# How to extend a short steerer tube



## ron m. (Aug 1, 2009)

I did the search and had these options:
1) find a short stack headset 
2) find a low profile stem (Spank Spike Stem)
3) use this extender (BBB - Extender Steerer Extender 28.6-25.4mm)

Well, since this was a cheap build and I didn't want to spend unnecessarily, I came up with an idea (based on option 3). Remove the star nut on the fork if it has one. The modification will pre-load the headset. Just an FYI, I still had enough steerer tube that the lower bolt was able to secure the fork in place. I just didn't feel comfortable being an inch and a half short so I figured I'd do this. I wouldn't recommend this if you barely have any steerer tube sticking up from the headset.

a) First, you have to find an old quill stem (1 inch of course). 
b) Cut the lower part (and in my case, I shaved off part of the diameter because it wouldn't fit (there must be an older quill stem that would fit a 1 1/8 tube)
c) find an excess 1 1/8 inch steerer tube (I called my local shop) to use as shim
d) mark the part of the tube that sticks out of the stem. That inserted portion will be your shim.
e) remove the tube and cut the shim (ideally 1/8 inch shorter than your marked length)
d) make a vertical cut on the tube (to allow the tube to pinch into the quill body later
e) insert the shim and press down so it sits at least 1/8 below the stem surface
f) insert the quill unit along with the bolt and cap
g) tighten the bolt until the headset bearings are pre-loaded
h) tighten the stem bolts

The fork looks tight and because the quill unit is between the steer tube and shim, I think it will make the mend fairly strong.


----------



## cobba (Apr 5, 2007)

Draw a diagram showing how it all fits together, I'm not too sure what you've actually done.


----------



## mack_turtle (Jan 6, 2009)

that looks terrifying. I hope you have good dental insurance because putting all your teeth back in your head is going to be expensive after that thing fails.


----------



## ron m. (Aug 1, 2009)

I'll just add labels to the last picture but hopefully I can describe it.

Insert your fork into the head tube (with the headset already there) and then the stem. Because you have a shorter steerer tube, a significant portion of your stem will not have any surface to clamp. That's what the shim will be for. Insert the shim until the lower portion butts against the fork steerer tube. Now insert the quill body (with the bolt AND cap attached but just barely threaded in). I positioned the quill body to be in between the fork steerer tube and shim to provide maximum reinforcement. Anyway, tighten the bolt until the stem pushes down on the fork and preloads the headset unit. Then tighten the stem pinch bolts and you're done.


----------



## ghettocop (Jul 26, 2011)

WTH? Credit to you for serious ingenuity, but wow!


----------



## tg (Feb 1, 2006)

Yikes!


----------



## customfab (Jun 8, 2008)

Are you using that on some kind of dirt jump bike? That looks sketchy as hell!


----------



## John Kuhl (Dec 10, 2007)

I would think twice before bombing down a hill
with that setup. A new fork is cheaper than broken
bones.


----------



## Brewtality (Jul 25, 2007)

Get video of you hucking it off some sweet jumps. The landing might hurt. You might be eating all your food through a straw for a couple months, but damn, the LULz will be awesome.


----------



## ron m. (Aug 1, 2009)

LOL! There will be no hucking on this bike. Love the LULZ!!! LOL!

This will be more of an XC bike type fun bike. As far as the stem integrity goes, well, I'll just have to find out, won't I? This really isn't ingenious, I just took inspiration from the extender that's commercially available and I would even think that my mod would be far better than the BBB unit (click the link on my original post so you have an idea) because the quill unit is inserted between the steerer tube and the shim I created. 

Lastly, would it still be sketchy if I bought one of those low profile stems (again, click the link in original post) as opposed to now having two pinch bolts applying pressure (lower bolt pinches against steer tube 100% and upper bolt pinches shim/quill combo)? 

Anyway, good thing I have awesome insurance. =P


----------



## mack_turtle (Jan 6, 2009)

this is going to become one of those epic, classic threads where someone tries to do something stupid, everyone tells them not to do it, they do it anyway, and it fails as everyone predicted. go get some popcorn.

I would not do so much as ride that off a curb, let alone any sort of trails.


----------



## ron m. (Aug 1, 2009)

Love your spirit, Mack. I'm sure the Wright brothers would have loved your heckling when they decided to build a plane. =P

What did bikes used to have to secure the stem before the advent of threadless headset systems? Quill-type stems. And if this was so dangerous, why is someone actually selling a fix-it system commercially? I bet they have a ton of lawsuits from failed installations. 

I appreciate all your concerns (sarcastic or otherwise), but someone has to be the guinea pig... although I don't feel like I am since I'm copying off another product.


----------



## AZ (Apr 14, 2009)

ron m. said:


> Love your spirit, Mack. I'm sure the Wright brothers would have loved your heckling when they decided to build a plane. =P
> 
> What did bikes used to have to secure the stem before the advent of threadless headset systems? Quill-type stems. And if this was so dangerous, why is someone actually selling a fix-it system commercially? I bet they have a ton of lawsuits from failed installations.
> 
> I appreciate all your concerns (sarcastic or otherwise), but someone has to be the guinea pig... although I don't feel like I am since I'm copying off another product.


The Wright Brothers had some actual build experience and a reality based concept by the time they got around to aircraft.


----------



## ron m. (Aug 1, 2009)

Dirty $anchez said:


> The Wright Brothers had some actual build experience and a reality based concept by the time they got around to aircraft.


Granted I am not a mechanical engineer, but we're talking about extending the steer tube 1 inch! I'd like to hear how my mod, which is a copy of a commercial product, is unsafe. If I get a good answer, I'll take it off.


----------



## sasquatch rides a SS (Dec 27, 2010)

Subscribed. Be sure to post pictures of your injuries.


