titanium frame cracked

Ric must be edykated coz e writed:

Quoted message said:

The titanium frame on one of my bikes has cracked around the pedal crank. It has the look of a
typical fatigue crack. It runs around half the forward down tube, and penetrates into the crank
case itself. The welding is not affected - seems it is stronger than the original metal. Luckily
the manufacturer is fixing it for free. But I am quite surprised as I thought titanium frames were
fairly fatigue proof.

Stress fractures can be introduced during welding, that do not show up until the frame is
under load.

--
Ian

catrike.co.ukcatrike.co.ukOpen ↗

Ric said:

The titanium frame on one of my bikes has cracked around the pedal crank. It has the look of a
typical fatigue crack. It runs around half the forward down tube, and penetrates into the crank
case itself. The welding is not affected - seems it is stronger than the original metal. Luckily
the manufacturer is fixing it for free. But I am quite surprised as I thought titanium frames were
fairly fatigue proof.

Titanium has a fatigue limit but it's rather low so not very useful
(i.e. you'd need a 15lb frame to guarantee it wouldn't crack over an infinite lifetime). Like steel
though, crappy building can introduce weaknesses that override any inherent qualities of the
tubes themselves. In a recent fatigue test I read, two of the frames that *didn't* break
- and there weren't many - were aluminium. Despite its total lack of a safe fatigue limit, a well
designed and built alu frame will outlast a poorly designed and built steel frame. Quality control
and design in bikes is very poor, and there seems to be little accumulated knowledge so
manufacturers keep reinventing the wheel (almost literally).

"Zog The Undeniable" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Ric said:

The titanium frame on one of my bikes has cracked around the pedal

crank. It

Quoted message said:

Quoted message said:

has the look of a typical fatigue crack.

What make/model out of interest?

--
Mark (MSA)

Bike shop assistant... "We couldn't repair your brakes, so we made your horn louder"!

Here you go...this is good fun for debunking the myth that steel lasts forever!
sheldonbrown.comframe fatigue test.htmOpen ↗