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Cannondale T2, is this frame OK?

Stephen Carson2025-10-17 11:58:08

Please see related thread 'Cannondale Fatty Fork Failure'

Frame - Cannondale T2 2010

Purchased second hand so no detailed use history

Recent front fork failure, see other thread, hence scrutiny of the frame

Me - life long cyclist, experienced amateur mechanic, I'm not a materials or tandem expert.  Limitations - I'm visually impaired so at my limits re. inspecting the frame.

Problem - photo's probably reasonably self-explanatory regarding my concern.

Both distal seat stays (drop out end of the tube), underside and inside I have noticed hard lumpy (almost feels like a bit of weld) area with some paint loss - for context, just under the S of USA - same place both sides.

What do I do next - my thoughts are that I need the frame inspected, but by who, where, what with?  I'm located on the Greater Manchester / Yorskshire / Cheshire border OL5

I feel very responsible for Des and Chris who pilot for me, they are good friends and they trust me regarding tandem care and maintenance.

Any help and advice greatly appreciated - if your response is 'I wouldn't ride that' please will you give me some more info, I'm genuinely seeking good sound advice and knowledge,

Thanks in advance,

Steve

Stephen Carson2025-10-17 12:10:40
Next 2 photos are non-drive side
Stephen Carson2025-10-17 12:12:15
Stephen Carson2025-10-17 12:13:09
Stephen Carson2025-10-17 12:13:42
Next 3 photos are drive side
Stephen Carson2025-10-17 12:14:31
Stephen Carson2025-10-17 12:15:19
Robert Lyon2025-10-17 12:43:05
Just looks like the paint is flaking off. There is a small (vent?) hole in the tube which is probably where the corrosion started. Sand off the loose paint i guess? I can't see it being an issue but highlight it to your pilot's and make sure they are happy with it.
Ian Condie2025-10-17 17:27:21
I have an identical Cannondale T2, and it has suffered from identical patches of corrosion under the paint for a few years now.  It doesn't seem to be getting any worse, and it doesn't appear to be in any highly stressed areas of the frame - I'd be more concerned if it was corroding around e.g. the rear bottom bracket area.  The frames seem to be generously proportioned in terms of the amount of material used, and there is the addition of a lateral tube running from front to back. If you do have ongoing concerns though, sand the corroded areas back to bare metal and inspect the integrity of the tube before etch priming and painting the tube again. Incidentally I also have a couple of Santana tandems, and my eSCApe one which is made from scandium alloy had a corrosion problem too on the captain's seat tube around the bottle bosses.  It is superlight for a tandem, weighing 27lbs all up, the alloy is barely more than a millimetre thick, and the corrosion went right through the tube - see photo.  The Santana doesn't have a lateral tube either, so all of the frame tubes are under much greater stress.  Even though it was well out of warranty, Santana agreed to replace the seat tube FOC and I just had to ship it back to the factory in LA.
Stephen Carson2025-10-17 21:31:43

Robert and Ian, thank you very much for your well received advice. 

I've taken another look at the frame using a 'pokey tool', yes - these are drain holes much to my relief, I hadn't even realised there were hole. 

I've had a read up on aluminium frames and corrosion, advice seems to be quite reassuring. 

I guess I had become a little 'spooked' following the fork failure. 

Plan going forward - Des is an engineer (tool making, medical grade injection moulding).  I'll get him to inspect the area (and whole frame) with me, take some paint off and then prime / make good - I'd like to try and leave the 'handmade in USA' decals undisturbed if possible.

Once we are satisfied I'll get a new fork ordered, I was wondering if I needed to cut my losses but I'm feeling very much reassured currently. 

I / we really like the bike, you take chances buying second hand, this looks like it's going to work out.