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-   -   Could use some clarification. (https://www.bikeforums.net/showthread.php?t=1168435)

Helderberg 03-16-19 12:18 PM

Could use some clarification.
 
I have read this on this site more than once but it seems so counterintuitive. If I move my bike seat back, away from the front of the bike, away from the handlebars, I will put more of my weight on my seat and less on my arms? Am I understanding this correctly as it seems it would be the other way around. Please do not feel that a long explanation is necessary just a simple "yes dummy, that is what you read" or "no that is not correct" is all that is needed. I feel very stupid asking this but I would really appreciate some clarity on my end.
Thanks in advance, Frank.

pakossa 03-16-19 06:01 PM

Basically, yes. But its more that you are taking weight off your hands, rather than "putting more weight on the seat." But its probably more complicated than that, depending on your exact posture, hip rotation, bike's geometry, bar drop, amount of power output, and so on.

Helderberg 03-16-19 07:22 PM

Thank you.

AnthonyG 03-17-19 06:22 AM

The centre of balance of a bike is measured from the bottom bracket (crankset). You push the saddle back then your more behind the centre of balance. You move the saddle forwards then you move forwards of the centre of balance.

Lemond1985 03-17-19 06:46 AM

Seat further back stretches out the torso, forcing you to reach further. Reaching further flattens out the body, lowering it. This improves aerodynamics and helps with breathing. It also seems to even out the amount of weight on both wheels, rather than a more upright position which tends to put all the rider's weight onto the rear wheel.

The more weight you can get onto your front wheel, the faster you will be. See Graham Obree:

http://bikeeventsscotland.com/wp-con...cannen0022.jpg

berner 03-17-19 10:24 AM

The best explanation I've seen is to stand with your back to a wall with heels touching the wall. Then as you lean forward you will fall forward. To prevent this step forward so that your keels are now, say, half a shoe length from the wall. Then as you lean forward your center of gravity can move rearward so that you remain in balance. If you try this little test it becomes immediately clear why moving the saddle back takes weight off the hands.

Helderberg 03-17-19 01:07 PM

Thank you all for your help.
Frank.

fietsbob 03-17-19 02:22 PM

a scale
 
Fast and low, is over Here <<<< >>>>> comfortable is over here , you choose what is more important for you..


somewhere in between.. ?

Helderberg 03-17-19 05:14 PM


Originally Posted by fietsbob (Post 20841908)
Fast and low, is over Here <<<< >>>>> comfortable is over here , you choose what is more important for you..


somewhere in between.. ?

By this I will take it you mean back, toward the rear tire, is fast and low and the other direction is the comfort setting.
Thank you, Frank.

AnthonyG 03-17-19 08:37 PM


Originally Posted by Helderberg (Post 20842099)
By this I will take it you mean back, toward the rear tire, is fast and low and the other direction is the comfort setting.
Thank you, Frank.

Other way around. You move the saddle BACK for comfort. You move it FORWARDS for a time trial position. Ie, Speed.

You know that everyone is saying this and you asked for confirmation because you didn't believe it. It looks like your looking for conformation of your own bias though.

Do what you want as its your bike but you move the saddle BACK to move the centre of balance back which puts less weight on your arms and shoulders. DO berner's test for yourself and you will see what we mean. Its dead easy to stand in a crouched position if you can move your backside back far enough to balance yourself. If your standing against a wall and can't move your backside back when you crouch down then you just fall forwards.

Helderberg 03-18-19 07:07 AM

"You know that everyone is saying this and you asked for confirmation because you didn't believe it. It looks like your looking for conformation of your own bias though."

No Anthony, I do not have a "Bias". If I did I wouldn't be asking for help and I would just do what I think is correct. I am and was looking for the facts, and not my perception of them. Now, thanks to you and the others that took the time to post I understand. Thank you for your contribution.
Thank you all again, Frank.

rando_couche 03-18-19 10:02 AM

Since I seem to be an outlier in general, here's my two cents.

I'm finding at age 65 (and after 40+ years of cycling) that saddle further back and handlebar further out and lower is more comfortable for the butt, back, arms and hands. As in, I'm using a more aggressive position now than when I was racing 25+ years ago. Go figure.

