Thursday, October 4, 2018

Fabike C3: Frame and Fork

What are the important attributes that a commuting bike should have? For a start, it should be able to handle all kinds of weather, especially rain in Singapore. Of course there is no snow here, but that is extreme and will require a special kind of bike.

In Singapore, there is only rain or sunshine. Any bike can handle sunny days, but not so many bikes are able to handle wet weather well. By handling, I mean being resistant to rust even when not serviced after riding in the rain. Normal bikes with derailleurs cannot handle wet weather well, as there are many parts in the drivetrain that are prone to rust, such as the chain, cassette, derailleur.

As for braking, rim brakes don't perform well when the rims are wet. Without a doubt, hydraulic disc brakes are more superior in this aspect, as they maintain excellent braking performance regardless of weather.

Lastly, a commuter bike must be able to maintain its function well even when not being serviced much. Although a bike with derailleur can be ridden in the rain, it needs to be serviced quite often, or the drivetrain will rust and not work well.

A summary of features to look for in a good commuting bike was already prepared before, just check out the link for the details.

Key requirements for a good commuting bike:
1) Disc brakes, with hydraulic type strongly preferred for more power
2) Belt drive, to make it maintenance free
3) Internal hub, to have multiple gears for efficient pedaling, and yet low maintenance
4) Mudguards to prevent road spray when riding over wet roads
5) Stainless steel hardware on bike to avoid rust

My previous commuting bike, the Avanti Inc 3, satisfies all these conditions. As with most of my bikes, I have modified and upgraded the parts extensively from the original components, until only the frameset is left.

The Avanti Inc 3 is a good bike and I have no regrets getting it, but I had 2 main complaints about it.

1) Aluminium frameset seems to be quite heavy, made even worse by the internal hub (+1 kg from normal derailleur bikes, based on whole system)
2) Unusual geometry. It is a small sized frame but with a long top tube and short seat tube. This means a less responsive ride, and also requires a very short stem to work. Probably works well for a trekking bike, but not for a road bike style which I preferred.

Other than these issues, it is a perfect commuting bike. I had upgraded it to a drop bar bike with Alfine 11 Di2 shifting, but it still does not ride like a road bike due to the geometry and the weight.

I have considered getting a new frameset to replace the Avanti Inc 3, but it is difficult to find a suitable frameset, especially a carbon fibre frameset with the requirements listed below.

Main requirements for the frameset:
1) Carbon fibre frame for lighter weight.
2) Belt drive compatible. This means having a split seat stay design.
3) Eccentric bottom bracket is strongly preferred for belt tension adjustment.
4) Mudguard mounting points are necessary.
5) Internal hub compatible, with rear 135mm OLD.
6) Disc brake compatible, with Flat Mount preferred for a cleaner look.
7) Road bike geometry, as it is my preference to have it ride similarly to the Canyon Endurace.

If you try to Google for such a frame, it is impossible to find a frame that has all these features. From what I see, the rarest combination of feature is to have a carbon frame that is belt drive compatible.

I chanced upon a picture of a belt drive bike by Fabike, which seems to have some of the features listed. After emailing Fabio from Fabike, I found that they were actually developing a new frame, the Fabike C3, which has all the features that I wanted! Fabio was also very patient and detailed in answering all my technical questions.

The Fabike C3 frame was not quite ready for mass production yet, so I had to wait patiently while they got it ready. Finally, after some waiting, the frame was ready for purchase, although not through the official website yet. After making the online payment, the frameset was sent to me, which took a few weeks as it passed through a few countries.

Finally, the Fabike C3 frameset is here! The C3 frameset was first shown at Eurobike 2017, but even until now (September 2018) it is not offered officially yet. No matter, now I have the C3 frameset, and it satisfies all the requirements that I had.

Fabike C3 carbon fibre frame! Looks very much like a road bike frame. I was in between XS and S size, but Fabio recommended S size to prevent toe overlap as I wanted to install mudguards.

Headtube with the Fabike badge in blue, and the ports for inserting the Di2 wire and the rear brake hose for internal routing.

