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New Fork Instalation Dillema
#1
I'm installing a new RST fork on my Schwinn Sidewinder, and I ran into a few problems today.
Steerer tubes on these forks are interchangeable, meaning that the tube is sold seprately, and installed by the customer.I chose a 160mm threaded steerer tube, because I wanted to keep the existing headset. I installed the steerer tube today without any problem, but when I went to put the new fork on the bike, I noticed two things: first that the new steerer is longer than the old one, and secondly that the crown race from the old fork doesn't seem to fit. The tube is mounted all the way onto the crown of the new fork, but the base of the tube is not as wide as the old steerer, so the race is loose enough to slip up the tube easilly.
Further, when I went ahead and assembled everything anyway, I found that the headset remains loose enough to allow excessive play, even with the adjustable cup tightened all the way down. It appears as if the bottom of the threaded portion of the tube is below the level of the bearings, and that the adjustable cup was tightened down against the fixed cup, which stopped it from being tightened any further.
Can anyone here help me finish getting the new fork on my bike? I imagine I could get spacers to take up the extra length on the steerer, but is cutting it to the same length as the old tube also an option? Does it matter if the crown race isn't press fit onto the new fork, and if so how do I get it to fit properly, or get a new race the right size? Finally, why was there still play in the headset with the top cup tightened all the way down like that?
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#2
(12-21-2014, 05:47 PM)painkiller Wrote:  hard to tell what is going on here. have you tried using your old tube if it is interchangeable? or is it a different fork than what you had? second if the race is not tight on the tube there will be a knock of looseness no matter how tight it is set. you could have your bearings installed incorrectly also. post multiple pics of what you had and what you have now, caliper the base of both tubes to compare.

Thanks for the reply.
The old fork is by the same manufacturer, but it's an older model and the tube is press fit onto it.
Sheldon Brown said something in his article on the subject about using adhesives to improve crown race fit, and I've also heard of people using aluminum from a beer can to make a shim, have you ever tried that? Also, what about cutting a threaded steerer tube? I'm pretty sure I have enough threading on there to just cut the top of the tube off and make it the same length as the old tube, but is that ok to do with a threaded steerer? (I guess another question would be, what if the threading doesn't go far enough up the tube, is there a way to put a spacer between the crown and the race?)
I'll try to see if I can figure out how to post photos the next time I'm back into it.
Thanks again, and Merry Christmas!
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#3
O.K., I think I may have worked this out, see if this sounds right.
I just checked by holding the new fork with the tube on it up against the bike, and it looks like maybe I was mistaken yesterday and the threaded portion of the tube doesn't go low enough, and that's why it was loose.
But then I thought of something that hadn't occured to me yesterday, which is that the weight of the bike and rider don't push down on the steerer, but rests on the fork crown, so there doesn't seem to be any reason not to cut the tube to length from the bottom, unthreaded part of the tube, and then make a shim for the crown race.
See, the way these forks work is that you slide the tube up into the fork from the bottom of the crown, then tighten allen bolts to hold it securely. You really have to pound the heck out of the bottom of the tube to get it in there all the way because the base of the tube is wider and knurled, so I thought it might not be safe not to push it all the way in, but like I said, the weight of the bike doesn't push down on the steerer, so it seems like it should be O.K.
Next year, when I'm ready to paint, maybe I'll think about replacing the headset with a new, threadless kind. All I'll have to do then is get a threadless steerer tube, and I can use the same fork.
Any comments? Anybody have any recomendations on adhesives for a crown race shim? I was thinking of J B Weld.
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#4
Shimming crown race - not advisable. Just get a new headset with the correct ID on the crown race. RST should be able to tell you what diameter to order. Headsets are inexpensive, not worth the hassle of trying to make a shim the correct size, or deal with the resulting off center rotation. If you are going to threadless, do it now.
Nigel
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#5
(12-22-2014, 08:55 PM)nfmisso Wrote:  Shimming crown race - not advisable. Just get a new headset with the correct ID on the crown race. RST should be able to tell you what diameter to order. Headsets are inexpensive, not worth the hassle of trying to make a shim the correct size, or deal with the resulting off center rotation. If you are going to threadless, do it now.

