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I recently purchased a new bike and I am trying to swap the original saddle for my own. On my previous bike both bolts holding the seat clamp together are down facing, i.e. accessible from below the saddle. On the new Bianchi one of the two bolts is facing upward and only accessible through the saddle cutout. This is fine when removing the original saddle however my saddle does not have a cutout, so I have no way of tightening that bold. There is not enough clearance to get an Allen wrench in there. There is a knob-like thing on the front bolt, but I couldn't dream to tighten it to 1 Nm, let alone the 8-10 Nm recommended.

I would go and ask the LBS but they are so busy right now they can't help anyone (some are downright dismissive when asking for help). Any help, suggestion or reading material would be appreciated. Thanks

top view of the original saddle. Bolt visible from cutout front view of the clamping bolt, knob visible under the clamp

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  • Is the rear bolt accessible from the tail-end of the saddle?
    – Carel
    May 18, 2021 at 19:32
  • Yes, the rear bolt is easily accessible from below the saddle. I felt uncomfortable torquing only the rear bolt while adjusting the front one with my thumbs but so far that is what people have suggested. I will try it out and see if the saddle slides on its rails.
    – Alex Rose
    May 18, 2021 at 22:49
  • It’s a Fizik Seatpost, right?
    – Michael
    May 19, 2021 at 5:20
  • It's the original seatpost from Bianchi, it's branded Reparto Corse however they could be sourcing them from Fizik and rebrand them, I wouldn't be able to tell
    – Alex Rose
    May 20, 2021 at 4:18

4 Answers 4

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You use the front bolt to set the angle first, then torque the rear bolt. Sometimes a few times to get it right.

The front bolt is adjusted with the thumbdial or a lever put into one of the holes in the thumbdial (eg 2.5mm allen key) when the rear bolt is fully slack. Hopefully it won't have blue loctite on it but if it does, you should remove it and replace with grease.

The thumbdial is shown in the second photo, the black, splined part on the bolt.

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  • Thank you for the advice. This is counter intuitive given that almost everything that has more than one bolt I usually tighten alternating to even out the pressure. I will try your trick and see if the saddle stays in place.
    – Alex Rose
    May 18, 2021 at 22:46
  • @Alex it's a common design and works well as long as the front bolt is not allowed to sieze.
    – Noise
    May 19, 2021 at 6:36
  • I didn't think about that, I guess it would be worth cleaning out and greasing the threads once every so often because if it does seize it will get a thousand times harder to undo.
    – Alex Rose
    May 20, 2021 at 4:21
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This is simply how two-bolt "infinite adjust" seatposts work. The front bolt acts as an angle adjuster, while the rear bolt does the actual tensioning. Tightening both bolts to the rated torque is first off too much clamping force, and secondly defeats the repeatable and adjustable nature of this style clamp.

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I can't be sure without seeing it from the side, but one option would be to cut down an allen key of the right size so it fits in the space available. You can take most of the short arm off with a good hacksaw or a grinder, just be sure to keep enough straight metal to engage the screw head. I've done this for a kickstand, as well as for a few non-bike applications

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  • There is very little clearance, but it could work. Unfortunately I don't have anything to cut down an allen key.
    – Alex Rose
    May 18, 2021 at 22:47
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    It sounds from other answers like you don't need to anyway, but basic metalworking tools do sometimes come in handy for bike tasks
    – Chris H
    May 19, 2021 at 7:10
  • For the rear nut there are very flat ratchet type wrenches available that remove the need to play around with the wrench. I have exactly the same problem on my bike. I adjust the angle at the front and tighten at the rear.
    – Carel
    May 19, 2021 at 17:29
  • @Carel I have two that use interchangeable bits (the common 1/4" hex type). They're nice if you've got space, but a cut down Allen key needs less than half the depth - I've got a 5mm in work that will fit in a 10mm gap.
    – Chris H
    May 19, 2021 at 18:00
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I have a similar clamp but with the thumbdial at the rear. The bolt above that I can’t access as there isn’t enough room with the saddle in place. Would I torque the rear bolt before attaching the saddle? Please advise. What would be the best way to proceed then with the front? Thanks

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    – Ted Hohl
    Jul 3 at 13:24
  • If the bolts are the same thread, swap them over? Is your seat post facing the wrong way, try rotating it in place then reverse the saddle.
    – Criggie ♦
    Jul 3 at 18:00

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