Handlebars

How often do you guys change your aluminum handlebars? Came across a couple of websites stating every few years, which means about every 3 years with my understanding. What criteria dictates you changing out your bars before failure?

I have never changed bars because of a concern about failure, but I am a chronic bar swapper, trying to find a perfect fit.

I'm also a mechanical engineer, and do a lot of work with aluminum fatigue. I can't guess about how aluminum handlebars are engineered, but aluminum does not have a fatigue limit, so it will eventually fail under very low cyclic loads (e.g. normal riding). That said - I would guess anyone designing bars is running FEA on them and has a life criteria (number of stress cycles to failure). Any reputable bars are also going to pass ISO 4210-5, which is the ISO spec for "bicycle steering equipment." Part of that standard is a fatigue life test on a bar, which is usually to 10 million stress cycles (unloaded -> loaded -> unloaded under the force generated by a "severe user").

Short story: yes, aluminum bars will eventually fail, but it will probably take a long time unless you are riding pro-level DH all day every day. If you want to be safe, replace them once a decade; 3 years seems very short given that there are a lot of older bars out there and they do not fail if you look at them wrong. If you damage the bar in a crash (visible gouges, which are stress risers and will decrease the fatigue life in that spot) or get hit by a car (forces much much higher than the bar is designed for) then I would replace them.

I don't plan/schedule for new AL bars. That said as preferences/aging/bikes all change/progress a bar probably only lasts on a bike say 3-5 years of hard riding. Some bars float around for 10+ years in the fleet, but they tend not to be ridden intensively that whole time. If I managed to keep a single bar going a long time on primary bikes so it saw a lot of use/abuse I would straight out replace it at some point. I don't have a trigger for that, but depending on how beat up it got or if there was a particularly savage crash it would cross my mind at eventually to get a new bar even if it was straight replacement.

I've been riding ~35 years and not had a metal bar fail on me nor had one fail on a friend's bike. So while I wouldn't dismiss the risk entirely it's not something that's happening a whole lot in practice.

Posted by: TristanC

I have never changed bars because of a concern about failure, but I am a chronic bar swapper, trying to find a perfect fit.

I'm also a mechanical engineer, and do a lot of work with aluminum fatigue. I can't guess about how aluminum handlebars are engineered, but aluminum does not have a fatigue limit, so it will eventually fail under very low cyclic loads (e.g. normal riding). That said - I would guess anyone designing bars is running FEA on them and has a life criteria (number of stress cycles to failure). Any reputable bars are also going to pass ISO 4210-5, which is the ISO spec for "bicycle steering equipment." Part of that standard is a fatigue life test on a bar, which is usually to 10 million stress cycles (unloaded -> loaded -> unloaded under the force generated by a "severe user").

Short story: yes, aluminum bars will eventually fail, but it will probably take a long time unless you are riding pro-level DH all day every day. If you want to be safe, replace them once a decade; 3 years seems very short given that there are a lot of older bars out there and they do not fail if you look at them wrong. If you damage the bar in a crash (visible gouges, which are stress risers and will decrease the fatigue life in that spot) or get hit by a car (forces much much higher than the bar is designed for) then I would replace them.

Thanks for the explanation! 

I thought 3 years seemed way too short, thus the question.

Posted by: TristanC

I have never changed bars because of a concern about failure, but I am a chronic bar swapper, trying to find a perfect fit.

I'm also a mechanical engineer, and do a lot of work with aluminum fatigue. I can't guess about how aluminum handlebars are engineered, but aluminum does not have a fatigue limit, so it will eventually fail under very low cyclic loads (e.g. normal riding). That said - I would guess anyone designing bars is running FEA on them and has a life criteria (number of stress cycles to failure). Any reputable bars are also going to pass ISO 4210-5, which is the ISO spec for "bicycle steering equipment." Part of that standard is a fatigue life test on a bar, which is usually to 10 million stress cycles (unloaded -> loaded -> unloaded under the force generated by a "severe user").

