[Closed] Ripped out bottle-cage insert, repairable?

Wouldn't be pretty but a jacknut and a washer would probably fix that. Don't make the hole bigger, just flatten with a gentle bit of force and I reckon that'd be ok

If you're going to leave 'as is', I'd be drilling a small pilot hole at the end of each crack to stop crack propogation.
I'm no materials engineer though.

Where are these cracks ?

There are tears which looks to have been caused by the removing of the boss bolt.

Cracks/tears/potatoes/tomatoes. Like I said, not a materials engineer. And we all know what what we're talking about. Either way, introduction of a stress riser, shirley?

Just needs a sticker.

Either way, introduction of a stress riser, shirley?

But they weren't caused by stress, they were caused by removing of the boss bolt as trail_rat said

Those cracks/tears are classic stress-raisers will likely result in crack propagation at some point - seat tube is relatively low stress and given the relative value of the frame, just carry on riding it as is. Can't really think of a cost-effective repair method apart from wrapping it a carbon 'bandage' - 'dales are heat-treated alloy, any welding is likely to weaken the metallic structure.

Ah, this takes me back..!
I did this to my (paper thin) Principia mtb frame. My Dad fixed it with a nutsert (he was in the trade) and it lasted years.
Mine had similar cracks round the hole and I’m sure they were caused by carrying the bike with pressure against the bottle cage. The Nutsert we used was slightly bigger to clamp the cracks.

Funny thing was, I showed the lbs owner who sold me the bike and he said they would’ve warrantied it if we hadn’t done our own modifications. In hindsight, wouldn’t have made any difference, but i was pretty annoyed at the time!

"Just needs a sticker."
hurray.

Tears/cracks.

Thnks for input folks. So far in no partic order:

1 - Jack nut(?) and washer, flatten
2 - Carbon wrap thing?
3 - Drill little holes to stop cracks spreading?
4 - Big nutsert to clamp cracks (fnarr)
5 - Sticker (like an 'ouch' one?)
6 - Leave as is

I like the sound of 4. Would it be worth combining 1,3,4 and some metal weld epoxy stuff?

I'd say so. Get yourself some decent epoxy and bond the nutsert into there.
Should stop any further crack propagation and hopefully stop the nutsert coming loose.

Personally I'd be looking at a combination of suggestions

1) pilot holes to stop it going further.

2) carbon wrap repair. Supposed to be stronger than steal. Someone on here used it recently. Someone with better googlefu skills than me will link it.

3) place a sticker over the top and forget about it.

I'd you need a bottle cage you could put a metal band around it that you can use for frames with no bottle mounts.

IANAE(ngineer)... I dont see any reason for the cracks to spread, but anything to prevent them from doing so would ease your mind when riding the beast.

Those cracks/tears are classic stress-raisers will likely result in crack

In the middle of a seat tube of a hard tail its Unlikely in you or I's Life time

I would get an old seatpost of the right diameter and cut a piece long enough to rest on the bottom one and extend an inch or two above the damaged one. Bond that into place, then drill and tap a new hole so you can attach a bottle cage. Fill the area around the hole and paint it or whack a sticker over it.

Epoxy putty and Fiberfix wrap. Awesome stuff.

Use a small aluminium drift / wood dowel to flatten the flared sections down a bit, use a large flange riv nut. Sorted.

Jubilee clip for the rat look.

I would get an old seatpost of the right diameter and cut a piece long enough to rest on the bottom one and extend an inch or two above the damaged one. Bond that into place, then drill and tap a new hole so you can attach a bottle cage. Fill the area around the hole and paint it or whack a sticker over it.

That's a great idea and could be a very neat repair. You could drill the pilot holes to prevent the cracks spreading too. It would need some care toget the epoxy into the right spot without getting it where you don't want it, further up the seat tube. I guess injecting, dripping or using a small brush to get glue through the hole would be the way to go. If you trued to put it on the insert then slide it down you might lose most of it. Good also need to try to clean and degrease the inside of the tube.

