Bicycle Mechanics - thomson x4 steerer tube

I recently replaced my Thomson elite stem with a Thomson X4. The steerer tube clamp has a space, so my steerer tube is exposed. This seems like an odd way to design a stem, and I'm concerned about rust on my steel bike. Does anyone else have this stem, and if so how did you fix it. Spray paint? black tape? Some kind of accessory?

Is your steel steerer 1-1/8" as I presume the stem clamp is?

I have an FSA stem with the same "open back" design but it's installed on a 1" steel steerer so the exposed steerer is covered by the aluminum reducer bushing.

If you don't need the bushing, I'd just paint the steerer to protect it. If you paint it black, everyone will think you have a carbon steerer. :)

Rust on a bike is a very minor problem, unless you like dock jumping into sea-water. I have seen lightweight steel bikes used for years and years on Northern Ontario's salt-covered winter roads, and they have plenty of life left in them.

The only concern you should have is one of aesthetics - that round window into a patch of surface rust is going to be ugly, but not a structural or safety problem. I reccomend, as someone said above, paint the exposed area... although I would be careful, if I were you, to only paint the exposed part... it is likely that your stem clamp will not grip as securely on black rust paint as it does on bare metal. As soon as you are sure you will not be adjusting your stem or headset too much, mask off the stem and headset and head tube of your bike, and spray a few light coats of black (or silver, or clear, or neon pink) rust paint in the hole.

I think the hole is for weight savings. Aesthetically, I think it looks different, not necessarily bad.

I have a Thomson X4 on my MTB and think it is great. It was almost too pretty to put on a MTB.
I had a KONA P2 rigid fork on it for about 3 years and just recently replaced it with a FOX F80.
The KONA P2 had a steel steerer and even though I rarely when rode in the rain, when I tried to remove it there was a distinct ring of rust that made it difficult to get past the headset. If your steerer is steel I would probably put some grease right at the headset/stem junction and once installed just cover the exposed area with it as well. I wouldn't cover the entire stem with grease/paint as it would probably affect the stem/steerer connection. If you have an aluminium steerer (like the FOX Fork) I wouldn't bother.

thanks all, for the suggestions. I think I will try spray painting the steerer tube. It might affect the stem grip on the steerer, but I think I would notice pretty soon if that was the case. If the stem feels loose, I can always sand the paint off... This is on my recreational road/touring bike, so I'm not putting a lot of stress on it anyway.

Curious why you replaced it. Was there something you didn't like about the elite or was it just a sizing thing?

^ Probably the latter. I've been thinking of replacing mine since I want 31.8 and I'm pretty sure the Elite is 25.4 only.

Yeah, it was sizing. I went with a slightly shorter (90mm vs 100mm) stem with a bit more rise (10 degrees vs 6 degrees). More importantly, I went with different handlebars (Ritchey Pro) that bring the brifters in a little closer. My old bars (Nitto Randonneur) weren't very comfortable. I also wanted to change to the oversized clamp diameter because it's hard to find drops in the 25.4 size...

My old stem and handlebars are going on my other bike, so nothing wasted...


Curious why you replaced it. Was there something you didn't like about the elite or was it just a sizing thing?

I have a Thomson Elite on my customized Trek with 22.2mm handlebars. And I am awaiting delivery* of a Thomson Elite X2 for my 31.8mm handlebars on my vintage Puch A-D.


* It's coming today! Yippieeeeeee!

It's interesting that the "new standard" of 31.8mm has finally provided the same handlebar clamp diameter for both road and MTB use so stems intended for either use will fit both road and MTB bars.

^ Yea, the old standard of two different sizes for the two bike types always bugged me. Made no sense.