My trusty old Scott Genius has gained a rather unhealthy looking crack along the seat tube/top tube weld.

Warranty ended a few years ago, so my instinct is to carry on riding and see what happens, but I’m wondering if and how it’s likely to fail and if there’s anything I can do to prolong its life.

I don’t think there is any riding left in that, however that weld looks really scabby!

Long seatpost and drill small holes at each end of the crack.

If I really liked the bike I’d weld up the crack, add a couple of bigass gussets and hope for the best.

My approach would be somewhat different if it were at the headtube, but I’d risk it where that crack is.

How much seatpost is in the frame?

Welding and gussets on an already fatigued aluminium frame without post weld heat treatment usually just results in more (often faster) cracking.

Drilling the ends will help slow it (a bit, not much). No harm in doing it.

It will probably start heading round the back of the seat tube rather than completely detaching the top tube (but can’t be certain as it hasn’t got conventional hardtail seatstays to support the area).

On my home made steel frames, I found that seat tubes that stick up quite high above the top tube make things worse at that weld. So you could try trimming 20mm off the top which might slow it down (might need to extend the clamp slot a little).

Mike Burrows always used to advocate fibreglass and resin wrap repairs on cracked aluminium (was once an article in ctc mag about it). You could even use hemp like bamboo bikes (that actually isn’t such a daft idea!)

My old BMX had a similar issue (it was cracked the whole way round though). The seat would rotate doing some stunters which was a bonus – lookbacks/turn-downs were more tweaked than with a proper unbroken frame. It never fell out/off but i wasn’t really using the seat for anything practical. As above – drill the ends to prolong it and keep riding until it breaks then keep riding it still. If the twisty seat is off putting then bin it or sell it on here as a ‘custom’ frame 😀

https://goo.gl/images/m4GeXM

Bend the arms and attach to the frame with a big bolt.

[video]https://m.youtube.com/watch?v=haPvuhznuyI[/video]

Thanks for the input. There’s 14cm of seat post in the tube which puts the tip just below the bottom of the top tube.

Interesting idea about trimming the tube a bit. I can see that that might reduce the chance of the crack spreading around the back of the seat tube, but without seat stays I think it might increase the chance of it spreading further round the weld.

I’m not looking to spend a lot to keep the frame going, just happy with the bike as it is and no desire to replace it. Time to start looking around for a new frame.

Good excuse to move on from the PITA DT EQ2 rear shock!

Get it welded and you’ll be right.

I cracked my Commencal just like that – went all the way around with about 20mm holding it together. Had it welded and ran it for another year or so, gave it to a mate who has been using since, no bother at all.

I think it cost me all of £25 to get it done then a mate powder coated it for me – looked rad, best weld on the frame 😆

have you spoke to Scott? they may do you a cheap(er) replacement frame under crash replacement

I’ve seen worse than that successfully repaired.

For reference to the above…

Good excuse to move on from the PITA DT EQ2 rear shock!

Hasn’t been serviced in eight years and still working just fine. The top shock mount develops play after about 3 minutes of riding, but I can’t fault the shock itself.

Something is making me want to suggest Fibrefix…

I’ve not come across it before, but it might just the right kind of bodge to prolong its life. On the other hand, 2nd hand 26″ frames are cheap… maybe it’s time for a change.