tt #3

Could get away with a single shifter if it's only RD. TTF probably have people splitting sets.
If you only run one shifter and one derailler do you still need a Junction A and Junction B? Could you get away with a single 3-port junction A?

Junction A (3 port)

• Shifter
  
• Battery
  
• Derailler
  
  

Need longer cables but what have I missed?

Also need to get a new pic - Position has barely changed, but I've got an 80mm stem on the way, and I want to bring the extensions back a bit (and will therefore probably require a trim). I might experiment with some angle to the extensions too.

20mm Supersonic was on the front all of last season - Has held up fine, but would maybe like a 20mm GP4000ii that I can swap to for riding out to club events. Anyone got one lying around?

55T aero chainring chainring fitted to a Quarq DZero PM - Easy to fit, has been fautless and ended up only about £100 more than a 4iiii that I was considering buying.

I've also got an actual disc now, which I promptly dented when it fell over against my turbo...

eTap?

I know hydration is important but come on, this is a serious build thread.

This is what I had on my Exocet2 - although I have a b junction in my bars/extension now so can use either shifter.

If you keep an eye on ebay/forums etc you can put it together fairly cheap - think I managed it for under £350 including cables/junctions etc

As I understand it you need two junction boxes, even if you’re only running a rear derailleur.

I’m currently accruing the parts to do this on my cross bike, as I’m going to run Hylex with the climber button modification. TRP say you need two junction boxes.

Figured it would be possible. I've read about some interesting ways of linking minimal stuff with MTB bits as well but that's another story.

I don’t think you do.
I remember testing this and being able to just use one. And it could be a b box also. But it was a while back, and my memory is poor.

I have never punctured a supersonic. But I puncture a 4000s, when it was on rear and supersonic on front. Go figure!

I’ve been following TRP’s guidance here;

https://www.trpcycling.com/product/helen-di2-adapter-kit/

Will try it without the second junction box first.

You definitely only need one junction box but it must be an A type one - ie one that has a chip in it to respond to the button press on it for alignment etc. The B type is not needed if you have only 1 shifter - or if you have the 5 port A junction.

The B type junction is completely dumb - its just a connector block.

Thanks Dan.

#hippyisalwaysright

#phew

In terms of kit the minimum you'll need is:

1. 1 battery
   
2. 1 Junction A
   
3. 1 rear derailleur
   
4. 1 2-button shifter (climbers or TT type) or 2 1-button TT shifters.
   
5. Cables to string it all together
   
6. Probably a B junction to connect everything together
   
   

In terms of mods to the frame, you'll need to drill a hole in the top tube just behind the headtube for the Di2 cable to go into. You'll then need some way of getting it out of the downtube - on the P2 I just used the normal cable exit port, which was big enough to get a Di2 cable end out of. Assuming you're putting the battery in the seat tube, you'll also need to open up the hole for the FD behind the BB shell and on the shelf on top of the chainstays. Working out how to cable it all together depends on whether there are any internal bulkheads in the frame. On the P2 it's possible to thread a wire directly from the seat tube, past the bottom bracket, and down into the chainstay.

On the P2 there's a hole at the rear of the chainstay which I used to get the RD cable out, and then used some Sugru to hold it in place around the seatstay. It looks like there may be no equivalent hole on the P3, so you might need to run the RD cable out through the bottom of the BB, and then along the outside of the DS chainstay underneath it.

The big challenge might be the battery. The standard Di2 internal battery is, I think, 17mm wide and I don't think it would've fitted in the seat-tube on the P2. For me it didn't matter as I'd hacked an external battery to make an internal one, and it is much smaller than the factory version. Details here.

I put my internal battery in one of my TT extensions :)

Yep, forgot about that option. I've never liked that idea, although I couldn't explain why even if I tried. On any rational level it's a perfectly sensible option.

I've done 1x di2 on a p2 and I do have both shifters so have
Batter
RD
Shifters x2
3 port Junction a
Junction b
wires

the battery is in the top tube in some bubble wrap, and I drilled a hole in the top tube to put the cables through, junction box sits on top of the top tube behind the stem, it was in a food bag last year but its just taped there at the moment..

I've never liked that idea, although I couldn't explain why

Increased moment of inertia of the steering parts around the steering axis tends to lower the onset speed and increase the amplitude of shimmy. Of course, electric buttons and a lithium battery are not as bad as mechanical shifters hanging out of the ends of the extensions 🙂

plus the battery in mine is at the other end to the shifters, so closer to the steering axis :)

the battery in mine is at the other end to the shifters

I assumed it would be, but even right at the front it would be less of a problem than hefty mechanical shifters.

Of course, if you all got proper electric gears, all this battery placement and frame wiring chat would be moot 🙂

Yeah, we'd be in the "SRAM shifting problems" thread.

Just discovered this brand new tech that is cheaper, easier to install, more aerodynamic than Di2/eTap and never need to mess around with indexing: Friction shifting!

Yes, I'm now running two front derailleur shifters as I couldn't get the gears set up just right - I assume due to the DIY internal routing...

I might install a 44T inner (130bcd) for the hilly SPOCO's in Feb/March - Does anyone have one?

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