Lay Back or No Lay Back Seatpost on a Custom Frame?

cal_stewart
cal_stewart Posts: 1,840
edited March 2011 in Road buying advice
About to buy a seatpost for new frame as its custom steel for me will i need lay back or not?
Plus it being made for a 130mm stem if that helps
eating parmos since 1981

Canyon Ultimate CF SLX Aero 09
Cervelo P5 EPS
www.bikeradar.com/forums/viewtopic.php?f=40044&t=13038799

Comments

  • neiltb
    neiltb Posts: 332
    wouldn't you better off asking the guy who's custom building your frame?

    edit
    the answer lies in what side of the bed you sleep on, left or right?
    FCN 12
  • edhornby
    edhornby Posts: 1,780
    if you're getting a custom frame built, presumably you've been for a fitting so the frame builder would be able to tell you what would replicate the measurements he built to

    whether you have layback or inline depends on whether you need to get your bum forward to get your knee over the pedal or sit more upright but the frame builder should have this sorted
    (there may be instances where a post with layback is percieved to be more comfortable but I don't think this would apply to a custom steel frame)
    "I get paid to make other people suffer on my wheel, how good is that"
    --Jens Voight
  • cal_stewart
    cal_stewart Posts: 1,840
    cheers thought as much, just didn't want to ask the builder a stupid question
    eating parmos since 1981

    Canyon Ultimate CF SLX Aero 09
    Cervelo P5 EPS
    www.bikeradar.com/forums/viewtopic.php?f=40044&t=13038799
  • MichaelW
    MichaelW Posts: 2,164
    130mm stem thats means a big frame. Is your builder designing for larger cranks because these feed into the layback requirements.
  • Berk Bonebonce
    Berk Bonebonce Posts: 1,245
    I can't think of a reason why someone would want to use an in-line seatpost with a road frame, other than as an attempt to make a frame that is too large for them smaller.
  • neeb
    neeb Posts: 4,467
    I can't think of a reason why someone would want to use an in-line seatpost with a road frame, other than as an attempt to make a frame that is too large for them smaller.
    Whether you need layback to get your ideal saddle position in relation to the bottom bracket is entirely down to seat tube angle and how this relates to your body dimensions. It's quite possible to have a frame which is a perfect fit in terms of reach, head tube length etc but has a seat tube angle that requires you to use an inline seatpost to get the correct position in relation to the bottom bracket. Such a frame would fit exactly the same as one with a steeper seat tube angle and a correspondingly shorter top tube which required you to use a layback seatpost.
  • Evil Laugh
    Evil Laugh Posts: 1,412
    The frame builder should be able to design the frame either way. As said it's only a means of virtually adjusting the sta. So in your case, if you have picked the seatpost and saddle you like your frame should be designed around that and your ideal distance between centre crank and sadlle tip.

    For example for me to use a modern style saddle on my steel bike I ideally need an inline post to put my behind on the same place as a brooks on a layback post and keep my pedal stroke and distance to crank centre the same. This is because the rails are located pretty centrally on the modern saddle but at the back on the brooks which also has a higher profile above the rails.

    So saddle choice and choice of seatpost aesthetics for me would be decided before finalising frame design. Presumably you'd want layback, inline looks odd on a road bike
  • Anonymous
    Anonymous Posts: 79,667
    If I had a frame that needed an inline seatpost then it would have a crazy slack seat tube angle, which would mean crazy long chainstays and kooky handling.
  • neeb
    neeb Posts: 4,467
    If I had a frame that needed an inline seatpost then it would have a crazy slack seat tube angle, which would mean crazy long chainstays and kooky handling.
    Depends on leg length and femur length. I must be at a different extreme, because with a 73 degree seat tube angle I am best off with an inline post. I can use a layback post but the saddle (Spesh Toupe) has to be all the way forward with the clamp at the back of the rails, which IMO looks weirder than an inline post.

    If I was getting a custom frame I would probably go for a 74 or 74.5 STA just so I could use a layback post with the clamp in the middle of the rails. On the other hand, it seems perverse to design a frame to put your arse forward and then use a layback post to shift it back again. In some ways a 73 STA with an inline seatpost would be a more elegant solution for my morphology, it's only because it's unusual on a road bike that it looks weird.