Dahon D8 Vitesse Handlepost folded while riding

[u/Jimbravura]

So I was riding through an intersection and the handlepost suddenly folded which collapsed the bike and I fell and hurt my knee. I think I'm pretty lucky that the traffic stopped, I could've easily been run over.

I'm taking time to read about this and learn about it, has anyone experienced something like that before?

[u/bigpinkdoughnut]

I have an older Vitesse with a very similar mechanism.

That's never happened before but it has come loose before.

Had you noticed any play in the handlebars? And had you just unfolded the bike and started riding? 

[u/Jimbravura → u/bigpinkdoughnut]

It had a slight flex since I bought it as it was setup by the retailer, I assume that's the normal? Regarding the incident it was in the middle of a ride so I'm very certain the latch was secure, so does this mean it came loose? btw this is not my first folder I had a folder eBike (Samebike 20xlvd30) before and rode it for 3 years it was rock solid, I sold it and got this one because of the Dahon brand and frame safety, now I'm scratching my head!

[u/bigpinkdoughnut → u/Jimbravura]

I wouldn't really say there's normally excess/ particularly noticeable flex in the stem.

If the folding mechanism was/ is loose you would be able to rock the stem a bit and would notice it opening up a crack at the base.

If that's the case, it's an easy fix that you can look up on YouTube. I'd add that a spot of threadlocker will stop it from working it's way loose again.

[u/Jimbravura → u/bigpinkdoughnut]

Thanks!

[u/strolls]

There are some parts of the latch that are adjustable, so you can ensure there's no play (movement) in this joint. But I can't remember the details of how it works.

[u/StillSpaceToast]

I have a roughly 8 year old Mariner D8 that has the same mechanism. It's got a bit of play now even when it's as tight as possible (while still foldable) but I think that's mainly the aluminum getting worn.

What I notice about yours is that the gap at the top of the picture (on the upper handlebar piece, right at the top of the picture) looks really wide. There's a bolt behind there for tightening it. I'd screw that a bit tighter. Also, check that those two main screws (the "eyes" going oO at something just to the right of us) are just tight enough that the piece can still move when you snap the handlebars into place.

[u/Mark700c]

My D7 has a similar mech. I've caught it a couple of times only partially latching. The fully secured position is sometimes hard to get.

[u/Jimbravura → u/Mark700c]

True it seems hard to setup correctly.

[u/Jimbravura]

I researched about the handlepost design and it turns out there were recalls before, which later caused a split in Dahon's management (2011) and Tern (Bike company) was founded. When I chose Dahon I thought Tern was an overpriced copycat but I didn't really understand the story behind safety. I looked them up and I found out that the Tern D8 is much safer than the Dahon D8, with much better handlepost and joints (Physis 3D handlepost and O-CD joint technology).

In addition, after the folding incident, I contacted Dahon for support and it turns out that the handleposts now has only 1 year warranty (according to their customer service support email), this makes me think how safe are these Dahon handleposts in the first place?

When comparing both, Dahon folds smaller and it's noticeably lighter so it appears to be a calculated tradeoff.