much difference on a hill using 26 or 28 cog?

On 2019-10-26 12:49, Luns Tee wrote:
On Saturday, October 26, 2019 at 7:17:55 AM UTC-7, Joerg wrote:
On 2019-10-25 21:45, wrote:
On Friday, October 25, 2019 at 4:49:51 PM UTC-5, Sir Ridesalot
wrote: ... Perfect shifting with the 42. Bad shifting with the
39. I cannot even imagine how awful shifting with those nutty
50-34 compact cranks is.


It probably depends on how cleverly the front derailer cage and
mechanism has been engineered. On my MTB the cage is much more
intricate that the square thing of the Shimano 600 on the road
bike.


Hey, we have electricity today! For a few hours, they say.


I think Russell was referring more to the step in gear ratio between
chainrings being too large an increment to be appropriate on its own
much of the time, and the hassle of having to trim things back more
at the rear with any such 52-39 shift, whereas a 52-42 shift can be
useful on its own.


I meant his 1st post on 10/24. It's the same for me, an 8% step isn't
much and I overshift all the time. On both my bikes I shift in coarser
steps that are similar to a car transmission. Mostly flipping both
down-tube levers with one hand or shifting both sides on the MTB. So a
compact for me would be great but I'd have to replace the whole front
works for that.


This is more of an issue with a limited range of gears in the back.
I've found that with a 42 chainring, my 13-24 cluster works well on
level ground, whereas with the 39 chainring I previously had, I'd
often find it didn't have quite enough range and I'd shift to the 52
and back off a gear in the back. Adding a 12 sprocket in the rear
could have addressed this just as well for me. This trend has
continued adding more and more sprockets in back.


You are probably a stronger or younger rider than I am. I used to climb
everything with 52-42T in front and 11-21 in back. No more. Now I have a
40T in back for steep hills. That last "bailout" step is 32T - 40T
which is just fine for me. The whole cassette could be like that so I
wouldn't need to constantly shift across cogs.


What makes the compact crank work is that the rear clusters that go
with them have such a wide range that incremental gear changes
usually happen without overflowing to a front shift. Incremental
shifts largely happen on level ground where the ratios you work are
in the overlap between the chainrings' coverage. Larger shifts happen
when your run out gears in the transition from level ground to climbs
or descents, but these are times where your gearing needs can change
suddenly and the large step of the front shift actually works well.


I like large steps even in flat areas and mostly cities with dense
traffic of lots of lights. When I ride the longer slog to Sacramento I
pretty much leave the bike on 52/15 the whole time because it's a
segregated bike path with grade separation.


So far as how smooth the front shift itself happens, I think the pins
and ramps on modern chainrings make as much of a difference if not
more than derailleur cage designs. I'm regularly amazed by how quiet
my modern triple crank shifts and still often find myself looking
down at my crank to see if an upshift I'm trying to do actually took
or not.


What surprises me is how smooth the front on my old Shimano 600 shifts,
bought around 1982. Even the department store beater bikes I had back in
the days because of rampant theft in the area shifted smoothly. When I
hacked a cassette, mixed gears and put in that 32T - 40T step I was
sure this step would be difficult to shift. But no, smooth as butter.

--
Regards, Joerg

http://www.analogconsultants.com/