SP
OC, OR

pakossa 03-18-19 06:35 PM

You just have to find what works for YOU. For me its "lower (more than 5cm bar drop) is way SLOWER (and a bit less comfortable)." I think the rearward saddle is more for increased reach ("stretched out"), whereas a forward saddle is for a lower bar with a shorter reach.

AnthonyG 03-19-19 01:05 AM

Could everybody, PLEASE, just do this test for yourself and stop making guesses which is just confusing the OP and anyone else trying to learn this principle.

Stand in the middle of the room. Bend down and pretend that your on a road bike in the drops in a tucked position. Was it hard to do? No it was dead easy and you have NO weight on your hands at all so how did you do it so easily?
Look where your backside is. Its WAY out behind you balancing your weight over your feet.

Now, back up to a wall and try to lean forwards into a crouch. You fall forwards. Why? Because you can't move any weight backwards to balance yourself.

On a bicycle the Crankset/Bottom bracket is the centre of balance of the bike. Moving the saddle backwards moves your centre of gravity back a little behind the BB placing less weight on your hands/shoulders. Moving the saddle forwards moves your centre of gravity forwards placing more weight on your hands/shoulders.

Aerodynamics, power, stretching out are all red herrings in this matter.

Road Fan 03-19-19 05:06 AM

Helderberg,

First I think your question is only about reduction of pressure on the hands, not about power or saddle to bar drop. They are all interrelated and fitters will worry about finding the optimum relationship between saddle to bar drop given your saddle setback, but I don't think you're asking that. At least it's not easy to be clear about it in a small number of words. And I'm not the one to try to attack it for you.

For that simplified problem, Berner's example is correct, same for AnthonyG's test. I saw it in a book by Lennard Zinn and I tried it - I think it makes perfect sense. If you pretend you are a ski racer and bend forward with your knees bent into a tuck, your center of gravity needs to be over your feet. Otherwise you will fall over, forward or backward. The skier accomplishes this by letting the butt move backwards. Since the only thing supporting the weight is the skier's feet, the skier has no weight on his hands. For a cyclist, the feet are each on a pedal, so the cyclist with zero hand pressure would have all weight centered over the BB. This would also dictate necessary saddle position, regardless of frame geometry. You have the challenge to position the saddle so it holds your sitbones. The solution could require moving the saddle, replacing the saddle, replacing the seatpost, or even replacing the frame.

In this case you would ride with your hands on the bars however you can reach them, and the maximum amount of weight on your butt, i.e. saddle. If you can position the saddle so the widest part is under your sitbones (fore/aft adjustment) and there is no pressure on the tender bits located forward of the sitbones. This can be very comfortable, in my experience. My legs can generate power in this case, by grabbing the handlebars and pulling up, say when climbing.

If you had your bars at "optimum" height before this position change (I can't, and won't try, to tell you what "optimum" is), you will probably want to lower them and possibly to move them back, but I can't say for sure. I know that I can feel where the best position as I acclimate to the new butt position, after adjusting the saddle height for good leg extension when seated. You might need a narrower saddle if this change has you folding your torso down more deeply. If you didn't have your bars adjusted well before the position change, the old handlebar position could be a better match or it could be a worse match.

Power? As I get used to these position changes and re-optimize my position, I get more power by riding in my new, more comfortable position and where necessary making use of standing and of pulling up on the bars. It usually fatigues my glutes, which means I am training them to produce more force. I don't race or measure myself by other riders - my goal is to ride longer with improved comfort. Comfort makes it easier to use the power I have.

I hope this helps!

Helderberg 03-19-19 11:14 AM

Thank you all for taking the time to help me out. I am trying to lessen the weight on my hands as I have arthritis, carpel tunnel, nerve damage from a fall down stairs resulting in a bone chip in the elbow and the general wear and tear of 47 years of plumbing work. I have slid my seat back about half an inch and rode that. It felt better. I then decided to try to remove the 30* rise stem and reinstall the stock stem. It felt good for a ride around the block I think the 30* stem will be going back on.
Thank you all again, Frank.

Road Fan 03-20-19 07:16 PM

Thanks for the feedback, Frank! I'm glad you had a positive result.

There is nothing wrong with trying to go farther back with the saddle, if the seatpost allows it. If it's too far, you can always move it back forward.


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