Short story: yes, aluminum bars will eventually fail, but it will probably take a long time unless you are riding pro-level DH all day every day. If you want to be safe, replace them once a decade; 3 years seems very short given that there are a lot of older bars out there and they do not fail if you look at them wrong. If you damage the bar in a crash (visible gouges, which are stress risers and will decrease the fatigue life in that spot) or get hit by a car (forces much much higher than the bar is designed for) then I would replace them.

I think this is good advice. The only bar I broke was a Cinelli road bar from the 80s that was drilled for aero brake housing. But the aluminum used for those was maybe a couple steps up from cheap folding beach chairs. It was common to see bikes with bars that had drooped from age. I’ve had a few bent too from crashes. 

Chromag recommend annual replacement of their aluminum bars when used in the bike park. I think that takes into account heavy use as well as crashes that may not seem too bad but it all adds up.

Posted by: TristanC

.....fatigue life test on a bar, which is usually to 10 million stress cycles (unloaded -> loaded -> unloaded under the force generated by a "severe user").

Short story: yes, aluminum bars will eventually fail, but it will probably take a long time unless you are riding pro-level DH all day every day. If you want to be safe, replace them once a decade; 3 years seems very short given that there are a lot of older bars out there and they do not fail if you look at them wrong. If you damage the bar in a crash (visible gouges, which are stress risers and will decrease the fatigue life in that spot) or get hit by a car (forces much much higher than the bar is designed for) then I would replace them.

Watched my buddy's cheap 25.4 Azonic bar droop on the left side eventually after years of hitting the same neighborhood 6' drop to flat, I'm assuming, like 10 million times. He continued riding that bent bar for years. Ah youth 

Hmm, have seen a few bars toasted from over torquing though.

Posted by: andy-eunson

I think this is good advice. The only bar I broke was a Cinelli road bar from the 80s that was drilled for aero brake housing. But the aluminum used for those was maybe a couple steps up from cheap folding beach chairs. It was common to see bikes with bars that had drooped from age. I’ve had a few bent too from crashes. 

I also broke a road bar back a long time ago, in the middle of the peloton on a cobblestone section in a race. It broke right next to the stem interface. It did sort of break in slow motion, giving me a few seconds to realize what was happening. I managed to keep it together and slow down to a stop. Spent the rest of the day in the sweep van.

I had bought that bike used. I think "couple steps up from cheap folding beach chairs" sounds about accurate for the quality of that bar, LOL!

I don't have any concerns about modern aluminum trail or DH rated MTB bars. I wouldn't replace a handlebar unless I had reason to suspect it was compromised in a crash.

Posted by: Hepcat

Posted by: TristanC

.....fatigue life test on a bar, which is usually to 10 million stress cycles (unloaded -> loaded -> unloaded under the force generated by a "severe user").

Short story: yes, aluminum bars will eventually fail, but it will probably take a long time unless you are riding pro-level DH all day every day. If you want to be safe, replace them once a decade; 3 years seems very short given that there are a lot of older bars out there and they do not fail if you look at them wrong. If you damage the bar in a crash (visible gouges, which are stress risers and will decrease the fatigue life in that spot) or get hit by a car (forces much much higher than the bar is designed for) then I would replace them.

Watched my buddy's cheap 25.4 Azonic bar droop on the left side eventually after years of hitting the same neighborhood 6' drop to flat, I'm assuming, like 10 million times. He continued riding that bent bar for years. Ah youth 

Hmm, have seen a few bars toasted from over torquing though.

I did similar waaaaaay back with a 3T 25.4 flat bar. I was young and (more) stupid, so I would just remove the bar and turn it upside down every time it would start drooping down!

