Handlebar Failure and Fatigue

Hi I've done a search of the Forum but can't find anything recent.

A few days ago on my roadie, the left side just dropped away at the clamp as i was track standing and about to pedal off at an instersection. I looked down and the left side of the drop bar literally cracked and ripped off just one the clamp edge and left hanging by about 5mm of alloy.

What scares me is that I was dropping into a few hills that morning over 60km/h and just lucky? 500metres from home I rode home holding one side. It still freaks me out thinking it could have happened a bit earlier in the day whill bombing down a hill.

I have done around 7000kms over the last 14months on the bike since it was new. (No crashes not even drop the bike maybe knocked over once or twice on the side by ignorant someone's)

I won't name the manufacturer yet in case we put it down to wear and tear.

1) Manufacturing Fault?
2) Wear and Tear ( uneven roads , pot holes the usual )
3) Clamp too tight?
4) Bad luck?
5) Combination of the above?

At the moment I'm inclined to replace with carbon bars do I need to change to clamp to match?

Anyone have any similar experiences or ideas or advice.?

 

Number one, maybe number 3, no doubt number 4. NOT number 2.

 

I'd guess one or more of the first three, but would also expand your list a bit. First, after "clamp too tight", I'd add "clamp poorly machined". If the clamp had sharp edges (no chamfer or radius), that could have created a stress riser right where the bar broke.

Also would add "bar too thin" for application. Even if the bar is perfectly made and installed correctly, it could be that it just wasn't a heavy enough bar for your usage. Bad roads, sprinting and standing climbing in a big gear (where you pull on the bars hard to keep moving) all put bending loads on the handlebars. If you're a heavier rider who uses upper body strength to pull big gears, a stronger (and heavier) handlebar could be a better choice.

 

Probably clamp too tight.

You really only need the clamp just tight enough to stop the bar rotating. Much more than that and you're just crushing the bar. In an age where everyone is all about weight, weight and less weight, too much force is not a good thing.

Now go buy some new bars and a torque wrench.

 

No-one here could honestly give you an answer on those 5 questions without inspecting the bars.

Having said that, I'm glad you're ok and weren't descending or sprinting at the time.

This is very rare, I'm 20 years I've heard of it happening a couple of times.

I always buy new gear, never buy second hand bikes and equipment. Fatigue is a factor on bikes, that's why we sell them.

 

All this discussion got me curious so I looked at the handlebar clamp on my Marin Fairfax. It has four 4mm allen bolts and it says "6N-m". I found a table on the internet that says 6Nm is about 53 inch-lbs. I have a 4mm allen wrench that is 6 inches long. I found a 10 lb barbell weight and marked where it would have to be to exert a 53 in-lb torque (5.3 inches from the bolt, nearly to the end of the allen wrench. I then positioned the bike such that the allen wrench was level when on the bolt and let the weight turn the bolt until it didn't want to turn any more (had to remove and re-orient the wrench several times but finally it balanced without turning any more.) This may not be that accurate, but I found it was somewhat more torque than I had the bolts set to previously. Now I can sleep at night without wondering about it (but I will get a proper torque wrench soon).

 

Thanks everyone for your replies, it's given me some more insight interestingly the bars came loose one time after a couple of months after I got the bike.

I did tighten it a bit then I don't think overly though. The bike usually goes in the shop regularly for service every 2-3 months. I've been going to them for over 3 years and are quite reliable.

I am getting brand new bars fitted at the shop once they arrive. It was actually booked for service a couple of days it happened.

The torque wrench is a good call.

Cheers

Here's an image I took afterwards the bike and old bars are still in the shop.

Hopefully I will be back on the bike soon.

 

I got my bike shop mechanic to check clamp/stem and make sure its compatible with the new bars. He did put a lot of effort into helping me choose the new ones and making sure they suit.

I think a combination of what you described in the last paragraph describes me.

I better stop pumping iron

 

Thanks, im glad too!

I do expect some wear and tear haha but not like this. I like your website btw!

 

Did your mechanic also look at the other side of the bars for notching at the clamp or other damage? Would be curious to know if the right side showed any signs of failure.

If your bars are from a major manufacturer, they should want to hear about your failure, and perhaps inspect the broken handlebar themselves. Suggest you call or email their tech support people to report the failure.

FWIW, when I got my new roadbike back in 04, I noticed right away that the bars (Richey WCS) were flexy vs. the older bikes I had been riding, particularly compared to the Fuji Track bike. The component makers know that light weight is equated with quality (and selling price) by many customers so they are under pressure to market their lightest/thinnest bars as "best" for everyone.

 

A lot of time and effort? How much time and effort does it take to figure out if the internal clamp diameter of the stem is the same as the external diameter of the bars? Factor in stem length/rise and bar width and drop style and you've factored in everything you really need unless you're a weight weenie.

If in doubt stick to the same manufacturer and model/series of components. Read the installation notes and tighten accordingly. If you buy carbon bits read the disclaimer about what too look for should you crash and what to do if your round bits like bars and seatpost, slip.

 

Here's the way I look at things...

Bikes are not rocket science and manufacturers provide really good installation instructions so you really shouldn't need a shop to install your components other than situations like needed a bottom bracket shell faced or headset races installed properly.

A $50 to $100 torque wrench would have ensured that those bars were fastened properly and likely would have still been in one functional piece to this day. The OP was lucky that a face plant didn't result. I really can't think of much that'll ruin your ride like shoving your hand in the front wheel at speed and grinding your noggin into the floor and risking being run over by something that weighs at least 1000kg.

$80 to possibly save myself from looking ever more like Joseph Merrick - a quality investment!

That said, to cover the range of torque required for everything on a bike you'll likely need two torque wrenches. If you can't afford two, get the one that'll be used for clamping stuff onto carbon bits like stems, seatpost and a clamp on front mech.

The other alternative - buy a steel bike and use old school Cinelli bars.

Sell the Garmin, buy some tools. If your bike shop put that bar on your bike, don't take your bike back there. I sleep easier at night knowing that when I work on my bikes and cars all the fasteners that have a required torque setting and torqued correctly and the correct lubricants or locking compounds used when required.

 

Thanks. It's nice to get the feedback. I need to work on the design stuff, but the content is coming along.

Good luck with your bike.

 

nooooo... I use the computer across 3 bikes and use to cache off road mtb rides so across the 3 its quite economical.

old school components everything seems to be more robust.

I agree with you on all your points especially investing in the torque wrenches & tools: life and well being vs $80 bucks? it's a no brainer.

I guess also it's pretty much important to check non moving parts as well as the moving ones regularly.

Yes the manufacturer of the bars will be contacted about this as well as I am sure they need to be interested.

 

thanks.

I manage web content as a job and look at a lot of pages.

Your site easy to read uncluttered and the content mix is right. I like the look and feel as well.

Often people make sites to gimmicky and busy.

Cheers

 

Thanks Steve, I appreciate it.

 

I would think bar/stem is an easy way to shave some grams, but is it really worth it? I like the nice stiff feeling of a ritchey pro bar stem while the wcs model feels kinda noodly. What's 2-3 oz when you really think about it.

I have all 31.8 stuff, but is 26.0 actually stronger?

 

It's not just the torque settings, it's also the correct use of applicable compound like loctite and that 'no slip' goop for carbon seatposts etc...