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-   -   what part of the pedal stroke do you shift? (https://www.bikeforums.net/road-cycling/976914-what-part-pedal-stroke-do-you-shift.html)

bbattle 10-15-14 01:46 PM

This thread wouldn't exist if we all had automatic shifting. :)

Leinster 10-15-14 01:57 PM


Originally Posted by bbattle (Post 17219639)
This thread wouldn't exist if we all had automatic shifting. :)

And if we all had tubeless tyres and carbon frames there's be no threads about them either.

StanSeven 10-15-14 02:21 PM


Originally Posted by Leinster (Post 17219679)
And if we all had tubeless tyres and carbon frames there's be no threads about them either.

But there's always the old standbys - are bibs better than shorts and what chain lube should I use?

bt 10-15-14 02:25 PM

the question was meant to imply while standing, my mistake.

Leinster 10-15-14 02:48 PM


Originally Posted by bt (Post 17219769)
the question was meant to imply while standing, my mistake.

Standing on the pedals up a hill, or standing at the lights?

For the first, see my previous answer. Maybe soft pedals, but still just shift as and when needed, I don't wait for a pedal to come to a sweet spot.

For the 2nd, I'll maybe kick my right pedal up to the 2 o'clock position, shift, lift up the back wheel, and spin a couple times.

Bandera 10-15-14 03:02 PM


Originally Posted by bt (Post 17219769)
the question was meant to imply while standing, my mistake.

It doesn't matter in the least with modern drivetrains in good nick.
Being derived from racing properly set-up indexing will shift under load w/o hurting their feelings, even into some awful cross-chaining.

It's a good idea to have a notion of which chainring will be required to carry a grade but shift when you need to in back, dropping the chain when going for the inner ring at hopeless low RPM is another thing altogether. If you can pick a pedal position to shift from you aren't pedaling fast enough even uphill.

-Bandera

I <3 Robots 10-15-14 04:52 PM

Whenever I feel like it.

RJM 10-15-14 05:08 PM

I usually make sure my feet are going round and round when I shift.


actually, sometimes I don't even do that.

Pirkaus 10-15-14 05:49 PM

I don't think about it but when I look at my cadence data I can see a sharp down spike for both up and down shifts.

macca33 10-16-14 03:41 AM

If you're stopping to wonder where your pedal stroke is during a shift, then you're not going hard enough....

bt 10-16-14 09:05 AM


Originally Posted by macca33 (Post 17221357)
If you're stopping to wonder where your pedal stroke is during a shift, then you're not going hard enough....


who said anything about stopping?

I was looking for the best part of the stroke for the cleanest shift while pedaling hard out of the saddle.

what's so hard to understand about that?

Looigi 10-16-14 09:14 AM


Originally Posted by bt (Post 17222067)
who said anything about stopping?

I was looking for the best part of the stroke for the cleanest shift while pedaling hard out of the saddle.

what's so hard to understand about that?

As discussed throughout the thread, timing it is not really possible or effective. In the rear, the force is on the top chain run but shifting first happens at the bottom where the RD moves the chain to the next cog. The cassette needs to rotate nearly 180 degrees before the jog in the chain between the two cogs reaches the top portion that's under tension. What that translates to in crank rotation will depend on what gear you're in. What can be done to ease shifting while standing is to reduce the pedaling torque by putting weight equally on both pedals while keeping them rotating for about 1 full rotation after shifting.

For the front, the FD needs to move the portion of the chain that's under tension. You need to soft pedal for that to work, though electronic shifters are better at this.

bt 10-16-14 09:17 AM


Originally Posted by Looigi (Post 17222098)
As discussed throughout the thread, timing it is not really possible or effective. What can be done to shift while standing is to reduce the pedaling torque by putting weight equally on both pedals while keeping them rotating for about 1 full rotation after shifting.

could there be a part of the rotation that is naturally under less torque and therefor a better spot to shift?

RollCNY 10-16-14 09:27 AM


Originally Posted by bt (Post 17222107)
could there be a part of the rotation that is naturally under less torque and therefor a better spot to shift?

The rear derailleur always sees the same torque, regardless of crank position, because it operates in the slack side of the chain. The delay in engaging has more to do with where the shift ramps are in the cassette than your crank position.

Bandera 10-16-14 09:33 AM


Originally Posted by bt (Post 17222107)
could there be a part of the rotation that is naturally under less torque and therefor a better spot to shift?

You are asking for an answer to a question that no one else asks, for good reason.
It's an academic concern that simply does not matter on the road as [MENTION=236201]RollCNY[/MENTION] explains .

Modern indexed drivetrains will shift cleanly and w/no discernable difference no matter whether the rider is right leg or left leg dominate, sitting or standing, at 12:00 or 2:37 in the pedal stroke. Adapting to a smooth high cadence pedaling style will make the whole system, rider included hum efficiently along.

-Bandera

nkfrench 10-16-14 07:55 PM

I am in the habit of shifting when my leg is at a certain position and soft-pedaling, always seated.
I think it would take a lot of concentration to change that habit even though my current bike has a modern drivetrain -- unlike the bikes I rode to school in the olden days 1961-1978.

Looigi 10-17-14 07:35 AM


Originally Posted by bt (Post 17222107)
could there be a part of the rotation that is naturally under less torque and therefor a better spot to shift?

When generating torque by pedaling, it will be greatest near the crank being horizontal and least with the crank near vertical. However, to control shifting to coincide with this is impractical because of the short times involved at normal cadences and the varying delay between clicking the shifter and when the shift actually occurs.

bt 10-17-14 09:58 AM


Originally Posted by Looigi (Post 17224819)
When generating torque by pedaling, it will be greatest near the crank being horizontal and least with the crank near vertical. However, to control shifting to coincide with this is impractical because of the short times involved at normal cadences and the varying delay between clicking the shifter and when the shift actually occurs.

right, so taking into account the delay, where in the stroke do you click the shifter.

BoSoxYacht 10-17-14 10:24 AM


Originally Posted by bt (Post 17225249)
right, so taking into account the delay, where in the stroke do you click the shifter.

it's irrelevant.

The shift occurs whenever it reaches the shift ramp on the cassette, regardless of where you are in the pedal stroke.

rpenmanparker 10-17-14 10:59 AM

I pedal so fast it is impossible to tell.

Alias530 10-17-14 12:01 PM

My fav thing about my switch to Dura Ace is that you don't even have to think about when you shift. Full power, climbing, doesn't matter. Just shift when you want.

banerjek 10-17-14 12:29 PM


Originally Posted by bt (Post 17222107)
could there be a part of the rotation that is naturally under less torque and therefor a better spot to shift?

Roughly the 12 and 6 position, especially when standing. Lag in torque is not a significant factor.

This is an easy experiment to do. If you shift at the 3 and 9 o'clock, the shift can actually happen faster, but it will sound and feel very different. Despite what people say, it's impossible for torque to be the same all the way around the circle -- that's just not how your legs work. Anyone who doubts that should see how fast they are off the line starting from the 12 (or better yet, 10:30) o'clock position.

I have found that shifting under load is a great way to spread some FD's which leads to mucked up shifting and thrown chains until you fix it. I have this issue with my FSA FD, but not with my Ultegra or 105 FD's.

Ptcycles 10-17-14 03:50 PM

Positron anyone?
 

Originally Posted by bt (Post 17217622)
I usually try to click when my left pedal hit the bottom of the stroke then i roll thru and have ful power on the drive side stroke.

Anyone out there still using their Positron system? I don't think about where my pedals are at. Smooth as silk, and quiet to boot!


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