tomknox

I've been looking for a steerer to repair an old bmx fork, i cannot find a staight gauge one that will work with a old 21.1mm quill stem. Nova sells some that are butted at one end but im unfirmilar with the sizing of butted tubing. It states:

25.4 x 2.3/1.5 x 300

Butt length = 50 Taper length = 30

I'm lost on the 2.3/1.5 measurement and the 50/30 measurement for the butt and taper. Would a quill stem work with those numbers??

Thanks!!

Andrew R Stewart 

tomknox- I believe you are looking at a road steerer. 25.4 OD. 2.3 wall at the thick end, 1.3 wall at the top. 300 tall. I think the thick end is 30 long with a 50 taper but I could be wrong.

Having said all that the top's ID is about 22.8. Not what you're looking for. Andy.

tomknox

Thanks Andy, i had a feeling it wouldn't work Does anyone out there know someone who could make me one or a company that sells them? I have searched Nova, Ceeway, Paragon to no avail...

tuz

I'm not familiar with that stem size, but I would guess a 1x0.083'' straight gauge tube would work. Aircraft spruce has some. Then you can have a machinist cut threads on a lathe? I think they are standard 1x24 tpi.

Andrew R Stewart 

Having had a custom pair of steerers made (many years ago) I might try another solution. The threading was roughly cut (4130 can be that way) and the thick butt at the bottom of the steerer had a sharp "transition". Both not what I'd want in a BMX fork. A .083" wall tube might be a touch thin at the crown too. Would a threadless set up be acceptable? Andy.

tomknox

Thanks for the replys guys! Tuz you are correct on the sizes, ive got my eye on the aircraft spruce but havn't pulled the trigger in hopes of finding someone who makes them ready to go. Looks more and more like that's not gonna happen. Local bike shops charge 25 an inch for threading if they can even do it with a dye(my shop can not). I'm not sure what a machine shop would charge to do a process like that but i do know Nova sells the steerers for ten bucks.

Andy why do you think that .083 would be too thin? I have some 1'' x .065 wall in hand and i know the quill stem is way too loose for that, if my math is correct it would have to be 1'' x .083 wall (from aircraft spruce) the inner diameter is .834'' = 21.1836mm. I figured that would have to be the closest/right size, i can't use threadless set up because it wouldn't be era correct and i also have a sweet DK stem that i planned to use.

Thanks for all the help fellas, i live in a small town so if anyone knows where i could send the tube off to have it lathed properly by someone who is fimiliar with bikes please let me know here, by pm, or whatever is best. Thanks again

tomknox

Would this shim allow me to safely use my stem with that steerer from nova? It would be a .2mm tolerence left(i think), my only other concern would be if the shim length would need to be so long that its around the wedge that holds it all together....

https://www.porkchopbmx.com/Wald-905-...905BUSHING.htm

rellis

That shim is made to fit the old Schwinn stems 13/16" 20.6mm diameter into a 7/8" 22.2mm ID steerer. If the shim is too thick just cut it down lengthwise until it fits. Still use regularly in the shop.

tuz

For BMX riding I'm not sure if a shim is a good idea. And it's true that a 0.083 wall might be too thin for the same reasons. If you can find a guy with a lathe for the threads (I would not recommend cutting threads from scratch using a die) then you could get a thicker tube (say 0.120 wall) and have him machine the OD for the stem (tapering the transition would be best vs. a square shoulder).

What's the issue with the fork?

tomknox

Thanks guys! The bike will be a carpet queen, no real bmx riding/jumping from me lol.

As for the .083 wall being thin, it shows on Sheldon Brown that the ID of old bmx is .833''(link below). Unless my math is incorrect, 1'' x .083 wall x .834'' ID from american spuce would be the right choice(or so i thought). I have decided after finding out that Nova wants 15.00-20.00 dollars to ship me one, i can buy a donor fork for less. Thanks again for all the help fella's!

https://sheldonbrown.com/headsets.html

ksisler

Could you not just replace the fork?

tomknox

I could for 500 plus if i could find one that is...

Andrew R Stewart 

tomknox- My "too thin" reference was to the lower portion of the steerer, the section that enters the crown and is brazed/welded on. The reason that steerers are butted is too have extra strength at the part that sees the most stresses and has had the loss of strength from the joining process. You could add a reinforcing sleeve at the steerer's lower end, many forks have this. But your lack of recognizing this aspect of fork design has me worried. Of all aspects of a bike, risking a broken fork steerer is just about the last failure I'd want to suffer. Just ask this guy. Andy.


https://www.metacafe.com/watch/436884...cord_accident/

tomknox

I understand steerers are butted now but i have a couple mid 80's to early 90's bmx fork's and trust me sir none are butted by any means. I certainly understand your concerns and i appreciate the advice also. Those company's used straight gauge tubing that accepted a 21.1 quill stem and they were threaded, that i know for a fact. Maybe i'm over looking something else i guess??

Andrew R Stewart 

tomknox- I won't argue your experiences. But those forks do swim against the tide of decades of bike design. It's this collective process of many millions of bikes reaching the same conclusions that I'm speaking of. I have seen MANY bent and twisted forks in my 40 years of wrenching. The vast majority were from incidents and abuse. (The most interesting few had blades bent both forward and back wards). But the number of and the degree of steerers being bent are less then the blades. I think this is good as the steerer is hidden from view and can't be monitored by the rider easily. If a rider is going to use the bike in a harsh manor (think tricks, wheelies, jumps, endos, all done by BMX and street riders frequently) then they need to be able to know their equipment is not going to be a problem when they land a tail whip off a dirt jump. So as the first guy who customers come to when their stuff breaks i am a bit sensitive to making this kind of bike robust enough.

