How much quill stem insertion required?

[RockiMtn]

Just curious if there's a general rule of thumb regarding how much of a quill stem should be inserted into a steerer? I know some quill stems actually have a min insert line marked on them, but not all, or they've been worn away and aren't visible anymore.

Reason I'm asking is I'm going to run a stem with very low rise and i would like to elevate it as high as I can to maximize height reach. It's a stem that's not easily found and I'm set on using it as I have invested quite some $ in modifying it to suit the build, so substituting isn't an option. I can ride it slammed all the way down but would like to maximize comfort as much as possible with it.

viewtopic.php?f=6&t=263251&start=60

I'm thinking since it's steel, I could probably get away with running it higher than an aluminium stem, say Syncros?

 

[marc two tone]

Having a look at stems that are marked....maybe halfway seems to be average.

If the whole of the quill wedge can pass the threaded bit of the forks then i reckon you should be ok.

 

[konatime]

is it about 65mm, i know a frame builder who once made me a stem marked it at 80mm and when i asked him he agreed some builders went a little less.

 

[RockiMtn]

is it about 65mm, i know a frame builder who once made me a stem marked it at 80mm and when i asked him he agreed some builders went a little less.

65/80mm??? that's it? are you referring from the top stem junction, or from the top of the bottom quill slant? :?

 

[cyclotoine]

Having a look at stems that are marked....maybe halfway seems to be average.

If the whole of the quill wedge can pass the threaded bit of the forks then i reckon you should be ok.

This advice is probably best. The threaded section is the weak section of having the wedge below the threads and you should be pretty safe.

 

[RockiMtn]

so is protecting from failure of the steerer, stem or both??? :?

 

[cyclotoine]

so is protecting from failure of the steerer, stem or both??? :?

The min line is really protecting the rider from the stem coming out of the frame. notched threaded steers can crack if a quill is over-tightened though. So i think ensuring it is below the threaded section is a good practice. I think you should have at least say... 1.5 inches of stem above the top of the angle cut in the steer tube to ensure the stem doesn't come loose. Maybe even that isn't enough. I know most syncros and old control tech stems were more or less designed to be inserted all the way or maybe have 10mm showing.

 

[konatime]

is it about 65mm, i know a frame builder who once made me a stem marked it at 80mm and when i asked him he agreed some builders went a little less.

65/80mm??? that's it? are you referring from the top stem junction, or from the top of the bottom quill slant? :?

i'm not sure the stem junction applies, me particular stem from bottom of quill to the stem junction was something like 150mm, so i had a 70mm allowance if i wanted the junction sat on top of my headset or fully extended (aches seem to start [for me] @ the 50 mile point, if i'm 50 on the out then i'm not at all embarassed to use the full 70mm for the home run)....but yeah..80mm min always inserted.

seem to rememebr it being something like the min insertion mark for a seatpost...so 65mm sounds about right.

 

[dyna-ti]

To the mark on the quill and never below it.
That said ive come across 100's with the stems at a scarily high point, well below the mark and they look like theyve been ok for decades

 

[jamswinna]

Frank - i run this logic when working with stems that are over 15 years old... If you intend to ride them.
*If it's mild steel and long or short in length - drop it.
*If it's alloyed steels that are one piece - safe to raise within 2" of the wedge.
*If it's alloyed steels that are multi piece and welded or filleted - safe to raise halfway.
*If it's Aluminum and either 1 or multi piece - drop it.
*If it's Titanium and 1 piece - raise halfway
*If it's Ti and multi piece - drop.