Well yeah, I thought of that, but why not do it any way? There's virtually no added expense, except for the cost of the JB Weld or whatever adhiesive I'd use. I don't think it would be unsafe, and it will probably give me some useful experience working on my bike. Besides, if I'm careful I'll get a good result, and then my project will have turned out just the way I envisioned it.
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#6
(12-22-2014, 09:29 PM)J. Hanley Wrote:  Well yeah, I thought of that, but why not do it any way? There's virtually no added expense, except for the cost of the JB Weld or whatever adhiesive I'd use. I don't think it would be unsafe, and it will probably give me some useful experience working on my bike. Besides, if I'm careful I'll get a good result, and then my project will have turned out just the way I envisioned it.

So how thick should the shims be? You'll need three, all the same thickness within ±.0002" - do you have the capability of measuring that? I don't.

If you get the crown race slightly radial offset, the steering on the bike will bind. Maybe not to an unsafe point, but definitely well past annoying when you are riding.

Gaining experience doing something that should not be done is not useful. Epoxy and well maintained bicycles do not mix.
Nigel
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#7
(12-22-2014, 11:55 PM)nfmisso Wrote:  
(12-22-2014, 09:29 PM)J. Hanley Wrote:  Well yeah, I thought of that, but why not do it any way? There's virtually no added expense, except for the cost of the JB Weld or whatever adhiesive I'd use. I don't think it would be unsafe, and it will probably give me some useful experience working on my bike. Besides, if I'm careful I'll get a good result, and then my project will have turned out just the way I envisioned it.

So how thick should the shims be? You'll need three, all the same thickness within ±.0002" - do you have the capability of measuring that? I don't.

If you get the crown race slightly radial offset, the steering on the bike will bind. Maybe not to an unsafe point, but definitely well past annoying when you are riding.

Gaining experience doing something that should not be done is not useful. Epoxy and well maintained bicycles do not mix.
I think the best way to carry out the procedure I have in mind would be to mix steel sawdust leftover from cutting the tube with the adhesive and then apply a bead of it to the prepared area of the steerer just above the crown of the fork. Then I'd set the crown race and clean up any excess adhesive before it sets.
Provided that there is no defect in the radial trueness of the steerer or the crown race, the result should be sturdy and true, with the steel saw dust providing compressive strength between the race and steerer.
Another way to do it would be to cut a strip of aluminum from a beer can, maybe 2cm wide or so and use the adhesive to affix it evenly around the base of the steerer just above the crown, and then, maybe after feathering the top of the shim with some very fine sandpaper, put the crown race on over that. Radial trueness would be achieved by using an even layer of aluminum all the way around the steerer.
I don't think the argument that adhesives shouldn't be used on bikes is very convincing. First of all, I got the idea from Sheldon Brown's article on headsets, and he's a noted authority on the subject of bikes, but also just from my own experience, the properties of modern adhesives can be pretty amazing. If I'm not mistaken, carbon fiber bikes are almost entirely built with them, from the producton of the tubes to joining them together.
Finally, I'd say that it's always good to try your best and see things all the way through. If it doesn't work, I'm not really out anything anyway and I think I should be able to get a good result from the effort.
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#8
An olde English saying applies: "...you can lead a horse to water, but you can't make him drink...."

Modern epoxies, even low end ones like JB Weld have plenty of strength for the job, the problem is you have no way to set, measure and hold the radial runout of the crown race. The capability of what you describe is two or more orders of magnitude looser than what is required.
Nigel
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#9
(12-23-2014, 02:06 AM)nfmisso Wrote:  An olde English saying applies: "...you can lead a horse to water, but you can't make him drink...."

Modern epoxies, even low end ones like JB Weld have plenty of strength for the job, the problem is you have no way to set, measure and hold the radial runout of the crown race. The capability of what you describe is two or more orders of magnitude looser than what is required.

O.K., well I'm not sure you're using that expression in the most commonly accepted way, but maybe, I guess.
Honestly, I think you're beimg kind of a Debbie Downer about the whole thing. The crown race isn't that loose on the steerer for the radial alignment of the race to be that much of an issue. It's a bicycle, not the Space Shuttle, the variability of the alignment of the race would probably be in the thousanths of millimeter.
This should be a pretty easy job. It wasn't my idea to begin with, and I've read plenty of reports from people online who did the same thing with good results.
JB Weld would probably be my first choice because it's cheap and readily available, but Loctite 660 would be another choice. It's a retaining compound made for this purpose in automotive and other uses. Their advertising on Amazon even mentions bicycle headsets as a potential application for the product.
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#10
(12-23-2014, 03:25 AM)painkiller Wrote:  This is the new fork that you want to bond up and later try to take it back apart to replace the steerer with a threadless one? Here is another old saying.
"We truly are our own worst enemy" Debbie downer suggested the right way. Another way does not always make two right ways, there may be more than one option such as get the correct parts or go threadless now since you said you like too sometime.

