The Dentist's Chair - Cervelo S2 Di2

I'm sure you could get away without having to open up the BB hole if you went with an external cable connector, but it would be impossible otherwise (except for putting it in the seat-tube, which I'm still considering doing) as the internal connector is simply larger than the hole.

I've been eyeing up the cable stop on the chainstay - can't decide whether to remove it or not. Part of says me it won't do any harm just leaving it there.

I did remove the chainstay cable stop in the end - drilled out the pop-rivets and levered it off with pliers. There's some sort of glue bonding it to the chain-stay, but it gave up eventually given a sufficient amount of BF&I. I've covered up the holes left by the pop rivets with a circle of frame protector material.

In order to get the Di2 battery inside the seatpost I needed to modify both the battery and the battery holder so that the former would fit inside the seatpost and the latter inside the seat tube. Of course it's now possible to buy a proper Shimano seatpost battery, but when I bought this lot it wasn't available. I hacked the battery to reconfigure it, while keeping all the internal electronics, some time ago, and I've now modified the charger so that it connects up to the battery. The thing in the charger is just the end of the battery casing with wires soldered to the tabs in the casing, and hot glue to provide a bit of strain relief. The flying leads are then connected to the RC servo connectors I'm using.

It's also necessary to modify the battery mount as the mount has electronics in it which need to be retained in order for it to work. If you strip down the battery mount, and hack away the plastic casing, you're left with this - a small circuit board encased in potting compound. The connector you can see is the standard Di2 2 wire connector which I've stripped down to expose the contacts.

On the other side there are two tiny contacts which the connectors in the battery mount connect up to. They're very small, so I got my friendly tame electronics genius to solder flying leads onto all four contacts. Then I soldered another RC servo connector onto one pair, and spliced in a standard Di2 cable onto the other pair, and wrapped up the electronics in heat shrink.

That got stuffed down inside the seat tube, wrapped in foam, and then I connected up the battery and stuffed that inside the seatpost, again with foam to hold it in place.

And I've finally finished threading the cables through the frame. The BB hole now has nice round corners, and the cables you can see here are the one which goes to the battery and the one which goes to the handlebars.

Threading the cables through the frame involved TIG welding rods, spoke nipples on lengths of cotton, bits of insulating tape and lots and lots of swearing. I thought I'd got all the cables in place, popped the frame on the stand, and then realised that I'd put the rear derailleur cable through the non-driveside chainstay. Cue lots more swearing.

Still, they're done now, so it's time to fit the derailleurs and cranks. And fit the tyres onto the wheels.

Dan. You are mental. (In a nice way) :)

Yeah, the stem was an experiment from the Red Bike which then grew a longer stem. It's a 90mm stem IIRC, and I normally have a 110mm. It'll do for now in keeping the handlebars off the floor.

Clicked on that link expecting to see some sort of pornworthy bike with SRAM Red on it. Oh dear.

I'd expected fitting the front and rear derailleurs to be nice and simple. The rear was, the front wasn't. The Di2 front derailleur has a little grub screw in it which is designed to brace the derailleur against the frame. Mr. Shimano provides some little stick-on metal plates to protect the frame from the end of the grub screw. However, due to the aero-shaped seatpost on the S2, and the funkily-shaped front derailleur mount, the grub screw was left dangling in the air, even when screwed in as far as it would go.

According to Damon Rinard on the Cervelo forum there are two options. One is to install the front derailleur carefully without the bracing screw and hope. The second is to build up a mount for the grub screw to rest against from epoxy metal putty. I went for the third option, which was to make a small aluminium block which fits against the seat tube, and over the lower part of the front derailleur mount. It's quite a complex shape, so I used my milling machine to rough it out and then finished it off by hand. The little recess is for the head of the pop rivet on the front derailleur mount

I glued it into place using the old bodger's delight, JB Weld, after giving the areas of the frame and FD mount I was attaching it to a bit of a rub down with some wet and dry to give the JB Weld a key to bond to.

And now the grub screw has something to push against rather than thin air:

I've now also glued the tyres (Vittoria Corsa CX Evos) onto the wheels (Zipp Firecrest 404 tubs). I knocked up a quick gluing stand on Saturday morning so that I could glue both wheels at the same time without using my truing stand for the job.

They're both done now. I've preloaded the tyres with some Pit Stop Evo TNT sealant (a very messy job) which has at least done an excellent job of sealing up the valve extenders. I've also fitted the cranks (FSA SLK - I think Ultegra cranks are very fugly, and that's despite owning two pairs) after having chased out the BB threads and faced the BB shell. So at the moment, things look like this:

Oh, and I've also swaped the stem for one less likely to make the Bebejeezus cry. But that's for my benefit, not his.

Next up, brakes and shifters.

the excellence is popping through the imperfection of your photos.
It is going to be good

Good work on the mech-adjustment enabling plate.

I have to admit to going "yes, like that, good, OH GOD NO" however, are you sure you want to use those cranks?

Your favourite company use them on some of their bikes.

Yeah, I like the FSA SLK cranks. Better than Rotors anyway, which I still think are seriously aesthetically challenging.

And yes, my photography is crap. Crappy camera, and insufficient time spent getting a clutter-free background.

I've connected up the shifters, pressed a few buttons, and there are whirring noises and things start moving. At least I know I haven't blown anything up by connecting things up the wrong way round. More to follow...

these cranks could work with some black rings I believe. osymetric:D

Not convinced by Ozymetrics. If I go for black 'rings, I'll go for Praxis Works chainrings. But I actually quite like the shiny silver rings. All black is so 2012.

I've got the Praxis rings, they are good but I feel that they are sometimes too happy to release the chain.

I've got Praxis rings on my sram red chainset - they are mega stiff. Changes into the big ring are really nice, changes from big to small less so unfortunately though..

I pulled the chain off the big ring when cross-chaining up corkscrew hill.

Hardly the fault of the rings it is true, but didn't happen with the old rings wen I abused them in the same fashion.

High torque cross chaining? User error ;)

One of the advantages of Di2 is the ability to run satellite shifters, including the climbing shifters mounted on the top of the bars, as seen here in Dammit's photo. However, they're a bit fugly in my eyes, the cable comes out of the LHS of the box, despite needing to go over to the right, and the buttons seem to me to be the wrong way round.

If you take the box apart, you end up with another small box of potted electronics like this:

Ignore the three coloured wires - they're a later addition, courtesy once again of my tame electron herder's soldering skills:

I've soldered the flying leads onto two small tactile buttons designed for PCB mounting and, using some spare handlebars wrapped in tape, I've encased them in PU sealant. This serves two purposes - firstly, it keeps them in place, and secondly it provides a ridge around the buttons to prevent the bar tape from activating them even if it's wrapped tightly. I hope it does anyway.

The PU sealant is busy hardening while I ignore the more important jobs to do before tomorrow's bike fitting...

so you will be pressing them through the bartape?

That's the plan, yes. According to this chap it should work.

the tape he is using must be thin if he can feel it even through double layer

I got my climbers switch mostly because I like gadgets, but they're actually one of those semi-jokey things that you buy and then end up using a lot.

Being able to shift from a couple of different places is, I suppose, one of the USP's of Di2, and one that a lot of people (TT'ers apart) don't in general experience I think.

...wait until you see the chain.

I'm starting to have second thoughts about my decision not to go for the all-black option for the DLC chain. Too late now.

Fox to the thread, calling Fox, Fox to the thread now please

Well, at least it'll get dirty. And wear out. Please God let it wear out.

#pukesoncock

WTF were you thinking?