Friday, 27 February 2009

Dahon D7 – Stem Mod






I’ve modified my Dahon D7 handlepost to accept a standard ahead stem, as detailed in a previous post. ‘Modified’ is probably a bit of a stretch – ‘sawn the top off’ is probably a little more accurate.

Last night I picked up a 100mm 10 degree rise four bolt MTB stem from Bikehut (rebadged Tioga) and scurried home, where, while dinner was cooking (primal diet compatible of course – mackerel with broccoli and peas…) I added the stem to the existing post and with some trepidation, trialled the new cockpit arrangement in the street.

It was a total revelation… The D7 now steers like a normal bike, it’s no longer nervous and demanding of constant attention to keep things in a straight line. Also, for the first time, the bike now fits me properly. Indeed, I’ve got enough reach to move the seat to the middle of the rails. The fit is very like the fit on by road bike and MTB.

I also trialled the other important thing – how the bike would fold. It’s inevitable that the new bar arrangement was going to mean a change in the folded size and the folding process, which now goes as follows: 

  1. Drop the saddle
  2. Fold the bike in half
  3. Undo the bottom handle-post latch and lower the post onto the saddle
  4. Undo the top quick-release on the handlepost and remove the handlebar/stem/telescopic bit
  5. Place the handlebar assembly between the two folded halves of the frame (I’ve found that I can pop the luggage elastic from the rack over it to keep it in place)

The fold isn’t as neat and tidy but it actually takes less time to fold and unfold, because there’s less time faffing getting the bars flipped upwards and the stem in the right place for folding. Of course it’s a little bigger folded than before, but it still fits in the end of carriage luggage racks, which is all that matters to me.

This morning I decided to seal the deal and hacksaw the hinge unit from the top of the post. It was a scary moment taking the hacksaw to the top of the handlepost to remove the hinged stem and leave basically a 1 1/8” aluminium tube, to which I reattached the stem.

Riding it to work and back today was, again, a breath of fresh air. Now the bike fits properly, I can climb out of the saddle and use a lot more upper body when I’m riding. The front end is stable, with much better weight distribution and if I closed my eyes (which I never recommend when riding!) it would feel like riding a full sized bike.

All I need to do to complete the job is get a star nut and top cap – not that it actually needs one from a functional point of view, but it will tidy up the exposed end of the handlepost. ***I've since used a tongue-in-cheek solution to the problem - a wine cork ;)***

Anyone else out there done this mod on a Dahon or other folder (I know the SP Brompton uses a similar setup and Bike Friday Tikits are set up like this)

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