My road bike has carbon forks and I’m a bit concerned about how strong they are.

I’m 18 stone and my commute is along a cycle path that has a few dropped kerbs for roads crossing it.

These dropped kerbs aren’t the best and some are quite hard on wheels.

I’m trying to lift the front up as I go up them but then I’m also clattering the rear wheel too.

How strong are carbon forks then. Am I worrying over nothing ?

Stop worrying, you think they just don’t bother making stuff properly?

Very. Yes.

I’d be more concerned if it has a carbon steerer as well.

I’ve properly wacked my carbon road forks on unforeseen potholes quite a few times and they’ve easily shrugged it off and carried on for a good few years.

I’d be more concerned if it has a carbon steerer as well.

Why, that’s pretty much every road fork apart from poverty spec models?

I’m 16st and regularly hammer mine on fire roads and farm tracks pretending it’s the strade bianche. Never given it a second thought in 10 years.

I did snap a steel steerer on a road bike once, just riding along honest. Although the day before I did ride it down Hagg Farm.

No idea about your forks but perhaps learning (or doing – if you already know) how to bunnyhop?

Personally, I wouldn’t worry about it. I am about your weight and put 5 odd thousand miles on my previous road bike with a carbon fork, the bike was 2nd hand when I got it and it was still good when I sold it.

Yep, don’t worry. I regularly take my road bike off road and it’s fine.

I wouldn’t worry. They are ludicrously strong.

Having said that, from an arse-covering point of view you would be over the warrantied weight limit for some of the more boutique forks on the market, so if you’re that concerned I’d ask the manufacturer.

Carbon is strong..
whatever your weight maybe use some finesse over obstacles…

Don’t worry about the carbon steerer either. In my side-on crash and dead stop at 20 mph, the forks snapped half way up the blades, not at the steerer – where you might have expected them to fail.

go onto youtube and type in ‘Paris Roubaix’ 😀

they’ll be fine, the wheels and tyres will be getting more hammer so check the spokes regularly for any breaking or loose, keep the tyres in the middle of the stated range on them, wider tyres will help if you can squeeze them in

did you see them smash through the cobbles hard and fast. Carbon is incredibly strong built right.

Cool cheers for the replies.

Fork is standard fit on a 2012 genesis equilibrium.

I’d be more concerned if it has a carbon steerer as well.

My Niner mtb forks are carbon straight steerer and I ride that as shoddily as someone who has never ridden before, I also like to pop off stuff on it, seems good to me.

A friend of mine had a fairly nasty accident due to a broken carbon steerer on his road bike. It was Chinese though….

It’s not a carbon steerer you want to worry about it the cheaper aluminium steerer bonded to carbon forks. Had a mate who in an E,1,2 road race had the bonding fail, so he could tun the bars with no noticeable affect on the forks or wheel 😈 Amazingly though he didn’t even come off, just brought it gentle to a stop.

It was Chinese though….

Most of them are.

Just remembered my MTB has a carbon steerer, hadn’t even thought about it’s strength (apart from when tightening stem bolts) before now.

The carbon forks on my Rocky Mountain road bike amazed me. So light! Like paper. But they survived the crash that did this

^ they survived because the wheel took the impact, folded and dissipated the force. The load and direction damaged the wheel only. I’ve seen forks folded underneath a bike with a straight front wheel attached, same thing.

^ they survived because the wheel took the impact, folded and dissipated the force[b]energy[/b]. The load and direction damaged the wheel only. I’ve seen forks folded underneath a bike with a straight front wheel attached, same thing.

FTFY, the fork and wheel experienced the same force, and it would all have been acting on the axle, if anything it’s concentrated on the axle as the force on the rim is spread over they tyre in contact with whatever you’ve hit, therefore the stress (measured in the same units as pressure) is lowest in the wheel, and highest at the axle/fork.

Either way, no point in over designing the fork or wheel, so unsurprising if it’s 50/50 which gives first.

TINAS, yes energy is the correct term, have a point : )

I’d say the highest stress concentration there was clearly at 2 points on the rim.. But there’s loads of people far more knowledgable about stress analysis than I am. It still says little about the general fork strength : )

I ride a set of carbon forks on a cross bike down rough singletrack, probably totalling 20 miles a week, as well as farm tracks and so on. They’re fine.

[pedantry]

I’d say the highest stress concentration[b]strain[/b] there was clearly at 2 points on the rim.

[/pedantry]

2-0

😈

I’m not at work today so have to get my engineering geek on whenever possible.

A friend of mine had a fairly nasty accident due to a broken carbon steerer on his road bike. It was Chinese though….

Yep, it’s well known that Chinese forks are far weaker than ones from the big manufacturers…

I’m rocking between 118 and 125 kilo’s and my cannondale super six (full carbon) is in great shape after 1000’s of miles on not always smooth surfaces. been through a few wheels mind.

TINAS, strain/deformation, yes. Stress as percentage of yield is what I had in mind but that’s probably another open goal.

In the absence of aracer, the plural of anecdote is not evidence!

My cheap Chinese full carbon forks have around 11000 miles on them so far without bursting into flames.

It still says little about the general fork strength 🙂

I think I was more make a strength:weight point, but, also the frame revealed cracks after time and the fork didn’t.
But yeah, they are really weak, stick with metal.

go onto youtube and type in ‘Paris Roubaix’

I totally agree carbon forks are very strong (see videos of trials on road bikes) but that’s not totally relevant to the OP’s question. A pro rider is only going to have 18 stone on the bike if he gives his teammate a backie to the shops.

DezB, strength or strength to weight, I know what you mean but all forks should hit a strength point via testing and regulations, generally carbon is ‘strong enough’ but lighter than other materials. My point wasn’t intended to come across as having a pop, more making the point that a folded frame or wheel with an intact fork doesn’t show a very strong fork necessarily. I’ve just seen a number of bikes that have been crashed where there’s a claim for a faulty frame or fork based on the front wheel not giving way first, that kind of thing. In a side-on impact or crossed-up crash of some kind I’m not suprised the wheel gave way first.

My daughter had someone pull across in front of her last month (she still has her leg in plaster).
She weighs next to nothing and this still happened.
On the other hand I ride my carbon forked cross bike on the Quantocks and takes some scary thumps (but nothing compared to hitting a car at 35kph).

http://singletrackworld.com/forum/topic/anyone-got-any-super-glue#post-6976650

If your worrying about dropping curbs might be a good idea to worry about technique .. Surely it’s going to take a really ugly approach to break even the weakest forks down curbs? – If this is the case slow right down and roll down it or get some new forks ..