Shortening steerer tube
 

I have decided to shorten my steerer tube after riding my bike for a long time and experimenting with different stem heights. I am ready to take the plunge.

I don't have jig for this purpose, nor do I own a pipe cutter large enough to cut 1-1/8" tube. Here's my workaround, please let me know your thoughts/concerns:

I was planning on using two old stems butted very close to one another (like, the exact width of a hacksaw blade) and thus using the stems as a guide. The only pitfall I can see is possible minor damage to the old stems. It may not yield QUITE as clean of a cut as the Park Tool jig designed for this purpose but I can file it down with a hand file and it will be obscured by the stem and cap.

The steerer on my old Ridley was cut really poorly but still rode fine because, while ugly, it wasn't so uneven that if affected the ability to tighten the stem or headset.

I know a lot of guys are on the far end of the anti home tools/take it in to the shop side of the spectrum. I get that and I respect that. I probably would because my LBS is amazing, they're just really backed up right now. I also grew up building race cars so hand fabricating metal stuff isn't new and doesn't scare me.

Also, am I the first one to think of this or have you guys used two stems as a saw guide?

Edit: This actually does scare me a little more - I was planning on shoving the star nut down past the cutting point with a mallet and a piece of PVC pipe marked for the exact length I want to push it down. I am a little worried about it getting cocked in there and not being able to straighten it out and put things back together. I have heard of guys doing this with some success and, worst case, I bung it up and have to buy a new star nut and have it installed. Not a big deal, I just don't want the downtime.

The most common saw guide used to cut steerers are two hose clamps tightened around the steerer spaced apart the same way as you proposed for the stems. Use a fine tooth hacksaw (32 tpi is good) and let the weight of the saw do the work. It is not essential to have an EXACT 90º cut. You could also leave the steerer a couple of mm too long and put a thin spacer above the stem as that will provide an exact 90º flat surface for the top cap.

don’t overthink it. I use a cheap stem as a guide. Clamp it snugly onto the steerer and run the saw blade against it. The stem gets a little scratched up, but no matter. To tap in the star nut, just get a 3” screw that matches the thread, screw it into the nut a bit, then tap the screw head to drive the nut in. If it goes in skewed, just pull it straight with the screw. The nut only has to resist 2-3 Nm of torque, So you’re not going to need a jackhammer to install it

1. My blade is 32 TPI so great! Didn't think of that, just checked (brand new blade so paint is not yet worn off!)
2. Good call on leaving space for a small spacer, but technically doesn't the cap sit on top of the stem only? If it touches the steerer tube in any way, it compromises the ability to preload the bearings in the headset, right?
3. Funny you mention hose clamps because I didn't mention this but I am also shortening my bars from 770 to 660, planning on using hose clamps for that project!

That's a really good point, it's only purpose in life is to preload the headset. Once you tighten the stem, then the stem holds every thing together.

Yes, you are correct the top of the stem defines the location of the top cap and it shouldn't touch the steerer at all. That's really why the exact 90º steerer cut isn't so important.

@davei1980-sounds like you've got it all under control. Re-star nut-I've never used anything other than a deep well socket, a little smaller than the i.d. of the steerer tube, to set the star nut.

You can use two hose clamps as a guide. Or really anything. You don't have to be precise. You can make corrections after cutting with a file.

Even if the cut is a little off, some patient file work will set it right. Just cut a little above, and then file down to, your guide. Even if I couldn't see it, I would know that the crooked cut was there and it would bother me; you may not care..

That's a really good idea, I have a large variety of deep sockets that I can pull from, I was shooting for something that A) wouldn't mar the other metal and B) approximated the I.D. of the steerer tube so that it wouldn't get cocked. I guess A) isn't that big of a deal....

Carbon steerer? Even if not, I thought its been becoming more common to cut the steerer tube long enough to extend above the stem by a couple mm and then put a five mm spacer between it and the cap. That eliminates the chance the stem won't have sufficient clamping force on the steerer tube because the end is too close to the level of the upper clamp bolt.

