Wednesday, June 10, 2015

Ultegra 6870 Second Thoughts, Third Thoughts, And Fourth Thoughts

Frequent commentator Damon pointed out in response to my recent Habanero rebuild that I was missing one of the biggest benefits of Di2; the TT shifters. He's right of course. In fact for the last week I've had a set next to the bike and just hadn't yet installed them.

Well, that's done.

So I took care of that last night. Along the way, I wrapped the aero-bars, something I've never done in many years of aero-bar use. Not sure I'll like it, but willing to try it out to see.

I'm also trying to replace the wire cover with electrical tape. Not sure yet how well the electrical tape will adhere to titanium.

 If it works, though, it's definitely quite a bit more subtle than Shimano's black wire covers. It blows my mind that Shimano doesn't sell a silver Di2 wire cover. It is tempting to use a strip of silver reflective tape. Could make for a cool effect at night.

The Use Case For Di2

So I like my Di2. I think it shifts well, and after a few rides I've largely gotten used to the different feel between 6700 and 6870. But I don't think it is anywhere near justified for the average cyclist (myself included). But there are some cases where I think it makes all the sense in the world.

Time Trial Shifters

See above. While this isn't a game-changer, it is a very nice feature. I'm still getting used to the fact that I can shift without pulling a hand back to the brifter, but as a result I'm shifting more and weaving less. More than once in the past I've whacked the pad of my aerobar when shifting. I'm not sold on the sprinter shifters or the climbing shifters. But then I'm not a sprinter or climber so maybe I just can't understand.

Tandem Bikes

OK, bear with me here. I only have a few hundred tandem miles, but I've noticed a couple things that are a real bear to deal with.

First, the cable runs are long. On my Hab tandem frame, I think I measured more than 70" from the brifter to the rear derailleur. And that of course means plenty of opportunity for cable stretch or frame flex to affect the shift quality. The shifting goes out of whack regularly. What an ideal application for Di2!

Second, remembering which chainring you're in is a pain. We have a triple, and while we're usually in the middle ring (being a slow tandem team, and all) sometimes we're actually in the little or big and then stuck in the wrong ring on a climb. XTR Di2, which supports shifting both the FD and the RD to provide 'sequential shifting' would be awesome for this.

Want a harder gear? Push the 'up' button, and the FD will figure out how much it and the RD should shift. That would be awesome for a tandem! Now, the problem? The XTR FD won't shift a road chainset well, and the XTR crank is a 38x28. A 38x11 isn't a terribly stiff gear. One could run a SRAM 10x42, but not sure whether synchroshift would know what to do with that.

Anyway, I bet within a year there will be some great Di2 options for tandems.

Poorly Shifting Bikes

Max' Cannondale falls into this category. Beautiful bike, but put a lot of torque into the frame and you'll get ghost shifts. I imagine this is due in part to its super short chainstays. A friend's Kestrel has a similar problem.. These bikes are ideal candidates for Di2, where cable stretch and frame flex is irrelevant.

The Future Of Shifting

Anyone who reads this blog, which is practically no-one, knows that I'm an unabashed lover of the 1x10 drivetrain for mountain biking. I've converted most of my mountain bikes to 30T or 32T chainrings. Some don't yet have a 40T or 42T cog, but probably will soon. The math just works out. Unless you're a XC racer trying to hammer double-track at 25MPH, you don't need a 42x11 (or bigger), and all but the toughest climbs can be conquered with a 32x42.

So where does that leave road? I have already converted my rain bike to a 1x10, but I'll admit that for road use my current setup is lacking. Part of that is down to the 12x27 cassette (I have an 11x36 I'll be installing), but even then on a road bike you likely will want to hammer at 25MPH or faster on occasion.

So I don't think we're quite ready yet for single-chainring road bikes. But I predict that the next step to 12-speed cassettes will be the beginning of the end for the road front derailleur. Imagine a 44T chainring with a 10-11-12-13-15-17-19-22-25-29-34-40. That gives you nearly the same top-end as a 50/11, and a ridiculously low granny. Count me in.


Max said...

Having now seen the Di2 on the Habanero in action, including the aerobar shifters, I'm sold. For mine, of course, I need a new junction box and the shifters. The bars and everything else are in place.

Nice report. Thanks for running the experiment.

sam said...

Are you sure you'll need a new junction box? My shifters have 3 ports on them; I just plugged the TT shifters into one of the ports. Of course it means unwrapping the bartape from your tops, but otherwise it may just plug in.