MrSparkles

I've ridden the past couple of years with a quilled stem and as the belly has shrunk I've adjusted the bar location (height & reach). Now I am interested in buying a new frame that comes with a threadless steerer and realize I don't know how they work, setup wise.

How do you determine at what height to set the stem? Is it based on my present bar height of a different bike?

Do you cut the steerer tube a little too long and ride for a while giving yourself the opportunity to adjust the stem location up and down?

Once you cut the steerer tube there is no adjusting the stem higher, right?

I am assuming there are many different lengths and angles of stems so that over time one can adjust their bar position?

If there is steerer tube protruding above the headset to the stem, is the steerer tube covered with any thing? Or does it come painted?

Thanks y'all.

Rowan

It pays to be conservative with cutting the steerer tube. If you are ordering a new frame, ensure that whomever is selling it to you does NOT cut the steerer tube at all. LBS are terribly guilty of cutting steerer tubes on all bikes way below what is practical for many riders.

If the steerer tube is left long, you can fiddle with the spacers and get to a ballpark height comparable with your current quill set-up. Yes, there are stems in various lengths and angles, but it's much better to settle on one to start with and stick with it. Check the length and angle to the quill stem you have, and transfer those dimension over to the threadless one.

The issue with leaving the steerer tube uncut, of course, is that you will have to add spacers above the stem. You'll also have to insert either the star nut or expander plug so you can tighten down the cap and get enough preload on the headset bearings. But don't worry.

Once you have ridden the bike a little and either moved the stem up or down to suit you, or settled on the right height, you are then in a position to have the steerer tube cut. If there is a star nut in there, it will either need to be left in place until after the cut, then knocked through the cut-off bit, then reinserted in the steerer; or if it is right where the cut is to be made, knock it down far enough to make the cut.

It's always a good idea to set the height based on the required number of spacers below the stem, the stem itself, and 1/8th inch/3mm spacer on top. Once you figure this height, cut the steerer tube according to the instructions, ensuring it is slightly short to account for the depth of the cap.

The additional spacer on top of the stem enables a little bit of further fine-tuning if needed, but on a CF steerer tube, it also helps prevent the stem from causing cracks around the top which then can work their way down the tube, and thus weakening it.

Hope that helps.

Rowan

I've separated this because it's important. There should be no steerer tube protruding above the stem or spacers. Rather, it should be cut so that it is slightly below the top of the spacer or stem. This is so the cap will fit down, and then when the cap bolt is tightened, the whole assembly will be tightened, and thus put preload on the headset bearings.

If you have the steerer tube protruding, the cap won't be able to pull down on anything except the tube, leaving you with loose and very clunky stem and headset bearings.

woodway

Well, that's a complicated question. If your current bike configuration fits you well, then that is a good place to start. You could also pay for a bike fitting.

That's what I do. You can move the stem up and down by shifting spacers from above/below the stem to below/above.

There are steerer tube extenders. I've never used one and don't know anyone who ever has used one. More typically people buy stems with more or less rise to fine-tune the height.

Yes, stems come in many lengths and angles.

You put spacers over the tube and then the headset cap goes over the top. Spacers also come in many sizes and colors.

woodway

You just add one or more spacers over the top of the stem. Put enough spacers on so that the top of the steerer tube is below the top spacer. The cap then goes over the top and will snug down to preload the headset bearings.

big john

Most of the modern forks have a 300mm steer tube (about 12 inches). Many bikes will already have the steerer cut before you see them.
Some guys who only keep their bikes a year or two will leave the steerer extra long to make it easier to sell.
Oh, and you're supposed to limit the amount of spacers you have under the stem to around 50mm, I think.

Rowan

I think if you look at enough pictures of bikes on BFs that have threadless, you'll find the 50mm is arbitrary, and there are many, including our bikes, that are well over that. Having said that, I wouldn't get too adventurous with carbon fibre steerers.

Doug64

Excuse the poor photo, but it relates to some of the discussion on this thread. When I built this bike, I planned on leaving the steerer tube on this Long Haul Trucker uncut until I had the fit dialed in. This was almost 2 years ago, and it still is not cut Most stock bikes come with the steerer tubes already cut to some hypothetically "correct" height. The only direction the bars can go are down without using some radically angled stem or other "make do" component. Even then the amount of bar height adjustment is limited.



Just add spacers above the stem, with the last spacer a few mm's above the top of the steerer tube to facilitate headset adjustment. I may get around to cutting it someday.

Retro Grouch 

I suspect it has more to do with the shipping carton size requirement than anything else.

lhbernhardt

The manufacturers of forks with cf steerers don't like you to use spacers higher than the diameter of the steerer. So for a 1 1/8" steerer, you don't want to use more than 2.8 cm of spacers. If you need your bars higher than this, you would use a stem that angles upward. But it's hard to get a flat stem (-17 degree rise, consistent with a 73 degree head tube) anymore these days anyway. Most stems now come with an 8 degree rise. I just hate this, since I prefer a flat stem, like in the old days.

Also, it's a good idea to always use a small (2 to 5mm) spacer above the stem before you apply the top cap. This acts like a washer, but also moves the top cap above the expander bolt ALWAYS used on a carbon steerer so that you are properly preloading the headset. Those expander bolts install right to the top of the steerer (unlike the star-fangled inserts used in metal steerer tubes), so you need a gap between the expander and the top cap.

That said, threadless headsets are such a HUGE improvement on the old threaded ones. Aside from the steerer tube no longer requiring threading (a big factor for shops, or if you've ever needed to get a steerer threaded - it actually requires a lathe; you don't just run a die over it!), installation is so much faster! When I convert my road fixie for track use, I even change the forks. This way, I don't have to disconnect the front brake (or the computer sensor), and it takes less than five minutes. Plus I no longer worry about the stem getting seized in the steerer tube after a winter of riding. Adjustment is dead simple: preload with the top cap, then tighten the stem to hold the adjustment. One 5mm allen key does it, unlike having to use two headset wrenches!

Luis

Rowan

It's worth saying that you never, ever, never use as star-fangled nut in a carbon fibre steerer tube. I've already saved one poster on BFs from damaging his fork beyond repair with that advice. Expander plugs MUST be used, but even then, you might have to experiment to find a design that will bind properly.

qcpmsame 

I am for the more modern thread less steerer tube with a stem and the necessary spacers. I don't subscribe to the flipped and slammed theory, I have about 25mm of spacers on the bottom and left the tube uncut. I have 2 spacers above the stem and I did go to a flipped stem after my back loosened up from riding a bit. I have both a quill and a thread less adapter for my other bike, a 95 R500 and can adapt it to fit me or one of my children should they need a bike for the day. The thread less or Ahead set set up offers me more flexibility and different stem lengths and the ability to use the newer over-sized bars, as mentioned above.

Bill

Onfixiate

I use drop bars, flat bars and mustache bars on my Wabi Special fixed gear bike. I have an IRD "locking spacer" that holds the front end together and maintains the headset preload when I remove the bar/stem assembly. The spacer is "loose" until the preload is set, and the stem is tightened. Then, once everything is tightened, the locking spacer is cinched. Everything above the spacer can be removed/swapped out without disturbing the headset preload.

fietsbob

Another 'locking Spacer' fan .. integrated headset, bike..
the 1.125 " Ahrens Wise cracker, pinch bolt version,
works too, secondary function, opens the (non twist off) bottle.