Cracks in aluminium frame: repair, or no repair?

I’m looking for a bit of collective STW wisdom on this, although I suspect I know what the answer will likely be.. 😉

I have a 2008 Kona Jake the Snake cyclocross bike that has done me well over the last 8 years I’ve owned it. Unfortunately I noticed a crack that had developed around the bottom bracket / seat tube junction, which is about 4cm long.

I talked to frame building specialists, Vernon Barker Cycles about this and they suggested they could repair the crack for £90, which seemed okay.

Now I’ve stripped the frame down ready to send off – I’ve discovered a second crack at the headtube / downtube junction, which is about 1.5cm long.

I’m sure Vernon Barker would be able to repair this one too, but there is a part of me thinking that this is the frame’s way of telling me enough is enough.

My head says – stick the frame on the wall, but my heart wants to be able to ride this bike again, as it’s a bit like an old friend with many miles and memories.

Is such a repair a good thing to do, or should I just leave it be?

(I’m somewhat guessing I know what the answer will be here.. 🙁

It’ll work for a while, how long, no idea. More cracks will crack.
Enjoy the time you’ve had together and move on. Put the money into a new frame IMO.

Fiberfix it.

Result would look awful though.

Crack at the headtube = time to retire it.
I’d be tempted to risk the back end failing in use after a repair but not the front end.

Does that £90 include the heat treatment and new paint? If not good luck riding an Al frame that hasn’t been heat treated…

I would probably bite the bullet and replace it – assuming you’d be looking at £180 for a frame that’s obviously tired and might well crack elsewhere, even assuming heat treatment would be performed on the repairs.

I’d be interested in whether heat treatment would be performed though?

Crack at the headtube = time to retire it.

This. It’s time is done.

I had a steel frame repaired with a new headtube. I wouldn’t ride an alloy one with the same.

Aluminium has a finite number of stress cycles it can go through before it is fatigued and will start to come apart, it sounds like you’ve reached that point to me! 🙂

Personally I’d say it’s time to wave goodbye and recycle your frame. I had a similar situation with an aging kinesis frame and found cracks around both rear drop outs. No idea how long they’d been there but decided it was time to scrap it.

Okay… thanks guys. Some sage words that pretty much confirmed my own sense of sensibleness. On the wall it goes then… 🙁

But hey, at least I get to keep all of my teeth, etc. 🙂

BTW – that Fibrefix ad is hilarious!!

absolutely best excuse for a new bike.

Isn’t it poor that so many very expensive bikes seem to crack like this?

I’ve discovered a second crack potentially life threatening defect at the headtube / downtube junction

no_eyed_deer – Member
….BTW – that Fibrefix ad is hilarious!!

Love to see someone tack a set of tubes to make a bike with it.

What’s the worst that could happen… 🙂

One crack on an expensive frame I’d get repaired, two I’d not bother, it probably means it cracked at one point and the whole frames flexed enough now to cause the rest to fail.

Isn’t it poor that so many very expensive bikes seem to crack like this?

Well the solution would be heavier frames, but no one wants that.

thisisnotaspoon – Member
…Well the solution would be heavier frames, but no one wants that.

Well some of us do. 🙂

It’s hard to break a Reynolds 531 ST frame.

Aluminium has a finite number of stress cycles it can go through before it is fatigued

So has steel, unless the levels of stress are very very low. Certainly far lower levels than are seen in performance bicycle steels under moderate bicycle usage.

It’s hard to break a Reynolds 531 ST frame

Not that hard. Dad’s only broken frame was a woodrups 531st custom built job that gave up last year.

philjunior – Member
‘It’s hard to break a Reynolds 531 ST frame’
Not that hard. Dad’s only broken frame was a woodrups 531st custom built job that gave up last year.

Where did it break?

Chainstay just behind BB?

Haven’t run across any of them that have broken before.

Aluminium has a finite number of stress cycles it can go through before it is fatigued and will start to come apart, it sounds like you’ve reached that point to me!

Whilst this is true it doesn’t mean that the whole frame fatigues at the same rate. The level of degradation due to fatigue depends on the number of cycles AND the stress concentration. In this case the cracks have appeared at those areas subjected to higher stress concentration and therefore areas of lower fatigue resistance/life. So if the repair involves removal and replacement of original material in this area then the resulting repair may very well serve you well for another long and happy service life.

Or alternatively it’s a great excuse to buy a new bike.

[Quote]Certainly far lower levels than are seen in performance bicycle steels under moderate bicycle usage.[/quote]

This I did not know! I suppose it hinges a little on what ‘performance’ means. I have a Surly Troll that I’m hoping will last for ever…

All correct wobbli. But how do you propose removing and replacing the fatigue damaged material? Because it isn’t just the weld but also the surrounding parent metal, so quite a lot of fresh air to fill 🙂

In aluminium planes they generally patch repair cracks to spread the load into the surrounding less fatigued material. And on steel frames, brazed or silver soldered sleeves or patches work well. So epicyclo’s suggestion of a wrap repair isn’t actually daft. I seem to remember Mike Burrows advocating a similar head / down tube repair using grp.

In the lab at work (non bike) I rarely see a successful simple weld repair of any kind of fatigue crack. So I’d go with hang it on the wall or get inventive and try to find the Mike Burrows article (think it was in CTC mag)

Epicyclo-Drive side chainstay fairly close to the bb. Took a while to notice, he just couldn’t work out why the gears kept ghost shifting.

8 years is good going for any bike thats been ridden a lot

definitely new bike time!

philjunior – Member
Epicyclo-Drive side chainstay fairly close to the bb. Took a while to notice, he just couldn’t work out why the gears kept ghost shifting.

The reason I asked is that some builders only use the good tubes for the main triangle.

The reason I asked is that some builders only use the good tubes for the main triangle.

531’s not been in production since the 80’s has it? Don’t know which tubes were in the ST range but it was only the wall thickness that changed wasn’t it to cope with panniers? What i’m getting at is, is there anything cheaper than 531ST apart from 531?

531 still available direct from reynolds, just limited diameters and lengths. Many things cheaper than 531 available, from plain guage steel tube up to reynolds 525.

Well my Reynolds list from 1994 only mentions chain and seatstays below 531 as 525 cromoly (501 and 500 just listed for main tubes). Also common for builders to use other people’s stays.

531ST is just a bit thicker in most of the tubes than say 531C. Chainstays 0.9mm vs 0.8, seatstays 0.9 vs 0.5, then 0.2mm difference in the comparative seat / top tubes and 0.1mm in the down tube.

531AT a bit thicker again.

Stuff like 853 only appeared in the late 90s, and 531 was still widely used for quite a while.

Steel chainstays also fail behind the bb partly due to corrosion from water collecting.

mick_r – Member
Steel chainstays also fail behind the bb partly due to corrosion from water collecting.

Mainly on welded bikes because the tubes often butt up against a blank rather than a hole.

Lugged bikes tend to drain into the BB.