Thursday, 3 December 2009

Mechanics view - New Shimano 6700


This week was the first time I've had to play with new Shimano 6700 and really look at it as I was doing a build from scratch on a Merida frame.

First impressions on getting especially the chainset out of the box were not good - it looked a bit low-rent & plasticky. That feeling disappeared as soon as I got the shifters and mechs out, though ... very competent execution as far as the aesthetics go.

The big news, of course, is the hidden cables (it's only taken them 15 years .... though to be fair, Dura Ace had concealed cables last year). The STIs themselves have had a hefty revamp and you can see the influence of SRAM in some of the aesthetics, and of Campag in the slightly heavier, more positive shift.

From a mechanics point of view, the levers have a couple of irritating design features, though.
First is the way that you have to take the plastic covers off the top-front of the shifter / brake lever unit to get the brake cable in (or to inspect the nipple end) - I can see a lot of those timy wee grub screws going missing on hotel forecourts where mechanics are working late at night & in a hurry, next season - I reckon we'll see quite a lot of the plastic caps they retain going walkabout, too :-(

The other irritation is in fitting the gear cables - again, I guess it's no better, no worse than the new Campag Ultrashift, but the SRAM system is easier for sure. The brake hoods are quite stiff (especially in a cold workshop) & peeling the hoods far enough forward to get at the access ports for the gear cables was a pain. Come to that, peeling them back far enough to get at the fixing bolts to mount the levers on the bars was also a pain, though at least they have stuck with 5mm allen keys for that, so you can use a ball-end to get in there for the initial tightening, unlike some other manufacturers we can name, who have used Torx (why, oh why, Campag?). Getting the LH cable in is not a mirror of doing the RH either, which was unexpected.

The STIs once set up worked nicely, felt solid and the increased leverage over the brakes (which benefit from a small mechanical re-design to improve cable routeing and a more linear response) was noticeable on assembly.

The mechs do what mechs do without any drama, and the finish on the rear gear especially looks good and durable, so score another plus for the mechanical aspects in tandem with the aesthetics. The rear gear gets an alloy jockey cage which shaves a bit of weight of Ultegra SL.

Chainset ... hmm, those of you who know me will know how much I loathe and abhor external BBs, and Shimano's version is the one I dislike most, only beacuse it makes no more sense to me now than it did when HTII was introduced, to have a spline that you eliberately side-load with two pinch bolts as a way of retaining the crank & holding it at 180 deg. to it's pair. I'm not going to bang on about this, but it is bad design - there are better ways to do it, as Campag proved conclusively with the UltraTorque system ... if you must have an external BB system (not that I am wholly convinced by UT either, but that's more about the original bearings, now thankfully superceded) than it is about the idea).

On the upside, a redesign on the rings makes for less chain rub on the outer ring when using the inner ring at the top of the cassette. We are also told that the new outer ring is stiffer.

Last, the chain - beware here, it has a right & a wrong way to fit as Shimano have engineered the inside and outside link plates to give better shifting especially between the rings.

I fitted a third party chain (just as an experiment - I forsook my usual favourite SRAM alternative choice for an FSA-branded unit) & found that very noisy in comparison the the Shimano chain. A point to note if you, like me, are one of the Shimano chain non-apprecation society!

I'll update this in a few weeks when the bike has returned for it's 6-week check, but for now I can't see that there will be much that needs doing - the feel all the way through was one of solidity and competence ...

2 comments:

  1. Interesting review. Just to chuck in my tuppence worth, I have also consitently found that the choice of gear cable routing from the shifter (there being 2 choices) can affect shifting performance, with routing to the rear of the handlebars seemingly ensuring less friction and a more reliable shift.

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  2. Cheers Craig ... you are right. It seems to make a big difference on new Campag Ultrashift, too, especially if you have one of the troublesome 1st generation Veloce or Centaur Ultrashift ergos. The best fix for that is, of course, a new 2010 lever body (available under the warranty), but we've had short supply of those consistently since the summer ...

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