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I rounded the flats on the seatpost clamp bolt (it's an Allen bolt; i.e. I turn it with a Allen key) that came with my bike (2014 Fuji Absolute). I found a replacement for the bolt at a local hardware store, but it's a Philips screw, not a bolt. It's the same size and fits the clamp perfectly.

Is it safe to install? Is there any chance of damaging the bike?

My primary concerns are due to not really understand what torque has to do with seatpost clamps, and other bike repair forums insisting you use a torque wrench lest you damage things. But I think that might apply more carbon fiber bodies.

Philips Screw Screw

Allen Bolt Bolt

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  • Yes, a picture would help visualise what you're looking at. Do note that tensile rating and material comes into it as well... a cheap mild steel bolt will rust, and won't be as strong as a higher-rated fastener. What was the old bolt made of? Steel, stainless steel, or something else?
    – Criggie ♦
    Jan 30, 2016 at 7:14
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    There is not a universally-accepted distinction between bolt and screw so it's probably a good idea to be more specific.
    – jqning
    Jan 30, 2016 at 14:49
  • @jqning I'd have thought a bolt is intended to screw into a nut or into a pre-cut thread, whereas a screw makes its own thread on inserting. OP has probably found a different bolt with the same thread, rather than a screw.
    – Criggie ♦
    Jan 30, 2016 at 21:38
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    @Criggie I think that's a typical understanding but it's not accurate. I won't give the definitions of bolts and screws, but machine screw for example doesn't cut its own threads. So in this case, yeah, a machine screw is fine.
    – jqning
    Jan 31, 2016 at 2:35
  • portlandbolt.com/technical/faqs/hex-bolts-vs-hex-cap-screws Since y'all seem to need definitions... But don't let that side conversation cloudy the waters... you know what he means. He had a hexbolt and now he's wanting to swap in a capscrew.... Pretty common thing.
    – david1024
    Feb 1, 2016 at 1:53

4 Answers 4

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As long it secures the seatpost I don't see how a screw instead of bolt can damage the bike. If it fails, the worst case would be a seat sliding down. You might find it inconvient if screw has head that requires tools not usually used for bicycles, like phillips screwdriver or a hex head.

New seatpost collars are cheap, so you can buy a replacement to feel subjectively safer.

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  • Some clamps even have bolts that can be bought separately from the LBS.
    – Carel
    Jan 30, 2016 at 8:52
  • Thanks. I took my bike into a bike repair shop today and the guy there said pretty much the same thing.
    – Jay
    Feb 1, 2016 at 2:58
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It depends on the grade, material, and the threading of the fastener you found. You'll want fine (a.k.a. machine) pitch threads and Stainless Steel for the material (otherwise it'll rust and sieze)

The collars are usually Aluminum and there is a galvanic corrosion that'll take place unless you use a lot of grease or some blue loctite (formula 242, or medium). Be careful with the torque if you have a carbon frame or seatpost--your LBS can do the fix pretty cheap/fast if you aren't comfortable doing it yourself.

Like the other poster said, you can easily replace the whole thing, but if yours will take the replacement fastener (if these ever break, I drill the threads out of the clamp, if it has any, and replace with a Stainless Steel cap screw and nut anyway--metric with a head that matches the other stuff on the bike.)

Good luck.

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  • It doesn't need to be stainless and they hardly ever are.
    – jqning
    Jan 31, 2016 at 2:41
  • Yes it does, and they are. Grade 5 bolts with zinc plating are a terrible idea.. they don't have the strength and will either strip or not hold the post firmly enough (e.g. you'll have to fiddle with it periodically to keep it the right height) But, it is your bike... Do what you want.
    – david1024
    Jan 31, 2016 at 2:58
  • google search for binder bolt, click clickity click click enter OK! Look, if you know that non-stainless will rust, seize, break, strip, or slip (I think I covered all the problems) you might have some explaining to do to 95+% of cyclists who rock em just fine.
    – jqning
    Jan 31, 2016 at 3:04
  • Believe you are confusing chrome plated with zinc. Chrome plated steel would be OK as long as the chrome stayed put. But Chrome plated fasteners are a lot harder to find at a hardware store than stainless.. Although there are a lot of hits when i search for binder bolt rusted.... so there are a lot out there using the wrong material.
    – david1024
    Feb 1, 2016 at 1:44
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I've done this when the LBS didn't have a bike to fit a slightly odd BSO seat post, but there was a hardware shop next door. The bolt was zinc plated rather than stainless, but I used stainless, and washers under the bolt and nut, and grease on the thread. None of it rusted or seized in the few years of light use before I gave the bike away.

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That pan head screw is fine.

I'm going to guess that the potential damage you read about is to the bolt itself. Those binder bolts are notoriously easy to break. There was traditionally an initiation phase amongst race mechanics that ended when the rookie breaks a campy binder bolt. And the bolts are deceptive, you can do 90% of the damage and have the bolt hang on fine, but the next guy barely touches it and it falls apart. It's a sinking feeling when that happens. But anyway, that's why the torque wrench.

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