Bike shop owners: Frame/component durability question

Triathlon Forum
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Questions for bike shops owners:

Every now and then I’ll read a discussion about the robustness, fragility, durability, etc. of certain materials. The underlying theme being that SOMEONE HEARD AND TOLD SOMEONE ELSE that frames or components made of will over a period of because of the repeated stresses applied by the .

I figured I’d ask folks that see lots of bikes every day. So, bike shop owners: over the years, have you seen any bikes come into your shop showing evidence of any of the following:

  1. Frame failure due to metal fatigue? (Al, Ti, Steel)

  2. Carbon frame failure due to fatigue?

  3. Component failure due to fatigue (I’m thinking about handlebars, stems, cranks)? If so, what materials were they made out of?

  4. Frame or component failure due to rider-induced stress (i.e., the dude mashed the pedals so hard that the bike snapped in half)?

  5. Frame damage from putting a bike in a trainer?

I’m not interested in brand names, I’m more interested in the material itself. It doesn’t matter if the bike is a top-of-the-line model, or a Wal-mart special. Road bike, mountain bike, cruisers. I am not interested in anecdotes – you have to have witnessed it.

Just curious…

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  1. Frame failure due to metal fatigue? (Al, Ti, Steel)

Well, I am not an engineer and also, a forensic examination of exactly what induced the failures we see is generally not available. Usually, to be honest- it is our best guess. Of course, the customer always says “I was just riding along…”

That said, we see an unusual incident of frame failures with cro-moly and 6/4 (NOT 3/2.5) titanium.

More later… We’re leaving on a ride right now and everybody is pissed at me becasue I’m always late…

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I’m not an Owner, but I worked in a shop for about 10 years. Frame failures are actually pretty rare. Aside from my own cracked Softride (and they did come through on the warranty replacement), I can’t think of very many frames that came into the shop broken.

Titanium has the reputation for lasting forever, but some of the old Merlins were notorious for breaking. The Extralights would crack at the shifter bosses and their RSR’s would crack at the monostay. It’s pretty sad that such snobby frames couldn’t outlive a bargain basement aluminum Fuji. I think Merlin coming under the ABG/Litespeed umbrella was a very good move for the brand from a quality standpoint. But I digress… Excepting crashes and garage-door incidents, I have seen very few broken aluminum and steel frames.

Old carbon frames with bonded metal lugs are prone to galvanic corrosion at the joints. Examples are the old Specialized Epis and Giants.

Component failures are common in old components with a lot of miles on them. Especially the old CNC’d lightweight cranks (Topline, Sampson, etc.). Shimano and Campy crank failures are rare. I’ve even had an old Shimano road derailleur to shear off near the fixing bolt while JRA. Old welded stems are prone to failure, especially the old Profile ones everybody used to use. The welded on “ear” for the bar clamp has a tendency to break off. Fortunately, handlebar breakages have historically been rare. The modern carbon bars may change this, but to be honest most carbon bars are heavier than the TTT Primas which have a good reputation for durability if changed out at sensible intervals (10,000-15,000 miles)

When a frame or component snaps suddenly, it is more from cumulative fatigue than it is from an acute application of force. TdF and track sprinters put out way more kW than us and they rarely break parts, but they don’t tend to ride on old parts.

I’ve never ever seen or heard of a documented case of a frame breaking because it was used on a trainer.

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5) Frame damage from putting a bike in a trainer?

Is this something to be worried about? I have never heard of this, should I do something different when mounting my bike in the trainer?

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Not a shop owner, but from the perspective of the engineer who’s owned my fair share of bikes, you really shouldn’t see any frame failures due to fatigue within the actual metal. Where you are likely to first see signs of fatigue are welds and/or joints and usually those are because of inexperience with hard to work materials or in “new” technologies (see notes above on older higher-grade Ti and Carbon frames). Unless the weld job is really flubbed or the design is really bad, you shouldn’t ever see a metal frame failure within at least a decade or two…barring soccor moms in SUV’s pulling out in front of you…

I can’t comment on carbon.

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"5) Frame damage from putting a bike in a trainer?

Is this something to be worried about? I have never heard of this, should I do something different when mounting my bike in the trainer?"

Answer to questions above – NO. I say again – NO.

But every now and then this question comes up, and I was hoping that the answers from LBS owners would help kill this “urban legend”.

