When I try to ride my touring bike in stand up position, it feels like my legs stay behind my upper body. It is like the chainset is positioned a bit backwards than it should be. I can't ride stading up more than a few hundred meters because of that. It is a bit better when climbing but feels really awkward on the flat. Why do you think that would happen?

Maybe lean your torso forward more, bend at the hips. Depends on the bike fit, the handlebar location. Put yourself and the bike in front of a mirror and you can see what is going on.

But note that on flat land, I don't think there is much need to pedal standing for more than a "few hundred meters". Usually you stand to ease over a patch of rough road, to stretch your legs, to accelerate, to sprint, and those don't last long. Where some people pedal standing for longer stretches is when climbing. Even climbing a hill, for me anyway, it would be unusual to pedal standing for over a mile or so; others may do differently.

on the flats standing on the pedals at green lights to get going ,

or long rides to give your butt a break should all be fairly natural .

I dont under stand the issue .


ride more ..

You may be leaning on your handlebars when you stand up, which positions you too far forward. I read somewhere that your hips shouldn't come past (in front of) the bottom bracket. Assuming your bike has been fitted to you properly, try shifting back and keeping more weight on your legs.

That said, I've been training to climb standing, so I can switch back and forth between sitting and standing. Standing for long periods is tiring!

Cheers

With drop handlebars it's a lot easier to stand and hammer if the reach is maximized, especially up steeps. If the reach is too short it's really awkward.

Unfortunately, I don't have drops on my touring bike and stem is really short, I think it is 80 mm. Could you tell me what should be the ideal frame size for 5' 8'' height? I found it to be around 21". Is that right?

Your touring bike is a converted mountain bike with 26" wheels I assume. I think 21" measuring from the center of the BB to the center of the top tube is probably a bit large but unfortunately I don't know what the ideal frame size is for you. Since it's being used for touring you could set it up for a more aero stretched-out position with lowered bars and perhaps it would still fit okay. With a frame on the too-big side you might have difficultly getting the bar low enough for a roadie position. I am biased towards a roadie position even on my mtb but I'm pretty tall and thin so that works for me.

Clem nailed it!

Too upright.

You can check out the photo of my bike here:

https://www.bikeforums.net/fitting-yo...l#post16649903

As you said, frame looks like a mountain bike frame but I don't know if it is really intended to be used with 26" wheels. When I check out the photos of hybrid bikes I see similar frames with mine.