Thursday, May 5, 2011

Techie Tuesday - Ultegra 6703 Shifters & Drivetrain

Amazing Shimano 12-28 Gearing
 I'll come back and update this from time to time, or link this in a post if I have a lot to say after using the system for awhile, but I thought it time to give my 2nd impressions after a half-dozen rides.

First, I have always loathed the stupid cables sticking out of the sides of Shimano shifters, so one of my initial attractions to the 6700 was getting rid of shifter cables sticking out into otherwise clean air and making a mess of the bike aerodynamics before there's much chance of do anything about it.

Second, I bought my Roubaix with 9-speed gearing at a substantial discount with the intention of riding that gearing until it wore out, or something close to it. That time had come, and I wanted a 10-speed system, or Campy 11 speed. The Campy's price was just too high going forward as their cassettes are ridiculously priced.  I'd also bought new rear wheels - a primary and a backup - and they were Shimano splines.

Third, the more I rode in the aerobars, the more convinced I became that Shimano's system is more precise when dropping the chain down the cassette. No way I was going to pay DuraAce prices to get that though. I also considered the Shimano 105 shifters, as they too have the new hidden shifter cables. The price difference didn't seem that much though, especially since I got all of this gear for what works out to be about 33% off at Performance Bike Shop.

I've waited about 8 months to pull the trigger on this, but when PBS opened a new store in Roseville, Ca, and offered 15% off, even on special orders, AND cash cards for old inner-tubes, lottery wheel spins, the first 100 people to show up for each of 3 days, and mentioning the bike club, I knew it was my time.

These same 3 days were also double dividend days, so that kicked in 20% on 85%, plus the cash cards. Also, PBS's prices on Shimano were already near the best to be found online, and being a member, I got free 2 day ground shipping to my front door. Pretty compelling.

Threading the cables is a bit tricky on the 6703's. The left and right shifters are threaded completely differently, as the internal mechanisms are completely different. The instructions are horrible, and I put a kink in the right shifter bad enough that I threw it away, a victim of really crap documents.

Once you figure out that you need to keep clicking the small lever that releases the cable the full 9 clicks, it's silly simple. What's described as a "view hole" is actually the hole you thread the cable through, and the extended discussion of the winding spool and cover plate are just a whole lot of mis-direction.The left shifter is pretty easy to thread too, but if you try to thread the right one the same way, you too will destroy your cable with a bad kink.

With what turned out to be $150 of dividends, I splurged on a carbon fiber set of bars with internal routing for the hidden cables - unlike my old bars. The new routing, swapped shifter cables, and swapped brake cables, convinced me to go slow and do a lot of trial fitting before I started cutting cables and cable housing.

The old bars were always a stop-gap, but since I ride in aerobars so much they were kind of irrelevant as long as I rode alone. I'm riding a lot more club rides now, so need to be on the hoods or drops, so based on a strong RX from a club rider with a severe elbow injury, I pulled the trigger.  With discounts, I managed to get PBS's house-brand Forte` bars for ~$100. They felt a bit rubbery when first on the bike, but seem pretty solid when climbing out of the saddle - so far so good.

Nobody at Performance knew if those bars were rated for clamp-on aerobars, and one mechanic laughingly suggested I tighten them until the main bar cracked and then back it off a bit. We had a good laugh about that. The stem clamping area is roughed up a bit to give it some tooth. Not so the clamping area for the aerobars. I was holding my breath, and ended up doing an initial tightening at night, and then a final tightening the next afternoon.

When you go from a 9-speed system to a 10-speed, you have to toss all of your old cassettes and buy new ones. Since Shimano has abandoned the work-horse 12-27 in favor of the 11-28, targeted at compact cranks, I was SOL - or so I thought. I studied the cassette gears thoroughly and found that if I took the spidered gears from the 11-28, and put them on a 12-25 I ended up with a completely stock 11-25, and an absolutely fabulous 12-28.

Now,  when I say absolutely fabulous, I mean the granularity of my 46/38/24 and 12-27 9-speed gearing, and the range of a 52/39/28 and 12-28 WITH NO 15T-17T gap - the one right in the power band. The first time out the gears were so lovely and intuitive I came home and put the gears into my gear chart. OMG, the best gears I have ever found. 12 through 17 in 1-tooth increments, and then fast ramping when you don't have time to drop the chain up front. Every time I do dump the chain up front I land on a gear so kind I wish I had selected it. Really and truly fantastic gearing.

The actual gear cogs are also much better made. They appear to be machined, and are the full thickness where they engage the freewheel hub. The CS-6500 9-speed cassettes were stamped, and therefore, pinched thin. A recipe for tearing out the splines on alloy freehubs. I am lucky to have Shimano 6700 steel freehubs though, as some of the spline engagement dogs have been removed from the middle gear cogs. Something to think about carefully if you have an alloy freehub.

I also bought a new rear derailleur, as Shimano warns that the 28T requires their new one. It's OK, works fine, is crisp, but nothing to spill a lot of electrons over.

Finally, I spent the money for a DuraAce chain, since the 9-speed chain won't cut it with the narrower spacing. It shifts like a dream, and is so gorgeous you just want to drown one in Lucite and make a paperweight out of it. I also really like the single pin connecting system, and it's easy to find on a hollow pin chain. The end of the self-guiding, solid, "bullet" link pin snaps off, so I'm sure it's case-hardened to within an inch of its life, and will therefore outlast the rest of the links.

For the first time ever, after adjusting the drivetrain on my stand, I went for a 20 mile ride and adjusted NOTHING. It was dead-solid perfect. The front derailleur now downshifts like a cannon. It's been a long time since it shifted that well. The rear shifter is almost perfect, and getting better all the time.

One thing worth mentioning. Although it added some work and worry, I crossed the cables under the downtube to get a straighter path for the rear shifter cable. It also makes the downtube slightly more aerodynamic I imagine, but that's not why I did it. It seems to be one of several things that makes for very crisp shifting, except for the transition from the 4th to 5th smallest cogs in back - but as stated, that's getting better as things settle down.

The ergonomics of the shifters are definitely better. I had a pretty bad thumb-web injury from the old shifters, and these have not aggravated that at all after the long layoff due to the collarbone break allowed a full healing.

Between that and the CF handlebars, the ride has noticeably smoothed out. I also took almost a pound of weight off the bike, and it's apparent  when I pick the bike up and move it around. I think it's a bit more aerodynamic too, as the cable routing and aero shape of the bar top are keeping the airflow nice and clean.

All in I spent just under $500, the list price on the shifters alone. It was 3-days work to get everything perfect, but a truly wonderful ride I am going to thoroughly enjoy this May - Bike Month!

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