I'd say max 80mm above the top of the head tube (this does NOT include the height of the headset top cap), but at 80mm you could easily go up 1-2 frame sizes.

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Strava

The number of under-stem spacers that you can safely use depends on, among other things, the steerer tube material, the length of stem that you plan to use, your body weight, the type of roads/terrain you expect to ride on, etc.

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Isnt it save to assume that you can safely use the bike with whatever headtube length its being shipped by the mfg? Usually you get an uncut headtube so if theres 30mm of spacers plus the stem then surely thats safe as they wouldn't ship it with this headtube length and that way if this wasn't the case.

I'd check with the bike mfg to see what they say or suggest. When I bought my BMC Team Machine, they said max of 30mm of spacers.

Is this is for the purpose of comfort at a proper fit, or getting a different frame to fit you in terms of size?

If comfort, are you buying the best touring or comfort geometry option the supplier offers?

You could always gain a few mm by swapping the stem out also for something with plenty of positive rise.

Reason I ask is there's a guy with a Giant racing bike in the parking lot that's the mid 2000's version of a modern Propel. He's gotta have the max spacers under it. He could have just bought something with a much longer head tube. Just sayin.....

If you need something really slack look for long head tubes in some kind of gravel/touring geometry bike before thinking about tossing on inches of spacers.

200 lbs, mixed terrain roads. 1/3 good roads, 1/3 rough roads, 1/3 hardpack or gravel. Maybe some easy flowy singletrack.



When you're 6'5" and long limbed, your out of the box perfectly fitting bikes are a bit more limited. But I'm looking at gravel/touring bikes, yeah. Thru-axles and 650bx47mm tire fitment are the other things I'm looking for.

Unfortunately, this is often not the case.

When one buys a frameset, one often gets a fork with a very long steerer. Why? Because, for a lot of frames, the same fork is used for the whole range of frame sizes. Each frame size has a different head tube length, but one fork (for manufacturing simplicity) must fit them all. So, many manufacturers make the steerer tube on the standard fork long enough that it will fit the biggest frame size they make, with enough extra that the rider can still use a few spacers with that frame.

The result is that the fork is WAY too long for the smaller frame size and the manufacturer expects that the fork steerer will be shortened substantially. You can't use the 'stock' steerer tube length as a guideline for how many spacers you can use.

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How long of a stem?

What steerer material?

Is this a gravel bike?

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