Integrated headset design, no need to press in any headset cups. Just place the sealed bearings in and you are ready to go!

Two bottle cage mounts are available! Very useful to have.

Integrated seat clamp design. There is a choice of colours for the anodized parts on the frame, I chose blue, out of the other choices of red, yellow, green, black.

Plate on the seat tube which covers a hole. You can install a front derailleur mounting bracket (not included) and leave it open to run a Di2 wire for the Di2 front derailleur. I don't think it is possible to run a mechanical front derailleur on this frame.

Bottom bracket shell. Press Fit 30 size, which means that you can install an eccentric bottom bracket using this! More on that in another post.

Flat Mount disc brake mounting on the left side chain stay. Hole for running the rear brake hose internally.

View from outside of the rear brake mount. Mounting point for mudguards on the seat stay, as shown by the bolt.

Mounting point for rear mudguards is hidden under the seat stay bridge.

Joint on the right side seat stay, which splits open to allow the installation of a belt. Also note the special dropout design.

Parts of the rear dropout includes the two special non-turn washers on the left and the two aluminium black axle bushes on the right.

Non-turn washers slot into the dropout, and the profile in the middle locks onto the hub axle which has two flat profiles, to prevent rotation.

The black axle bushes have a chamfered profile, which centers itself onto the chamfers on the dropout. Main purpose of this special dropout design is to avoid the use of conventional non-turn washers on the outside of the dropout which can be unsightly.

Frameset also comes with a carbon fork, which has a really long carbon steerer tube.

Oversized carbon steerer tube. Although the surface condition is not so nice, it does not matter as it cannot be seen once installed, and does not affect function anyway.

Internal routing for the front brake hose!

Brake hose exits near the front brake caliper. Also note the subtle Fabike branding on the inside of the fork legs.

Flat Mount brake caliper mounting, for a clean appearance.

12mm thru axle for mounting the front wheel, which is better for disc brakes. Location of the bolt indicates the mounting point for front mudguards.

Another view of the front fork legs

Mounting point for front mudguards is hidden at the back of the front fork

Weight of Fabike C3 frame includes seat post clamp, non turn washers and axle bushes shown here. 1296 grams, which is quite heavy considering that the Canyon Endurace frame weighs only 807 grams!

Weight of fork is including compression plug (28 grams). Actual weight of fork alone is 512 grams (uncut). Also considered heavy as the Canyon Endurace fork weighs only 361 grams.

The total frameset weight is thus about 1808 grams, not including the headset. From this, we can see that this is not a lightweight carbon frameset. In fact, the weight is similar to that of a good aluminium frameset that has a carbon fork (about 1400g + 400g).

Other than the weight, here are some other details of the frameset:
1) Seatpost diameter is 31.6mm. Due to the curved shape of the seat tube, it will only be possible to insert 120mm of the seatpost into the frame. This means cutting of the seatpost is almost guaranteed, as the insertion length has to be between 100mm (usual minimum insert length) and 120mm (maximum insert length allowed in this frame).

2) Wheelbase is 995mm, which is short for quick steering, just like a road bike.

3) Chainstay length is 415mm (BB centre to rear dropout, not accounting for eccentric BB adjustment). This includes the clearance for rear mudguards, which is impressively short. The Avanti Inc 3 has a much longer chainstay length of 444mm.

4) Thickness of rear brake mount (Flat Mount design) is only 7mm. This is thinner than the minimum of 10mm as recommended. I'm not worried about the strength of the mount, just that I will need to get the shortest bolt and still add spacers to make it work.
Recommended bolt lengths for different frame mount thickness.

The introduction of the Fabike C3 frameset is complete! Although this carbon frameset is not that lightweight, it is still quite a bit lighter than the current Avanti Inc 3 aluminium frameset. Also, it has some unique features that cannot be found in 99% of other carbon framesets, such as belt drive and internal hub compatibility, eccentric BB, Flat Mount disc brake mounting.

In the next few posts, we shall take a closer look at the other parts of the frameset, such as the special rear dropout, the eccentric BB and others.

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