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What is the practicle difference between 1" & 1 1/8" S.T.?(9 posts)

What is the practicle difference between 1" & 1 1/8" S.T.?OwenMeany
Nov 12, 2003 8:17 PM
I have noted that Colnago is now introducing 1 1/8 steerer tubes (C50 & CT2)...I also took note of a comment I heard at the LBS such as "finally Colnago gets with it and uses 1 1/8"...

What are the practicle differences between a 1" and a 1 1/8" that make most builders prefer 1 1/8?...Stiffness? can't be weight...

Thanks, jb
re: What is the practicle difference between 1" & 1 1/8" S.T.?lyleseven
Nov 12, 2003 9:13 PM
Stiffness....and I feel, less twitchy steering, but others will differ, I am sure.
Nov 12, 2003 10:03 PM
Less twitchy steering? Probably not. If you felt that, it was probably from some other factor and not the headtube diam.

Although the larger tube is stiffer by any objective measure, I have never had flex problems from any threadless 1 1/8" or 1" setup.

I did have problems with plenty of 1" quill setups, which leads me to believe the real improvement in stiffness has been the result of stiffer threadless stems and CF forks rather than the larger headtube diameter.
The practicle reason is...russw19
Nov 12, 2003 10:02 PM
The practicle reason is that it alloys for the use of alloy and carbon steerer tubes. They are a bit on the fragile side in a one inch diameter. The stiffness issue is not a big issue and is collateral to the ability to use carbon steerers.

Colnago finally got with the program because they started to realize the limitations on fork weights with 1 inch steerers. They couldn't get much lighter unless they used a 1 1/8 steerer. It's kinda like how Cannondales got lighter as they started to use oversized tubes... same for steerer tubes on forks.

From what I know, Ernesto himself doesn't like the idea of carbon steerers on anything but pro race bikes.. thinks the rest of the real world should use alloy or cromoly steerers as they are stiffer and safer, but to hold to that line and his frames would be limited to a handful of forks, so they went to 1 1/8th. But you have to keep in mind that Ernesto is also a big advocate of straight blade steel forks for the best ride in a bike. The catch is that they are heavier, but I have never riden a nicer fork than a Colnago Precisa Nivachrome fork. I won't go so far as to say it's the best fork, but it sure rides nice. But old Ernesto is old school and doesn't like ever-changing standards of cycling. The fact that every 5 years there is something new that won't work on old bikes, making bikes obsolete before they are worn out.

Fox and RockShox don't make forks with 1" steerers.BowWow
Nov 13, 2003 12:16 AM
So you can't put a really nice suspension fork on an old Colnago!

Any frame builders want to chime in???biknben
Nov 13, 2003 6:35 AM
I've heard it is prefered by frame builders because it provides more surface area to weld the headtube to the TT and DT. Is there any proof to that?

When considering the diameter of some downtubes I could see where this might become an issue. The downtube on my last frame was wider than the headtube. The downtube was reshaped (made oval) towards the end so it could join the head tube. It always looked odd to me.

I think the driving factor in the change was to increase stiffness while reducing wall thickness and weight. This was driven by the MTB croud. While it helped on the MTBs, god bless you if you are able to notice the difference on the road. I can't.
The fundamental reason...elviento
Nov 13, 2003 7:46 AM
The fundamental reason is that aluminum and carbon tubing have optimal characteristics (stiffness/strength/lightness)if they are oversized compared to steel. Headtube and steerer tube are no exception. Industry standards were set on steel frames and now they are being slowly but gradually revised to fit the needs of new materials.

It might be counterintuitive, but 1/8" is actually pretty big a difference. The cross section area increases by over 25%.
There Are Several ConsiderationsHeron Todd
Nov 13, 2003 8:55 AM
1) Larger diameter steerers mean larger diameter head tubes. This makes it easier to build aluminum frames with oversize tubing since the top and down tubes won't need to be ovalized (or won't need it as much) to fit the head tube. This hasn't been much of an issue with steel frames until the super OS S3 tubing hit the market.

2) Larger diameter steerers increase stiffness. For aluminum this can be important. Unfortunately, when done in steel, and sometimes in carbon, the result is too much stiffness. Fork compliance provides much of what we perceive as ride quality. The fork flexes primarily at the crown and the steerer. A steerer that is too stiff won't flex enough and will provide a harsh ride.

3) Using 1-1/8" provides more commonality with mountain bike components (fewer headset SKUs).

4) 1-1/8" steerers on road bikes are relatively new so are perceived in the marketplace as better.

Todd Kuzma
Heron Bicycles
LaSalle, IL 815-223-1776
Good post. (nm)Chen2
Nov 13, 2003 10:51 AM