hokiefyd 

I got this fork from a very generous BF member, knowing that the 1" threaded steerer was way too long for my head tube. I plan to use it as a threadless setup. I think I know what I need to do, but I'm hoping to get some affirmation from you guys.

Length: to my understanding, I cannot (or should not) clamp a threadless stem around the threaded section of the steerer. My plan would be to cut the steerer tube at the very bottom of the threads (where the cone nut is in the picture) and use spacers under that for height, as with a normal threadless steerer. Is this correct?

Cone: my top cone is obviously a nut right now (with a spacer or two and a lock nut on top of that). I need a non-threaded cone and a plastic insert to center the steerer tube, right? I assume that the cone needs to match the race, and that it would be best to buy a 1" threadless headset, and at least use the top race and cone out of that. Is that the best option? My other option would be to file the threads off the current cone nut to turn it into a threadless cone, on top of which I would install spacers and my cap. Is that a no-go, or is that an okay way to do this?

Nut and cap: I've looked around and nuts and caps exist for 1" steerers (I guess it'd be a 7/8" star fangled nut). I will need to buy these and the right amount of spacers.

I appreciate any and all comments and suggestions.

IMG_20170901_112846449 by jnjadcock, on Flickr

thumpism 

If you don't need the steerer length then by all means cut off the threaded portion. If you need all the steerer length you can get, don't be shy about clamping on the threaded portion. I've done it. If you feel the need for reinforcement or additional strength, use Bondo or JB Weld in the threads and smooth it.


You will need the top half of a threadless headset. Your local co-op might have the pieces cheap to be used as a test setup before you spend real money on a new component, or that might just work well enough for you to live with. Star nut and cap should be available but you might need to search for them.


If you can't find the top pieces easily and are just itching to get this thing built, then go ahead and file the threads out of your top cone. I'd be concerned about some slop in the setup that the real threadless cone and centering washer would eliminate but, what the hell, go for it! Good luck!

fietsbob

the stem and all those spacers add thickness.. Ideal would be a BBB BHP 20, its a Quill internal stem raiser, its 7/8"

just wont need the various shim spacers (there to match the 1" OD of the syeerer)

.. it includes a bolt, threaded in its top, to use the top cap threadless headset pre-load ..

Wiggle in England exports, cost, under $20, + shipping..




...

JohnDThompson 

Filling the threads with Bondo or JBWeld won't do anything to strengthen the threaded section. You could, however, stick a threadless adapter in the steer tube to reinforce the tube from the inside.

hokiefyd 

Thanks, all. My goal is to spend as little as possible. As you might be able to glean from the picture, this is an old steel MTB. The decal on the frame claims that it's chrome-moly, but the fork has a "Hi-Ten" decal, so I wanted to upgrade the fork to something else. The yellow fork is a Tange chrome-moly fork from the 1980s. I knew it would be too long, but I also want to set this bike up as more of a touring bike with upright geometry, so the length of the fork is fine (with spacers). Until I'm confident of the setup, though, I do want to keep my cash outlay small. I will likely see if I can source a centering nylon washer locally for the 1" steerer and might sand the threads out of the cone with some sandpaper wrapped around a tapered dowel. That should keep it more or less of a circular hole, and the nylon washer should lock in pretty good I'd think.

I probably will either cut the steerer or have my bike shop do it, as I really won't need the threaded portion.

I have only two bikes in the family with threadless setups, and they're our daughter's bikes (which I try not to mess with!), so I don't have a lot of experience with threadless (which is why I want to do this conversion and learn more about it and gain experience with it).

Dave Mayer

With respect to *not* clamping the new (threadless) stem on the threaded portion of the old steerer tube, you are absolutely correct. Unless you do not value life & limb.

In my role as mechanic at a busy bike Co-op, I regularly see the frightening products of backyard mechanics. But this ghetto conversion is among the scariest: where a threadless stem is simply clamped on the top of a threaded fork steer. Often, the stem is barely secured - hanging on by 10mm or less to the very end of the steerer.

So the main problem here is not as much the clamping forces of the new stem, but it is that the threads introduce as major stress riser to the steerer tube. Think about the constant back and forth forces on the steerer in the gap right under the stem. Reinforcing from the inside, doesn't fix this. It may only buy you a few miles of the bars hanging on to the rest of the bike when the steerer fails.

Bottom line: a threadless setup simply requires a smooth, strong steerer.

And yes, get a 1" threadless headset, or at least the top parts.

hokiefyd 

Dave, thanks. Yes, my intention is to either cut the steerer below the threads. I'm going to check out both local bike shops after work to see if they have 1" threadless headset parts. I really don't want to spend 30-40 bucks on a new headset at this point (especially in such an uncommon size) until I figure out the final setup.