Posted by: Hepcat

Watched my buddy's cheap 25.4 Azonic bar droop on the left side eventually after years of hitting the same neighborhood 6' drop to flat, I'm assuming, like 10 million times. He continued riding that bent bar for years. Ah youth 

Hmm, have seen a few bars toasted from over torquing though.

That's the "severe user" that all reliability engineering designs towards!

At least for the kind of riding I do, I would worry much more about over torquing than human generated forces on the bars. I also do a lot of bolted joint calculations and the torque range between "joint is tight enough to hold the things together without slipping" and "strip the thread or crush the thing you are clamping" is pretty small. Please, please use torque wrenches, everyone!

Back in the day (I think it was 2001) I broke an Azonic bar just riding along. Which is to say that a crack inside the bar decided to find its way to the surface and fail completely when I dropped off a curb one afternoon. I managed to stop with the right half of the bar in my hand the left hand and both feet still on the bike. I've been a bit leery ever since then but the rate at which I swap bikes or experiment with rise and backsweep means I rarely keep a bar for more than a couple of years. If a bar gets a major scar I tend to get rid of it pretty soon because you can never really know how bad the damage is. 

I think that minus a major impact or visible damage I think a modern bar should be good for 3+ years. But I tend to buy a new bike every 2-3 years and that almost certainly involves replacing the bar to improve fit so I naturally end up on a shorter timeline, which I have no problem with.

I don’t generally go past 3 years for handlebars and forks, even though academically I have confidence that products are reliable for far longer now. 

It’s mostly because I’ve broken bars (and forks) and paid a hefty price so I feel more comfortable on the bike if I swap out somewhat regularly,  but it’s also because shit just happens, manufacturing defects happen and parts accumulate unnoticed damage over time.

Posted by: craw

Back in the day (I think it was 2001) I broke an Azonic bar just riding along. Which is to say that a crack inside the bar decided to find its way to the surface and fail completely when I dropped off a curb one afternoon. I managed to stop with the right half of the bar in my hand the left hand and both feet still on the bike. I've been a bit leery ever since then but the rate at which I swap bikes or experiment with rise and backsweep means I rarely keep a bar for more than a couple of years. If a bar gets a major scar I tend to get rid of it pretty soon because you can never really know how bad the damage is. 

I think that minus a major impact or visible damage I think a modern bar should be good for 3+ years. But I tend to buy a new bike every 2-3 years and that almost certainly involves replacing the bar to improve fit so I naturally end up on a shorter timeline, which I have no problem with.

I had the exact same thing happen with an Azonic bar of that vintage - mine broke on the up stroke of a drop off a curb. I fell/dismounted off to the side but was otherwise unhurt.

Posted by: Ride.DMC

Posted by: craw

Back in the day (I think it was 2001) I broke an Azonic bar just riding along. Which is to say that a crack inside the bar decided to find its way to the surface and fail completely when I dropped off a curb one afternoon. I managed to stop with the right half of the bar in my hand the left hand and both feet still on the bike. I've been a bit leery ever since then but the rate at which I swap bikes or experiment with rise and backsweep means I rarely keep a bar for more than a couple of years. If a bar gets a major scar I tend to get rid of it pretty soon because you can never really know how bad the damage is.

I think that minus a major impact or visible damage I think a modern bar should be good for 3+ years. But I tend to buy a new bike every 2-3 years and that almost certainly involves replacing the bar to improve fit so I naturally end up on a shorter timeline, which I have no problem with.

I had the exact same thing happen with an Azonic bar of that vintage - mine broke on the up stroke of a drop off a curb. I fell/dismounted off to the side but was otherwise unhurt.

Mine was that model with the double aluminum layer over the stem clamp area and the bend, which in hindsight is a terrible idea and a perfect stress riser since my break happened right at the end of that collar. The PDW Chubby bar was its name.

Mine was their more traditional riser bar and it broke right at the edge of the stem...  It is entirely possible it was all my fault - I did not know what a torque wrench was back in those days, let alone use one.  I most likely overtightened the stem.