Carbon forks?

[quixoticgeek]

Another in the series "Geek tries to understand modern bikes":

I see a lot of bikes with ali or steel frames, and then a carbon fork. I've read blogs/threads about people upgrading to carbon forks. All of these seem to talk of the weight saving that comes from a carbon fork. Is there any reason to upgrade a road/touring/gravel/adventure bike's steel fork to a carbon one other than to save weight? Does it dramatically change handling? or ride comfort?

Thanks

J

[The French Tandem]

Alu forks are crap, so it makes sense to use a carbon fork on an alu frame. A high end steel fork can be pretty comfortable and light, so "upgrading" to carbon is not always a huge improvement.

[quixoticgeek]

Alu forks are crap, so it makes sense to use a carbon fork on an alu frame. A high end steel fork can be pretty comfortable and light, so "upgrading" to carbon is not always a huge improvement.

I must admit that I really don't like ali as a frame material, doesn't have enough spring to it. This does explain why carbon forks on ali is so popular.

Cheers

J

[Biggsy]

It's not all about weight, but it is mainly, so don't rush to upgrade if you don't care about that.

Carbon fibre is very strong and provides a little bit of vibration damping.  It's complicated by there being variations of steerer tube material and reliability of bonding.  Most "carbon" forks are not entirely carbon fibre, although some are (some even including the dropouts).  There's no difference in steering handling when the rake/offset is the same.

[mrcharly-YHT]

I ended up with an aluminum-framed bike with a heavy-duty ('audax') carbon fork. It did an admirable job of absorbing road buzz. Instead of that electric buzz you get with hard tyres, it was more of a hum.

IMO, the only real disadvantage of carbon forks is that they are vulnerable to abrasion damage.

[T42]

I bought one second-hand in 2004 and used it for 8 or 9 years. It took a lot of punishment, including one descent in the Vosges that turned out to be little better than hard core for a couple of km.  I only replaced it when a friend's fork broke and landed her in hospital with a broken neck.

It turned out that her fork wasn't the primary cause: an idiot in her club had filed off the lawyer's lips.  She had gone out in a hurry and without tightening the QR properly: front wheel came out of the drop-outs and rubbed the fork, which snapped. But even if it hadn't she was due a tumble.

Anyway, abrasion is a weakness, but for withstanding and absorbing shocks they're great.

[LittleWheelsandBig]

I deliberately file off lawyer tips from my bikes, except for hub brake bikes. I know how to use a QR.

[quixoticgeek]

I deliberately file off lawyer tips from my bikes, except for hub brake bikes. I know how to use a QR.

Lawyer tips?!?

J

[sojournermike]

Generally, I think that aluminium forks/steerers are a bad idea. Aluminium fatigues and will eventually fail.

The same is true of frames and overbuilding to avoid this makes them stiff and non-compliant. On the other hand, my alloy Kinesis Aithein feels much more 'absorbtive' of road noise/shock than my steel Genesis Volare. I'm not sure the Aithein was built with an open ended design life and it has a 14st weight limit applied too.

Back to forks - I'm happy with steel or full carbon monocoque, but not carbon with alloy bits bonded in. Just for peace of mind/safety and not performance.

Mike

[Martin]

I deliberately file off lawyer tips from my bikes, except for hub brake bikes. I know how to use a QR.

Lawyer tips?!?

J

I thought they were called Lawyer Lips; the little bushes that prevent the axle from coming out of the forks if the skewer comes undone unless the retaining nut is also loosened, not sure how they prevent this with a nutted axle

[mrcharly-YHT]

My Genesis, with disc brakes, has tapered dropouts to achieve the same purpose. Seems a sub-optimal solution to me, I think I'd almost prefer the lawyer lips.

[rogerzilla]

Carbon forks are usually the cheapest and most freely available replacement option if you want to convert a threaded headset arrangement to threadless.  1" steerers are a bit rare now, though.

When replacing forks, you are generally ok with road racing bikes, since the geometry is nearly always the same (43-45mm offset and just enough length for a 700c wheel), and MTB fork swaps are reasonably easy if you know what length travel suspension fork the frame was designed for.  On other bikes...anything could happen.

[Martin]

Carbon forks are usually the cheapest and most freely available replacement option if you want to convert a threaded headset arrangement to threadless.  1" steerers are a bit rare now, though.

indeed; the alu forks on my Ribble frame gave up the ghost (or rather the mudguard eyes buggered) after 11 years service on two bikes. I thought probably a good excuse to upgrade to carbon, but the only place I could find a 1" fork was Kinetic One, cost a lot more than the frame but going strong 4 years later,

is there a recommended life for carbon forks?

[rogerzilla]

They don't fatigue like metals; failures tend to be where they are bonded to metals because of corrosion and/or failure of the glues used.  A real "full carbon" frame or fork should last indefinitely.  UV light is something I'd be wary of as pretty much any plastic degrades in it - keep CF bikes out of sunlight when not being ridden.

[LittleWheelsandBig]

Unless the plastic has something to block the UV, as most plastic structures do (as opposed to many fabrics).

[P Walsh]

If you have good steel forks, keep em. Carbon will save weight, and that's about it. Carbon will not dramatically improve handling or vibration damping, and it will not inspire you with confidence when it has a few years of use in it. And carbon is not necessarily an "upgrade". Cheap carbon forks are cheaper than top end steel ones.

(I'd not trust ally for forks.)

[zigzag]

i had 531 steel forks some time ago and they would move about 1.5mm fore-aft looking from above when going over rough tarmac (i know this "test" may not tell much..). carbon forks move a bit less, about 1cm looking from above. the main difference is that i have much more confidence in the way the bike handles with carbon forks, it just goes where you point it, very precise. with steel forks any quicker steering input or jolt would unsettle the bike, which was perhaps amplified by a noodly frame. there is some attraction in riding such a bike, more engaging, but i prefer more predictable handling.