Carbon fiber fork in threaded 37mm head tube?

[daddyduca]

I have a steel bike, and I want to change from a steel fork to a carbon one to save weight. Does anyone know if a carbon fiber fork will fit into a 37mm steel head tube threaded for a 1" headset? (I know that traditional steel head tubes were 32mm.) I realize that the carbon steerer tube is 1 1/8" but I'm hoping the oversized head tube will have enough room for the 3.18mm (1/8") difference in steerer tube diameters. What do you think? Will this work?

[rogerzilla]

What's the *internal* diameter of the bare head tube? Is it a normal 34mm for 1 1/8" forks - possibly with a reducing headset? If so, just get a threadless 1 1/8" headset - the most common kind - and the choice of carbon forks is endless.

If the internal diameter is 37.0mm, it's a frame made for 1 1/4" forks, like old Cannondales, and quite unusual. Look for a Devolution headset* or reducing rings to convert from a 1 1/4" fork to a 1 1/8" fork. In all cases, the current headset will be discarded.

*King no longer make the 1 1/4" to 1 1/8" size, which is ironic as the name derives from 1 1/4" being called Evolution size by Gary Fisher. There may be NOS ones around.

[daddyduca]

Thanks a lot, Rogerzilla! The headtube has an outer diameter of 37mm. Do you know if that means the inner diameter is 34mm?

[531colin]

I have a steel bike, and I want to change from a steel fork to a carbon one to save weight. Does anyone know if a carbon fiber fork will fit into a 37mm steel head tube threaded for a 1" headset? (I know that traditional steel head tubes were 32mm.) I realize that the carbon steerer tube is 1 1/8" but I'm hoping the oversized head tube will have enough room for the 3.18mm (1/8") difference in steerer tube diameters. What do you think? Will this work?

What is the diameter of the current (steel?) steerer?

[daddyduca]

Colin-

The frameset is Columbus Zona (except for the larger diameter head tube) so I'm guessing 1" (25.4mm).

[531colin]

I think you will need to do a bit of measuring.
Carbon forks with ali inch and eighth steerer are easily available.
I'm guessing its a quill stem/threaded headset, so i think the first step is to measure the existing stem quill.
If the stem measures one inch (25mm), its happy days because the existing steerer is inch and eighth.
If the existing stem measures 22mm (seven eighths of an inch) then you will have to find out if an inch and eighth headset will fit the head tube.....sizes are here...https://www.hopetech.com/_repository/1/ ... 011Web.pdf
You will need a threadless headset, stem, spacers as well.

[rogerzilla]

Thanks a lot, Rogerzilla! The headtube has an outer diameter of 37mm. Do you know if that means the inner diameter is 34mm?

It's highly likely, but tube gauges vary.

Threaded 1 1/8" forks exist - I have two 90s Kona MTBs like that - but were a bit of an evolutionary dead end.

If the stem quill is 25.4 (not 22.2) then get a threadless headset and the fork world is your oyster.

The frame doesn't know or care if the fork.is threaded or threadless.

[Brucey]

a photograph would be helpful

[daddyduca]

So, the stem has a post diameter of 22.2, standard for threaded forks with outer diam. of 25.4 mm (1″). Here's a picture.