----------



## AZ (Apr 14, 2009)

ron m. said:


> Granted I am not a mechanical engineer, but we're talking about extending the steer tube 1 inch! I'd like to hear how my mod, which is a copy of a commercial product, is unsafe. If I get a good answer, I'll take it off.


If you leave out the less than ideal tolerances, a steer tube that was never intended to have a wedge in it and the additional piece that you added I guess you would have a "copy" of a commercial product. Sometimes you look at something and you get that little nagging "that just doesn't look like a good idea", otherwise refered to as "Preservation of the Species". Good luck to you.


----------



## eb1888 (Jan 27, 2012)

This seems a logical useful option when you think about the stresses involved. There isn't much trying to pull your fork down out of the head tube. All the force pushes it into and up.
I've pounded tech sections for lots of miles over time with a stem gabbing with just the lower bolt.
Zero problems even through crashes. The bars would show looseness side to side before they would pop off anyway.
Everything is dangerous if you don't think about it for a minute.


----------



## floydlippencott (Sep 4, 2010)

General Discussion needs a "Darwin Was Right" sticky.


----------



## fishwrinkle (Jul 11, 2012)

why not just order new uppers?


----------



## Mr5150 (Dec 20, 2011)

fishwrinkle said:


> why not just order new uppers?


Way cheaper than the cost of false teeth and plastic surgery.

(gads)


----------



## fishwrinkle (Jul 11, 2012)

^^^ who knows, maybe he could benefit from a lil plastic surgery


----------



## Mr5150 (Dec 20, 2011)

ghettocop said:


> WTH? Credit to you for serious ingenuity, but wow!


Perfect example of how there is no correlation between intelligence and common sense.


----------



## Berkley (May 21, 2007)

ron m. said:


> Granted I am not a mechanical engineer, but we're talking about extending the steer tube 1 inch! I'd like to hear how my mod, which is a copy of a commercial product, is unsafe. If I get a good answer, I'll take it off.


FYI, the "commercial product" isn't that safe either. Its not intended for mountain biking and it is a band-aid fix to a bigger problem.


----------



## vqdriver (May 8, 2009)

sorry dude. fix it right or fix it twice.


----------



## Thor29 (May 12, 2005)

There are several reasons not to do this, but the biggest one is that there are two different torque requirements here - one to secure the wedge inside the fork, and one to set the bearing preload. You can't get two different torques out of one bolt. If you tighten it enough to keep the wedge secure, your headset will be too tight. If you get your headset just right, the wedge will work loose.


----------



## deke505 (Jul 29, 2012)

eb1888 said:


> This seems a logical useful option when you think about the stresses involved. There isn't much trying to pull your fork down out of the head tube. All the force pushes it into and up.
> I've pounded tech sections for lots of miles over time with a stem gabbing with just the lower bolt.
> Zero problems even through crashes. The bars would show looseness side to side before they would pop off anyway.
> Everything is dangerous if you don't think about it for a minute.


Except when bunny hop those kids or pull a wheelie to get your front tire over a obstacle.


----------



## justin_amador (Dec 2, 2009)

Thor29 said:


> There are several reasons not to do this, but the biggest one is that there are two different torque requirements here - one to secure the wedge inside the fork, and one to set the bearing preload. You can't get two different torques out of one bolt. If you tighten it enough to keep the wedge secure, your headset will be too tight. If you get your headset just right, the wedge will work loose.


^
This chap's got it. If you could isolate the steer-tube extension clamping forces from the bearing pre-load forces, you'd be a happier camper. I'd test to expected load conditions or failure and figure out if that's acceptable or not before riding too much. Don't forget about fatigue, corrosion, etc . . .


----------



## fishwrinkle (Jul 11, 2012)

i know this is several months old, but i want to know if the OP is still alive?


----------



## cobba (Apr 5, 2007)

fishwrinkle said:


> i want to know if the OP is still alive?


http://forums.mtbr.com/search.php?searchid=688952


----------



## fahza29er (Jun 26, 2012)

fishwrinkle said:


> i know this is several months old, but i want to know if the OP is still alive?


Or at the very least still has his teeth.


----------



## Shane5001 (Dec 18, 2013)

I had to follow the link to option #3 to figure out what you were building. Basically just trying to copy their idea. Problem is, is your version isn't solid, that 1 1/8" "shim" is what you're clamping your stem to? It's split. For $20 you could have bought option #3, which is still a bad idea in my mind, but much safer. You're playing with a chunk of real estate that takes one hell of a beating, even on an xc bike.


----------



## girlonbike (Apr 24, 2008)

Oooohhhh. Where arrrrrr hisss teeeefffff?


----------



## ron m. (Aug 1, 2009)

Wow... I was looking at some of my old threads and saw this. Thanks for the concerns, btw. It's been a year since I did this mod and so far, so good. I've been riding the bike about 10-15 miles of moderate trails (Lake Chabot, all the trails of Joaquin Miller including Cinderella and Chaparral) and it's performed admirably. Surprisingly, I've got her just a shade under 25 lbs right now. As I said in the beginning, I took a calculated risk but felt it was safe enough based on the stem I had and the amount of steerer tube I had left (I know guys who run equally short steerer tubes without the mods I did and they're also good so far).

Anyway, I DON'T recommend doing this, especially if you're not comfortable with your work or don't understand the physics and mechanics involved. Caveat Utilitor.

And no, I don't baby this bike on the trail. I suck at going uphill but I love the DH. This is my regular ride:






Here she is (sub $500 build, under 25 lbs, 1 X 10 set-up)


----------



## Austin Popper (Feb 2, 2014)

Get a fork that fits, so you don't have to rely on luck.

Christ on a crutch!


----------

