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I've gone through four five frames in the last decade or so, all from different manufacturers, all steel but both lugged and welded both steel and aluminium. Every one of them has eventually developed a crack, and the steel ones have been repaired and then re-developed more cracks until I give up and get a new one.

It's usually on the seat tube down near the bottom bracket, but once on the down tube near the headset, and once twice on the chainstay.

I generally just use the bike for commuting (~150km / week) and occasional weekend riding—all on the road. I weigh about 90kg. It's never cold enough for the ground to frost here, but it does get hot: 48°C or more sometimes! I've been on my mountain bike for the last couple of years, but I miss my skinny tyres and I'm thinking of getting a new road bike.

Does this point to something wrong with the way I ride? Do you think doing track stands at lights would exacerbate the problem? Is there anything I can do to make it last longer than a couple of years or should I give up and just stick to mountain bikes?

Here's a list of the frames I've broken:

Make or Seller Material Origin Comments
City Cycles Sydney steel unknown really nice
Cecil Walker Melbourne steel Ken Evans, a well-respected local framebuilder custom fit for me, also very nice
KHS steel Korea kind of cheap and nasty
Kona aluminium Taiwan (?)
Soma Doublecross steel USA from the weight of it, I thought it would last, but no

Seems I don't buy bikes, I rent them.

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    Do you keep the saddle at the proper height, legs straight at the end of your pedal stroke with the heel of your foot on the pedal? If you keep the saddle low, you might be putting more weight on the saddle than you should. I suppose it's possible that could be stressing a weak frame a little bit. Commented Dec 15, 2010 at 22:15
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    Once cracked do you take the frame back to where you bought it - I had a Dawes frame that developed a crack in the head tube after about 5 years - the shop sent it back to Dawes and they replaced it free of charge (it took them about 6 months though).
    – Mr_Thyroid
    Commented Aug 6, 2017 at 19:15
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    Most manufacturers give a frame warranty. The frame shouldn't crack under normal use. Pedalling is definitely considered normal use, even if you have the saddle badly adjusted. Not sure about the custom frame builders but Kona certainly have a lifetime frame warranty. Were you the original owner of the bike?
    – Qwerky
    Commented Aug 8, 2017 at 13:01
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    13 years later - are you still cracking frames ?
    – Criggie
    Commented Dec 5, 2023 at 7:39
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    I haven't cracked a frame, but in 2021 my front forks snapped on me, which landed me in a spinal brace for 4 days (fortunately I walked away with just a couple of scars), and last week one of my cranks snapped, so my war on bikes continues.
    – stib
    Commented Dec 11, 2023 at 3:25

9 Answers 9

21

It is very likely that you are putting too much stress on the frame when you are cycling due to your power stroke.

It took me a long time to train myself to avoid standing and powering the bike through the acceleration of starts, or even powering through it while sitting. I've long since learned that while I have plenty of power, I actually am able to transmit it more effectively to the wheel using a faster cadence with lower power.

Try to start out in lower gears so that it's easy to get up to 90rpm quickly (quickly, as in within dozens of feet, while you are still accelerating). If you don't know your cadence, or have an easy way to measure it, the disco tune "Stayin' alive" is just over 100bpm. There's a lot of other music you may be familiar with that is about 90bpm, you can do a google search for "90bpm song" and you'll find lists such as this: http://www.edenathletics.com/90bpm

The location of the stress fractures really suggests that you are standing up to push more power into the pedals. If you are doing that, stop standing - road bicycle frames are not meant to take the pounding that this type of riding entails. The standing position puts a tremendous amount of force on that particular joint, and the pedals are not long enough to really transfer that energy into the chain - you are wasting a lot of power flexing the frame. It you are a fan of geometry and physics, imagine putting the frame on two stands where the wheel hubs are usually located. Now place a bouncing 1/2 ton load on the bottom bracket. You'll find the stress fractures are disturbingly similar to the ones you are experiencing - the two triangle shape of the frame will force the top tube and seat up, while the bottom bracket is forced down, leading to fractures in the seat tube. If the seat tube is strong, you may instead fracture the chain stay on the chain side.

