Brimstone

I had apparently EXACTLY the same thing happen to my Mini stem. Complete with shorts-staining traffic incident. You can see pics of before and after I had it welded here under the Dahon handlepost recall thread:

https://www.downtube.com/Folding_Bike...read.php?3,699

GOOD LUCK finding a replacement stem. The only one I found was at a Dahon dealer in England who, when I told him it was for a Downtube, told me to go suck eggs. Yan told me I was SOL, just get it welded.

I tried to buy the older style Dahon 1 1/8" stem from Thor a couple of years ago to fit the vertically adjustable handlepost but he sent me the wrong thing and I never follwed up. Boy do I regret that.

I considered buying a lot of these from China, very cheap of course, but the smallest shippable quantity was 50.

My weld is holding BUT I still have wobble, about 1cm. Apparently it comes from the design whereby the actual quill wedge is inserted into the bottom of the handlepost and held in place by two set screws. Probably so that 1" or 1 1/8" quills could be interchanged for manufacturing versitilty. It seems the play from the steel quill wearing on the aluminum ahndlepost is causing wear, and I theorize the motion induced is transmitted to the hinge weld and destroys it. I'm considering driving a couple of finishing nails into the small space between the top of the quill and the handlepost to shim it.

I'm also considering trying to fit the new, weird Dahon stem to my steerer tube...maybe by threading the inside of it? Or maybe welding the Dahon contraption to an Ahead stem riser with a 1 1/8" quill. Any thoughts on this anyone?

Or maybe I'll come to my senses and throw the damn Mini in the dumpster while I'm still alive.

Please let me know how things work out for you, especially if you find a source for a 1 1/8" folding stem.

jur

An easy solution would be to get a quill-to-aheadstem adapter and fit a modern handlepost such as a Dahon or one of those posted earlier.

rhm

I have been having a bizarre problem on my Mini handlepost so I thought this an appropriate place to mention it.

The QR that keeps the post upright sometimes fails. That is, suddenly, while riding, it slips into folded position, making steering problematic. When this happens, as long as I keep the handlebars upright (i.e. I press forward on them a little) I can keep control of the bike to get out of traffic and retighten the QR. And every time this has happened, the QR had not come undone; it had somehow pivoted so the handlepost got loose.

What exactly is happening? I don't know! Nothing is broken (including, so far, my teeth). Still, I worry....

Obviously my chief suspect is user error; but since this has happened a half dozen times over the last year, and with increasing frequency, I've become increasingly cautious. Now I always make sure I have tightened the QR correctly; and even so this happens with increasing frequency (and completely without warning).

Has something like this happened to anyone else?

jur

Perhaps the QR sliding surfaces are worn? With lower cost QRs, the plastic may wear through and them you have lost the resilient block that is an important part. The movements from riding the bike and pulling on the bars can easily work it loose if there is no 'give'.

Also, maybe some mild Loctite in the thread to prevent it from turning?

rhm

1. The QR's sliding surfaces do appear to be worn, which is puzzling; how could they be worn? I'm thinking I may be able to fix the problem with a flat file; if the parts don't mate perfectly there will be movement that may be causing the problem. But removing metal seems a bit drastic....

2. Yes, good suggestion, I'll have a look at that resiliant block; I'm pretty sure it is not missing, but it may have lost some of its resiliance over the last 33 months and 7000 miles.

3. No, Loctite is not the answer; the QR adjusting nut is not turning.

Above all, though: I'm wondering if anyone else has noticed this!

jur

Actually I meant worn through or at least very thin, not missing as in fallen out. Ie missing a thick amount of plastic; so, not much resilience left.

Wearing would be inevitable - dust and grit would settle and with each operation, erode some material. I think a new QR or at least a new piece of plastic would be worth investigating.

Are you lubing the sliding surfaces from time to time?