As in 10mm depth into the stem before the SGN.

Sounds a bit low but depends on where the bolts are – I’d make sure the steerer is just above the top steerer clamp bolt.

do you mean 10mm between the top cap and the top of the steerer tube?

10mm’s OK IMO.

fine if the stem stack height is still enough to clamp securely.

personally I always cut steerers 5-10mm over and run a spacer on top giving the best possible clamping surface

I’d agree with mama

Sorry- to clarify, 10mm below the top cap. Stem is a Thomson Elite with double bolts and a high King headset- I couldn’t change the headset to a zero-stack as I like my king 🙂

..and presumably you weren’t going to change the “oh so STW” Thomson stem so what exactly were you going to do if we all said it wasn’t acceptable? 😛

personally I always cut steerers 5-10mm over and run a spacer on top giving the best possible clamping surface

Me too, but more because I never cut a steerer to less than 200mm because it makes the fork so much easier to swap between bikes or sell on.

Do you mean the steerer is 10mm below the top of the stem?
With a Thomson won’t that put the top of the steerer below the top pinch bolt?

The depth of the SFN doesn’t really matter as long as the bolt is long enough

my stem height would be the exact same (give or take 5mm) if I switched frame and I’ve never sold a s/h fork for more than a tenner.

Headtube length: 129.54mm
Thomson stem heigh: 24.545mm
King headset depth: Say 6mm total?

Total 160mm. Steerer 185. Am I being thick- this should make it alright?

gotta be more than 6mm for the headset

Jesus wept

yes you are being thick! a king ?Headset has a higher stack height than 6mm (there are 2 cups) 🙄

Thompson stem has to more that 24.5mm you sure your not on about 25.4mm bar diameter? Depth of the stem must be in the region of 40-50mm

X4 is 41mm and CK 32mm according to my spreadsheet

Gain 4mm back by switching to a FSA headset and avoid scoring the steerer tube at the same time

I reckon you need at least 195mm of steerer

Bugger 🙁

Alternatively I could use them on my 456 Summer season

Maybe just dont try and work it out, you dont sound like you have got one measurement right…

What frame has a 129.54 headtube? It sounds like an odd figure & 10mm more than an 20″ inbred…

SC Chameleon- size Large (old style)- it is an unusually long headtube.

Sure you’re not measuring the headtube and headset cups together? Chameleon headtubes are shorter than most iirc.

Taken the measurements off the SC archive

10mm is too low.

5mm under is maximum, and any wrench monkey worth there salt will tell you to cut them long by 5mm and use a spacer over the stem.