Noob quill stem question

[gibbon_rider]

Once upon a time, in about 1995, I bought a new Ozone CO2 from my local bike shop. I loved it in every way (except that way), but I could never get the headset to stay tight. I put it down to my inabilities as a mechanic and not having the right tools - or indeed any tools apart from a single adjustable wrench.

Nearly 25 years later, I am now refurbing that bike, and want to sort the headset once and for all.

It's a Mavic 317, which the internet tells me is the inch and a quarter flavour. The headset itself says 31.8mm on it which would appear definitive.

However, the stem is an old Club roost ibeam which says "28.6mm minimum" on it.

And here is the noob question. Does this mean my LBS fitted the wrong stem 25 years ago? Or are you able to use a 1 1/8 stem on a 1 1/4 headset??

Is this why it wouldn't stay tight? Or am I just a shit mechanic with crap tools???

 

[Gerard]

Re:

If it is an A-head stem, not you can't.
If it is a quill stem, the stem is always smaller as it goes into the fork.
Photo would help.
I have just changed stems for the same reason, Syncs would just work loose.

 

[MR OX]

Re:

Allow me to step in having had nightmares with my failed Ozone Co2 build :facepalm:
Headset has the external measurement, quill stem has the internal measurement.

 

[Retro Spud]

Hi

I’m afraid it’s the latter

Your headset goes round the steerer, your quill does in it therefore the external diameter is inch and a quarter but the internal one is a lot less.

For example
An inch headset (25.4mm) takes a 22.2mm quill

I’ve got a CO2 - pretty rare bikes out of the three Bigfoot/Smokestone/Ozone

 

[Retro Spud]

Mavic headsets should never come loose as they have a grub screw that locks everything in place once you’ve got the setting right


105 and 305 are Inch
306 an inch and eighth
307 is deffo the big daddy of the lot

 

[gibbon_rider]

Re:

So from the sounds of things, an inch and quarter headset, and inch and an eighth stem is correct. I just need to find the grub screw to get it to tighten properly...

Is that right?

 

[Retro Spud]

It’s located under the black rubber ring that normally splits and falls off

Here’s my CO2 with its make Graham Foot viewtopic.php?f=6&t=274579&start=20#p2207218


Here is the screw that locks it in place

 

[gibbon_rider]

Re:

That is lovely.

Mine's got blue decals and highlights. Pace blue fork crown, blue rear drop outs, blue pace bars. Just need to find a silver zooka to match the moby and then I'm pretty much done for parts.

 

[danson67]

You'll be needing an M3x0.5 thread 18mm long stainless steel caphead screw like this:



All the best,