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-   -   Longer stem or setback seatpost? (https://www.bikeforums.net/road-cycling/1120772-longer-stem-setback-seatpost.html)

seypat 09-06-17 08:41 AM


How do you unweight the torso by moving the saddle? The whole thing is absurd.

Originally Posted by 3alarmer (Post 19841757)
...I did that once on a horse. Never again.

I used to have a mule that was really good at this. She would hold her breath, flex her muscles and make her belly as big as possible. You would put the saddle on and cinch it up. Then you would get on and take off. She would then let out the air and make herself as small as possible. The saddle would come loose, swing upside down and dump the rider. She would take off for the other side of the field/pasture. Sometimes, the rider(me) got dragged a bit if he couldn't get out of the stirrups. Straight out of a Western comedy.

She was an expert in unweighting the torso by moving the saddle. That mule and I had a lot of good and bad times together! :roflmao2:

rpenmanparker 09-06-17 08:48 AM


Originally Posted by f4rrest (Post 19843710)
The saddle is to the pedals as your seat was to your feet in the floor.

Moving saddle back relative to pedals is similar to moving feet forward relative to seat.

Right, now so what? Sure there is a right place for feet relative to the saddle, but what does it have to do with balance.

kcjc 09-06-17 09:23 AM


Originally Posted by 3alarmer (Post 19842496)
....how would Jesus ride ?

Can't, he only walks.


Originally Posted by rpenmanparker (Post 19843469)
Test done and results are as you expected. 35 lb on the legs when sitting upright. 75 lb at 45°. 105 lb at full tuck. Now tell me so what. I want to be peddling as well as possible first and foremost. I am happy to support my torso weight with my hands. Maybe a I just fortuitously have my saddle in the perfect Hogg position. I wonder how that happened. KOPS anyone?

Try going down a technical down hill or cornering at speed. Riding that cruiser of yours wouldn't be much fun or carry much speed. There is a reason why a 50/50 balance is a gold standard for maneuverability. A "proper fit" is balance between power output, efficiency, and functionality and can include KOPS but the opposite, KOPS is that balance is just false.

woodcraft 09-06-17 09:36 AM


Originally Posted by rpenmanparker (Post 19843833)
Right, now so what? Sure there is a right place for feet relative to the saddle, but what does it have to do with balance.




Kudos for doing the experiment.

Fiery 09-06-17 09:50 AM


Originally Posted by rpenmanparker (Post 19843833)
Right, now so what? Sure there is a right place for feet relative to the saddle, but what does it have to do with balance.

It's easier to balance (unweight your hands by transferring weight to your feet) when your feet are in the right spot.

rpenmanparker 09-06-17 09:53 AM


Originally Posted by kcjc (Post 19843916)
Try going down a technical down hill or cornering at speed. Riding that cruiser of yours wouldn't be much fun or carry much speed. There is a reason why a 50/50 balance is a gold standard for maneuverability. A "proper fit" is balance between power output, efficiency, and functionality and can include KOPS but the opposite, KOPS is that balance is just false.

What is a technical downhill?

More seriously, where are those weight percentages measured? Not the wheels. Something you can't accomplish like 50:50 weight split on the wheels can't be a gold standard.

kcjc 09-06-17 10:25 AM


Originally Posted by rpenmanparker (Post 19844000)
What is a technical downhill?

You're kidding, right? You can always just go straight and see where you land.


Originally Posted by rpenmanparker (Post 19844000)
More seriously, where are those weight percentages measured? Not the wheels. Something you can't accomplish like 50:50 weight split on the wheels can't be a gold standard.

Again, you're kidding, right? No one is talking about cutting you up and balancing the weight equally between the two wheels. Center of mass relative to the wheelbase and "accomplishment" depends on you.

WhyFi 09-06-17 10:38 AM


Originally Posted by kcjc (Post 19843916)
Can't, he only walks.

This reminds me of the Twin Six Eggplant Jesus t-shirt. I'm going to order it one of these days.

https://cdn.shopify.com/s/files/1/08..._1024x1024.jpg

indyfabz 09-06-17 10:40 AM

****?

WhyFi 09-06-17 10:45 AM

Okay, so I'm confused here - when people are talking about balance and leverage, what levers are we talking about? Levers only have a few variables; lever length and the relative locations of: fulcrum, resistance, and effort. What is changing that results in better balance/unweighting of the hands (which would be the effort, I assume) while moving the saddle?

seypat 09-06-17 10:47 AM


Originally Posted by WhyFi (Post 19844152)
This reminds me of the Twin Six Eggplant Jesus t-shirt. I'm going to order it one of these days.

https://cdn.shopify.com/s/files/1/08..._1024x1024.jpg

Sweet color! He definitely looks balanced in that image. I like his protective headwear. No heat buildup. Probably aero too, but that upright position cancels it out.