1 – Jack nut(?) and washer, flatten
2 – Carbon wrap thing?
3 – Drill little holes to stop cracks spreading?
4 – Big nutsert to clamp cracks (fnarr)
5 – Sticker (like an ‘ouch’ one?)
6 – Leave as is

7 - Weld a spoon into it

I would get an old seatpost of the right diameter and cut a piece long enough to rest on the bottom one and extend an inch or two above the damaged one. Bond that into place, then drill and tap a new hole so you can attach a bottle cage.

I like this idea a lot. Good suggestion. Cleaning the inside of the tube is the only tricky issue I can see, but as a repair it would surely be a solid fix and cosmetically invisible if I also drilled and filled the small tears away before touch-up paint/sticker.

Use a small aluminium drift / wood dowel to flatten the flared sections down a bit, use a large flange riv nut. Sorted.

'riv nut' 😑😉
This could be a great and simple solution, just not sure the tears would allow it. Unless after de-flaring the hole I could somehow combine epoxy and nutsert to bring it all back together. Sounds dodgyish?

I would get an old seatpost of the right diameter

Potential issue - aren't seat tubes reamed to ensure the seat tube fits properly? Is it possible the seat tube won't be a consistent internal diameter at that depth and you wont' be able to get the section of seat tube down there?

you wont’ be able to get the section of seat tube down there?

Getting it in probably won't be the difficult part.

But they weren’t caused by stress, they were caused by removing of the boss bolt as trail_rat said

Stress is the force divided by the area. If you decrease the area you increase the stress for the same load.

The key part is whether there is enough material left to resist the force and wether the tear is likely to continue.
As its a seattube and the cracks wereent formed by a fatty* bouncing his arse on the saddle will probably be okay.

So basically it is a stress riser it just not a concern probably.

Also *not calling mr malvern a fatty.

Wasn't a spoon

Those cracks/tears are classic stress-raisers will likely result in crack propagation at some point

would run with that call....

here's an off the top of the head tick list:

is the material prone to fatigue cracking Tick
are there stress raisers present Tick
is the site cyclically loaded Tick
is there a change from the original design Tick
is there less material present than in the original design Tick

to clarify fatigue cracks start and propagate from a stress raiser - could be a void or inclusion in the metal, rough machining, a micro crack formed when a weld cools

some sort of reinforcement may work and pretty sure people have got away with it ... the emphasis being on got away with it

(not an engineer do have a degree in metallurgy never worked as one...have had to deal with the commercial consequences of high performance alloy failures on a routine basis)

I don't dispute it's a stress raiser.

I just wouldn't be worrying about it due to location.

Being a Cannondale I'm more worried about the head tube coming off.

Seat tube all the way to the bottom after pasting epoxy in and around hole from outside through the hole.
Drill new hole for rivet nut.
Fit new rivet nut.
Sure one of us on here can help with the rivet nut depending on where you are.

Is it possible the seat tube won’t be a consistent internal diameter at that depth and you wont’ be able to get the section of seat tube down there?

Good point. Luckily I tried the existing (long) seat-post pushed all the way to the lower insert, and it (snugly) fits all of the way down 👍🏼

Brake cleaner & an adapted baby-bottle brush should get the inside of the tube clean enough.

Being a Cannondale I’m more worried about the head tube coming off.

🤣 This is the third of these (2001 F500) that I've owned, others were moved on and I always regretted selling. (Massive) head tubes intact BTW. In fact, I never had a problem from them, even with a fat man hooning them over rocks down Dunkery and Horner Woods. This will be the one to go won't it? Third time unlucky... 😬

Thanks nofx, btw, great cleaning tip. This place still amazes me often, and thanks all for taking time to advise.

Disappointing update. I had a ride on it and what used to be my favourite bike feels utterly crap since being spoiled by better geometry (for my type of riding) and fatter tyres. Sold to someone who wants to do it up 😎