bikeclub

My Bike Friday Tikit has been having some problems. It’s a hyperfold model that I bought in 2016, just a year or so before they stopped making them.

Last year I was riding it and the hyperfold stem was excessively loose and popped open while riding; I managed not to crash but had to tighten the cable at a LBS to get home.

Tightening the cable tightened both the stem, but also the steering, since the hyperfold cable feeds into the bottom of the fork. But now the bearing at the bottom of the fork that allows the fork to spin freely around this funnel-shaped piece where the hyperfold cable feeds in has failed.




Bike Friday says that they no longer stock this part. The option they’ve offered is to replace the existing fork, headset, and a new removable stem riser, which sounds like a new PakiT feature.

In order of preference, I’d like to:

1. Find a replacement bearing
2. convert it somehow to the simpler model T mechanism
3. convert to this stem riser (least desirable).

Any ideas?

tudorowen1

Go with the simpler Model T..

biker101

I had several problems with this trumpet bearing. When BF send me a replacement and I tightened the stem, it stopped rotating freely. After one more attempt, I gave up and converted to the model T. I think the hyperfold is over-designed and not worth maintaining.

linberl

Call Bike Friday and talk to them, or post on the BF facebook page. there are many tikit owners there who have dealt with the cable.

tcs

OP sez:


Poster suggests:
Shakes head.

I'm shocked that BF doesn't still have a small bin or shelf of replacement Model T tikit stem assemblies, since the originals failed (resulting in injuries) and there was a big recall effort trying to get them replaced. That said, be wary of 'net offers of a Model T stem - there's plenty of the old ones that snap off around.

Could an old, failure-prone tikit Model T stem be sleeved/reinforced by a skilled frame brazer and returned to safe use in the repair of a hyperfold tikit? No idea, but it might be worth pursuing.

bikeclub

Hi all, thank you for your advice and comments. After visiting my machine shop -- I'm lucky to have a great one where I work -- a colleague and I decided on this fix, based on looking at how Brompton hinges work, and the following logic:

1. the cable is doing the work of holding the pac-man clamp in, and therefore the pac-man clamp does most of the work of holding the halves of the folding stem together
2. from experience, the cable solution is unnecessarily complicated and hard to adjust
3. BF however, does not have any old Tikit parts anymore and has only offered the removable stem option
4. looking at the existing cable holes, they fit a 6-32 or M4 threaded rod
5. so I put a threaded rod in; anchored it with two nuts lightened against one another; and then put a wing nut on the outside.

The solution is about as tight as the original cable before I tightened it too much, which probably helped to destroy the trumpet bearing. I may class it up with a nicer bakelite handle or another kind of handle, but so far this solution cost me $2.

Pictures below:

bikeclub

In case you're wondering what the Brompton hinge clamps look like, they're similar but bigger, which makes sense, especially since they use the same clamp where the main frame beam splits.

bikeclub

Also, a couple of people suggested that I contact BF. I have corresponded with them, but their main answer is that they don't service the Tikit anymore; and offered either to build a new fork or a discount on a new model. I don't really like either option, so am going with the cheap hack / fix for now.

biker101

Nice work.
I am wondering: Can you put an M5 thread on the 4 mm hole? Then you would have something very similar to the model T solution.