Any flex issues with 1” carbon steerer tubes w/ spacers?

[Louis]

I’m in the market for a replacement fork and I’m considering going to an Ouzo Pro. I’ve never used a fork with a carbon steerer tube, but have heard some hints that a 1” tube with spacers (say about 3cm) might be “too flexy.” The other option would be the Ouzo Comp with aluminum steerer, but to be honest, I don’t know if that’s any stiffer.

Also, how does the ride of the Ouzo Pro compare to the Comp?

(More info: I weigh just under185 lbs and don’t need this to withstand racing finish line sprints, but on occasion I do stand on our many short roller coaster climbs. I doubt my stem would be longer than 10cm, but as mentioned above, I would have about 3cm worth of spacers.)

Any thoughts this issue?

Thanks
Louis

[zap]

I have an Alpha Q w/1" medium stiffness carbon steerer on my ti bike. Currently run 5mm spacers w/current stem but did originaly have 20mm spacers when I used a Newton stem. I did not notice any lose of stiffness with either spacer amount compared to the original al fork w/steel steerer.

The carbon steerer gets a little stiffer when you epoxy the al insert/nut assembly that comes with the Alpha Q fork.

If you need 30mm of spacers, I would recommend getting the stiffest Alpha Q carbon steerer.

[victoryfactory]

Louis;

I think your frame size is the critical thing to consider re flex with the 1"
carbon steerer. Further, I'm not sure that a little "flex" here is all that bad,
after all why do we use carbon in the fork, bars, stem anyway? aren't we
looking for smoothness, vibration absorbtion and ehem.. "flex" for comfort?

A very large frame (with long head tube) probably would allow more flex.

I have that fork on my atlanta with no problems, 52cm frame.

I'd try to keep the spacers down to 1.25" max, also look into the
Serotta "heads up" gizmo as an alternative to mucho spacers.

VF, btw, I think the heads up thingys are on back order

[Big Dan]

I'm using 1' inch Alpha Q fork with 20m of spacers and find really no flex at all.
Also using a Kestrel 1' inch with cro-mo steerer that is more than stiff. The Ouzo comp has a bonded legs to an aluminum crown and is made overseas, the Ouzo pro is full carbon made right here... :D

[shinomaster]

I have a 1" all carbon Columbus Muscle fork on my Cannondale, built up with about 10mm of spacers. At first I was freaked out by the flex and thought my steerer tube was going to fail me. It hasn't and I actually like the flex now. I still wonder how long it will last though. I Would have gotten an aluminum steerer tube but I am such a weight weenie. With an inch of spacers the flex might be a problem. You can get a Easton carbon fork from Performance with a steel steerer for $99. Probably much stronger.

[Larry]

If you are into statictics and testing, go to

www.Reynoldscomposites.com

Go to the section on forks...... test results and all that stuff.

I am using the Reynolds Ouzo Pro carbon steerer 1 inch.
I also have the Serotta Heads-Up Ti insert, plus Serotta spacers.
It seems very solid to me, and I do not notice any flex on my CSi.
It rides even better than my old F1 fork, which I liked alot.
The Heads-Up insert looks fine, and the whole set-up is an improvement.


Ouzo Pro 1 inch, Chris King Headset (fantastic), Heads-up,
Ti Serotta spacers (all three), Bontrager 46 mm. handlebar,
Ritchey WCS stem 100 mm., Fat Wrap 2.5 mm bar wrap.

[Sandy]

I sent you an email about your blood pressure issue. I also posted on your thread.

Sandy

[dgauthier]

(. . .) a 1? tube with spacers (say about 3cm) might be ?too flexy.? The other option would be the Ouzo Comp with aluminum steerer, but to be honest, I don?t know if that?s any stiffer.

Any thoughts this issue?


The "rule of thumb" for carbon steerer tubes is that the height of the spacers shouldn't exceed the diameter of the steerer tube. So, for a 1 inch steerer, you'd be limited to 2.5 cms of spacers (1 inch = 2.54 cms).

The issue here isn't one of flex, but rather safety - too many spacers and a carbon steerer tube can fail!

Stick with an aluminum steerer if you need 3 cms of spacers, and you'll avoid the issue entirely. (As a bonus, you'll also avoid the issue of inadvertently cracking your steerer tube - a ruining your fork - by over tightening your stem.)

[Louis]

dg,

Thanks for the feedback. Some additional info:

2 cm of the 3 cm number I used is going to be the Serotta Head's Up thingy (I got one of the last ones they had in stock.)

I don't know if that should count as spacer or not. I don't think so, so therefore I would not be in violation of the rule of thumb.

I may be wrong, but I do not think that this is a safety issue. As best I can tell, the whole pupose of the Head's Up head tube extender is to allow you to do this...

Louis

[dgauthier]

Yes, the Heads Up extender is part of the head tube from a structural standpoint.

You only need to pay attention to how much steerer tube sticks up beyond the top of your headset, ie: the portion of the steerer tube supported solely by spacers. So if you'll only have 1cm of spacers, you should be fine.

[Jeff N.]

You can get away with 25mm of spacers (max) with a 1" carbon steerer, 30mm with an inch & one eighth. Use more and you take the chance of the steerer snapping, which would/could be fatal, obviously (I hate the visual I get when I think about it.).But I've seen bikes set up with more than those maximums though.But I'd never chance it, myself. I actually prefer the alloy steerer of the Kestrel EMS Pro OS fork. Safety vs. spacers is much less of an issue....I ride much more worry-free. Jeff N.