Todays daft question.

[compo]

My turn with the question. I need to buy a new threaded headset. It may be blindingly obvious but which bits do you actually measure to get the right size. The hole in the headtube where the cups fit is 30mm across. The forks are in the shed now and it is dark so will measure the steerer tube in the morning. it seems that 1" or 1 1/8" seem to be common sizes. It is for a 1980's Raleigh road bike by the way.

thanks.

 

[accountantpete]

You first job is to identify whether the forks are original. If so they may have a special Raleigh threading of 26tpi as opposed to the normal 24tpi.

If that is the case then you are going to need to hunt down 26tpi headset.

 

[Andy_R]

A bit more info here, Sheldon to the rescue as usual. Do you need to replace the entire headset, or just part of it?

 

[compo]

You first job is to identify whether the forks are original. If so they may have a special Raleigh threading of 26tpi as opposed to the normal 24tpi.

If that is the case then you are going to need to hunt down 26tpi headset.

Mechanically and functionally I don't need to change it at all. The bearing surfaces are perfect. Problem is it is quite rusty on the outside. I could clean it up with a rotary wire wheel then spray the assembly black, but it would be easier to just fit a new one if I can get the right size. To be honest I totally forgot about the threading issue.

Update: My wife has a Elswick Hopper shopper bike, and this morning when she wasn't looking I popped off the bars and unscrewed the top of her headset. It screwed onto my Raleigh forks with no problem so I think it safe to assume the threading is standard 24tpi. ??

(I have reassembled my wife's bike).

 

[RecordAceFromNew]

My turn with the question. I need to buy a new threaded headset. It may be blindingly obvious but which bits do you actually measure to get the right size. The hole in the headtube where the cups fit is 30mm across. The forks are in the shed now and it is dark so will measure the steerer tube in the morning. it seems that 1" or 1 1/8" seem to be common sizes. It is for a 1980's Raleigh road bike by the way.

thanks.

This is the link you need. Commonest mistake is not getting one with the correct stack height.

 

[accountantpete]

+1

The only other variables are JIS or ISO but I'm sure yours will be ISO with a 26.4mm inner crown race as opposed to a 27mm JIS inner measurement.

So just ensure you have a 26.4mm headset with the correct stack height.

 

[compo]

I have just had a measuring session and the crown race internal diameter is 27mm, as is the fork seat. I am now wondering if I could put the fork in a lathe and turn the seat down to 26.4mm. It is a shoulder on the fork so there is plenty of material to lose .6mm. I could then just fit a standard unit. I have access to an industrial lathe so I think it would work. The other alternative is to just clean up the rust on the existing headset as the bearing surfaces are in good condition and just paint it black.

 

[accountantpete]

I'd keep the existing and just clean it up.

If the bottom is JIS standard then the rest will presumably be so too and there are small differences.

 

[compo]

just a quick update: I measured just about everything that could be measured on my rusty headset and hunted until I found a replacement headset with the same dimensions. I now have an identical, but nice shiney, headset to go on the frame when I get it back from the painters.

 

[migrantwing]

Sorry for jumping in on your post, compo, but can someone explain 'correct stack height' as mentioned a few times in this thread. I will be needing a new headset soon and have narrowed it down to a handful of hedsets, but how important/what revelance does the stack height have? TIA

 

[accountantpete]

Sorry for jumping in on your post, compo, but can someone explain 'correct stack height' as mentioned a few times in this thread. I will be needing a new headset soon and have narrowed it down to a handful of hedsets, but how important/what revelance does the stack height have? TIA

The stack height is the vertical space taken up by your headset ignoring the bits that fit inside the headtube.

So for an integrated headset (where most of the bits are inside the headtube) there is just the top cap so stack height is pretty much irrelevant.

It is more important for traditional headsets as if you get too big a stack height it may not fit the forks etc.

 

[migrantwing]

The stack height is the vertical space taken up by your headset ignoring the bits that fit inside the headtube.

So for an integrated headset (where most of the bits are inside the headtube) there is just the top cap so stack height is pretty much irrelevant.

It is more important for traditional headsets as if you get too big a stack height it may not fit the forks etc.

Thanks for that, accountantpete