Mountain Biking - Cutting steerer tube to length: Part II

If my understanding is correct, it is the star/nut/cap assembly that provides the head bearing tightening. I need to install my new forks and cut the steerer tube. Basically, are you supposed to cut the tube so that its top edge is Xmm below the top edge of the stem? Does my question make sense? If so, how many millimeters?

I couldn't find any articles on this....if any of you have a link please post it.

Follow-up questions:

1) Can the bottom bearing race be gently tapped off my old fork so I can put it onto the new fork?

2) How do you know how thick to make the stack of spacers underneath the stem? It looks like my bike came with 3 spacers of about 3mm each. So...is this a somewhat arbitrary spacing distance depending on the dimensions of a new stem and a newly cut steerer tube? In otherwords, does it really matter if I had a stack height of 5mm as opposed to let's say 12mm?

Hope all this makes sense guys. I think I am over complicating it, but I just haven't done this before and want to make sure I cut the tube properly in my new fork.

Thanks

http://www.parktool.com/repair_help/howfix_forksize.shtml

2-3mm cut below the stem

yes it can be tapped off with a punch/screwdriver

as many spacers as you like its preference put some in see if its too high or to low and cut away

ok...thanks....and I will check out that link as well

Do you remember the old style stems? (Quill Stems) With those you could adjust the height. With a threadless, you cannot. (KINDA) You adjust the stem height by leaving the steerer tube a bit longer an moving spacers from below the stem to on top of the stem until you find a comfortable height.

Now, once you've determined your "best" height, you can cut your steerer tube 2 - 3 mm below the top of the stem, or do what I and many others do, leave it a bit long. Like 2 -3 mm above the top of the stem.

The beauty of the threadless system is that the top cap doesn't really hold the headset tight. It does so, just until you tighten the pinch bolts on your stem/steerer tube connection. You could actually unscrew the top cap and completely remove it if you so desired. So, you only need enough tension to hold the headset together. You can stack 2 or 3 spacers above the stem and have everything work just fine.

The drawback is that you don't want the steerer tube sticking out above the stem too far. You don't want to have a "nutcracker" incident.

Now, once you've determined your "best" height, you can cut your steerer tube 2 - 3 mm below the top of the stem, or do what I and many others do, leave it a bit long. Like 2 -3 mm above the top of the stem.

The beauty of the threadless system is that the top cap doesn't really hold the headset tight. It does so, just until you tighten the pinch bolts on your stem/steerer tube connection. You could actually unscrew the top cap and completely remove it if you so desired. So, you only need enough tension to hold the headset together. You can stack 2 or 3 spacers above the stem and have everything work just fine.

Okay...I understand that the top cap doesn't hold the tension and that it is the tightening of the stem pinch bolts that holds everything. However, don't you need the initial tensioning of the cap assembly? If so, then how can the the stem be cut longer like you said many of you do? I am confused? Or if you cut the steerer higher than the stem, do you then need to put a spacer directly below the cap so that you can get the tensioning? In other words, doesn't the bottom of the cap have to be surfaced against either the stem top or a spacer in order to "pull" the steerer/fork up and tight/snug?

I guess you confused be by saying a lot of you leave it longer. Explain...

Or if you cut the steerer higher than the stem, do you then need to put a spacer directly below the cap so that you can get the tensioning?

Exactly. If you're leaving the steerer a little long, from top to bottom, it should go:

Cap
Spacer
Stem
Additional Spacers (optional)
Headset

Yeah, what Gastro said.

You can leave the steerer tube longer, if you put a spacer or two above the stem, so that the top cap has enough space to NOT bottom out against the steerer tube.

Exactly. If you're leaving the steerer a little long, from top to bottom, it should go:

Cap
Spacer
Stem
Additional Spacers (optional)
Headset
Okay...it's making more sense. I just read the Park tool link that another poster gave me above.

A couple more follow-up questions for you guys and then I think we can let this thread die.

1) Is there any advantage to leaving the steerer tube longer and using subsequent spacing above the stem?

2) If you are supposed to have the top edge of the steerer tube 2-3mm below either the top edge of the stem or the top edge of a spacer above the stem, then does it really matter if the cut on the steerer is perfectly square other than for aesthethics?? As I posted last week about the Park Tool cutting guide...it seems the "2-3mm below" negates the necessity of this cutting guide?

Comments?

thanks

Okay...it's making more sense. I just read the Park tool link that another poster gave me above.

A couple more follow-up questions for you guys and then I think we can let this thread die.

Threads never die, they just dwindle into nothingness!!!



1) Is there any advantage to leaving the steerer tube longer and using subsequent spacing above the stem?

The advantage is future adjustability. Plus, if you have a nice fork and install it on a frame with a short steerer tube, then upgrade your frame, you are stuck with a nice fork and too short a steerer tube.

Plus, I may set up my bike more XC biased with a longer stem, or more FR oriented with a shorter stem and a more upright position. Depending on what I do, I want to have the option to raise or lower my stem accordingly.



2) If you are supposed to have the top edge of the steerer tube 2-3mm below either the top edge of the stem or the top edge of a spacer above the stem, then does it really matter if the cut on the steerer is perfectly square other than for aesthethics?? As I posted last week about the Park Tool cutting guide...it seems the "2-3mm below" negates the necessity of this cutting guide?

Comments?

thanks

Agreed to a point. You want to cut as straight as possible to prevent the top cap from touching on one side but not the next. So, in actuality, a perfectly straight cut is not absolutely necessary.

But, when I was a shop mechanic, I would have been embarrassed if I cut a steerer tube and it wasn't straight. More representative of the time and effort you give in the details will speak volumes of the type of person you are.

The advantage is future adjustability. Plus, if you have a nice fork and install it on a frame with a short steerer tube, then upgrade your frame, you are stuck with a nice fork and too short a steerer tube.

Plus, I may set up my bike more XC biased with a longer stem, or more FR oriented with a shorter stem and a more upright position. Depending on what I do, I want to have the option to raise or lower my stem accordingly.


Great help! Okay, before I let this dwindle...

Follow-up question partIV: :D

1) For the future adjustability aspect, what is a reasonable mm amount above and below the stem in spacers? As stated, you don't want to go too high above the stem. Yeah...how high can I go without looking like a dork on the trails?

I guess this was kind of already answered. Is 2-3mm longer stem and then a 5-6mm spacer above that about the limit?

I have had about 3 spacers on the top of my stem before. that is about 2 more then most would run.

I may have looked like a dork to some, but that has never really bothered me. :D

uuggghhh! GOD! I just can't let it die.

Follow-up question XVII:

1) Does it matter if I use carbon spacers? Should they be Al?

You already know the answer to this one. The only load the spacer bears is compression from the cap, and the preload is not significant. Carbon is fine.

You already know the answer to this one. The only load the spacer bears is compression from the cap, and the preload is not significant. Carbon is fine.
Right...now I feel ********.

Thanks everyone for your help. The Internet is great. As usual, I walk away feeling like an expert.

No *********** implied nor intended.

Did you ever get an answer about the crown race? (yes, you can gently pry or gradually tap it off).

No *********** implied nor intended.

Did you ever get an answer about the crown race? (yes, you can gently pry or gradually tap it off).
:D

Yes about the crown race. This is good because my head set is still in mint condition.