If you prefer that riding style, however, then you'll have to settle for mountain biking frames, which are designed for powerful stroking techniques. This is one of the reasons messengers often use mountain bikes - they are standing up a good portion of the time with very powerful strokes to accelerate in very short bursts.

While spinning doesn't allow such high acceleration it is much more efficient in transferring energy from you to the forward motion of the bike. And you can still stand up and accelerate if a situation calls for it, but doing it often is going to fracture your frame.

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    What happens to the power you use to flex the frame, given that the frame does not deform?
    – lantius
    Commented Mar 7, 2011 at 7:39
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    @Lantius The frame does deform, though different frames will deform at different rates depending on construction and materials used. The frame flexes, and then it springs back. Some of the energy is lost in heating, but that's fairly minimal. Note that the deformation is very small, especially on very brittle frames. You could see the deformation with strain gauges, for instance, but it's not something you'd be able to easily see visually since the deformation is very slight. Aluminum tubing acts like a spring when compressed lengthwise, but only for a few mm.
    – Adam Davis
    Commented Mar 7, 2011 at 15:29
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    A good frame must withstand sprinting or steep hill climbing while standing. If it brakes your frame, it is a bad frame and you should claim your warranty. Many brands offer extended warranties for their frames. Commented Dec 5, 2023 at 9:17
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    I have to agree with Vladimir. If you stand, you put out more power, but bike frames have to account for that. If there was not enough safety margin to take you standing to pedal, then there is basically no safety margin at all. It would not seem like reasonable design.
    – Weiwen Ng
    Commented Dec 5, 2023 at 14:38
  • @WeiwenNg My impression of the bike industry is, that safety margins on structural elements are non-existent. While I have not got to five broken frames, I did have them, and they were all steel. I've also broken forks, handlebars, luggage racks, you name it. All these components are perfectly fine the first 100 km. But none of them endure heavy daily use indefinitely. With steel that should be possible. That it is obviously not possible means that the daily use puts the steel beyond its fatigue limit. Consequently, there is exactly zero safety margin between use and fatigue limit. Commented Dec 5, 2023 at 21:40
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There are certainly techniques that will put unusual strains on the bike, track stands could be, I certainly think that excess use of a turbo trainer does. I (try) to do track stands where possible and my commute bike (~150k per week for a number of years) only died when I crashed it ...

Quality of the ingredients is certainly one factor. Another could be the manufacturer (although you have already mitigated a little for that in your question). Many people, in particular those who come to cycling from other sports, might try to deploy their power in different ways. I used to row and when I was looking at a new bike, I spotted a lovely looking candidate, but the guy in the shop said "I won't sell you that, it's a Bianchi, and I find that all big rowers break Bianchis", his theory was that lugs like me (I'm only 6' and 200lb but that's big for a racing cyclist) tend to grind out in the bigger gears while the Bianchi tended to favour the lighter rider who'll spin it higher, but in a lower gear.

So the chances are that it probably is something about how you ride, but that doesn't mean changing your style, just finding a bike designed around you.

Or maybe you should change your style ...

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    I can see that being a problem with Al frames. I'm 6'2" and 210lbs. My CAAD7 roadbike frame flexes like mad when I'm really getting on it... I keep checking that one for cracks. None yet, but I guarantee it'll happen eventually. Al does NOT like repeated flexing. Commented Dec 16, 2010 at 16:11
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    Hey, I'm an ex-rower. Maybe I need to learn to spin a bit higher.
    – stib
    Commented Dec 20, 2010 at 4:47
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I had a run of bad luck with road frames quite a few years ago, going through about three in rapid succession. Like you, the faults were always in different places. Since then I haven't had any troubles, but I did start using a slightly higher upgrade of frame materials. I currently ride about 120K a week,mainly commuting, doing track stands wherever possible.

My advice would be to perhaps try a slightly better grade of steel frame next time. I was using low grade steel, then a couple of manganese alloy based frames, before going onto Reynolds (not too sure of the number, early 531 I think) and Columbus No.2 frames. No problems with them.

I currently ride a composite frame, aluminium main tubes with carbon forks and rear stays. Going strong since 2005. I am also not particularly light, being over 85kg at the moment (must train more!)