BTW you mention that you're repairing a BMX fork. My i ask why it needs replacing the steerer? Do you work out of a shop and are under their insurance umbrella or do you have your own company? Andy.

tomknox

Yes, old bmx is just that, old, and outdated! Like i said, no insurance issue's with a carpet queen bike. Speaking of insurance, take a look at these forks made by the great Linn Kastan. They actually raced them hard back then, naturally they didn't last...worthy of carpet queen/cruise around the block status dont you think?? Worth a lot of coin also...

fietsbob

I see it has one blade welded to the steerer, if your spine were removed what will your leg hook onto?

I see a machine shop project IF it's not going into service again. JRA at most

Is it thread damage ? or what ?, it is possiblre to Cut, down and and weld on steel machined to be the diameters you need
a quality weld penetration then bore out some bead from the ID, is an approach to consider ..

Andrew R Stewart 

It's been a long time since i saw forks like that (out side of Cannondale and show/weird bikes). I have never been fond of the one sided forks or rear triangles either. Sure they can work but you either make them heavier, have less strength/stiffness or need to ride them lightly. Again i go back to the collective wisdom of the world and don't see this kind of stuff done in any numbers. The bicycle is a pretty well figured out device. That's why it's remained basically the same for so long. Most every recent claim of "new idea" has been done before. The ideas that actually do work better are the ones that become the standards from then on. Andy.

Andrew R Stewart 

fietsbob- I'm not sure tomknox is showing the fork he originally posted about. I think the one sided fork is an example of questionable design that some one who people think was cool did. Andy.

fietsbob

I'd think, any Unicrown fork shares that issue, only of the fork were using a fork crown
to join blades and the steerer, could a steerer be removed..

BMX manufacturers, hve run unicrown forks for a long time..

tomknox

Im not sure what really makes one cool or not. A pioneer for sure, first tubular chromoly forks (saying bye-bye to bladed junk forks) and then the first tubular cranks. I guess that might make you pretty cool. Since it seems like some people need a little bmx lesson here's an exerpt for wiki:

The company Redline Racing Frames was founded in 1970 by Linn Kastan and Mike Konle in Chatsworth California for making chromoly motorcycle frames and swing-arms. The company consisted of a staff of 6 people and was receiving much success with their motorcycle swing-arms. In 1973 Kastan decided he would weld a bicycle frame for his son as a Christmas gift that same year. His son soon after raced this bike under his fathers company name Redline. The bike was noticed by a company called Pedalers West and they challenged Kastan to come up with a stronger and lighter fork specifically for 20" bmx racing. Kastan accepted the challenge. In Feb. of 1974 the first pairs of tubular chromoly forks were being produced. They were an instant success and became a favorite amongst racers at the time. Later that year Redline would release its first chromoly frame the Squareback. Due to the high price at the time of $85.00 the frame sales were dismal. In 1977 Kastan and Konle agreed to go separate ways and Kastan would take over full ownership of Redline Racing Frames and Konle would carry on with the motorcycle side renaming his company Champion. By this time Kastan had designed and was releasing the Proline, their first official Team Model frame and fork. Soon after the famous V-Bars handlebars, the MXll frame and the Microline frame (mini series) were released. With these additions the company was gaining success again and by January 1980 Redline Flight cranks were going into production. They would be bmx's first tubular chromoly 3 piece cranks which would become Redlines most popular product they had ever produced.

Andrew R Stewart 

Linn Katsan wasn't the only dad to make his kid a BMX bike and grow a company. Redline was there early on but they didn't discover anything for real, like the vast majority of companies, they borrowed from previous designs. What made them cool was the timing of their efforts and the market they served. When you sell to a market that has little sense of history it's no wonder why many feel that some products are really new.

My comments about the single sided fork was more about it's being an experiment that didn't make it in the main stream bike world. If it really was a better way then others would have copied it. But this, also, has been done before and the collective bike world decided it wasn't a better way to make a fork.

In my youth i worked for a number of years in a shop whose owners collected bikes, largely from the turn of the old century. Every winter we would break down one or two of the collection to freshen up the lube and such. I was in a very impressionable period, starting to build frames and riding in a "serious" way while finding myself as an adult. So i asked a lot of questions and listened to a lot of history about the bike business and designs. Full suspension, ultra light steel tubing, fiber construction, anatomical saddles, index shifting, fixed gears and single speeds, integrated bearings, sloping top tubes, clipless pedals are all examples of designs that many today think are new in their life times. Single sided forks and tubular forks and cranks included.

Still it's neat that some are pushing the designs. Just not for others with out insurance. Andy.

tomknox

That sounds like great times no doubt Andy, not bashing anyone at all but i never meant to start any debate about what methods are more superior than other out-dated methods or any other rebutle. My first post explains that i was looking for, an old steerer and didn't know if anyone supplied them. Thanks again for the help.

Andrew R Stewart 

tomknox- And my hope was that in your attempts to replace the steerer you wouldn't end up with a result that was less capable then before. The steerer is the one tube that is stressed through one end only. Given it's duties and the consequences of it's failure i would think you'd wish to be conservative. Everything else I've mentioned is to give a fuller context and impart the importance of this one tube. I still have questions unanswered but I guess we will just agree to disagree. Andy.