Bike shop has the saw guide makes it quick work..

of course holding the saw in one place and rotating the steering tube underneath it could work too
V block to center the tubing..







....

THX. My old Ridley was REALLY crooked but still worked fine. I wound up switching forks because that one was cut too low and I don't ever ride in a peloton so....

I will use a few stems or hose clamps. We'll see. I am also shortening my bars a smidge, still should have all the hand positions the Jones H bar is famous for but fewer strikes up in the woods, my primary riding location since COVID ended my commute (and ended my riding for 3 weeks all together in June!)

If I could only get in to be seen! They're super busy right now; I say let em take the bike boom $ now, I was their patron before and I'll be their patron when things return to normal volumes. No sense in putting added stress on the system.

When I was home sick, I did order too many parts I wanted because I was bored and couldn't ride. Now I have swore off all but the most necessary repairs and upgrades until after this boom ends (banging around on worn out pedals and a dented front rim right now)

Good call, and no, it's metal. I am assuming CrMo because that's what the fork is but could be alloy, I've not taken it apart yet really and checked.

I was thinking about doing this anyway, if for no other reason but to bake in a little more upward adjustment. Plus, I am running a CHUNK of a MTB stem and it's REALLY flat on top, it's possible my cap won't interface well with the top of the stem, but I know it will with a 5mm spacer because I have some on there now (hacking off 30mm, by the way)

why assume? get a magnet and know..

This information would have been very useful at the beginning of this thread. Steel forks are much more forgiving than ones made of other materials. I used a miter box the first time I cut a threadless steer tube. Worked perfectly

As a shop mechanic...
Yeah, your plan sounds fine, or hose clamps. You don't need to get it absolutely perfect to do an acceptable job preloading the bearings. You can also square up small imperfections with a file.

Small spacer above the steerer isn't a terrible idea, not necessary on steel though.

I guess it’s steel. The frame and fork are steel, I guess I didn’t think to think about it when I posted. That is one of the defining characteristics of steel. Alloy would be fine too. Carbon is another universe. I thought about a miter box but then remembered I don’t own one.

i will when I get it apart. Fighting my automatic sprinklers right now. Dang suburban life!!!

UPDATE - went really well! I left 10mm of adjustability in the upward direction, I may trim that down later or just leave it. I no longer have an 1-1/2" post sticking up.

For the star nut, I found a deep socket and marked on it with electrical tape how far I wanted to knock it down. The mallet took care of the rest. My steerer tube (unlike my handlebars) turned out to be CrMo and so it didn't cut as easy but not a big deal with a sharp saw blade.I park tool jig would have done a little better job and saved some time but this is a once-in-a-blue-moon thing so I think my approach was just fine in the circumstances.

Now off to go ride and enjoy all those grams I eliminated!!!! (jk)

Hey good job. Save a gram in 2268 different places and you've lightened it by over 5 lbs. <grin>

Hahaha yep! my bike is about 35lbs so if I did that it would still be a 30lb bike!!

I am 5'8" and 173lbs. The internet says I am overweight and need to be 149lbs to be cool or whatever. IF I can loose 24 lbs and get there, then my combined weight with me and my bike will be 24lbs less, so it's like the current me riding an 11lb carbon fiber super bike!!! LOL

I used to ride a 46 lb Schwinn Varsity. I still think it was the best and smoothest riding bike I've ever ridden. Partly maybe the 27" tires. (630 x 32). It served me well when I lived in the lower part of the state that is much flatter. However in the rolling part of the state it left me using too much energy to climb hills.

If you climb hills, even short 20 foot high terrain very much on your ride, then a lighter bike sub 24 pounds will let you have energy left to ride longer. Riding longer will give you more benefit, IMO. But I'm talking about on pavement and I only use a road bike, so YMMV.

Nonsense.