The method of retaining the crown race to the steerer that I described would not prevent me from removing the steerer tube and replacing it with another one. It might damage the existing crown race, but if I were going to replace the headset I would get a new crown race anyway.
I think you guys are stretching the limits of these expressions you're using. I can't imagine how what I'm talking about doing would make me my own enemy, the headset I have is perfectly good, and to throw it away just because the crown race is a little loose would be a waste.
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#11
(12-23-2014, 04:21 AM)painkiller Wrote:  Its Ok J. just having a bit of fun no problem. Have at it, your mind was made up before you ever posted. Support for that idea just did n meot happen here this time. no Biggie. Never said it could not be done that way, I just would not do it myself so I could never back anybody else that would. That would make me a 2 faced Hippocrate. Smile

Well, these replies don't do anything to convince me not to try it, even if it's just out of curiousity. I mean, the argument that the race might not be centetered correctly is just extremely implausible, it's centered already without something to hold it in place. It turns on the steerer, but there's no lateral movement, so unless I misunderstood the comment, that doesn't seem relevant.
I didn't understand the intent of your comment about me being my own enemy. You seem to have been making a joke, which I can appreciate, but that doesn't seem relevant either.
Again, Sheldon Brown recomends the use of adhesives for this purpose, there are testemonials all over the internet from people who tried it and said it worked, and there are products made specifically for the purpose. That, plus the fact that there's virtually no expense involved in the effort, convinces me that the next step in this process should be to get some JB Weld and try it out.
I welcome any other serious comments. Have a Merry Christmas and a Happy New Year!
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#12
(12-22-2014, 01:22 AM)J. Hanley Wrote:  But then I thought of something that hadn't occured to me yesterday, which is that the weight of the bike and rider don't push down on the steerer, but rests on the fork crown...

I've given this some more thought, and it's not entirely true, is it? The steerer tube doesn't hold the full weight of the bike and rider, but it does hold some weight, otherwise the bearings woud bind up.
So then, would that be the objection to the plan I described? Judging from my seatpost, I doubt I'd have a problem.
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#13
(12-28-2014, 10:46 PM)painkiller Wrote:  Dang, looks like you have been naughty. I was hoping Santa would have given you your threadless tube, stem, and headset

Ha ha! No, I got a new bike rack, a set of skb fenders, a new front derailleur and a new brake set instead. So I was pretty good anyway.
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#14
[attachment=5633][attachment=5635][attachment=5636][attachment=5637][attachment=5638][attachment=5639][attachment=5640]O.K., I finally finished installing my new fork. It seems tn have gone pretty well, and just in case anyone's interested in doing something like this, I thought I'd give a description, and post a few photos.
In the end, I had to combine both of the methods I described in the above posts as the degree of lateral play in the crown race was much greater than I thought after I cut the bottom of the steerer tube. I used two strips of aluminum as a shim. I adhered them to the tube with JB Weld, then set the crown race by hand over a bead of the epoxy, so that the race is attached to the tube, not the crown of the fork. I used superglue to clamp the race to the crown while the JB Weld dryed.
The result is concentric and durable. The race is firmly seated, and the adjustment of the headset was trouble free, no play with fluid movement of the handlebars.
This kind of modification isn't a first choice, but there are situations where it might be an acceptable option. In my own case, it was a solution I could use to stay on budget with my overall project and still use my bike. If I decide to, later I can replace the heafset and still use the same fork because the steerer tubes are intetchangeable, and I affixed the race to the tube, not the crown of the fork.
Some tips: surface preperation is very important when using JB Weld. The sufaces have to be roughened and free of even the least bit of grease. Don't use alcohol with JB Weld, use acetone.
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#15
(01-04-2015, 01:19 AM)painkiller Wrote:  Classic example of one of my biggest nightmares of buying used bicycles. The stuff one finds after you get it home. Yep, I think I will have to start asking people if I can test tear their bike apart instead of test ride before I buy! Smile

