Stiff fork to Suspension fork problem

[mtnbikr]

Hi all,

I have a junky single track bike that has a non-suspension fork on it. While rooting around in a box, I found a suspension fork I thought could fit the frame. The wheelbase and the bearings all fit, but the threads coming from the tube of the fork are too tall for the head tube of the frame by about 1/4 of a inch. I was just wondering if it could be possible to either put a washer or two over the bearings and then screw it on like that, or if I could grind new threads into the tube. Thanks in advance for all replies!

-mtnbikr

[nfmisso]

The sell spacers to do exactly what you want. Here is an example.

http://www.amazon.com/Nashbar-Alloy-Headset-Spacer-Kit/dp/B005QD074A/

Personally, I would not down grade to a suspension fork. I have one bike with a suspension fork, and have a rigid fork to replace it, waiting to get done on my project list.

[Painkiller]

spacer would be a proper enough name, washers are not the way to go. The question would be. What size is the steerer tube? 1" or 1" 1/8
and remember to get a more exact measurement. You have to pre load the bearings without bottoming the top nut to the fork tube. This is assuming your threads are far enough down for the race to preload the bearings. without pics I am not for sure exactly the case.
If it is the absence of enough threads to pre load the bearings. then you will have to tap more threads, Then the spacer, or even cut the fork down a bit, which for ease you should opt for the spacer. You really need a Tube clamp saw guide and good blade to do a nice job of cutting a fork and then finishing the burrs and threads, I use various files for this process as it would be cool finishing the steel vs a grinder that may altar the temper of the steel due to heat.
Here are some pics of headset spacers, they come different thicknesses to suit most needs, and colors. Now a quick lesson in design variants. in the scale pics with the weight shown you will see the difference of 2 styles of a 20mm spacer. This is where the weight-weenies come in at. "Gram Shaving". notice the 10gr. spacer is I-beam hollowed vs. the 16gr. solid spacer. big saving when talking percentage. It is these little details that count when building light,tight and right steeds

[GeorgeET]

Good info re spacers Nigel and PK.

BTW PK did you ever try a small plumbers pipe cutter? It looks like a C-Clamp with rollers and a cutting wheel. Gives a nice straight cut, with very little burring. I usually put the nut bellow the cut and than spin it off cleaning up the threads.

[nfmisso]

(02-07-2014, 06:59 PM)GeorgeET Wrote:  .... did you ever try a small plumbers pipe cutter? .......

Hi George;

A pipe (aka tubing) cutter will work okay on hi-ten steel, but not very well on cr-mo. Most are designed for copper pipe which is much softer than even hi-ten. Cr-Mo is too hard for them to do a good job. There are a few cutters out there for stainless steel tubing, which is also softer than cr-mo.

If you do use a pipe cutter, plan on replacing the cutter wheel - which is not possible in low end cutters.

The Nashbar Guide is rather inexpensive.
http://www.amazon.com/Nashbar-Steerer-Tube-Cutting-Guide/dp/B004UMEID4/ref=sr_1_1?ie=UTF8&qid=1391818446&sr=8-1&keywords=nashbar+cutting+guide

[GeorgeET]

Yes Nigel that's true. Cheap ones would wear out quickly. The good ones have a a tool steel cutting wheel same as drill bits so they are hard. (M-2 steel IIRC) However take small cuts at a time do not push the tool. Also I do not think the steering tube in most cases is cro-mo steel.

That's a nice cutting guide. But you also need a proper hacksaw. I'll keep it in mind.

[Painkiller]

All good points George and Nigel of ways to cut a tube of some type of steel or another.Warranted on the fact that one might already own a pipe cutter vs owning neither and buying the right tool for the job. Georges point about the top race race on below the cut and used as a one edged guide is very doable, but I would use a scrap upper race as to not scuff or scar the good one. Then finish the burr and thread run. For me, between the amount of tubes I would cut over time, plus the types I cut.. meaning threaded/non-threaded, steel, alloy, and even straight up carbon steerers. Will take the same saw but with entirely different designed blades. Which compression style score cutters are useless. One will do what it takes to get the job done thats for sure. But if you have to do it for somebody else, in my opinion it should look as if it were machined and natural as possible in a state of finish. So that is why I use specific guides and blades. For the Op and a one time deal, thats why I recommended the spacer thang. But really, if you knew someone with a band saw even in his case, use it and finish it proper and all will be fine. It is all about getting a true and square cut no matter the case. one could get away being more sloppy with threadless more than threaded I think in the overall run of it.

[GeorgeET]

Yeh, for sure PK spacers is the best way to go. AS per cutting methods we were considering manual methods. Yes band saw conquers all. Now if you got a lathe I'd be really impressed. :-)

[nfmisso]

My Nashbar cutting guide arrived yesterday, and was promptly put to use. I screwed it to the end of my bench, and used it to cut a cr-mo road fork. Using the guide, the saw cut was straight and clean. Just a little bit of clean up with sanding drum in the drill press - I don't have a bench top belt sander, some day.....

This is only the 2nd fork that I needed to cut, the first I took the Wheel Away on Hamilton in Campbell a few years ago. Now with needing to cut another, and probably more in the future, I decided to purchase the guide.

Thread clean up "trick" - using a bench belt sander or large diameter sanding drum in a drill press; position the cut end of the threads at a 45° angle against the sanding surface, and rotate the threaded piece; in a few seconds you will have formed a slight cone on the end, and a nut will thread on easily.