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-   -   Straight vs. Setback Post (https://www.bikeforums.net/fitting-your-bike/958861-straight-vs-setback-post.html)

PhotoJoe 07-12-14 03:50 PM

Straight vs. Setback Post
 
I've got a Lynskey that I LOVE the ride of. The ONLY gripe I have is as I'm riding, I find myself sliding forward on the saddle, until finally I realize I'm sitting more on the horn than sit-bones on the appropriate points of the saddle. Today on my ride, I stopped and slid the seat forward (as well as raising it, but that was just because it was too low). I'm now at the front of the adjustment of the seat rails on the set-back seat post. So, my question is: Is there anything with a straight seatpost that I should be concerned with? Or, would I be better off with a shorter stem? I'm not sure the measurements of the stem, and no, I've never been professionally fit.

Or....is this just too tough to answer over the interwebs and I should seek professional help?

Thanks.

Before sliding the seat forward:

http://i798.photobucket.com/albums/y...nskeyR230B.jpg

1986raleigh 07-12-14 04:18 PM

Nothing to be concerned with for that adjustment, sliding forward off saddle is usually one of two things, downward tilt or overreach to hoods, forward adjustment and raise its likely gonna solve problems.
If not next solution would be a no set back post or shorter stem IMHO.

Kopsis 07-12-14 04:26 PM

Using saddle position to adjust reach is not the ideal solution. The saddle needs to be positioned relative to the BB to achieve desired power, weight distribution, and knee happiness objectives without regard to reach. The right way to adjust reach is with a shorter/longer stem and/or different bars.

MichaelW 07-12-14 05:13 PM

What size cranks
How tall/inside leg?

PhotoJoe 07-12-14 05:24 PM


Originally Posted by MichaelW (Post 16932424)
What size cranks
How tall/inside leg?

175mm
6'2". Not sure about leg length. Don't have anything here to measure with. If it will help, I'll measure when I get home. I'm curious. What does this info tell you?

I looked up the invoice for the bike. It's a 110mm stem. I think I have a crappy looking 90mm or 100mm stem off my daughters bike. Can't stand the way it looks, but may be worth a try.

TakingMyTime 07-12-14 05:25 PM

I have the same problem as the OP. Everything seems to fit right but I keep slipping forward. I'm actually going to get a micro adjust seat post since my OEM Trek is slotted and doesn't give you ability to fine adjust. If I do go 1 click up in the nose, it's just a little too much I also think my other problem is that there is too much curvature to the seat. I'm going to experiment with a new seat post first and then a new, flatter seat.

tonski 07-13-14 06:25 PM


Originally Posted by Kopsis (Post 16932345)
Using saddle position to adjust reach is not the ideal solution. The saddle needs to be positioned relative to the BB to achieve desired power, weight distribution, and knee happiness objectives without regard to reach. The right way to adjust reach is with a shorter/longer stem and/or different bars.

This. Adjusting reach with the saddle isn't the solution. If you're sliding forward tilt your saddle up (very little makes a big difference), if you're intentionally moving yourself forward because it's more comfortable then move your bars up (stack) or back (stem)

PhotoJoe 07-13-14 08:56 PM

I found the shorter stem that I took of my daughter's fuji. I'm guessing it's a 90, but I'm not entirely sure. It's not marked. Hoping to go for a ride in the morning to see how it feels.

fietsbob 07-13-14 09:57 PM

To my eye your saddle is nose down ..

maybe , because I dont push the pace... Cycle-tourist type speed is not my goal,
I dont have so much tendency to slide forward much
Using the Unrace setup ..higher bars . & all that ,,

or just put in more work.. watch the time trial races, they work harder pushing the pedals and really arent sitting much at all .
they do slide onto the nose, though , standing over it more than sitting on it ..

not much I can do on a keyboard to resolve your concerns,, its a race sorta road bike ,so be it.

keep a limber lumbar .. hips more Up-right bend your spine above them ..

by moving the seat Back there is a bit more weight bias onto your back side ,,
going to a zero set back post , like Thomson (etc) straight ones ,
you shift more on the arms and perhaps encouraging to get the pedalling fast er...

IDK ..

MichaelW 07-14-14 02:16 AM


Originally Posted by PhotoJoe (Post 16932451)
175mm
6'2".
I'm curious. What does this info tell you?

Crank length affects the fore-aft saddle position to achieve a typical riding position, ie "KOPS".
Yours should be OK.

the other reason for a forward saddle is an odd proportion of upper/lower leg. the leg triangle may be higher and shorter across the top than normal for total leg length.
I use an in-line seatpost for a very forward saddle position.
See here.

Road Fan 07-14-14 05:21 PM


Originally Posted by fietsbob (Post 16935747)
To my eye your saddle is nose down ..

maybe , because I dont push the pace... Cycle-tourist type speed is not my goal,
I dont have so much tendency to slide forward much
Using the Unrace setup ..higher bars . & all that ,,

or just put in more work.. watch the time trial races, they work harder pushing the pedals and really arent sitting much at all .
they do slide onto the nose, though , standing over it more than sitting on it ..

not much I can do on a keyboard to resolve your concerns,, its a race sorta road bike ,so be it.

keep a limber lumbar .. hips more Up-right bend your spine above them ..

by moving the seat Back there is a bit more weight bias onto your back side ,,
going to a zero set back post , like Thomson (etc) straight ones ,
you shift more on the arms and perhaps encouraging to get the pedalling fast er...

IDK ..

