Broken bike bits. Text and pictures from http://www.m-gineering.nl/oopsg.htm as of 2008/01.
|This is a crank which after years of faithfull service has had enough. Cracks are growing from the sharp corners of the internal square, here visible at 3 and 6 o'clock. Time to order a new crankset, and no heavy sprinting please.|
|The accompanying righthand crank has also suffered: the crankarm is trying to part company from the spider. Again a crack has started on a sharp corner in a heavily stressed area.|
textbooks can't be wrong! This is what happens when you incorporate all
stressraisers known to mankind in a single dynamically loaded part.
the designer thought the part wouldn't know where to start failing
for all the possibilities! The other side:
Photo's courtesy of Bert L:am
|Crack in the righthand crank. A notch caused by a dropped chain has nothing to with it, as demonstrated by the lefthand crank:|
go back to oldfashioned spindles with external flats? Here 's an axle
an internal 8mm hexagonal in the threaded end. That doesn't leave much
meat. The result is two cracks originating from the points of the
straight through the threads
Removal was a bear, as the force of the allan-key expands the thread! (solved it by chucking the axle in the lathe) Removal of this kind of pedal on the chainwheelside is a risky business anyhow, you won't be the first needing stitches
from a spinning bike.
A spinning bike doesn't see any rain, so the bearings will last indefinitely. This isn't true for the axle, certainly when the axle meets with a very hard steel crank. With a steel crank the stresstransition is much more severe, and it looks as the axle snapped just where the crankbolt ended. Spinning bikes can't move from side to side, which must make things hrder on the crank too.
The crack clearly started in the lower half. The continuing motion has polished the crack-surface until the remaining section grew so small it failed. The fresh failure zone is course.
(picture courtesy Marten Hoffmann)
|This is the shell of an XT rearhub (freehubside) The bearings are well lubricated, judging by the grease coming out of the crack! The 5 YO hub has done about 15.000 km's worth of commuting and loaded touring. Crack corresponds with the start of the innerflange which is very thick because it has to support the freehub.|
|This is what an overloaded QR axle looks like. The previously round hole has elongated and the sides show serious necking. It is always a good idea to lubricate the skewer, with less friction there is more clamping force available, and you get a better idea what you're up to|
with severe deformation in the clamping area. In fact the deformation
so severe that the bars kept rotating. Excessive tightening, an aero
and a large hole in the barclamp (see the bulge) were probably
Replace at once!
|With a carbon bar a spill will have far reaching effects. I've never seen a alloy bar crack here, the norm being that you can at least finish the race|
|There are many ways to stop a bike! See here the downtube-headtube junction in a filletbrazed frame which met with a solid object. The downtube sprouts a double chin (yes, that stubble is cracked clearcoat), and the forkrake suffered a lot too. With a new fork this frame is probably good for another few thousand miles, but it won't handle like new. And keep your eyes peeled for the start of a crack in this area.|
are not immune from problems, and the guarantee didn't extend to the
The crack has started from the sharp point of the bottom lug. From the rust at the bottom section you see it has been awhile and the crack could possible have been spotted before total collapse. The crack took some time untill the remaining section couldn't handle the strain and snapped.
(picture courtesy Niels Alsemgeest)
|The rivnut (bottlecage mounting) is being pulled through the frame. Not very threathening in this stage, unless the crack starts growing in another direction and then things will happen fast!|
|A waste of a fresh powdercoat-job. This side is the final crack, the tear starting on the left side. From the looks of it, it has been there for quite some time. This frame was probably around 25 years old.|
|Rear dropout with the mudguards mount nearly fallen off. The spotwelded protrusion wasn't meant to take a fully loaded rack|
expensive frame but luckily with a guarantee*). The crack started on
left side in the heat-affected zone. The tear looks a bit oxidised, and
not as bright as the final crack on the right. Also note the cracks in
the clearcoat (picture on the left) which show that the tube has
as it broke.
in a week
pictures courtesy Franke Nieuwenhuis
|The government health surgeon has determined that pressing on regardless when the chain has caught between chainring and chainstay is detrimental to your -aluminium- frame's life! Here's a fatiguecrack which not accidentally coincides with a deep dent. This won't last a single hard race.|
|A very thin Tange Prestige doesn't like chainsuck at all either. Pity the painter didn't spot this before applying a thick coat of bondo.|
in an aluminium rear triangle. This one starts in the thick weld
attaching the bridge to the chainstay (dee insert)
|Small racing accident, this is a cracked wishbone. The droplets are water, leaking out through the crack. Frame had to be replaced, the funny sized glued-in wishbone wasn't available: $$$$ !|
|Not a bike but it is Reynolds 531! This is a 40 year old subframe from a well-used Jaguar E-type Cracks start around the stiffener/ suspension mounting point.|
this time the toptube has started to part from the seattube on this
MTB. The seattube is unaffected, which points to a defective weld. Too
short a seatpost (or a short adapter sleeve) (*) could give similar
but then the crack usually starts at the rear or from the sides.
(Photo courtesy Bert Lam)
(*) Seat post or sleeve should be inserted at least 2 cm below the toptube
of why loose non-welded seatclamps are popular. The stressconcentration
at the junction of the hefty lump to the thin walled tube in the heat
zone was a bit to much.
Fixed under guarantee by welding up the crack, replacing the clamp with a non-welded version and repaint
(Photo courtesy Chris Leurs)
|Rather embarrasing if this clamp breaks during a ride, but easily replaced with a sturdier version with more meat where it counts|
steerer. Probably due to insufficient support by the plug, I'd rather
a full tubular style here. But a fancy cutaway stem wasn't helpfull
I try to fit stems on carbon steerers with a 5mm shim on top of the stem, which should move some of the clamping force away from the edge.
|See here the forkcrown of an only 5 holidays old Giant Expedition.The stiff boxsections of the crownhalves are welded to a flexible (thinwalled & large diameter) steerertube. This ensures that the welds are higly stressed. The undercutting (^) in the steerertube, where the weld goes round the corner gives this poor design the kiss of death. I would hate to ride this fork much further, the fork will probably collapse if you have to make an emergencystop.|
|The welder has cut through the seatrail, creating a notch. This stressraiser does as can be expected|
|Double eyeletted Mavic which cried enough after 3000 km's. The rim stayed true enough to finish the trip but you can see straight through! Rim was advertized as featuring 'bomb proof strenght' and a for best use of 'heavy loads'.|
|Another cracked rim, but you can't really blame it. Some cycleshop had managed to build it with straight gauge #13 spokes (aka telegraph poles) at 150 kgs of tension. Massive overtensioned spokes without give do not build into a reliable wheel. You'll never break a spoke again sir, indeed!|
yet another one
|This is a spokenipple of a Mavic Ksiruim SSC rim. The nipple is threaded into the rim and cannot move. With a heavy sprinter the spoke will now have to bend at the exit: The nipple has cracked open and the aluminium spoke has sheared in two|
|Unless you're into watchrepairs I suggest you leave a STI shifter wll alone. No spares are available, so try to get a failed shifter warrantied first! Note the broken sintered? parts|
See also General bike pics, including other failures.