3alarmer 09-06-17 10:52 AM

.
...too much weight on your saddle ? Ascend an eighth of an inch up toward heaven.

3alarmer 09-06-17 10:54 AM


Originally Posted by rpenmanparker (Post 19844000)
What is a technical downhill?

...technically, anything not level or uphill is downhill.

redlude97 09-06-17 10:55 AM


Originally Posted by WhyFi (Post 19844178)
Okay, so I'm confused here - when people are talking about balance and leverage, what levers are we talking about? Levers only have a few variables; lever length and the relative locations of: fulcrum, resistance, and effort. What is changing that results in better balance/unweighting of the hands (which would be the effort, I assume) while moving the saddle?

when more of the pedal stroke is driven from behind the axle with more setback you can keep more of your mass back. To visualize it, just do a squat with your arms extended from the body and back nearly horizontal, away from the wall and with your heels against the wall and observe what your butt naturally does when it is free, and when it is restricted. You will probably topple over with your heels against the wall before you can reach the same depth. This simulates the two extreme positions between road and time trial position with saddle setback and neg saddle setback

3alarmer 09-06-17 10:56 AM


Originally Posted by Fiery (Post 19843991)
It's easier to balance (unweight your hands by transferring weight to your feet) when your feet are in the right spot.

...well duhhh. If your feet are not on the pedals then none of this stuff works.

rpenmanparker 09-06-17 10:58 AM


Originally Posted by kcjc (Post 19844112)
You're kidding, right? You can always just go straight and see where you land.

Again, you're kidding, right? No one is talking about cutting you up and balancing the weight equally between the two wheels. Center of mass relative to the wheelbase and "accomplishment" depends on you.

Nope, not kidding. Never do that kind of stuff. Not downhill, not technical.

As for the balancing, I am asking the question that no one is willing to answer. What do you mean by balance, and more to the point, 50:50 balance? You can measure the weight distribution of a bike by putting a scale under each wheel. Is that what you mean. I'm just saying that 50:50 measured that way is almost impossible on a bike. If that is not what you mean, then what do you mean?

redlude97 09-06-17 10:58 AM


Originally Posted by kcjc (Post 19843916)
Can't, he only walks.


Try going down a technical down hill or cornering at speed. Riding that cruiser of yours wouldn't be much fun or carry much speed. There is a reason why a 50/50 balance is a gold standard for maneuverability. A "proper fit" is balance between power output, efficiency, and functionality and can include KOPS but the opposite, KOPS is that balance is just false.

where is this 50:50 number coming from? Weight balance on a bike is usually closer to 60R:40F and tire pressure should be set accordingly to near this balance. You should actually shift even more of this weight back on a descent because the slope changes the effective weight balance?

redlude97 09-06-17 11:01 AM


Originally Posted by rpenmanparker (Post 19843469)
Test done and results are as you expected. 35 lb on the legs when sitting upright. 75 lb at 45°. 105 lb at full tuck. Now tell me so what. I want to be peddling as well as possible first and foremost. I am happy to support my torso weight with my hands. Maybe a I just fortuitously have my saddle in the perfect Hogg position. I wonder how that happened. KOPS anyone?

now move your saddle all the way back and remeasure, then slam the saddle all the way forward and/or flip the seatpost around and remeasure the numbers. I bet they will be different.

rpenmanparker 09-06-17 11:08 AM


Originally Posted by redlude97 (Post 19844232)
now move your saddle all the way back and remeasure, then slam the saddle all the way forward and/or flip the seatpost around and remeasure the numbers. I bet they will be different.

First of all there was no saddle, remember? This was on a chair. Second, so what? I keep asking, so what. Managing weight on the bars depends much more on where the saddle and bars are with respect to each other than it does on where the saddle is with respect to the BB. There are too many more important factors in saddle placement than balance. When you get those right, then you can set the bars. Balance is just not the main issue.

Doug28450 09-06-17 11:18 AM


Originally Posted by 3alarmer (Post 19844214)
...technically, anything not level or uphill is downhill.

What if the road/path is on a side hill and the slope across the road is down?

woodcraft 09-06-17 11:40 AM


Originally Posted by rpenmanparker (Post 19844223)
Nope, not kidding. Never do that kind of stuff. Not downhill, not technical.

