UnCruel 

This is my first time building a bike from a frameset (obviously), but I didn't think I'd have newbie questions this soon. It's a 2022 Farley AL frame and fork. The headset parts were supplied with the frameset, and the stem is a Bontrager Kovee Pro 35 Blendr Stem, 13° × 50mm. Even with all the spacers on, the steerer tube is at least 57mm too long. Am I supposed to be cutting down the steerer tube? The length of the steerer tube is 235mm right now.


Doesn't look right

rickpaulos

sure, cut it.

None of this applies to forks with carbon steerers.

A plumbers pipe cutter will do a fairly good job.

Freehand with a hacksaw will come out crooked and ragged. You can spend the next hour trying to file it to look good and to get it square so the top cap will put equal pressure all around on the headset bearings.

Park Tool makes a guide for squared cutting with a hacksaw. Or you can use two old stems clamped on with a 1/16" gap between them to guide the saw blade. For threaded forks, I use two old top races threaded on back to back with the gap equal to the width of a hacksaw blade.

Some would use a cut off wheel on an angle grinder. You need a pretty steady and strong hand to make a clean
cut.

A machinist would put the fork in a metal lathe and make the cut perfect.

I'd use a hand hack saw for aluminum as aluminum will clog up abrasive wheels.

Cutting aluminum with power tools can send bits into your eyes. Steel 'sawdust' is usually much finer and not as much of a danger to your wallet when some eye md has to try to clean out your eyes.

There is a star fangled nut installer tool for (re)setting the nut. You need that to pre-tension the head set bearings before tightening up the stem clamp that holds it all together. Star fangled nuts need to be driven in as square as possible. Once crooked it's a real bugger to fix.

Trying to extract an already installed star fangled nut upwards is a royal pita. If it's in there and now where you need to cut, I'd make the cut and drive the star fangled nut out the bottom end of the cut off section of steerer.

The final fit should have the spacers/stem be about 4 to 5 mm taller than the steerer. The top cap and bolt needs some space to pull everything snug.

delbiker1 

Yes, to cutting the steer tube, with considerations. The tube on new forks purposely come with a long length. That gives the person using the fork the option of different lengths, depending on bike fit to body and other considerations. Usually, riders will leave more length than is really necessary for making future changes an option, such as selling the bike and/or fork. A prospective buyer may need more length than the seller. Often, it takes some time and miles to get to where an owner might realize the set up they have is wrong, with the possibility of needing to raise the handlebar some. Just those two reasons alone make it prudent to leave some extra length. However, too much length can be an issue also, including the safety factor. A lot of stems will state the minimum/maximum length for spacers for beneath and above the stem. Not as important is the aesthetics, too long and it may not look right to you.
It is also important to have a clean and level cut at the top of the tube to insure the stem and top cap are seated correctly for proper operation and safe usage.
There is likely a general rule for the amount of not necessarily needed length left on the tube, but I sure do not know what that is. Others on this forum are sure to chime in. I am not a highly experienced mechanic or bike builder, but I have cut a few steer tubes. One had to have a bit more removed as it was not a straight level cut, ergo, the top cap would not seat properly. Another, after riding for a while, I realized I needed to raise the stem/handlebar a bit, no big deal with enough tube to work with. I do not have a cutting guide, but I used hose clamps for alignment, then lightly filed the rim edges to smooth them.

Iride01 

I don't have the complete answer for you, but when you do decide to cut it off, leave some sticking above the stem and just fill that up with spacers too. That way if you later decide you don't like that much drop on your bars you'll be able to easily get higher by removing a spacer from above and putting it below.

While it use to be fashionable to cut the steerer so the end cap could set on the stem, now more and more people are leaving 5, 10 millimeters or even more worth of spacers on top the stem. I've gotten use to the look and even do that myself now.

cxwrench

Of course you need to cut it. Hacksaw is the way to go, with a cutting guide. If you use a pipe cutter it will nearly always bulge the steerer a few thou and make it really hard to put the headset top cover on. Use a saw and finish it w/ a reamer to make it smooth.

alcjphil

I made that mistake once with a steel suspension fork steerer. Took a fair bit of work with a file to carefully remove that bulge

UnCruel 

Thanks, everyone. I'm not worried about how to make the cut. I have a self-feeding bandsaw that will cut it off good and square, and then I'll dress it up on a belt grinder. My lathe doesn't have the right kind of chuck for the job However, I am a little worried about the length. The bike's geometry and fit are total unknowns to me right now. I guess what I should do is order another tall spacer and cut the tube for the whole stack, and once I have the bike more assembled, I can make a more final decision about the height of the stem.

alcjphil

It it always best at first to cut the steer tube too long and use extra spacers until you dial in your fit. You can take it off, but you can't put it back if you make a mistake

delbiker1 

Truer words have never been spoken.

FBinNY 

Yes, ultimately you'll cut the steerer to a length that has it end about 2 or 3mm below the top of the stem. (anything from 1 to 8mm is fine)

It's an easy job you can do with a fine tooth hacksaw, ie. 32t per inch. This isn't precise work because nothing depends on the end. If you're worried about a straight cut, place a hose clamp on the good side of the cut.

Finish by cleaning up the edges with a file or emery cloth.

PLEASE NOTE that I don't suggest cutting it to the final length yet. Leave it a bit longer for now, using more spacers above the stem as needed. It's not rare for people to later want a higher stem.

You can always cut it shorter later, when you're sure, but cutting it longer is very difficult.

IPassGas

I love this commentary! I have access to a Hardinge and others, with much shop experience. I would try to chuck it up and cut, but I imagine the fork spinning at some distance beyond and hitting something cause I can't move stuff out of the way. Yes, the band saw seems better, but I'd prefer the accurate cut of the lathe. Anyways, there are simpler methods of cutting of a bicycle tube, but not as precise. And of course...precision with a bicycle is important, cause it is our mobility on an amazing mechanical transportation device that matters

UnCruel 

The photos of full factory builds of Farley bikes on Trek's web site all show them set up with one 10mm spacer. I may be overthinking it.

urbanknight

Absolutely. Get a bunch of spacers and put them over as well as under the stem to adjust the height to your liking. Then make the cut, and even then I prefer to keep an extra 10mm on the steerer with a spacer on top, just in case I want to go a tad higher later.

urbanknight

Factory photos are all about advertising appearance and have nothing to do with bike fit for you or anyone else. If they thought it should be that way for everybody, they'd cut the steerer at the factory.

cpach

Forks with aluminum or steerers are generally designed for relatively modest maximum spacer stack heights (often around 2-3cm) , though that is taking into account liability protection against failure for the largest, strongest rider riding the roughest terrain expected--obviously, the actual mechanical stresses relate heavily to rider weight, position, technique, and terrain.

Forks are pretty universally uncut for framesets--they are long enough for any frame size, and usually are some stock tubing length unrelated to the size needed for the largest frame sizing.

That spacer stack looks like it's probably about as Trek intended. Assemble everything and cut 2mm short of the top of the stem. I have good luck with a pipe cutter + file and reamer, but a hacksaw with guide is also a great solution.

urbanknight

Is that true? I need to go home and measure my spacer stack.

HillRider

The only forks I've seen with recommended spacer stack limitations are carbon steerers which are usually specified as a maximum of 25 mm for a 1" steerer and 40 to 50 mm for a 1-1/8" steerer. I've never seen a published limit for aluminum or steel steerers.

BTW, if you are going to cut the steerer long enough to use a spacer above the stem (which you should), the steerer cut does not have to be accurately flat since the spacer provides the bearing surface for the top cap.