Again, I’m interested in cases of material failure due to normal use – we all understand that parts will fail when a bike crashes into the parking curb of Mini-mart because the rider forgot his rims were wet from the rain and therefore the brakes don’t work, (specifically, crank cotters shear off and forks bend – not that I ever did this when I was an 11-year-old). Or that when an improperly carried shopping bag gets caught in the front spokes a Cro-Mo fork will bend spectacularly (not that I ever did this, either).

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  1. Frame failure due to metal fatigue? (Al, Ti, Steel) **Fatigue…sure, but the frames are OLD OLD frames that were not good to begin with. A higher percentage of thin walled lugged AL and early carbon frames. These frames are 20 years old though. **

  2. Carbon frame failure due to fatigue? - Most of the time if carbon is going to break it is due to traumatic impacts, not a rider wearing the frame out.

  3. Component failure due to fatigue (I’m thinking about handlebars, stems, cranks)? If so, what materials were they made out of? - most common of all failures. Stems, Bars, Pedals - some due to crashes, some “drillium” and some just break…mostly old stuff (there is no reason to ride 5 year old handlebars if you race) They are usually AL.

  4. Frame or component failure due to rider-induced stress (i.e., the dude mashed the pedals so hard that the bike snapped in half)? - I only ever seen that once - on a Kestrel 4000 years and years ago…broke on the maiden voyage.

  5. Frame damage from putting a bike in a trainer? Yes

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  1. Frame damage from putting a bike in a trainer? Yes

Please explain

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Curious how a frame can be damaged in a trainer during normal use. Details? And remember – you had to have seen it.

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I think Zinn has a general guide for replacing parts in his books. Probably based on what he’s seen over the years.

Anyhow, to your questions. This is from my own personal experience. I’ve never broken any frames or components on road bikes, and I’m a big dude (6’4", around 190 lb). However, when I used to race cross country mtb’s, I broke a stem (aluminum, though I think it was my own fault, potentially overtightened the screws on the faceplate), and mashed a few handlebars. Actually, the last handlebar I toasted (aluminum EC50), I didn’t notice as it got squashed underneath the grips. Rode it for another few months before changing grips and noticing this. Never had any catastrophic failures, and I think this is relatively rare in either road or mountain bikes.

Oh yeah, I also have a 20 year old steel framed fixie I use for commuting to work almost daily (in winter I break out the mtb). No problems with fatigue/failure.

I think the biggest things that wear out are chains, derailleurs, and tires. That, plus the occasional broken spoke. I really think the better companies do a lot of extensive testing on test frames to see how they’ll hold up (hence the high price). I remember reading an article on Cannondale’s testing, and they really put their frames/bikes through the wringer, doing things that you’d never think of doing in real life!

As a final note, I think most of us get new bikes often enough so we never have to worry about any of these issues :)!

Chris

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I was on it (them)…I have for me old frames that I put in a trainer - usually someones old steel frame. I have torn the chain stays off the BB shell during hard standing sprint / interval training. A bicycle frame is just not built for the stress of a 175lbs man standing the the pedals pushing with 600 some odd pounds of force on the 175mm lever that is attached to the spindle of a shell that is not designed to be held in a static position from the rear. All frames have natural flex - but anyone who thinks that a frame has more stress on a road than on a trainer (other than rollers) is a fool.

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And another thing folks – understandably, craftsmanship will come into the discussion, but please avoid mentioning specific brands if you can. Just interested in the materials - don’t want to start a flame-fest on brands.

Record – tell me more about 5-year-old handlebars and why I’m on borrowed time with my 10-year-old bars.

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Carbon damamge from rider induced wattage…Yes!

My Kestrel EMS carbon fork (right blade) sheared nearly in half at the initial force of a hard “jump”. Caused me to head directly over the handle bars and my head hit first!! Hurt like hell and I saw stars for a few minutes. Yep, the fork was a number of years old, although I don’t know the exact number of years.

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Handlebars will incur more stress than you think - multiply that if you are a sprinter. This is thin walled Al that “cycles” thousands of times every time you ride. It is also being held static in the center by your stem. The bars are also victims of about every crash ever - sure there are marks in the bar from a crash…but you just tape over them right? Well, every scratch is a potential area for failure, add to that the area next to the stem (most common site of failure). Take this 220 gram aluminum tube, bend it time after time after time - one day it just snaps off, usually with out warning. I have had three handlebar failures that I can recall, once while I was at a dead stop trying to find a “creak” - pushed down on the bar it broke and from a standstill I crashed.

