• This topic has 9 replies, 6 voices, and was last updated 1 year ago by P20.
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  • Reach & Inline Seatposts (Gravel Content)
  • Premier Icon P20
    Full Member

    Thinking of changing my gravel bike. New frame has a reach 4mm longer, but toptube 15mm longer. As I already run a shortish stem, presumably I can pull it back with an inline post? Current bike is layback. Any benefits/drawbacks of this?

    Premier Icon DanW
    Free Member

    It sounds like the STA is the thing you want to look at and if you know that on both bikes and if you know your saddle height then it is easy to work out the horizontal difference in saddle position between the two. It would be better that way as top tube length could be a little misleading. Also, what is the amount of layback on your current post?

    Premier Icon jameso
    Full Member

    New frame has a reach 4mm longer, but toptube 15mm longer.

    Then your new frame’s seat tube angle is approx 1 degree slacker, at a guess*. An inline post usually moves the saddle fwd 10-15mm, also roughly equivalent to a 1 to 1.5 degree steeper seat angle. So, yes. Likely to put your saddle in very similar position relative to BB.

    *is stack is similar between them – if not, reach may be only +4mm but by the time your bars are set up where you want them the BB to bar reach might be more or less different, but so may the bike’s handling and weight distribution needs etc ie at that point you’re best just getting it to feel right rather than measure everything within +/-5mm.

    Premier Icon P20
    Full Member

    So frame dimensions:

    Frame   TopT.  ST.  STA. HTA.  STACK.  REACH.

    FrameA. 535.  500. 74.5. 71.      538.        386

    FrameB. 550.   510. 74.   71.5.   568.     390

    currently have around 20mm of layback on current seatpost

    Premier Icon mashr
    Full Member

    On a gravel bike wouldn’t you want to setup the saddle properly for pedalling then adjust the length by changing the stem?

    Premier Icon trailwagger
    Free Member

    On a gravel bike wouldn’t you want to setup the saddle properly for pedalling

    Isnt that true for all bikes?

    Premier Icon mashr
    Full Member

    pfft, shows what you know, my DH bikes were always well out of line

    Premier Icon trailwagger
    Free Member

    pfft, shows what you know, my DH bikes were always well out of line

    DH bikes dont tend to get pedalled much from the seat so we can count them out, also BMX. Anyway just asking, the norm is to set the saddle for pedalling not for reach, right?

    Premier Icon Bez
    Full Member

    If you’re sitting down and pedalling a lot, yes.

    Anyway, the difference between those two frames is going to mean thinking more about getting the bars in the right place than the saddle (which you can probably just slide forward 6mm or so). The seat angle’s only 0.5deg different but there’s 30mm of extra stack to deal with.

    How many spacers do you have under the stem, and what length/angle stem?

    Premier Icon P20
    Full Member

    So current bike is Planet X Full Monty in small. 100mm stem, 30mm spacers. My Cross bikes and road bikes have always been on the smaller side, it just works for me.

    the new frame I’m looking at is the Reilly Gradient. I’ve always had a titanium itch that needs scratching and the Reilly is truly stunning. The frame sizes I posted earlier are the medium. The small would be a direct comparison to the Full Monty, but I’ve found a medium for sale. To add to the confusion, the tests I’ve seen have a layback post, the Reilly builds appear to be inline posts!

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