Material fatigue

[Simon]

Whilst cleaning my bike a came across this crack (sorry for the rubish pic) at the rear dropout,
now its no where near any of the mods I've done
and its an easy fix,
BUT just wondering if with the age these frames are now wheather there starting to show signs of age related fatigue,
my bike gets riden hard (well I like to think it does)
but I'm not into big jumps etc just general XC/Enduro etc,I don't believe I''ve subjected it to excess stress.
anyone else had similiar experiances.
Simon.

[bmwcarver]

We are looking at the bottom of the swingarm on the drive side right?! If I am looking at it right the crack is running right close to the replaceable derailleur hanger?

Now for the question, you have your wheel in and out quite a bit?!  That area gets quite a load just from clamping down the QR skewer, especially if the face of the dropouts aren't exactly parallel.  We used to check that on assembly at the shop I worked at.

Unfortunately this is a drawback of Aluminum.  It will fatigue if cycled.

[Carbon_Angus]

yes it's fatigue from riding. My LBS has seen the same thing on a few Pro~Flex and other bikes.

FWIW it seems that riding style....doesn't have to be gonzo and constant use will fatigue a frame in it's weakest point over time

It's not so much hard use, just use!

Glad you can fix it, this time! [smiley=laughing.gif]

[smiley=beer.gif]

[Simon]

Yeah its the diagional line you can see at the der
hanger,
No I've not taken the wheel out often but I've only
had this frame around a year so don't know its
history,anyway never seen this before on any of my
previous/present bikes,
pretty sure its just age related this frame is getting on for 10 years old now,and though I've heavily modified it (faux bar conversion) I'm confident this has
has not contributed to the crack,
just wondered if this was something thats common on this bike or bikes of this age,

carbon angus,yep can fix it this time,anyway as you know if it broke in half I'd still find a way to fix it
Simon.

[shovelon]

Hmmm, interesting place to crack. Goes to show you how well built the rest of the frame is.

Did a seatpost repair on the same model frame as yours couple of months ago, and found another crack at the swingarm mount where there is an opening. Hate to have the guy lose his swingarm! Got to say the workmanship in the 857 series is top notch.

Mountain Cycle has alot of cracks at the dropout mounts. GT has alot at the seat mast. Once repaired they seem to last much longer, almost as if they needed the reinforcement.

Maybe carbon has a hidden benefit.

Terry

[Simon]

Hmmm,

Maybe carbon has a hidden benefit.

Terry

Good point Terry,though if the carbon cracks you've pretty much had it repair wise,fortunatly the 4500/5500/Oz appears to be pretty much bomb proof,
not nice to say but seeing other makes, more resent
models to having cracking problems is sort of good news in a perverted way  [smiley=laughing.gif]

Simon.

[colinv]

seen this fault on my mate 857, we had it welded and ground down, this was over 5 years ago and its still going, I've had my 959 swing are repaired twice now and it is as strong as ever, we have a carbon fibre repair facility at work so I just give it to them, trying to design some new carbon bits for them to make for me [smiley=beer.gif]