More of your hyperbole, in my view. This method of fixing a loose crown race is a safe, durable alternative to throwing away perfectly good components. It keeps my project on budget and on track. If I want to later, I can replace the headset anyway, but now I'm installing a new set of v-brakes with the money I would have spent.
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#16
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(01-04-2015, 02:29 AM)painkiller Wrote:  No, Not Hyperbole. Just a fact. Perfectly good parts do not need this done if they were "Perfectly good Parts" installed correctly. I would not exactly call this a "little hidden treasure" if I discovered this on a bike that I just spent my hard earned money on. Just saying. Glad its your bike and you are happy with the results. On the other hand, If you took your bike to a shop and they explained to you this method that you just did, would you of had the work done? I doubt it, you would have thought they were nuts. I am not saying your nuts, that would make us to much alike ! Ha
Saying that using adhesives to retain a crown race is a nightmare is clearly an exageration, even from the point of veiw of having purchased a used bike in this condition. Assuming the person who sold you the bike were unscrupulous enough to fail to mention it to you, it still wouldn't put you at any personal risk in terms of your safety, and at most you would be out the price of a new fork and headset, unless of course those components had some intrinsic value, in which case a procedure similar to the one I described might be an alternative for restoring them.
As for the evaluation of the parts I'd say thier relative value depends on their use. If you are buying or selling something that's one thing, but I use my bike, and so yes I would say the headset works perfectly well, no play at all, no binding or tightness, a perfect adjustment.
I'd be happy to let a bike shop do this with my bike after discussing the options with them. This fix is likely to last for the life of the fork, for many years, and nothing prevents me from changing the headset at any time anyway. In the meantime, you can't shim worn out brakes and so the resources are better spent there, and of course for more beer!
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#17
(01-04-2015, 03:24 AM)painkiller Wrote:  The nightmare part of it is very real if had not budgeted for that in my purchase because these types of repairs cannot be found so easy on a visual inspection. You should understand that more than anybody, you have repeated budget woes numerous times as the reason for doing this in the first place. Enjoy, thanks for sharing.

I think this post has taken the discussion off topic, as this is a forum for people who are seeking information on maintaining and repairing thier bikes, not for people who are buying and selling them.
I think I'll elaborate on my point of view here by descibing how I adjust my headset, for the benefit of those in the later category who may be interested. What I do is to stand my bike up on the rear wheel so that the frame is perpendicular to the floor and the handlebars are parallel. Then, while holding the frame, I let go of the handlebars. If it's at all possible to balance the bars so they don't immediately flop over to one side, then the headset is too tight and must be loosened. If this can be achieved without allowing any play at all in the headset, then it is perfectly adjusted, and that's the condition my headset is in after performing the procedure I described in this thread. JB Weld is tough stuff, and it will probably stay this way beyond the usefull life of the fork.
If I was buying a bike that was an antique that had this kind of mod done to it , I'd be disapointed, especially if I planned to turn a buck on reselling it, but my nightmares consist of more serious matter.
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#18
(01-04-2015, 04:48 AM)painkiller Wrote:  Don't worry, we are not off topic at all. You are almost right, this should be a site on how to repair a bicycle "correctly" and to certain industry standards. As far as buying and selling, it most certainly is just another one of many aspects of bicycling. I try to help people to do that to learn and earn $$ so they can free themselves from having to ride substandard equipment having to utilize shoddy repair techniques. Trust me I am more sorry than you, I ever chimed in on a thread that you never really wanted to hear answers to your questions for in the first place. Enjoy!

I would maintain that the method I described for fixing a loose crown race isn't shoddy. Sheldon Brown recomends it in his article on headsets. He is a regognized authority on bicycle repair and maintainance, and many examples of people using similar methods are available on the internet.
It isn't true that I didn't want to hear answers to the problem I had. When I first posted I didn't know what to do, and then after concidering what I felt was germane to the subject, I made a decision about what to do and saw it all the way through to completion.
Owning, riding and maintaining a bicycle is a lot of fun. If you have a similar problem with your bike and you don't know what to do, then you can add my comments and photos to the things you're concidering and make a decision that suits you. I'm not selling anything, and I can tell you that what I described on this thread worked.
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