Bicycle Mechanics - Steel Frame Re-Alignment

I've read that eventually a steel frame if ridden will go "dead", but that this can be cured with a re-alignment. Is this true, & if so, what's the average cost for this job? (Out here in the sticks there's nobody nearby who does such work anyway).

I've read also that any jig-built steel frame needs to be stress-relieved. But if it is, is the result very noticeable to the rider?

I'm always loking for new reading material. Where did you read these things? Thx.

Hi Don. It was something i saw some years ago, don't recall the source. I believe the article was about a wellknown custom road bike frame-builder in CT. Possibly in Bicycling magazine.

Most high end steel tubing is stress relieved before building. This eliminates the alot of the after work involved once the tubes are welded. You still have to stress relieve but not as intensive as in the old school days. Hand built frames for the most part alwaya provide a better fit and ride, just like hand built wheels. If it is done correctly, then yes it is noticable to the rider.

These are common "urban myths"; that's why I asked. Obviously, all materials have a fatique limit, but most people riding a properly constructed steel frame of, say, Reynolds 531 or Columbus SL will never see the fatique limit reached to the point that it will affect how they perceive the bike to ride. With regards to the newer thin walled tube sets , the school is probably still out on these.

As to stress relieving a frame after brazing, if the frame is brazed in an improper sequence, stresses can be built into the frame. Reynolds used to and may still recommend a specific sequence of brazing from the bottom bracket to the headtube/downtube to the headtube/toptube to the toptube/seattube to eliminate the possibility of torsional/heat related stress being built into the headtube joints, the most critical joints for safety on the bike.

Other than that, if a builder inadvertently builds some stresses into a frame, it will show up in misalignment, which will be superficially removed in the frame shop by coldsetting the frame into proper alignment. This may not remove all the stress however, as it really isn't intended to do so. In fact it may/may not put more stress into the frame.

With regards to a jig contributing to the stresses built into a frame, once again, I believe the sequence of events and the skill of the craftsman are probably much more important than whether the frame is built in a jig or not. There is a school of non-jig advocates and their antithesis. I worked in a frame shop for a short time(6 months) and we did not use jigs; the joints were tack brazed, given a preliminary alignment, then bronze brazed in the sequence I described above.

Thanks, Don - i find discussions of materials & construction fascinating, altho i'm not a builder.

According again to what i've read, steel has an indefinite resistance to fatigue as long as its rated limit is not exceeded. Aluminum on the other hand has a finite number of fatigue cycles before it fails, even tho no individual stress exceeds its rated limit. (I probably don't have the terminology right, but you get the idea).:->

Too bad Bicycling mag is propagating urban cyclomyths, but this is not the first time i've been told their info is often faulty. It seems to be mainly a promo vehicle for the trade. I don't look at it these days except to drool over the latest road bikes.:->

Ebro, once a frame fatigues theres nothing you can do to 'bring it back'. If a frame is out of alignment then yes, a 're-alignment' will bring new life back into the frame. If the alignment on you car is off a good alignment can change the characteristics of ride.

Fatigue is a final and irreversible condition. Once a frame (or any piece of steel) is 'fatigued', it is scrap.

Also, the myth of a steel frame "going dead" was probably something invented by the aluminum/carbon fiber/titanium frame cartel.

Thanks men. My impression was, though, that properly tempered steel will never fail as long as the stresses remain within its rated limits, whereas aluminum can take only a finite number of fatigue cycles.

What does it mean then for a steel frame to become "fatigued", short of actual failure? It loses its elasticity?

Carbon fiber & Ti are environmental villains, but where do they fit in as regards material fatigue?

Fatigue technically means failure. Yield strength is the amount of force required to deform a tube or cause it to change position. A racing frame may be crashed and go out of alignment(yield), be re-aligned by cold setting, be crashed and go out of alignment, and be re-aligned by cold setting more than once. The coldsetting work hardens the material and at the same time diminishes its yield strength, making it more prone to failure(fatique) in the future. This frame would lose elasticity and resilience, or yield strength and it might go out of alignment more easily and it may feel more flexy.

For a frame that is not subjected to the above stresses, the loss of resilience or yield strength may happen over the life of the frame, but is probably so small as to be imperceptible to the rider. Many people have assumed that an older frame naturally loses resilience or yield strength, becomes dead. This is probably the urban myth. But obviously if a frame is ridden, it is subjected to cycles of stress, but normally not enough stress to push it to it's limit or affect it's basic riding characteristics.

Ti is generally considered to have the best yield and fatigue characteristics of steel, alu, and Ti. Speaking in generalities, it is the least likely to go out of alignment or fail. It has been said to have the characteristics of a yoga master. The downside is that while it may not bend or break, it is more prone to flex, has a lower modulus of elasticity(Young's Modulus), requiring larger dia. tubes to achieve the same deflection characteristics(stiffness) as steel or oversize alu.

For these reasons, I am a big fan of oversize tube Ti frames. You get stiffness, and high yield and fatigue characteristics, the best of all worlds in my mind.

Carbon fiber can be custom fabricated to achieve pretty much any characteristic you want. It is the lightest for comparable strength, tubes/frames can be fabricated so the carbon is built up in the key areas of flex, etc.... It gives the greatest amount of flexibility in frame design and construction. It also has drawbacks like degradation when chipped or scratched.

Sorry to go on and on. I love to talk about this stuff too.:beer:

Originally posted by don d.
Sorry to go on and on. I love to talk about this stuff too

No apologies needed! :beer:

Thanks, Don. I understand alum. has a similar problem of being weakened by a scratch or nick. I've always preferred steel over alum. for the live feel, but to each his own.

What ever happened with the injection-molded plastic frames that were being touted a few years back?

I have a write up & photo,s of a cast magnesium frame somewere , if I find them I,ll post them , what ever happened to that idea????

I have a write up & photo,s of a cast magnesium frame somewere , if I find them I,ll post them , what ever happened to that idea????

What happened? I think the first owner was out riding and decided to light a fatty....the rest is history.

don d. gave a nice explanation of fatigue/failure. Most people, including myself, associate fatigue with loss of stiffness. Once a frame losses its stiffness these nothing that can be done about it. Steel looses very little, if any stiffness, over the lifetime of the frame.

If I remember correctly titanium is very susceptible to failure if scored. Am I remembering this right???

The Kirk cast magnesium frame, in a fetching shade of purple, can still be seen if you look hard. One of the mechs at my LBS rides one.

"Pure" magnesium or mag/alu alloy? Modulus of elasticity of mag slightly more than half that of alu.

Magnesium is really hard to work with and weld, due to the fact that it is extremely combustible.