Monday, August 29, 2011

The Phoenix Project - Dura Ace RD 7800 GS Rear Derailleur

Background on The Phoenix Project is available here and here.

There was never a whole lot of question about what rear derailleur I would get. It had to have enough capacity for a triple and be rock solid reliable. I had been very pleased with the durability and smooth shifting of my Dura Ace RD 7700 GS. Alas, these are only infrequently available new, so I moved on to the RD 7800 GS:

The specs on it are max rear cog of 27 teeth and chain wrap of 37 teeth.  This model, incidentally, is the last of the triple Dura Ace rear derailleurs.  And even if it wasn't, I would prefer the shiny silver-titanium finish and smooth styling to the angular/matte styling of the 7900 series.

Street Cred

Dura Ace rear derailleurs are the best in the world in my book and in lots of other ones.

Gizmo Lust

Gosh, where do we start?  Sealed bearing pulleys, cold forged Dura-Luminum body?  Or how about the flourine coated link pins for lower friction shifting?  And we shouldn't forget the polymer push plate for smoother shifting.

But all that functional nonsense aside, the fit and finish on this derailleur is exquisite, reminiscent of the good old days of Campagnolo C-Record cycling jewelry:


The combination of this derailleur with the Ultegra CS-6500 12/27 cassette and the Dura Ace SL-7700 downtube shifters is putting the 1985 Trek 620 dangerously close to Total Shimano Integration.

Tweed Factor

If I were going to throw down for a Rivendell frame (and be patient, I will someday, especially if they go back to level top tubes), this is exactly the rear mech I would put on it.

I suspect I'm not in the minority on this.  Searching around the web, there are lots more occurrences of Dura Ace rear derailleurs on older models, i.e, level top tube frames like Rambouillet, than on their more recent offerings.

So come on Rivendell, enough with the 650b, double top tube, hyper expensive frames adorned with cheap component drill.

Phony Accent


This is good old Dura Ace, not a copy of anything.

Lily Gilding

Tough call on the lily gilding.  This was expensive, no doubt.  However, it was cheaper than for what I've recently sold a few NOS Suntour 1st Generation Cyclone rear derailleurs.

Plus, you get a lot of value beyond the Dura Ace name on the part.  Here is an interesting comparison of various Ultegra and Dura Ace components specifically trying to determine whether the price differential is worth it.

Honorable Mention

I really wanted to love the Shimano T661 rear derailleur.  It supposedly handles rear clusters up to 36 teeth with a 43 tooth chain wrap capacity:

The 36 tooth max cog capacity on this one is very appealing, especially when I was considering running a wide range compact double.  But as we shall see in a future post, I've moved on from that concept and regressed to a traditional triple with a closer range rear cluster so that I can have some really low gears and tight gear spacing without having a bunch of front derailleur shifting.

This wasn't before I picked up a couple of these derailleurs and some HG61 12/36 cassettes, though, so if I'm ever pulling logging trucks up a mountain somewhere I can just slap one of these on and be good to go.

Running Tally

$3628 USD

We bring forward $3499.  I paid $129 USD inclusive of shipping from some obscure bike shop that was blowing out their remaining stock on Ebay.  This was a bit of a bargain, as these seem to be going for around $160 USD these days.  I recommend picking up one or two of these while they are still available from retail joints as, again, they are the last of the Dura Ace long cage derailleurs.

Organ Sales

$259 USD

Geez, been a while for the Organ Sales section.  We bring forward $103 USD. I sold the Shimano FC-6206 crankset for $110 and the Shimano BR-MC70 cantilever brakes for $46.

The Sausage Factory

There are a lot of horror stories about threading the derailleur cable through the inside of the chain stay on bikes with this configuration.  The Internet abounds with tales of an afternoon spent fishing around trying to feed it through so that it meets the outgoing hole, using magnets and other schemes.  However, it was simple and direct on this bike. 

I do need a tighter fitting step-down ferrule.  An unstepped 5mm is too large for the inset at the end of the chainstay and the 5mm to 3mm step down ferrule that accompanied the derailleur is a bit loose fitting.


Jon said...

I am really enjoying the on-going build reports. Nice bike, too!

Alex said...

I was also dreading running the cable through the chainstay after hearing the horror stories, but when I did it it was completely trivial and came right through on the first try.