I really wish we could buy SPS here in the UK :-(  You can now buy a Wilton interlocking system but I don't think it's as good and costs a fortune.  I only use it for my all-buttercream wedding cakes.  *daydreaming of a trip to the US with a large and empty suitcase*...

If you got the dowels at Michaels they were probably the newer bamboo ones. They stink: https://www.facebook.com/acaketoremember/videos/vb.92855088670/10151703211293671/?type=2&theater

I use wooden dowels, and I've never had a slide or a collapse OTHER THAN when I had a cake with strawberry preserves. That is the slipperiest of all the preserves, so I suspect that might have had something to do with the second cake moving.

When you said you baked, decorated and transported the second one in such a short time...That's just a recipe for disaster.  A freshly-baked cake is much softer and they really need to COMPLETELY cool off, which only happens after a number of hours. Even if you stuck it in the fridge that won't help if your window was that short. Then when you said it had strawberry in the icing, forget it, strawberry is a villain for stability. That would need to be completely cold to transport without the possibility of movement.

When I dowel cakes I use half the diameter of the tier to determine how many dowels I need. Plus one if it's an even number because odd numbers seem more stable to me (not that there's necessarily any science behind that.) So if it's a 6" tier there would be three dowels in the tier below it holding it up. An 8" tier would have 5 holding it up, because that's 4 (half the diameter) plus 1.

I don't bother with a center dowel because that's false security unless it's driven completely through all the tiers and securely into the base board.

If you were just using cardboard rounds you could also look into using poly boards instead. They don't absorb moisture and if the boards get soft that will affect the structure too.

 Always transport cakes cold, and like MKC said, transport the tiers separately over a certain height depending on what you're comfortable with. I'll stack three and bring the rest to assemble on-site, but if there's any question it's safer to transport everything separately and assemble totally on-site.

I'm glad your client was so nice about it! Better luck next time! 

I don't want to make this thread about something else...I think there is a misconception that SPS will hold the cake together. Maybe Leah can confirm, but I think SPS is good to make sure the tiers stay together. The cake can still collapse from the sides during transportation (not sure if I am being clear)

I agree...I leave mine in the fridge overnight before delivery. It takes about 90 minutes to come to room temperature.

MKC and Costumeczar...that definitely could have contributed to the problem as well. The cakes were very soft, I noticed. I tried to put them in the fridge and the freezer as much as I could while I was rotating between them. The filling was also strawberry. The cake (first one) probably would have been fine, had I used SPS and put it in the refrigerator over night. 

And 90 minutes to come to room temperature...Plenty of time to deliver while it's chilled. 

Definitely would have helped to transport the tiers separately and assemble at the venue, as well. Wouldn't have had to worry about the weight shifting those skinny dowels.

So many things I've learned...

It was a beautiful cake! So sorry this happened to you.

I just wanted to share how grateful I feel. Through everything that happened to my poor client's cake, she was so kind and sent me a portion of the refund back yesterday evening. I sent her a thank you email immediately, telling her what an incredibly kind gesture it was and that I was looking forward to providing her with a complimentary cake, when the need arose. There are so many nasty people in this world, and I feel so lucky that she wasn't one of them.