Comparing old 105 to new Sora

In article <[email hidden]>,

Wayne Menzie said:

I have a bike with old but very nice condition 105
components. It's a 6 speed with down tube shifters (rear
indexed) and single pivot brakes. I'm wondering about the
difference in performance in this old drivetrain and a new
Sora setup. I can think of several factors to consider:

1. STI vs. down tube shifters
2. Rear derailer performance
3. Dual pivot vs. single pivot brakes
4. 8 vs. 6 speeds
5. Front indexing vs. friction

I'm probably missing some things so please feel free to
add to this list and give me some insight. Thanks.

I think I can give you some insight, since I have a
Pinarello with the same vintage of 105 components, except I
have added a Sora right-side brifteur and 8-speed cassette
on a replaced freehub body.

I can't speak to derailer performance, except to say that
the 105 derailer seems quite happy with the new setup. My
bike already has very good RSX dual-pivots, which I perceive
(despite Jobst's best efforts to discourage me) as being
markedly superior in braking performance and ease of
modulation to single-pivot.

8 speeds is nice (And a regular comparison for me, since the
Pinarello is my race bike; the commuter is a friction-
shifting 6- or 7- speed (I can't remember what the current
freewheel is), but the brifter is more noticeable.

The awful truth is that unless you intuit a gearing issue
that you can't solve without an 8v cassette, the 105 is
really good stuff. Brifters are nice, and I quite like the
one I have, but I wouldn't bother except that I race, and
when I get into the heat of a good race, I like to be able
to shift while standing and to shift while causing as little
distraction or disruption to my oxygen-deprived brain and
body as possible. In non-racing situations, who cares?

I haven't even bothered changing out the front shifter; for
2-ring setups, a DT left shifter works just fine, and even
has some minor advantages (mainly, easy and precise
trimming) over a brifteur.

I have not checked the weight of the Sora brifteur, but it's
a relatively beefy component, and probably carries a small
weight penalty over the old 105 components you already have.

If you decide to "upgrade" to Sora, I would purchase the
brifteurs (your call, but I suspect the reason you want to
do this), the dual-pivot brakes, the freehub body, and the
chain and cassette. Your derailers will work fine with the
new parts, assuming they are still in good shape.

Note the Sheldon boilerplate here: if you're considering
8 speeds, it's almost always worthwhile to skip that and
go to 9 speeds. The only expensive part is the shifter,
and the only other necessary parts are the 9-speed chain
and casette.

You can trust me: I just put a 7-speed mountain bike
drivetrain on a BMX (named BMX LX, both for the drivetrain
component level and for "BMX Lunatic eXperiment"😉. So cool.

--
Ryan Cousineau, [email hidden]
sfu.cawiredcolaOpen ↗ President, Fabrizio
Mazzoleni Fan Club

Wayne Menzie <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I have a bike with old but very nice condition 105
components. It's a 6 speed with down tube shifters (rear
indexed) and single pivot brakes. I'm wondering about the
difference in performance in this old drivetrain and a new
Sora setup. I can think of several factors to consider:

1. STI vs. down tube shifters
2. Rear derailer performance
3. Dual pivot vs. single pivot brakes
4. 8 vs. 6 speeds
5. Front indexing vs. friction

I'm probably missing some things so please feel free to
add to this list and give me some insight. Thanks.

Probably the most noticeable difference, second to the
change in riding habits and interface feel caused by STI
levers vs downtube shifting, would be having a cassette and
chain with hyperglide. Hyperglide really is one of the most
notable things Shimano's ever done.

Rear derailer performance really hasn't changed, although a
6-speed 105 derailer will have had plenty of time to develop
excess slop.

STI is not clearly better than downtubes, but most people do
find the lever hoods much more comfortable than regular aero
levers. STI levers die though. (Personally I'm currently
trying to find some spent STI's or Ergos to gut the shift
mechanisms out of and use as regular aero levers with bar-
end shifters, because I find the bodies so comfortable).

Good single pivots are fine.

Front indexing is just not all that superior to front
friction (or front "semi-indexing", like campy ergo) in most
applications, and so there's a very strong case that it's
not worth the hassle of having all your drivetrain
components match up perfectly.

Having more rear cogs does make a difference in your
efficiency level as long as you actually take real advantage
of them, which is a perfectly reasonable thing to just not
feel like bothering to do. Also your rear wheel will have
more dish and lower non-drive side spoke tension, limiting
the wheel's strength more.