Sunday, February 8, 2015

Controltech Stem for Dahon (25.4mm to 31.8mm handlebar)

On my Dahon Boardwalk, I have been using a special stem as an adaptor, to convert the 25.4mm handlepost clamp to use a 31.8mm handlebar. It is a good idea as I get to use a 31.8mm dropbar which is more common nowadays, and has many more choices than a 25.4mm drop bar.

However, one thing that I am concerned about is the strength of the stem. Ever since I detected the broken clamp on the stem, I always worry that the stem might not be strong enough. Even with the replacement clamps from a PRO stem, the base body of the stem might not be strong enough.

Also, although there is no problem with the function of the stem and handlepost, it does not look too neat as there are so many bolts at the handlebar area.

Up to 10 bolts at the centre area. 4 from the handlepost clamp, 4 from the stem, 1 from the Cateye Bar Fly and 1 from the handlebar extension mount.

If I can change the stem, I will be able to reduce the number of bolts around the handlebar area. Also, I can stop worrying about the strength of the stem, if I use a good, strong stem from a reputable brand. The difficulty is finding a good stem that converts a 25.4mm clamp to use with a 31.8mm handlebar.

Most stems that are available only extends the reach, but maintains the clamp size at 25.4mm. An example would be the popular LitePro stem.

There is also an alternative stem for 31.8mm handlebars, the Ridea stem. This also converts the 25.4mm handlepost clamp to use with a 31.8mm handlebar. However, this stem extends rather far forward through multiple joints, and thus will not be as rigid. It also takes up a lot of space on the handlebar which leaves very little room for accessories. Lastly, there are even more bolts and holes on the stem which will look even less neat.

Ridea stem. Gets the job done, but is not an elegant design.

This does not leave me with many choices. Luckily, Controltech has such a product that can satisfy my requirements. It will convert a 25.4mm clamp size to a 31.8mm clamp size. The difference is that it only comes with the clamps, and thus you will need to find a way to attach it to the handlepost.

Controltech 25.4/31.8mm aluminium stem. It also comes in a carbon version, but it is more expensive and also heavier...

Aluminium Controltech 25.4/31.8mm stem, with a weight of 96 grams.

Recommended max tightening torque on both sides are set at 8 N.m Best to use a torque wrench to get the correct torque.

2 separate clamp bolts for the 31.8mm and 25.4mm section. Looks very strong with plenty of material around the clamp bolt areas.

Centre to centre distance is about 33mm, which is smaller than the distance for my other stems.

A very short centre to centre distance. Main function is not really to adjust the reach, but to convert 25.4mm clamp to 31.8mm clamp.

Comes in a pair for use with handlebars. Works exactly like a LitePro stem.

The first piece of this new project is in place! Stay tuned to see how this project progresses, and how I plan to install this new Controltech stem onto the Dahon Boardwalk.


  1. Hi Steve, where can I buy the ControlTech 25.4/31.8 stem in Singapore, and how much does it cost?

    1. You can find it at most places that sell controltech stuff, such as Dahon Pro Shop or MyBikeShop. Around 60 dollars for the aluminium version. The carbon version is more expensive.

    2. Hi Steve- Where can I find this stem in USA. I am in Los Angeles

    3. Check with Thorusa to see if they have it.

  2. I have this problem if I get this adapto, cos I do not have another 25.4mm bar for this adapter to clamp onto. do u have any idea on this?

  3. Is anyone able to find this stem? I have been searching for hours on Google and couldn't find it. Would love to find it in UK


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