I certainly agree the saddle nose looks too far down. I'd suggest leveling it and if there is perineal pressure, lower the saddle just a teentsy bit, maybe 2 mm or 1/16 inch. That should tend to focus the pressure more on the sit bones without greatly affecting reach. Then look at whether hand pressure is good or bad. Should be able to be in a deep position and remove hands for the bars without sliding forward on the saddle or clenching the saddle to keep you from falling forward. Should not also end up with your butt bones on the heel of the saddle - that's not where it's designed to hold you.

Leisesturm 07-14-14 05:51 PM

Yep, I think we have a trifecta. I think its clear that the nose of the o.p.'s saddle needs to come up a little. Dead level is a nice ideal to work towards but a couple or three degrees of nose up are sometimes necessary to prevent sliding forward. I am 5'10" and 110mm is the length of stem on my road racer. I'm just not seeing why the o.p. needs less. I know it isn't scientific (but no less so than the o.p.'s efforts) but, with your elbow on the nose of the saddle (centered on the rails) where do your fingertips wind up when aimed towards the bars? Do they just touch? Wrap over? Not even come close? It is also possible to reverse engineer a workable position for the saddle by starting with the fingertips at the rear edge of the bars and bringing the seat nose to where the elbow is. Thousands of cyclists have been measured to compile the methodology that formulates rules like this.

H

PhotoJoe 07-14-14 06:50 PM


Originally Posted by Leisesturm (Post 16938450)
Yep, I think we have a trifecta. I think its clear that the nose of the o.p.'s saddle needs to come up a little. Dead level is a nice ideal to work towards but a couple or three degrees of nose up are sometimes necessary to prevent sliding forward. I am 5'10" and 110mm is the length of stem on my road racer. I'm just not seeing why the o.p. needs less. I know it isn't scientific (but no less so than the o.p.'s efforts) but, with your elbow on the nose of the saddle (centered on the rails) where do your fingertips wind up when aimed towards the bars? Do they just touch? Wrap over? Not even come close? It is also possible to reverse engineer a workable position for the saddle by starting with the fingertips at the rear edge of the bars and bringing the seat nose to where the elbow is. Thousands of cyclists have been measured to compile the methodology that formulates rules like this.

H

Very interesting. I'm a COMPLETE fitting noob, so I claim to know NOTHING except that I don't like sliding forward on the seat. I'll play around with all of this and post results. Thanks.

cicli_masi 07-23-14 08:31 AM

Could be as simple as saddle height...

bike_forever 07-25-14 01:29 PM

I have found that a straight seat post works best for me if the bike is not too small or tall. From there I will fine tune adjust the seat rails. I have to agree that there is less fatigue for me if the seat is tilted slightly up. Most high end saddles will have a contour to accommodate for a slight tilt back/upward.

gregjones 07-26-14 09:32 PM


Originally Posted by Leisesturm (Post 16938450)
I know it isn't scientific (but no less so than the o.p.'s efforts) but, with your elbow on the nose of the saddle (centered on the rails) where do your fingertips wind up when aimed towards the bars? Do they just touch? Wrap over? Not even come close?

Here's a perfect example of where I don't fit and get confused....

According to Competitive Cyclist's fit calculator, my saddle nose to bar measurement should be 48.2-48.8cm. I'm one more seatpost/stem swap (awaiting ordered parts arrival) from being in that range. I'll match that range while meeting the BB/Saddle Setback recommendation.

But....if I put my arm on a counter and push my elbow against the wall the measurement to my fingertips is 46cm. That put me long according to that method of measurement with my, soon to be, current set up.

I don't know enough about all of this to just do it myself and don't really think that I'm enough of a rider to actually tell the difference between right and wrong. About the most difference that I've found is correcting my saddle setback distance to as close as possible until new parts get here. I could actually feel as if the bike "surged" when I put all 130lbs of my butt into the pedals.

I am grateful for any info I get out of this forum. I lurk a lot, but don't have a lot to post about.:)

Leisesturm 07-27-14 02:19 AM


Originally Posted by gregjones (Post 16977707)
Here's a perfect example of where I don't fit and get confused....

You're having me on right? CC recommendation is 'long' by 2mm? Go and look at 2mm on the tape you used to measure your forearm. 5mm is about the smallest change you might perceive as a change. Most people wouldn't even feel 5mm. I'd say your experiment is yet another validation of the not so scientific "rule" that many of us use but rarely admit to using. Since you asked, I'll expand a little bit on the science: I suspect that youth and flexibility influence the final result. A 20 something might be fine going as much as 25mm or more past their cubit distance to the bars and be fine. With each additional decade they might bring the bars back 5mm. In their 40's compact bend bars start to feel good. I'm in my 50's I'm actually running a little short of my cubit distance (my fingers reach 1/2 way up the bars instead of just touching) and I'm rocking a compact bend Civia Emerson bar. More than you wanted to know I'm sure.

H

gregjones 07-27-14 08:56 AM


Originally Posted by Leisesturm (Post 16978014)
More than you wanted to know I'm sure.

No, actually it's exactly what I was hoping for!!!

I keep reading about two degrees up, 170vs172.5, 100/110 and other one size difference, smallest of changes making or breaking someone. And I can't tell that I've done anything to the bike unless I make a change.

Of course, I'm not that much of a rider. 59 years old and only 5 years of recovery from 35 years of about every abuse possible (with the exception of drugs). I'm certainly not the perfect specimen for experiments in mechanical improvements. Yet, at times I wonder what's wrong with me.

Thanks!!!:thumb:

gregjones 07-30-14 08:49 PM


Originally Posted by Leisesturm (Post 16978014)
You're having me on right? CC recommendation is 'long' by 2mm? Go and look at 2mm on the tape you used to measure your forearm. 5mm is about the smallest change you might perceive as a change. Most people wouldn't even feel 5mm.

Oooops.

Change the mm to cm.:p

Now, it's 20 not 2 mm.


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