Steerer lenght

[baron von greenback]

How do you work out exactly what steerer size you need size of head tube on bike and are all stems and headsets more or less same size especially if you have not got everything ie stem headset cheers

 

[Tootyred]

Are you talking threaded ?

 

[winjohn]

This is a reasonably clear overview.

https://www.parktool.com/en-int/blog/repair-help/fork-steering-column-length-and-sizing

 

[baron von greenback]

Are you talking threaded ?

Both mate

 

[Tootyred]

For Ahead Basically measure the head tube, add the stack of an average headset and add the height of an average stem.

As you can cut down steerers, err on the side of long.

So if your head tube is 150mm and you imagine using a 35mm stack headset, and you guess at a max 45mm ahead stem, then you need a steerer of min 230mm. But tbh..you probably want a few spacers too, so you can adjust your bars..so....260mm.?

With a quill just forget the stem and spacer measurement off your calculation.....as you can cut down treaded steerer to a degree in most cases err on the side of long, but not massive as you dont want to end up cutting more threads to be able to tighten the headset.

 

[Splatter Paint]

For ahead:, what he said^^

Head tube
+Headset
+Headset spacers (say 20-25mm to start)
+Stem

Headset and stem stack can each vary >5mm….

Steel and alloy steerers to my knowledge can be a little under (few mm) the top of the stem to allow for ahead compression. Carbon steerers however, I always have fully through the stem and a spacer on top. I.e. the steerer is a few mm longer than the sum of the stack height.

Others will disagree and say a spacer above the stem looks ugly, which is true…. But clamping my handlebars to a stick made of fibre and glue needs to be as safe as possible so I’ll do it my way!

Measure thrice
Check twice
Cut once

 

[baron von greenback]

Ok cheers are threaded steerers and non threaded steerers made in different sizes ie threaded are usually longer or the other way round or you just get what you get and can you thread a non threaded one yourself thanks

 

[bikeworkshop]

Threaded steerer Forks are usually supplied new in different lengths.
You don't want the Threaded section to extend into the area stressed by the quill.

There's often 20-30mm thread.

A girl made fit 5 frame sizes would be made with 5 steerer lengths.

Ahead, non Threaded steerer, usual comes in one full length, and is then cut to suit the job.

The tube wall thickness and diameter is the same, but it's hard to cut an inch or more of thread onto a plain tube. the tool and corresponding wear will likely be more expensive than just buying the right fork.

Cutting thread on a steerer is usually reserved for putting a few mm extra threads on.

On 2 similar sized bikes (ahead/Threaded) , the ahead steerer will be longer because it protrudes abovr the headset bearing through the stem.

Some people use a Threaded fork on ahead if its long enough, but the cross cuts of the threading offer a potentially catastrophic weak point right on the stress riser of the bottom of the ahead stem.

I've seen them failed.

 

[baron von greenback]

Nice one bike workshop great help thanks