There are quite a few top end forks now coming with carbon steerers, and I am considering them for a bike I am building up, and was wondering if there are any disadvantages over alu in certain circumstances.

ie Are they more likely to suffer in crashes, stems being overtightened and overweight rider scenarios. I know carbon can be made stronger, but have they maximized the weight loss at the cost of durability?

I think you could make the same arguments as you would for a frame of the same material

as long as you keep spacers above the stem so the pinch bolts are properly on the steerer and observe the torque settings on the stem you’ll be fine.

I think you could make the same arguments as you would for a frame of the same material

Some fames are made t be lightweight and I wouldn’t touch, other have gone for a balance of lower weight and strength which I would consider, while some are just stronger than their aluminium or steel counterparts.

There isn’t the same level of comparative information about carbon steerer’s yet, and I did see one break at the start of a worlds xc race last season, which did make me wonder if that was a standard unit or especially lightened because not much happened to justify that kind of breakage.

as long as you keep spacers above the stem so the pinch bolts are properly on the steerer and observe the torque settings on the stem you’ll be fine.

Do you know that or are you just assuming so.

Do you know that or are you just assuming so.

Rock Shox (among others) say you must have at least 5mm of spacers above the stem on a carbon steerer to ensure it’s clamped properly.

The headset tensioning thingummies weigh a lot more than a SFN, the old RS one was about 50g IIRC, which is a good chunk of any potential weight saving out the window! In the case of the SID WC XX it also only comes with the Xloc hydraulic lockout, which adds more weight over a crown mounted lockout, so actually the fork ends up being virtually the same weight, if not slightly heavier than one with an alu CSU. Dunno if the Rev is the same.

I’ve had SID WCs, Reba WCs and Spesh AFR forks with a carbon CSU, and never had any problems.

The stem goes on the least stressed part of the steerer anyway…. I can see increase risk of wear at the crown race (avoid old Chris Kings!) and if you either overtighten and squish, or undertighten and abrade, the steerer with the stem then maybe trouble.

I am, let’s say unconfident in mine. But it’s never done anything bad. And if it does, it’ll be the execution not the material.

Do you know that or are you just assuming so.

well, I can’t give you an insurance backed guarantee for every carbon steered fork that’s ever been made but generally, if you don’t over torque the pinch bolts and make sure that the stem is full over the steerer by having spacers above it you will be at the least amount of risk having a problem.

Trek, for example, only honour warranty on carbon steerers where at least 5mm of spacers have been used above the stem.

[edit] and obviously not hammering an SFN down the tube is a good idea too.

if not slightly heavier than one with an alu CSU

To be honest the alu steerer sid xx is my most likely choice, the carbon steerer ones are a bit above budget, but I thought if I did see a deal over the next couple of months if they were worth the extra.

I am not overly worried about the weight, but if carbon was stronger/stiffer/and lighter then that may sway me to start throwing money at the proprietor of a cycling emporium.

Do you actually want the Xloc? I don’t like it, and it adds weight, so I wouldn’t bother with even the standard XX unless you really want the hydraulic remote.

The only installation difference is like everyone’s said, the steerer has to be above the stem unlike Ali steerer’s. I know when I was looking at a set of DT Swiss forks they had a rider weight limit….sadly I didn’t qualify

Some fames are made t be lightweight and I wouldn’t touch, other have gone for a balance of lower weight and strength which I would consider, while some are just stronger than their aluminium or steel counterparts.

Heard of CEN testing?

You have carbon-paranoia

CEN testing doesn’t say much about durability, though- all those cracked Yeti swingarms pass CEN just fine frinstance. Not a carbon observation, lots of CEN frames are cracky.

My Rev W/C’s are 3 years old now and 3 trips to the alps old too if that helps

I’ve been looking at RS Revelations RCT3 and World cup (both dual position) and the only difference I can see is the carbon steerer, which is about 140g lighter but about £140 more expensive.

If i’m right I don’t see the point in spending the extra

Northwind – Member
CEN testing doesn’t say much about durability, though- all those cracked Yeti swingarms pass CEN just fine frinstance. Not a carbon observation, lots of CEN frames are cracky.

Aren’t there some cyclic tests under CEN?

Are cracking swingarms and the other cracks you refer to covered by CEN?

I do doubt carbon steerers haven’t been over engineered, given they will be used in the litigious USA with its punitive damages.

Do you know that or are you just assuming so.

Very very easy to crack a carbon steerer if you’re slightly overzealous with the tightening torque.

Not if you use a carbon steerer bung and are not a ham fisted spanner monkey.

Not if you use a carbon steerer bung and are not
a ham fisted spanner monkey.

Sadly a lot of people out there are ham fisted spanner monkeys…

We once got a cracked steerer repaired for a guy on his Sid wc. At the time of repair we also had a threaded ‘bung’ bonded in to save hassle.
The guy then took the bike back to his original lbs for some service work to be undertaken. The bike shop proceeded to then remove said captive bung whilst also de laminating the inside of the steerer!

Carbon steerers in my experience have always been fine. Their failings are that of the person working on them.
It’s generally important to observe the recommendations of the fork and not them stem, 12nm is too much for any carbon steerer no matter what the stem says! We’ve had a good number over tightened but barely a single failure due to stress.

cynic-al – Member

Are cracking swingarms and the other cracks you refer to covered by CEN?

No- which is exactly the point, you threw CEN-testing at the boy because he was nervous of lightweight carbon frames, when it’s not really relevent.

the boy

Heh, he’ll like that. I believe he has more wrinkles than Shatner’s scrotum…

we also had a threaded ‘bung’ bonded in

What was the bonding agent? I’m thinking of doing similar to a slipping bung.

No- which is exactly the point, you threw CEN-testing at the boy because he was nervous of lightweight carbon frames, when it’s not really relevent.

My point is that carbon can be made as strong as needed, which seems relevant to the OP.

That was his point.

I wish I knew what the bonding agent was!
he machined up an alloy plug to fit and bonded it in after he’d repaired he steerer.

I bought a second hand Kona Hei Hei Supreme last year from a nice lad in Wilmslow called Alex Stock. The bike had Rockshox XX World Cup Sids attached (im presuming its the Kona Team rider as i’m unfashionably out of touch with the athletes these days).

Blooming light they were too and very strong for an XC fork. I was nervous at first but never worried after that.

There’s chap on Youtube who rides in BC on Carbon Sids and swears by them. They get a fair workout.