Headset Help. Tolerance in regards to stack height.
 

I've been reading past threads about headsets, stack heights and the like. I'm having a hard time answering my question, so I thought I'd pose it here in the new thread.

I've got a frame and fork which has a stack height that measures ~35mm. It seems most of what I've been reading suggests and ideal headset would be 1-2mm larger stack height than measured from the frame. Unfortunately, the headset I'm most interested in is the Tange Levin NJS campy copy which has a stack height of 38.4mm.

Would I be pushing my luck? Is the 3.4mm going to stop me from getting enough threads on the lockring?

The alternate would be the Tange Levin CDS which has a stack height of 33.4, and would require a spacer.

What are you thoughts? Should I risk it?

- Jeff

http://bikeforums.net/attachment.php...hmentid=292910

Jeff, Are you measuring with the lower half of the headset, races and bearings in place?

Brad

This is why I hate cutting forks so they are an exact match to the headset. If that 35mm is all the steerer you have available I would almost look for something smaller like an old 105 or ultegra.

http://www.bikeforums.net/attachment...0&d=1357856673

Nope. The head tube is sitting flush on the fork crown.

I agree about not cutting. Unfortunately, I picked up this frameset sans headset, so I'm at its mercy. I'm not sure that a 105 of 600 would suite the build, but they are on my radar now. I've also put the lbs to work, and they're going to try to piece together a franken-headed that looks the part. Thx, - Jeff

I don't know what this frame is and your budget but FtWelder just did a great job of lengthing two steerers for me. I got some $10 Tange steerers from Nova Cycle supply and sent them to Frank with the forks. Excellent job.

Jeff, I measure stack height like this:

-Measure the head tube end to end without any cups installed.
-Measure the steerer tube from where the bottom race seats (no race installed) to the top of the tube.
-Subtract 1 from 2 for the stack height.

While you possibly are, I don't know if you're reading a true measurement.

Brad

I think both methods get the same results.

Your out of luck. Maybe a 1mm tolerance but not 3.

Jeff, is also including ~2 mm of unthreaded steerer tube with his method into the stack height.

Brad

My rule is not to go too tall with the stack height as it could negatively affect the amount of thread engagement at the top bearing race and locknut. You should maximize the amount of threads engaging on those two parts to have the safest installation. Going a little bit short (than just right) with the headset stack height is safer as you can always make it up with spacers between the top race and locknut as needed.

Chombi

Which is OK because the unthreaded part of the steerer disappers once the headsets installed. Cut threads shouldn't extend down to the stems expander area, its a trade-off

Seriously? He replaced the steerer tubes for you? That is so cool! Did he weld or braze? Not that it matters. ftwelder is SO the man!

Outside the scope for this project, although interesting to know that it can be done. Worst case scenario, I'll just buy the other Tange headset that has a 33mm stack.

Agreed. Once the lower portion of the headset is installed, the unthreaded portion will disappear. I measured the fork steerer, and minused the headtube and got the same result. Although I'm not 100% clear about the -2mm. I'm guess this is used when calculating the steerer length when the stack height of the headset is known. I think in my mind I'm working backwards by measuring the frame stack height adding 2mm to the headset stack height. Or I may be a lost puppy altogether...

Regardless, I think if the LBS can't find some bits that will work, I'll probably just order the smaller stack height Tange, and space it up as required. Thanks everyone for your input.

- j

Also, for those interested, I tracked down and exert from The Barnett Manual.

They tell me to measure the fork tube and minus the head tube. Straight up. Of particular interest to me is the dimension "C" in regards to measuring stack height of the headset. As such, the do not include the section of the lock nut that is above the threads. This is the section I was assuming the 1-2mm tolerance would factor in. Is the way most companies are measuring their posted stack heights?

https://lh6.googleusercontent.com/-n...Untitled-1.jpg
Interestingly, I looked at the Tange Levin NJS headest on their on website. Here the clearly list the stack height as 28.2mm, but when you add up the numbers on their diagram, we get 37.9mm. Weird.
http://bikeforums.net/attachment.php...hmentid=293094

I think I need to quit this and buy the shorter one. haha.

Look again -- it's listed as 38.2" ;)

Ooops, typo; I meant 38.2. Still isn't the same as the 37.9mm when calculated from their dimensions.