is just nice to ride around town on a cafe cruiser, or a beach cruiser (400 miles form the ocean) when I really don't want to put a lot of effort into the days ride.

As far as the sprints go, I like that - that is what I should be, except I have about 50 pounds too much baggage (what happens when a power lifter quits). I can still win the town line sprint on a group ride at 66 years old, but don't ever expect me to go over that hill at your pace - wait at the top for 10 minutes, please. Ride the gruppetto to the top.

Some seats will tilt and flexible seat mounts are available which would also allow for a different angle without compromising the strength of the seat post. If the post is Al it might bend a bit without making a break point but not very much.

Thanks for the followup and pictures. Good job.