Focus Paralane: Fork and Headset

Following up from the Focus Paralane frame details, here is the info for the corresponding carbon fork and unique expander design.

Focus Paralane carbon fork, in the matching Racing Green colour. Front brake hose enters from the top and exits at the side of the fork leg, same as most other forks.

Production code of the fork is manufactured into the fork itself.

Also uses the RAT thru axle design at the front. This design is patented by Focus, and is not widely used.

The "nut" for the thru axle is fixed to the fork by a bolt. Can be replaced if necessary.

Flat Mount brake caliper mount on the front fork. Good to see that the surface is flat instead of bring painted over.

Mounting for mudguard stays. The mudguard stay will stick into the hole as shown, and be fixed by the set screw as shown above.

Threaded insert at the back of the fork leg, also for mounting the mudguards.

As the stack of this frame is really high, I expect to set the stem at the lowest possible point on the steerer tube. This means that cutting the steerer tube will be necessary, as I do not want a tall stack of spacers above the stem.

Upon removing the included top cap, I noticed something special inside the steerer tube, which I have not seen before. Normally, for carbon steerer tubes, an expander will be placed inside to grip onto the internal walls of the steerer tube. However, this looks different.

Is this an expander? Looks different and works differently, as I could not loosen it to remove it.

This is what the manual that came with the Focus Paralane bike shows. Obviously what I have on the bike is different from what the manual states.

Time for Doctor Google to come to the rescue! I found some info in an obscure forum, talking about the expander used on the Focus Paralane. Apparently the mechanism inside is like a wedge, that is pulled upwards when the top cap is tightened. To loosen it, I need to screw in a long bolt, and tap on the bolt to loosen the wedge. This reminds me of the eccentric BB that I had on my Avanti Inc 3, where the wedge needs to be knocked loose first.

I inserted a long bolt, and knocked it to loosen the wedge.

The wedge will push against the knurled sleeve as shown below, when it is being pulled upwards by the top cap bolt.

Knurling on the outside of the sleeve, and a sloped inner surface (look carefully!) that interfaces with the wedge to act as an expander.

The top cap is also of a special design, with a spring below the top cap.

This design is really unique, but sadly it does not seem to work properly. First of all, the sleeve is so far below the stem clamping area, that it does not support the steerer tube internally. Then, it tends to slip when I tighten it. The spring design is puzzling as it resists the pre-loading of the headset bearings.

Stock expander and top cap design. Lightweight but does not work well. Perhaps I am using it wrongly?

Decided to switch to a conventional expander design.

Using the Cervelo top cap from my Cervelo Aspero, which I could not use because of the PRO Vibe stem.

New conventional expander plus top cap assembly weighs 62 grams, which is 20 grams more than the stock assembly. This includes a slim spacer and the stock tapered spacer.

Before cutting, the fork weighs 376 grams.

After cutting, it weighs a bit less at 370 grams. Almost as light as the Canyon Endurace CF SLX fork (361 grams).

I am happy with the weight of the Focus Paralane fork, as it is within the expected weight. The frame weighed a bit more than expected, but still acceptable.

In summary, the frameset (frame + fork) weighs 1375 grams, which is pretty OK. I couldn't find any lighter frameset with integrated mudguard mounts.

Frameset weight (with cut steerer tube)

Fabike C3: 1296 + 512 = 1808 grams

Cervelo Aspero: 1177 + 416 = 1593 grams

Focus Paralane: 1005 + 370 = 1375 grams

Canyon Endurace CF SLX: 807 + 361 = 1168 grams

As you can see, all are carbon frames, but the weight varies greatly. I am still amazed at how lightweight the Canyon Endurace frame is, given that it is not even claimed to be a climbing frame, but is instead an endurance frame.

On the other hand, the Fabike C3 weighs more like an aluminium frame, and I can save over 400 grams just by switching all the same components over to the Focus Paralane frame.

Stock headset of the Focus Paralane weighs 63 grams.

The first quirk that I have discovered on this Focus Paralane frame is the expander plug design, which is a bit more lightweight but does not work well. I'm sure there will be more as I continue building the bike.