As for the balancing, I am asking the question that no one is willing to answer. What do you mean by balance, and more to the point, 50:50 balance? You can measure the weight distribution of a bike by putting a scale under each wheel. Is that what you mean. I'm just saying that 50:50 measured that way is almost impossible on a bike. If that is not what you mean, then what do you mean?



I guess that's good because when you go downhill,

your knee is not over the pedal spindle anyway,

& there goes the "Perfect Perch"

redlude97 09-06-17 11:40 AM


Originally Posted by rpenmanparker (Post 19841803)
Use your own brain. Does it make sense? No matter where you put the saddle, if you sit on it no hands, your weight distribution on the saddle will be almost exactly the same. Maybe a small difference for how your legs interact with the pedals, but all your weight is on your butt. Now put your hands on the bars. The distance to the bars and slope of the torso will affect how much weight you need to support with your hands, arms and shoulders. That is why you move the bars with different length stems. You don't move the saddle for that purpose. The saddle is fixed by pedaling efficiency considerations. But wait, I've said that before.

Heres the big issue, this is wrong.

Originally Posted by rpenmanparker (Post 19844263)
First of all there was no saddle, remember? This was on a chair. Second, so what? I keep asking, so what. Managing weight on the bars depends much more on where the saddle and bars are with respect to each other than it does on where the saddle is with respect to the BB. There is too many more important factors in saddle placement than balance. When you get those right, then you can set the bars. Balance is just not the main issue.

Balance is very much an important consideration and saddle setback plays a major role in this. You are balancing flexibility/aero/fitness.


Originally Posted by rpenmanparker (Post 19841803)
The distance to the bars and slope of the torso will affect how much weight you need to support with your hands, arms and shoulders. That is why you move the bars with different length stems.

But for the same distance to the bars and slope of the torso, the saddle position dictates how much weight needs to be carried by the hands/arms/shoulders. For example, with 20mm of setback and a 100mm stem, you will have a certain amount of weight on your arms. If you decrease the setback to 0mm and used a 120mm stem you will have more weight on the arms for the same arm and torso position.


Originally Posted by rpenmanparker (Post 19841803)
You don't move the saddle for that purpose.

Agreed, but that doesn't change the fact that saddle setback plays a major role in your weight balance


Originally Posted by rpenmanparker (Post 19841803)
The saddle is fixed by pedaling efficiency considerations. But wait, I've said that before.

If the goal is to ride as fast as you can then the saddle position is not fixed, it is balance between pedaling efficiency and aero. Think of your position as a pivot around the axle. To keep hip angle the same when lowering the bars you have to decrease setback and raise the saddle a corresponding while increasing the stem length. This increases pressure on the hands and is a tradeoff, yet many pros are doing this now that the UCI has relaxed restrictions on saddle tilt, just look at how many zero setback seatposts you see in the peloton today and look at fit evolution for seasoned pros. If you don't change seat position because you think it is fixed for pedaling efficiency, then you have to close up hip angle to achieve the same aerodynamic position.

rpenmanparker 09-06-17 11:51 AM

So redlude97, how do you measure this balance?

redlude97 09-06-17 12:03 PM


Originally Posted by rpenmanparker (Post 19844365)
So redlude97, how do you measure this balance?

You can use scales if you care about a number, or you can just do it by feel on the hands. Any good fitter will have this discussion with you when you talk about your objectives for your bikes, especially if they are fitting multiple bikes with different positions for various road/cross/gravel disciplines. Its pretty easy to feel the differences, and if you have a chance to get a guru dynamic fit they can run you through a range of these fit parameters in real time to try to achieve the best balance for your riding style and position requirement.The fast road bike has less setback and more weight on the hands because the stem is slammed compared to my cross bike for example where the position is more upright and optimized for technical handling.

rpenmanparker 09-06-17 12:08 PM


Originally Posted by redlude97 (Post 19844393)
You can use scales if you care about a number, or you can just do it by feel on the hands. Any good fitter will have this discussion with you when you talk about your objectives for your bikes, especially if they are fitting multiple bikes with different positions for various road/cross/gravel disciplines. Its pretty easy to feel the differences, and if you have a chance to get a guru dynamic fit they can run you through a range of these fit parameters in real time to try to achieve the best balance for your riding style and position requirement.The fast road bike has less setback and more weight on the hands because the stem is slammed compared to my cross bike for example where the position is more upright and optimized for technical handling.

Seriously, how do you use scales? Have you seen that done or had it done? How does that work? I mean how is it set up?


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