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] http://www.sfu.ca/~rcousine/wiredcola/
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.