I'm starting to plan to build a bike and am looking at parts. I found a frame I like (Poloandbike CMNDR frameset) which is chromoly, but am now trying to find a seatpost to go on it. I believe the seatpost on the frame is 31.6 mm. I found a seatpost I like (Kalloy Laprade SP243) which is made of Al6061T6. My question is, is it alright to have an aluminum seatpost on a chromoly frame? I know some alloys will need grease or different conditions, so I wasn't sure if this would be an alright things to do. Any help would be greatly appreciated.

  • I don't know of any reason not to. Pretty sure I have done it for years. – paparazzo Jun 18 '17 at 21:13
  • Yes, but do make sure the size is right though. Looking at the official page, that doesn't seem to be the case: poloandbike.com/track/geometries The seat tube diameter reported there is 26.4 – Alessandro Cosentino Jun 18 '17 at 21:21
  • Interesting, I saw on another page on their site it was different. I'll contact them about the discrepancy. – TheStrangeQuark Jun 18 '17 at 21:28
  • 2
    Note that building up a bike from scratch can be more expensive than buying the complete bike and swapping out parts you don't like on it (and possibly selling these parts). – Batman Jun 18 '17 at 23:39
  • Yeah, I've thought about that and think it will be a nice project to build it all on my own – TheStrangeQuark Jun 19 '17 at 15:37

There isn't a problem with putting an aluminum seatpost in a steel frame. It's a pretty common thing to do.

Make sure to grease the seatpost before putting it in, lest it get stuck. If it does get stuck, you could try ammonia or drano (sodium hydroxide) or chilling the thing (e.g. with a CO2 cartridge to unstick it). See this page for other stuck seatpost suggestions.

Also, make sure you have the right diameter seatpost. This can be done by checking the documentation for the frame, or using a seatpost measuring tool (which most bike shops should have), or a pair of vernier calipers.

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