Minimum steerer tube length above top cup ?

Just building a frame and looking at used forks… as a general rule of thumb how much excess steerer tube above the top headset cup would you you say is sufficient taking into account stem and spaces ? 5cm ?

Also – as a guide – what length steerer comes with a new set of forks ?

Thanks

steerer above top cup depends on your stem. You don’t need spacers other than to get the bars at the right height so just slightly less steerer than stem height is sufficient. Measure the headtube on your frame, your stem, and decide if you need spacers for the bar height.

new forks come with a very long steerer – just look at any picture of a bike set up without cutting it. No idea of the actual measurement.

Yep, as MrNice says, depends on how many spacers you want. 25mm will be adequate if you’re happy with no spacers.

The shortest stems are about 35mm so you need that (well, say 32mm as it doesn’t need to reach the top of the stem) as a minimum. Most stems are more like 45-50mm – at least this was the case a couple of years ago when I needed a really short stem to fit a short steerer fork.

Most new forks come with something like 26-30cm steerers

FSA OS-150 is the 35mm stem I have. IIRC though sunline do an AM type one that is even shorter – something like 25-30mm.

Cheers – still need to purchase a stem yet, but looking at my other bikes, im thinking 5.5cm excess which should allow for a couple of spaces if required. (which can be removed depending on test ride etc.)

Cheers

5.5cm will be fine.

The shortest stems are about 35mm so you need that (well, say 32mm as it doesn’t need to reach the top of the stem) as a minimum

Spike Spank is 25mm, others come in under 30mm.

I’d not chop my steerer down with that in mind though, I was thinking more from the POV of having bought a pair of forks that may be a little short.

Seems that’s not the issue for the OP anyway, which begs the question of why you’re cutting the steerer at all without the stem in place!

I still need to purchase the forks on the used market, so finding some with a decent length tube is the key part at the moment.

Cheers all

Interesting – seems there’s more choice now than when I last looked then though the spank is short (50mm longest length)

EDIT – CRC list the Spank stem as 35mm stack.