drewfio

I have been rebuilding an old Specialized Rockhopper, and I was tackling new bearings in the headset today. When I pulled the fork, I found the crown race was not tightly seated. There is very slight play, and I could pull it off pretty easily with my hands.

This has me wondering if the wrong headset was installed. I measured with calipers (see attached images), and the crown race is 27.0 on the nose. The race seat on the fork is very slightly smaller, ranging 26.88 to 26.93, to 27.04 depending on direction.

From looking at catalog, I believe this is a 1993 Rockhopper FS, but mine has a rigid fork instead of suspension. It looks identical to the photo besides the fork though. The paint on my fork looks slightly different from the frame as well. The fork paint is a very slightly bluer black, whereas the frame is straight black. Both with subtle sparkles and the decals have pink that matches. My guess is it was swapped with a closely matching rigid fork either when purchased or after at some point.

All this has me scratching my head. I suspect this is the wrong size headset, since usually the race seat is larger than the crown race. But maybe it is JIS with sloppy tolerances? Is this close enough? Should I replace it? And if so, I'm sure what to replace it with given the odd measurements. Any help would be appreciated.

Thanks!

drewfio

And here is a pic of the whole frame if helpful:

oneclick 

Some form of gap-flling liquid from Loctite, or cut the seat and use a 26.4.

Maxey

As near as I can tell, if it is a 1993, I think it's a base Rockhopper, as it doesn't have a 'Sport' or 'Comp' decal on the seat stay as they did in 1993. I do think it's likely it's a '93 as the base Rockhoppers were available in black, as were the Rockhopper Sport, but again, unless the 'Sport' decal was removed, I think yours is the base model. The fork certainly looks like it came with the bike as the Direct Drive decal on the fork matches the other graphics. As far as the headset issue, I'm more of a novice mechanic so no help there other than to say the base '93 Rockhopper did come with a black headset. In any case, base model or not, it's a nice, well-made frame in good condition.

madpogue 

What's the serial number on the frame? What markings, if any, are on the steerer tube?

John D

You can take a pin punch to the race seat on the fork, just go around the fork punching around the surface of the race seat to give it more edge.

curbtender

Ran across this once on a bike that had a carbon replacement fork. Used a strip of adhesive backed aluminum tape.

juvela

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if guide for mill not snug enough it can happen that cutter can wobble slightly and cut too small

what one wants is a tight press fit
the rule of thumb is that the seat should be .1mm larger than inside diameter of race

if headset marked Specialized it will be a Hatta product


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unworthy1

LocTite Green would be the right choice, but it's an expensive investment for the few drops you'd use (unless you like having a supply on hand).
Otherwise either a shim or "peening/knurling" the crown race with a sharp punch may work just fine and cost will be minimal.

drewfio

Thanks for the replies. An update:

I recalled from previous headset installations that a Tange Levin CDS headset fit very tightly in other frames, so I got one (JIS) to try since the old one was worn anyway. The crown race is in fact more snug now that I have it in hand. It's ever so slightly smaller diameter, enough so that the fit is tighter. I can however still get it on by hand, if I work really hard at it for a while. There is no play I can feel, but if I grip very tightly I can get it to rotate around the (greased) crown race seat. I suspect if I cleaned the grease off I might not be able to install or rotate it by hand. Is this tight enough, or am I asking for trouble if I don't get it secured even more?

juvela

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crown race seat & inner face of crown race should not be lubricated

fit should be tighter

two options for tighter fit:

a) Loctite type compound as mentioned previously

b) dimpling vertical face of seat with centrepunch as mentioned previously

each dimple creates a tiny parapet which increases the effective diameter of the seat

the nice thing about the Hatta headsets from Specialized is the presence of the O-ring seal to keep dirt out of the bearing; a feature especially helpful on a mountain machine

Tange Levin is an excellent value in a cup & cone headset but lacks this seal

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drewfio

all right, I think I’ll get myself a center punch and try that method then. Will report back.

cudak888 

This is way overbudget for a single build, but the J.A. Stein tool is my favorite way to get a slightly undersized crown race to behave. Always works too, within reason.

https://steintool.com/portfolio-items/knurling-tool/

-Kurt

gugie 

That's how I was taught in my decades-ago LBS job.

JA Stein makes a nifty knurling tool for this, an improvement on this method. I do a lot of framework and have run into this issue from time to time, so I got one.



edit: looks like @cudak888 beat me to it.

cudak888 

It's such a lovely tool to use. I realize the punch method does do the job, but the Stein knurling tool just guarantees success the first time, every time.

There's no question if one has peened the crown enough and no worries about future loosening. Just spin the fork in the vise in the tool, install the crown race (this time nice and snug), and install. It provides such peace of mind to fix it so well that one forgets that the problem ever existed.

-Kurt

drewfio

I saw this tool when researching my issue. I'd love to have this tool, and it looks like it is a great one for its purpose! But I'm having trouble convincing myself I need it for this project or that it will get much use in my hands in the future, at my relatively infrequent rate of working on new to me bikes.

gugie 

For one time use, it's not worth it. Peening the race with a punch, as recommended by others, is my recommendation to you. Just start with opposite sides, then quarters, eighths, etc. to try and make it symmetric.

drewfio

Okay another update:

So I got a center punch and made divots around the race seat, as suggested. And hey, it did the trick. Took no time at all, and the fit is tight. I’ve got the headset fully installed now. Thanks for the advice!

Maxey

Well done, drewfio! Post some photos in the 'Show us your Vintage Mountain Bike' thread once you have it all put together. I'm sure others along with myself would like to see the completed bike.