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Wednesday 25 December 2019

Derailleur front mount cover

On bikes that ship without the front derailleur but with the welded on mount, they usually have a blanking cover on the bracket.

Typically a plastic tile or even an aluminium shaped billet. Easy enough to buy but also very easy to model and 3D print.

I've created some custom ones.

3D printed.

I filled the letters with Milliput and sprayed with clear lacquer.


25.4mm wide, 26.5mm tall, 4.6mm thick, 2mm radius corners. 5mm wide x 2.2mm deep keyway on the back. Fit using an M6x10mm or M6x12mm countersunk screw.


Sunday 15 December 2019

Fitting dropper posts

This weekend I fitted two dropper posts.  One was the old Rockshox Reverb that Roy and I had serviced a couple of months ago, fitted to Roy's Whyte. The other was a new Rockshox Reverb Stealth (B1) fitted to my Giant Stance.

Internal Hose Routing

There are plenty of videos showing how to fit dropper posts, so I'm not going to repeat those excellent tutorials, however, what many of them assume is that you are replacing an existing dropper.

I was threading a hose through the frame of a bike that had not had a dropper before. That makes getting the hose in place a whole lot more difficult. The reason I chose the Rockshox over other makes was because, apparently, the hydraulic solution is more tolerant of tight bends. I'm glad I did.

I thought I might be able to use the cable threading fishing tape and rods, that I already have, to get the hose in without removing the bottom bracket from the frame. I was wrong, the local bike shop was right! I had to remove the bottom bracket.

The bottom bracket is a SRAM DUB pressfit and I found a couple of videos showing how to remove and install similar.

Luckily, one of the many articles I looked at mentioned to watch out for the spacer (4.5mm) on the right hand, chain-ring, side. It would have been very easy to miss that. It just pulls off or drops off while you are not looking and rolls under the work bench!

I was glad I had bought a drifting tool designed to remove push fit bottom brackets. Without that I don't think there was any chance I would have got the job done. I only bought a budget tool from Amazon. It needed the splines bent out a fraction but worked fine. I needed to use a lot more force than I was comfortable with but the job needed to be done.

I'm pretty sure that drifting out the bearing housing from the frame is very likely to have misshapen the bearings. They still run, just, but if I was doing it again, I would have bought a new bottom bracket, rather than re-use the one I took out. A new bottom bracket is on order.


  • The right hand end of the inner sleeve of the SRAM dub pressfit bracket is fixed to the bearing cup. The left hand cup slides along the tube with a fine washer to seal the gap. That allows the same component to be used for both 89.5mm and 92mm shell widths. (SRAM part number 00.6418.016.000)
  • With the SRAM dub pressfit, it is only necessary to remove the RIGHT hand, chain ring, bearing, along with the inner sleeve, to be able to thread the dropper hose.

I wasted a fair bit of time trying to fish through the frame. Once I had the bottom bracket out, I could see that was never going to work.

There are flanges, lips, where the tubes join. It was hard enough getting past the flanges when I could fish in there from both ends.

With the hose routed, the rest of the jobs were relatively easy. The bearing press I had ordered had not arrived, so I used a long M14 bolt with some big washers, which I had to hand.

It needed some care to ensure it was pushing in straight but the nuts, bolt and washers, worked perfectly as a bearing press.

Everything else was as per the SRAM video.

Sanding the inside of the top tube, using friction paste, torquing up the saddle stem, adjusting the length of the hose for the handlebar remote and fitting the remote.

Not forgetting to slide on the grommet before attaching the remote.

Finally fitting the saddle. By which time it was late and very dark, so I test rode it the following day.


External Hose

That next day, I fitted the externally routed hose on my brother's bike. That was much easier.

I 3D printed some hose guides so that it did not touch the tyre or anything else when in the dropped position. It needed two guides but they worked well.

As an extra job I tried to adjust the front derailleur because initially it would not move up or down a gear. Again I followed an excellent video.

Although I have managed to get it working, it is not very positive. I'm fairly confident that too many of the components, including the chain-rings are just too worn.

As a side note, I found a way to stop the rubber ends falling off my work stand clamp. As simple as a couple of cable ties!

Roy's Whyte is now in a rideable condition and my Giant has a nice new dropper post, ready for those steep hills.


Download 3D models:
Dropper Tube Guide, STEP, Fusion 360 and STL files (Zip)
Licence attribution - small business exception


Saturday 7 December 2019

Sources of components for 3D models

When creating models, quite frequently, I use standard, nuts, bolts, extrusions, motors etc., even linear rails and other more complex, off the shelf parts. 3D models of many of these are often available from the manufacturers but it can be difficult to find or even to know which manufacturers provide 3D models that are suitable to include in my own designs.

The following are sources I use to look for pre-built 3D models of components: - many suppliers include their models on this site. Available in numerous file formats. - this vendor has all sorts of fixing, nuts, bolts, threaded rod and many, many more. Their site is also included under the insert menu in Fusion 360. - this tends to be individuals who upload their own designs.