Advice request - steerers and stems =]

[SquirrelStu]

Hello All!

I have a bit of a weird issue which I can't work out:

I bought a really nice condition '96 Pine Mountain and it's all really lush except - whilst riding, the stem mis aligns from the wheel a little over time (10 mins).
For reference it has the original rigid forks on.

After tightening and still having the issue, I looked closer - seems the stem is at max tightness (bolt hole flanges are touching each other) and yet the steerer is not gripped tight.

When I loosen stuff off there's like a 1mm gap all the way round between the steerer outside surface and the stem inner surface - this is when the stem is not under pressure from the bolts.

So - I don't think I remember this from before, I'm sure they were a tight fit back in the day.

Also bike does not have a star nut or top cap ("original ditch plastic top cap) so I presume this was on that switch over faze - I vaguely remember the star nut being a big deal back then.

My questions really are:

1. Seems like I need a 0.5 - 1mm shim between steerer and stem - is that right? any suggestions for material, or where to buy one?

2. Is it just the case that over time the stem has flexed outwards a bit? Or could it be a manufacturers defect and buying another retro Marin stem would probs fix it?

3. I guess same question as above but for the steerer instead of the stem - except it's steel, so I don't think that shrinks - I feel there'd be bigger issues if it did.

4. I'm going to add a top cap and star nut or similar (Hope head doctor?) as this will also help I think - is that the right thing to do, or is it not needed?

5. Is there anything I am missing/completely got wrong/clearly don't understand (within context - otherwise we'll be here all day)?


I thank you in advance for your help and suggestions and for tolerating my less than adequate knowledge - but we all learn some time right? =D

Stu

 

[Gtpulse]

Hello, is the stem original to the bike? Photos of the stem etc would help in diagnosing. Could be someone has tried to put an aheadstem on quill forks.

 

[jimo746]

It sounds like maybe you have a 1" steerer fork and a 1"1/8 stem. (Is fork original? I'd have thought it'd be 1"1/8 by 1996 though).
Maybe.
Or as above an Aheadstem clamped onto a threaded steerer (I'd avoid this if possible), But a few photos would help clear things up.
If that is the issue then you can buy ready made shims for that purpose . But a correctly fitting stem is always a better option.

 

[SquirrelStu]

Thanks Gtpulse - good point!

It is a Marin Lite stem - but maybe it is from the next year on, but looking at the bike in the catalogue uploaded to this site (https://www.retrobike.co.uk/gallery2/d/128424-3/Marin_1996_18_rb.jpg), it does look the same.

I will try and take some pictures in around 10-20 mins! =D

 

[SquirrelStu]

Thanks jimo746!

I'll take some pics in a mo - it's weird, I looked up the conversion and in theory the diff between a 1"1/8 and a 1" is just over 3mm - this gap is barely 1mm, but defo more than .5mm.

I'll take a few more measurements. Normally I would have thought it was ovalised, but there isn't too much diff on the diameter of the steerer all the way round, and the gap is pretty consistent xD

 

[raidan73]

I'm thinking the original fork is a 1 1/8" threadless? If someone has fitted a 1 1/4" threadless stem to the steerer then you would have a 1.6mm gap all the way around. Does this sound plausible?

 

[SquirrelStu]

Thanks raidan73 - it could be a 1.6mm gap - looking again, it might be bigger than 1mm.

 

[raidan73]

Thanks raidan73 - it could be a 1.6mm gap - looking again, it might be bigger than 1mm.

Going by the catalogue the original fork would be 1 1/8" ahead, so a 1 1/4" stem seems feasible

 

[SquirrelStu]

Pictures =]

In the picture it looks massive to be fair, I'm taking measurements now.

 

[SquirrelStu]

using some cheap callipers -

Steerer is defo just under 1"1/8 - very slightly oval - certainly not only 1"

Stem gap, when bolts are loose, is larger than 1"1/8 but no where near 1"1/4 - basically a difference just shy of 2mm...