Barry2 

I’m looking at a 2008 Cervelo P2c 10sp Ultegra and wondering if there are any obvious gotchas in switching to 11sp Ultegra Di2 ?

FD, RD, Cassette, Shifters, all got to go. But are the mounting points for 10sp the same for 11sp ?

Thanks

Barry

Iride01 

You might need to consider where you are going to put the Junction A (ew-rs910) or one of the other types pictured.



https://bettershifting.com/building-...s-do-you-need/

I don't think your bike has the standard bars this fits into. The other two Junction A's are fully external and will detract aesthetically IMO. Otherwise you are probably good for everything else. Though double check your brakes, not certain those older brakes have the same pull. So those might have to go too.

I have seen some of the EW-RS910 on some bike put on an access panel for the downtube that a lot of recent bikes with large down tubes seem to have nowadays. Also I think I remember seeing one in a hole drilled into or maybe specially made in the top tube of one bike, but I might be delusional.

There might be some more recent models of the Junction A, so you'll have to check on that.

Barry2 

I've seen the Junction in the Bento Box (or whatever they call it.

Why do the brake calipers or levers need to be changed at all?

Barry

Iride01 

They probably don't. I'm just guessing at stuff since I've never owned a TT bike or whatever that bike properly is and was just going by a quick look at a pic google came up with. Plus I've only ever dealt with Di2 on STI equipped bikes.

Weekends tend to be slow here, but maybe someone that knows better will answer if this thread doesn't get buried by other subsequent threads.

cxwrench

The P2C wasn't designed w/ Di2 in mind. It's possible, pretty much everything is. I don't remember what that frame looks like inside but I'd damn sure take it apart and make sure you can route the wires through the frame and there's a place you can put the B junction. You're gonna be wanting to use the standard SM EW-90 Junction A under the stem, if you're using normal brake levers and just shifters on the extensions you can use the 3 port. If you get the brake levers w/ shifter buttons you'll need the 5 port box. You only need to run 1 wire from the front of the bike to the middle, then the 3 other wires branch out to the rear der, front der, and battery. Speaking of the battery, you're gonna probably mount that in the seatpost OR in the seat tube. Can't remember if there was a kit to mount it in the post or if it even fits.

alcjphil

All of this is great advice and totally valid. However for a TT bike I would wonder if the effort is in any way going to offer any meaningful reward. Most time trials are over relatively flat or undulating courses. The sort of quick gear changing provided by DI2 is kind of superfluous to the needs of anyone apart from a top pro. If you are serious about improving results, invest in training. I once won a Canadian National TT championship on a 27 year old converted road bike.

Barry2 

Bit of a thread derail, but sure, I’ll bite.

I’m a, 58yr old, for fun, diabetic, cyclist.
I’ve never been in a race, and have no plans to do so.
Despite the above, I’ve had a professional cycling coach since my 2019 return to cycling.
And now own a 2022 Cervelo R5, not because it made me faster, but because I just wanted one.
I’ve never ridden a TT bike, but thought it might be fun to try, and I like Di2 on my bikes.

I reject your reality, and substitute my own!

Barry

Edit: and I like wrenching a lot

icemilkcoffee 

For retrofitting an older bike, it seems to me the SRAM etap groupsets are far better. There are no external wires, no external batteries, no junction boxes etc with SRAM.

Iride01 

Do you really feel that Di2 is quicker shifting? I don't. Not compared to the 105 5800 group that I came from. With the 105 I could make very quick in succession shifts. And on the downshifts with the big lever grab two to three gears lower (larger tooth count cogs) on the rear with ease on just one lever throw.

For my Ultegra Di2, It's not speed of shifting. In fact I am still not quite happy with the interruption to my cadence that sometimes happens when it shifts from the big to small ring and also has to shift the rear two or three cogs. With my cable pulled stuff I was able to do that with more minimal interruption of my cadence. And yes in eTube I have set the shifts to happen very fast.

Where Di2 shines is in the lack of need for periodic adjustment, IMO. And as time goes on and manufacturing costs continue to get lower, then I expect to see electronic shifting on the lower tier bikes of the future.

squirtdad

Nice mythbusters reference.

maybe you can borrow/try riding a TT bike to see if you really like it first? before the tinkering starts? and then if you really like it see if you can find one set up for Di2 (or even a new one with the 105 di2?)

have fun any way you go

Barry2 

Iride01 yes Di2 is quicker. When configured to do so, it’s fast and will go from one end of the cassette to the other with a single long press of the button.
plus, I get to change gear from the extensions as well as the aero bars.

squirtdad I wrench on many bikes, but I have a rule of only crashing the ones I own. (Where possible)
As my first attempt at a TT, a sub $1k bike is ideal.

Barry

alcjphil

Thank you very much for the additional information. It is very useful. The Cervelo P2c is very much a bike designed for competition, whether individual time trials or triathlons. You say that you have never ridden a TT bike. Before modifying this one, ride it as is after doing a proper fit. Fitting a TT bike is a huge fiddle, tiny changes in fit have to be made before you get things sorted out. In my younger days, I was something of a TT specialist having won a national masters championship along with several podium spots in Quebec provincial races. As well, I was involved in multiple team time trial races at distances up to 100 km. TT bikes are not all that much fun to ride, they don't handle as well as a regular road bike(not helped by the position you are in). They can have strange frame geometry(my Look 496 has extreme toe overlap which is pretty common). One thing that TT bikes are great at is going very fast in a straight line, but not so good when the road gets twisty. Even very good TT riders have had bad crashes in training(think Chris Froome). All that said, before investing in what could be a very expensive upgrade path, just learn to ride the bike as is to see if it is going to be a bike that you want to invest time and money in
As an aside, with rare exceptions you will need a new rear wheel

Iride01 

Not from my experience. However it is pretty close. I already mentioned that in eTube I set the values for front and rear DR to very fast. What else can I do to make it faster?

Though perhaps it's just that I had my 105 5800 adjusted perfectly and kept it adjusted to shift perfectly. While Shimano specs say I should have only been able to pull two clicks at a time with it, I was able to pull three clicks at a time with the big lever shifting the rear to lower gear ratios. And shifts seemed to complete on the rear with only a 1/4 turn of the crank.

cxwrench

The extensions ARE the aero bars. You can shift from the brake levers and the aero bars IF you buy the Di2 TT/Tri brakelever/shifters. On a TT bike you have 'base bars' and 'aero bars/extensions'.

Barry2 

Well you got the gist of it.
I meant the sticky-out break thingies.

Barry

(Yes I did spell it Break, just to annoy the spelling police)

Barry2 

You can set the allowed steps/cogs to unlimited.

Barry

Iride01 

I'm not quite certain what you are talking about here. However if it's what I'm thinking it is, then it's that way by default. Or at least the mechanic that set up my bike originally configured it that way.

The longer I continue to hold down the lever or button the more it continues to shift. And as I said, I have that set to happen "very fast" which in the 3.4.5 version of eTube that I use is the fastest setting there is.

Barry2 

I'm using E-Tube 5.1.0.8
IIRC On R8000 shifting setting per button press are 2 cogs, 3 cogs, unlimited cogs.

Barry