[Closed] Layback seatposts on Souls, 456's etc

Everyone is a different size /shape. I'm in the inline camp, and convinced bikes are getting too long.

run a 50mm stem on my FS and LTHT (456) and tried a layback for a while as i thought it would help me 'stretch out on long rides' with back and wrist ache being common after riding.
after buying a set of wider bars the layback REALLY didnt work for me so i tried an inline, back/wrist problems have disapeared as i sit more upright/centered on the bike and control has been improved as i can get my erse off the back easier on the downs and the front end is more planted on climbs

cant really workout the benefits of a layback anymore ???

PS, i know somebody who cracked an ali frame at the seat/top tube weld whilst running a layback at max length. as frames dont usual crack in this area im thinking the 'extra leverage' didnt help 😐

Cy recommended I used a layback post. Feels fine to me

everybodys different mate, twas just my 2 penneth 🙂

brooess - Member
Cy recommended I used a layback post. Feels fine to me
POSTED 23 MINUTES AGO # REPORT-POST

What was his basis for recommending a layback post? Were you too big to fit any of his frames?

I use a layback on my BFe, as recommended by someone from Cotic. Just because i'm slightly too big for a M frame, but didn't want to stretch up to the L. Works fine, never even thought about switching to an inline one.

I think they were designed for a layback set post although I'm not sure why, I ran a layback on my medium Soul and it was absolutely fine for climbing and decending. When I switched to a Simple I needed an inline post as my legs seem to like to push down and through rather than forwards/down and through. My road bike has the saddle slammed all the way forward on the rails which is a bit of a faux pa, but it's the only position my knees will tolerate.

rudedog - Member

What was his basis for recommending a layback post? Were you too big to fit any of his frames?

I think you have a bit of a lack of understanding about bike geo/setup if you think that's the only reason for having a layback post.

And there's also fashion.

[b]I think you have a bit of a lack of understanding about bike geo/setup[/b] if you think that's the only reason for having a layback post.

Yes, I'd like to know more which is why I was asking a question. Not exactly a helpful reply though.

Bike sizing including stem length and seat layback is subject to many variables including personal preference and fashion.

As a guide, you want to be centred on the bike. Sit too far back and front the wheel will be more inclined to lift when pedalling uphill in the saddle. Too far forward and you're more likely to feel like you'll pitch yourslef over the bars on the downhills. To stay central, you should match a longer stem with a setback post. Also, if you're at the upper end of height relative to frame size, you'll appreciate the extra length in the cockpit where a larger frame would lose the 'chuckability'.

Then there's riding style, referring to road bikes: a time trialist will sit further forward as it's a position where they can exert more power and be more aerodynamic but it can't be maintained for a long period. A TdF set-up will be more neutral, providing the necessary long distance comfort.

Best advice is to try a few different things within the range that seems right for you and see what suits best.

Here is an example for you.

The 456 has a slack head angle due to the long forks. To stop the seat angle being too slack the seat tube angle is steepened to stop the front wheel lifting too much going up hill. Now suppose you were to stick 100 mm forks on a 456 or a rigid forks even dropping the front end. The head angle would be more normal xc style. In fact the same as a normal inbred but with a steeper seat tube angle. This pushed your weight too far forward so a lay back can help here by moving your weight back.

Another point to remember is the relative position of the seat to the pedal also effects which muscles you use and your gearing preference. A steeper seat tube angle tend to favour spinning more and using your big muscle on top of your leg but a seat further back favours slower bigger gears and the big muscle on the back of your leg (I forget the names!).

This last point is not as likely to be the main issue for a MTB such as a 456 e.t.c, it's more to do with weight distribution and playing with that.

That man up there said it betterer!

For me, layback / inline is just a function of setting the saddle fore/aft position - I agree about weight distribution as mentioned above, but for me it's much more about getting correct alignment of the knee & leg over the pedal as I've a tendency for my knees to splay in / out esp when tired (weak glutes apparently).

I read (in a Spanish MTB mag I think) that to set up, with the pedals level, on the front foot the bony protrusion just below the knee should be directly over the axle (use a plumb line if you're keen); saddle should be adjusted fore/aft to accommodate. If you raise or lower the saddle, it will change this position so you may need to realign.

The above has worked for me so far and I'm about to get a 456 built up so we'll see how that works out.

I moved to a layback post when moving from a 20" Inbred to a 19.5" rigid (so not a LT HT) Pipedream Sirius (slightly shorter top tube and possible a marginally different seattube angle). I know virtually nothing about geometry and setup, I work on the "does it feel right?" principle, I just knew that my weight distribution and foot placement on the pedals just didn't feel right with an inline post and the saddle moved aft to its maximum; the difference with the layback post was remarkable.

i know somebody who cracked an ali frame at the seat/top tube weld whilst running a layback at max length. as frames dont usual crack in this area im thinking the 'extra leverage' didnt help

I'm not sure about that myself and I'm not sure that a layback post makes much difference to leverage on the frame. Frames do crack in that area, especially if the post's too high to meet the minimum insertion criteria of the frame (which is not the same as the min. insertion criteria for the post - which is designed to protect the post). A post, layback or otherwise, run at it's maximum could exceed the minimum insertion requirement for a frame (especially with an extended seattube design) which usually requires the bottom of the post to extend some way below lowest point of the seattube/toptube weld.

I've got shorter legs and a longer body than most people my height (6ft.), so a 70mm stem and layback post keeps me happy uphill and down on my large Soul.

The myth of kops (knee over pedal spindle)
http://sheldonbrown.com/kops.html

I like my saddle quite far back, I use layback posts, on a new bike I tend to set it as far back as it will go then bring it forward if needs be until it feels right for the bike/way I ride.
Whether this is a good thing or not I don't know, I dare say playing around moving the saddle much further forward may produce mixed results, better on some bikes worse on others, CBA at the moment tho, limited time nowadays so I just ride rather than experiment.

Layback posts look weird imo

Thomson layback only offers 17 mm

FSA do a setback post of 20 mm but only single bolt

ControlTech do setbacks of 20 mm or more, double bolt

but for me it's much more about getting correct alignment of the knee & leg over the pedal

+1

layback for me, for this reason alone

plus mtbs tend to run their saddles a tad lower than road bikes, which effectively moves the saddle forward a tad.

Layback posts look weird imo

Can't really argue with that, I think that my bent Thomson looks a bit naff compared to an inline one. However, the difference in feel it gives by allowing me to get things set just right (primarily getting my foot place where I want it naturally on the pedal) is so great that I wouldn't dream of changeing back to an inline post for aeshetics.