Should I need to measure the diameter of my head tube, or should any 1" threadless setup work? This one on eBay is far and away the least expensive option (and is even cheaper than just buying the star nut and cap separately). I'm not a weight weenie, so a steel headset is just fine. Should this one work? For 10 bucks, I'll just do this instead of trying to cobble together other parts.

FBinNY 

This is actually very simple.

If you cut the threaded section, it's a threadless steerer plain and simple, no matter that it wasn't so before.

The only time the situation wouldn't be this simple, is when the length is such that you cannot cut off the entire threaded section, and have to consider the implications of where the threaded section ends.

Dave Mayer

The 1" threadless headset on EBay should work, except if lists a crown race diameter of both 26.4 (ISO) and 27.0 (JIS). Well, it cannot be both. So you have to figure out what your frame and fork dimensions are. Most bike shops will be less than no help here, and their slim 1" headset inventory consists of useless, orphaned JIS units. And they don't know the difference.

And when they try to install your new headset, they'll be mystified when either the new headset cups are loose (diagnosis: you need a new frame), or the immense compressive forces they've had to apply to get the cups in has split your head tube (diagnosis: Wtf??).

So you need to know with absolute certainty if your bike is JIS or ISO...

BTW: your frame and fork may be different (mixed) specs. As may be the headset..

If it was me, I'd leave the bottom headset parts in place, unless it is 'indexed'.

hokiefyd 

Dave, thank you for posting that; I'm glad you did. I tapped the old cups out of my frame and my head tube measures about 29.9mm inside diameter. It looks like ISO cups have a 30.2mm outside diameter (obviously a press-fit into the head tube). All that sound good so far?

The Tange fork has a 27.0 crown race area (there is no crown race on it). Looks like this is a JIS fork (makes sense, given its 1980s Japanese provenance. I wonder if the Sunlite set includes two crown races, to fit either. Probably not likely at that price.

My bike shop here had an Aheadset TR.1, and it looks like it's an ISO unit. I reckon this would be okay for my frame, but I'd need a JIS race for the fork, right? I live out in the country; no co-ops here unfortunately. That's probably what I need, though -- a huge parts bin of C&V bikes/parts.

Edit: it looks, from Sheldon Brown's crib sheet that the JIS cups are 30.0mm in outside diameter. Given my head tube is 29.9mm, maybe my entire setup is JIS? I guess that might make this easier, given that it's just one standard, huh?

Dave Mayer

I think you have a JIS compatible frameset. There should be about 0.1mm interference fit between the cups and the head tube. If your frame is 80s Japanese, this reinforces this assessment. But you need precise measurements of the headtube, the cups, the crown race, and the fork steerer.

Don't assume that what it says on the headset box matches what is actually in the box. Assume that the parts in the box are a jumble of mismatched take-offs from a old upgrade.

Finally, don't assume that Internet sellers or local shops know anything more than you do about this.

And the internet seller is simply confused: headsets never come with both crown races.

hokiefyd 

I'm pretty sure it's all JIS. It's a 1995 Motiv mountain bike. I don't know a whole lot about the Motiv brand, other than I have two of these '95 Stonegrinders, and they seem nearly bomb-proof. They seem like an Asian-based builder/reseller.

The outer diameter of the cups are 30.0mm and the inside diameter of the frame tube is about 29.9mm. The outer diameter of the crown race seat on the steerer is 27.1mm and the inside diameter of the crown race is 27.0mm. This is all on the old stuff. My Tange fork also has the 27.1mm crown race seat.

So it looks like I'm looking for a 1" JIS threadless headset. These seem to be difficult to find (I don't see much on the internet). I will go back to the bike shop tomorrow, though, and see what standard their set is. If ISO, I'll know to move on (and I'm pretty sure it is).

Edit: And, actually, now that I've learned what I have (thank you!), I think I'll just modify the top race by removing the threads and finding a compression washer that'll work. That should be as good as any headset that I can buy (and much cheaper). And if I decide I want to go back to threaded, I haven't ruined anything that I can't replace -- threaded headsets are 5-10 bucks online all day long.

xenologer

Nope, that's not how it works.
You'll need to remove the threads, and then machine a bevel at the same angle as the sides of the 'nylon washer' (better described as 'compression ring') ?got a lathe? I doubt it, just buy a threadless headset upper.

it's not just about centering the cone, it transfers force from the bearings to the steerer. so its important that the faces match. and get an aluminum or steel compression ring, the nylon ones are cheap and squish and lose adjustment.


true story:
guy comes into the shop with a craiglist bike, says the fork is wobbling around
I check and find that the threadless headset is frankenstiened together from other dead headsets
instead of a compression ring, a piece of copper plumbing pipe has been hammered onto the steerer to try and shim against the cone.
It didn't work.

don't kludge stuff, do it right



edit: on second thought, money always trumps good advice and I know you won't listen
so waste your time trying to kludge it
when you find out after that the headset can't be preloaded properly and it wiggles around no matter what you do
then go buy the real one, or ignore the problem and sell it on craigslist to some sucker; that seems to be the status quo...

hokiefyd 

Thanks; this is helpful. My challenge is finding a JIS 1" threadless. I've checked Nashbar, Jensen, Chain Reaction, eBay, etc. I seem to come up with the Ritchey Logic, the Miche, and the Sunlite I posted earlier. But, each of these seems to be ISO.