I just have troubles with wheels now :-(

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  • I was thinking about a bike with the same specs, but was worried that it might be worse than steel, with aluminium and carbon having the tendency to catastrophically fail instead of tearing like steel.
    – stib
    Commented Dec 20, 2010 at 4:56
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This may be more of a comment rather than an answer but you seem to think the only alternative to a road bike is a mountain bike.

Have you considered getting either a cyclocross or a touring bike with drop bars? These have a similar look and geometry to a road bike but are built much more strongly.

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    I did exactly that. Got a Soma Doublecros CX frame a couple of years ago. …it broke last week.
    – stib
    Commented Aug 4, 2017 at 4:10
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    Hahaha! You need to get a side job as a quality control person for Trek or Colnago. :)
    – RoboKaren
    Commented Aug 4, 2017 at 4:18
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Do you think doing track stands at lights would exacerbate the problem?

I doubt it. During a track stand, you and the bike are essentially stationary so the bike's doing little more than just holding up your weight. That's peanuts compared to the forces involved in pedaling hard and bouncing through potholes.

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    +1 for answering a facet of the question that was otherwise unaddressed.
    – Criggie
    Commented Aug 3, 2017 at 23:15
  • If I'm doing a trackie facing downhill I often feel there's a bit of flex going on. You have to bounce off the front brakes, the forks certainly flex a bit.
    – stib
    Commented Aug 10, 2017 at 7:52
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    @stib Downhill track-stands are well beyond my paygrade. But, still, you're breaking frames, not forks, and the forces involves in braking a barely-moving bike are small compared to the other things that happen to it in normal use. Commented Oct 11, 2017 at 11:56
  • I am here because my steel track bike suddenly snapped at the seat tube-bottom bracket lug when initializing an acceleration from a long trackstand at a red light on a substantial incline yesterday...
    – dotism
    Commented Aug 19, 2021 at 0:09
  • @dotism If the accepted answer is correct, it's not the trackstand that did you in, it's the high-torque acceleration. Commented Dec 5, 2023 at 1:28
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As an avid cyclist and every day NYC bike commuter, I had a similar problem with road frames. Aluminum frames would last about 9-12 months and steel TIG welded frames generally lasted about 18-24 months before cracking at the bottom bracket (full disclosure, I'm 6'1" and 210 with all my gear).

Alas, there is a solution, with the advent of twenty-niner mountain bikes you can now get a good rugged frame (Surly Karate Monkey is my favorite) and build it up with road tires (I'm partial to Continental Ultra Gatorskins in the 25cc variety) with nice rugged mountain bike wheels (I'm using XT hubs with 700c Mavic rims). Sure your frame will weigh about 2 pounds more than a road steel frame, but it won't break.

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I broke two steel frames in different ways, but both were used for commuting under heavy loads.

  1. I stretched the rear dropouts of a frame built for a 7 speed hub to fit a 9 speed hub, and this put stress on the chain stays just behind the rear bottom bracket. After about 6 months of daily riding, the right chain stay cracked.

  2. I rode my bike head on and it crimped the downtube just barely enough to notice - I could only tell if I ran my thumbnail over it - and about three years later, the down tube cracked at this spot.

The bottom line is, steel (or any metal) fatigues; but in both of these cases it was helped along by my own abuse - both were learning experiences for me.

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  • So you're saying that how you treat the bike, and what you do to it has a long term effect. Seems fair.
    – Criggie
    Commented Nov 21, 2017 at 19:27
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I used to ride 12 centennials a month with a crew for several years. The answer is not to restrain your power so you don't flex the frame, the answer is to get a more durable frame.

We rode French, Italian and German road frames; Peugeot, Colnago, and Daimler. I don't remember one frame failure. The frames were steel with lugs and silicon bronze brazed joints.

We knew some other cyclists that built road bikes from welded titanium track frames without lugs, those broke at the down or seat tube at the bottom bracket.

0

Get a carbon "adventure" or "gravel" bike

These are chunkier and stronger than a road bike but with the right tyres are quite lively to ride

Carbon bikes won't fail in the way you describe so that might help

I weigh 85Kg and the only bike I had that had the symptoms you describe was titanium. Probably my experience was due to a manufacturing defect

It's interesting that your problems were with a wide range of makers

It you want to stick with steel either go back to the nice local framemaker or get a Surly, maybe you were just unlucky several manufacturing defects

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