But don't you find it annoying that you can't have internal cable routing on your Cervelo? I'm not sure if the older models had the internal routing, but I have an 08 SLC-SL and was told it's risky drilling out extra holes. It was recommended I get the external cable kit which makes the whole look of the bike spoilt ( at least that's what I think, I've never seen it done). Also considered getting an S3 but what a waste to get such a sexy bike and not have it able to utilise internal routing (it loses it aerodynamic supremecy!).

That front hanger is just rivetted on. Surely to fit a compact it would be a cinch to unrivet the hanger, lengthen the slot downwards with some careful welding, then rivet back on? Has anyone done this? Or is there another way?

Why not just unrivet the front hanger and use a clamp on dérailleur?

"Squoval tubing" means that the cross section of the tube at that point is not circular, but more squared off, so a clamp would not work.

If you're willing to un-rivet and re-rivet the front derailleur mount, then just make new rivet holes about 6mm farther down on the seat tube.

Do you know something I don't about this? I'm not sure what process is used to "unrivet" and "rivet" carbon fibre. Can you give me more details? I think that there's actually enough material on the hanger to grind a little more to allow the compact crank to work. It appears to be a small additional amount of material that will still allow adequate support for the derailleur.

You're probably right, I was only replying to the poster who said why not take off the bracket (to weld it). If you can take it off, then you can put it back on a little lower, no? 

Repositioning the bracket should be pretty straight forward for someone who is used to fabricating things:

(1) drill out the existing rivets,  (2) heat the metal (not the carbon) to soften the epoxy,  (3) pull off the bracket.

(4) Choose the new location,  (5) drill a few small holes, then  (6) install with new rivets.

Probably don't even need to bond it (some other frames rely on rivets only). Touch up the paint if desired. Of course this probably voids the warranty.

Filing is also a good solution, and probably easier. But the material at the bottom of the slot looks a bit thin to me, and I've seen two bent brackets, so would be reluctant to file it there, though I suppose you're right: it could be okay if no "unusual" forces get applied onto the front derailleur.

Looking again at goodboy's pic, I think some further careful grinding with a Dremel will be enough to get the mech low enough for a compact to fit. That plus maybe taking a bit off the derailleur cable housing which isn't going to upset anything. I'm going to get a Di2 front mech and have a play. Wish me luck.

Yup. I agree. I will be going to Italy in May, when I will need the compact crank. I measured up what I needed to grind the other day, and I think its doable too. Please let me know how you make out.....with pictures if possible.

Just one more tip on the Di2 install. Make sure you have a well aligned rear deraileur hanger. R3's are notorious for bent ones, and when I did the install, the rear shifting was not perfect. The Di2 has a +- 12 position adjustment range around the neutral point. Each adjustment "click" is .2mm. On my initial install, I was at the end of the range, and the shifting was still off slightly in the 23 and 25. After checking everything, I noticed my hanger was not aligned. After alignment, the adjustment went back into the middle of the range and the shifting is perfect. Its stayed that way since. The extreme precision of the Di2 will show up any existing imperfections that you used to just put up with.

Just to confirm, here is the link to another discussion on this same topic, and a couple of people who have had success in R3/Di2/ Compact Crank installs. So, it looks like this is a go. Thanks to all for a good discussion on this.

 

http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=67854

Success! Only a very tiny amount of "Dremel'ing needed, and the front derailleur is now perfectly positioned. I am using an Ultegra 6700 50/34 crank. Shifting is great. So, don't worry about R3 Compact Crank, Di2 compatibility. It's all good.

Here's a picture of the "after" with the derailleur in the same postion as the first photo in this thread, so you can compare. Note that the derailleur is NOT positioned for the compact crank in this photo, but there's lots of room now. I've moved it back to reinstall my regular crank for indoor training.