The Origin8 headset that Harris Cyclery sells says it comes with both crown race sizes, so maybe most of these do, or he ones that specify two crown race sizes, at least.

https://www.sheldonbrown.com/harris/...hreadless.html

I guess the best option is to have my bike shop ream out the frame for an ISO headset, and just get an ISO headset that also comes with a 27.0mm crown race (like that Origin8 one)? Interestingly, the picture appears to be of a threaded headset!

rosefarts

You can order any 1" thread less headset. Just use the top half. The bottom half doesn't need replacing. So no need to worry about matching your race.

hokiefyd 

I can't use EITHER half of an ISO threadless headset in a JIS frame without modification, right? I'll have to have the head tube reamed out to use either of the cups from an ISO set, right?

Yes, I do agree that I can use the existing bottom half if I can't come up with a new crown race. It's the top half parts that I'm having trouble finding. Which was the genesis of my idea to just remove the threads from my existing top race. But I understand the concept of the compression ring spreading the preload to the bearing, requiring a pretty precise taper in that top race.

rosefarts

I don't have a ton of experience with them but I'm pretty sure that a 1" head tube is a 1" headtube. So any 1" cups will press into your frame. The ISO thing refers to the diameter of the crown race.

Again, I am not certain that this is the case, just pretty sure. Someone here will confirm or set me right soon I'm sure.

Dave Mayer

All correct. Except for what I've posted previously, basically ignore all else.

You need to find a JIS threadless headset, or at a minimum the top parts. There is only a slim chance that your current upper cup will mate with the bearings etc from some store-bought unit.

Or get your frame reamed to take an ISO cupset, or just the top. I don't know of any shop that I would trust with this; an expensive disaster in the making.

Or what seems to be the only reasonable option remaining: mods to your existing headset.

BTW: attempting to install ISO cups into your JIS headtube will require immense compressive forces that will break either the installation tool, your frame, or both.

hokiefyd 

Unfortunately, 1" is not 1" in this case.

https://www.sheldonbrown.com/cribsheet-headsets.html

My frame and fork are both JIS, meaning I'd have to ream my head tube to install most threadless headsets (which are ISO).

I'll probably bring my upper cup and bearing with me to the bike shop today to see if the threadless race in their headset will seat with the bearing and cup from my old headset. If that will work, then I should be able to use both of my existing cups, and I'd be home free.

hokiefyd 

I figure it will be a long-shot. I agree that the chances of this are slim.

It does seem to be so. I will post what I eventually end up doing. In the worst case, if I modify my headset and find that I can't maintain adjustment on it, then I'm back to square one and I'm not out any real money.

hokiefyd 

I went to my local bike shop today. They had an Aheadset brand (Cane Creek's cheap line I think) 1" threadless that is, I think, full ISO (30.2 mm cups and 26.4 mm races). Model TR.1. In this one, the crown race and head race are actually identical, and they have a special compression ring/seal at the top. Eh...it's what they had so I tried it. They installed it for me. The cups are actually slightly stepped, and Aheadset's installation instructions says that the head tube needs to be 29.9 mm. Okay...that's what I have -- and I thought that was JIS. But the cups on this are 30.2 mm. Whatever.

https://www.aheadset.com/downloads/AH...structions.pdf

AHEADSET :: Bicycle Headset Manufacturers

You can see that the webpage confirms that the cups are 30.2 mm. And the PDF instructions say your tube can be 29.9 mm. Weird.

He did have a hard time getting the top cup in and said it was due to paint over spray in the head tube. He had a ball hone on a drill and used that to clean up the inside of the head tube. He then greased the head tube and the cups appeared to go in without too much trouble. That just left the crown race for me to deal with. I filed the 27.0 mm crown race seat on the fork down to about 26.4 mm and seated the crown race at home.

I think it's gonna work. I do not have a jig to cut the steerer (but the bike shop does, so I'll probably take it to them to cut and face it next week). Then I'll paint and install it.

I'm left just a touch confused with Aheadset's documentation on this headset. It seems to say that their 30.2 mm cups will work in 29.9 mm head tubes, which goes against a lot of what I've read. Maybe they have that "stepped" cup design to accommodate both standards. It seems like it's going to work for me. In the future, if I need to replace this thing, I guess I'll be able to use a standard ISO headset. And my fork is now ground down to 26.4 mm as well, so I'm good to go there.

Thanks, all, for the help.