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Discussion Starter · #1 ·
Alright...first post on the forums too.. Fairly new to road biking as I have come from a mountain biking background. However, I recently purchased a 99 or '00 Specialized Allez Sport that is in really awesome shape. I'm riding to work, working on fundamentals, etc. of road riding since its more condusive in my area...however, I'd like to make a few upgrades to the bike. Its full 105 w/ less than 1k on the bike when I bought it

I just recently picked up a Specialized 1 1/8" Carbon Monoque 4 fork for a steal of a price and would love to use it on the bike. However, to my suprise tonight when I was working on the bike I found that it is a 1" threadless setup at the current moment and of course the new fork is a 1 1/8" unit. My question is. Can the 1" threadless headset be simply switched out in favor of a 1 1/8" headset so I can use it or with the fork not work at all with my setup? Any help would be much appreciated!!!

Joe
 

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Discussion Starter · #3 ·
The headtube itself is def. larger than 1" if you measure its ID without the cups in. I haven't removed them yet but I def. know this to be true. I simply compared the difference between the fork that was in there and the diameter of its steerer vs. that of the fork that I bought for the bike. 1" vs. 1.25" on the steerers' respectively

Maybe I stated it wrong?

I remember on a friends older beater Raleigh M-80 MTB that I successfully helped him convert it to 1 1/8 threadless from a threaded setup he had easily. Removed the old setup, old cups, etc. New threadless set pressed in and never had a problem with it.


Joe
 

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joeallison said:
The headtube itself is def. larger than 1" if you measure its ID without the cups in. I haven't removed them yet but I def. know this to be true. I simply compared the difference between the fork that was in there and the diameter of its steerer vs. that of the fork that I bought for the bike. 1" vs. 1.25" on the steerers' respectively

Maybe I stated it wrong?

I remember on a friends older beater Raleigh M-80 MTB that I successfully helped him convert it to 1 1/8 threadless from a threaded setup he had easily. Removed the old setup, old cups, etc. New threadless set pressed in and never had a problem with it.


Joe
The headtube isn't going to be 1", it's going to be bigger. It's going to be the size needed for a 1" headset plus 2x the thickness of the tubing. Measured outside, it's probably around 36mm or so.

On a bike that uses a 1" fork, the inside diameter of the tube is bored to 30mm to allow for the 30mm cups on the appropriate headset. The inside diameter of a 1" headset is 25.4mm, as you'd expect.

A 1-1/8" fork uses a headset with 28.6mm inside diameter and 34.0 outside diameter. The headtube on the bike that would use this headset is milled to 34mm.

If you try to put a 1-1/8" headset into a bike's headtube that is built that uses a 1" headset, it will not fit (34 vs. 30mm). If you try to put a 1-1/8" fork into a 1" headset, it will not fit. (28.6 vs. 25.4mm)

There are products that allow the use of a 1" fork in a 1-1/8" bike, but not the other way around.
 
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