In my former years working at LBS, Wrenching at pro races, and riding I have seen many a handlebar failure - mostly like I said from racers and sprinters who use their bars for leverage.

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I’m not a bike shop owner, but I did break a titanium-spindle BB stomping up a hill. There are applications that titanium is unsuited for (given the size constraints), and BB and pedal spindles are two of them.

The chain stay bridge on my eight year old high-zoot Ti frame developed a crack which then spread into one of the chain stays; it was repaired free (with new frame and fork paint) under lifetime warranty.

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Not a bike shop owner, but I have had a few failures over the years, all on mountain bikes or BMX.

  1. Broken fork (steel) mtb

  2. I have blown out no less than 6 bottom bracket bearings - ever get the forward free spin on the cranks? I seem to have a knack for breaking these things.

  3. Several Taco’d rims and bent spokes.

  4. Two broken head sets.

So far so good on the road though.

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Agreed on the Ti…I think that it can change however with pedals that dont have a super long distance from the pedal interface with the crank - and the first supporting inboard bearing in the pedal body. Speedplay for instance has a weight limit on their Ti pedal (this mean run from them)…first year engineering students can see why a Time Ti pedal is stronger than a Speedplay Ti Pedal.

http://www.speedplay.com/images/xall.jpghttp://www.cbike.com/images/time_rxs_carbon_ti.jpg

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Record – tell me more about 5-year-old handlebars and why I’m on borrowed time with my 10-year-old bars.

I’m on 16-year-old bars and stem on one bike, 14 on the other. I bought some Nashbar-sale Modulo quill stems and bars but haven’t quite got around to replacing them yet. As a 160-lb weakling rider, I’m not too fussed about it.

The only frame I ever broke was a steel Taiwanese frame, welds at the BB/seat-tube gave up.

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OK, I’m back. Awesome ride. Beautiful here. http://images.snapfish.com/344%3B75%3A323232fp64%3Dot>2337%3D736%3D376%3DXROQDF>2323%3B528%3B46%3A6ot1lsi http://images.snapfish.com/344%3B75%3A323232fp7>nu%3D3246>645>285>WSNRCG%3D3232<437<37%3A6nu0mrj

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OK, so:

“1) Frame failure due to metal fatigue? (Al, Ti, Steel)”

Like I said, we rarely see it, and when we do the culprits are 6/4 (not 3/2.5) ti and cro-moly. When you consider that around 40-50% of the modern bikes on the road (conservative estimate) are aluminum and the other materials take up the reamaining 50% that speaks well of aluminum: Cheap, light, easy to work with, durable and comfortable.

“2) Carbon frame failure due to fatigue?”

I am not qualified to say if a failure is due to fatigue or some other factor. I wager almost none are fatigue oriented. People abuse their bikes and damage them without even realizing it: Roof racks, trunk racks, exhaust fumes (heat), solvents for cleaning- all of these these things culd contirbute to a conspiracy of things that shortens a frame life. In general, we see very, very few carbon frames fail. Carpon seatposts and bars fail frequently enough that I am not a huge fan of carbon bars, but frames made of carbon seem to be the most durable around.

“3) Component failure due to fatigue (I’m thinking about handlebars, stems, cranks)? If so, what materials were they made out of?”

Again, I am not qualified to say if a failure is due to fatigue or some other factor. Wear and lack of maintenance are the two culprits. I would suggest that fatigue rarely is. People need to learn to maintain their equipment.

“4) Frame or component failure due to rider-induced stress (i.e., the dude mashed the pedals so hard that the bike snapped in half)?”

We’d all like to think we are finally strong enough to destroy components by brute force. But the truth is, when they fail, they usually do so under some increase in laod or use and often times as a result of some prior problem suddenly surfacing under an increase in load and strain. The best cyclists in the world rarely break the best components. The cheap stuff, yeah, it breaks all the time.

“5) Frame damage from putting a bike in a trainer?”

I’ve never seen this happen even once in 25 years in the bike industry. I emphasize, not* even once. *I would suggest this notion is an urban legend from the local bike “expert”. With my own eyes, living in a state where trainers are in use at least 3 months out of the year- I’ve never seen it even once. I would suppose that riding your bike on the road is much harder on it than using it in the trainer.