Boardman fork snapped what should I do?

[bigjim]

Because then you'll have a proper steel bike

Oh. Gotcha. I was being a bit slow.

 

[Jameshow]

Indeed; galvanic corrosion is one since the carbon fibres are conductive. Another is simple stress raisers resulting from damage in high-stress areas such as the steerer tube (if it's all CFRP construction) from poorly-specced or over-tightened stems or steerer-tube bungs, or scoring from careless disassembly / reassembly.

In use I love my CFRP Boardman and I know there must be many tens of thousands of placcy bikes being ridden without issue in the UK. Equally it seems the cycling industry hides a murky underbelly of hushed-up, potentially fatal failures of CFRP parts - with fork assys being a favourite as they're so highly stressed (and the outcome of failure is potentially so severe).

I've heard many stories of such failures (some pertaining specifically to Boardman bikes) and I'll now never buy anything other than steel. I've not ridden my Boardman for any significant amount of time recently after getting cold feet about it's safety / acquiring a lovely steel gravel bike.. As much as I like it, know I really need to punt it on. Shame as I really like riding it, however it certainly gives zero peace of mind compared to a steel equivalent.

If you're not already familiar, check out Luescher Teknik on youtube - guy knows his onions and his content is certainly an eye-opener!

I reckon that particular fracture is caused by a stress riser caused by the disc brake mount. Chances are the op rode around the garden and did a very sharp stop on the front brake putting massive load on the caliper mounting plate which in turn pushed into the fork leg. Carbon fibre Achilles heal is point loads.

 

[Illaveago]

Here is my front fork. The hairline crack can be see going across from left to right. I thought the other stay was free from the split but I have discovered that it is on the inside . It would be interesting to know how these forks were made . I am assuming that they used a mortice and tenon type of joint and epoxied together. I have tapped a coin on the fork slowly listening to the sound as I gradually worked my way up. The sound has remained constant until I reached the split where it changed to a dull tone. I will be sourcing a replacement steel fork. Once I have a replacement I will remove the paint from the damaged fork to see what is going on.

 

[Jameshow]

Here is my front fork. The hairline crack can be see going across from left to right. I thought the other stay was free from the split but I have discovered that it is on the inside . It would be interesting to know how these forks were made . I am assuming that they used a mortice and tenon type of joint and epoxied together. I have tapped a coin on the fork slowly listening to the sound as I gradually worked my way up. The sound has remained constant until I reached the split where it changed to a dull tone. I will be sourcing a replacement steel fork. Once I have a replacement I will remove the paint from the damaged fork to see what is going on.

View attachment 674011

Yeap alloy crown hence the bubbling the carbon forks. Poor design imho.

Better are alloy steer / carbon forks

Best are all carbon

 

[wafter]

I reckon that particular fracture is caused by a stress riser caused by the disc brake mount. Chances are the op rode around the garden and did a very sharp stop on the front brake putting massive load on the caliper mounting plate which in turn pushed into the fork leg. Carbon fibre Achilles heal is point loads.

Yup - could well be.. I think disc brakes put a lot more load on the fork but of course this should be taken into account during design.

Yeap alloy crown hence the bubbling the carbon forks. Poor design imho.

Better are alloy steer / carbon forks

Best are all carbon steel

Fixed that for you

 

[cyberknight]

Full carbon forks should help with this issue ?

 

[bonzobanana]

Full carbon forks should help with this issue ?

I think it does, a few years ago I noticed there was a lot of carbon fibre fork recalls and when I looked at the details it was more bonded carbon fibre blades to an aluminium steerer than full carbon fibre forks. The bonding was failing over time. Forks are the most potentially dangerous component on a bike because failure can be so horrific. A carbon fibre frame is much safer than a carbon fibre fork purely because how they fail and what level of control you have, to deal with the failure as you ride. The big issue with CF is manufacturing consistency and thats because its a manual process done by hand there are far more opportunities for faults at the manufacturing stage compared to steel, titanium or aluminium. Boardman aren't a manufacturer they are a brand they will keep moving production to different factories in Asia to get the best price same as most US and European brands which have no real manufacturing, most bikes are imported in full from Asia although sometimes you get assembly plants in Europe mainly because of the EU tariff situation. Typically Boardman bikes you get more for your money as its a factory to retailer direct business model. It's hard to think of a brand that hasn't had a carbon fibre fork recall at some point if they have sold bikes with them. It's a performance component with a much higher failure rate than steel and aluminium forks and needs regular examination to check for issues.

 

[Ajax Bay]

@Illaveago revisited this 'old' thread after two years. Which itself was one resurrected from 2017.
I thought that @Fab Foodie 's posts on another thread were useful so here they are:

For completeness:
https://spacycles.co.uk/m21b0s29p2625/SPA-CYCLES-Carbon-Alloy-Audax-Road-Fork
https://spacycles.co.uk/m21b0s29p3677/SPA-CYCLES-Steel-Road-Fork
So from their 2 test bikes one with each fork, they say that the Carbon is better/smoother and as a result that's what they end-up fitting to the majority of their Audax bikes.
Carbon forks are cheap too, try buying a set of 531 or Reynolds R blade forks with a 1 1/8th steerer or having a pair made (as they are generally not off the shelf) these days and they cost a few hundred quid and a bit.
The 350g weight saving is a bonus....
It's a punt I can afford as I can re-purpose one of the forks elsewhere.
Once done - I can add to the large body of anecdata....

Fitted the Spa Carbon Fork - the difference over the 853 original is notable immediately!
Just pushing the bike along by the saddle it feels more 'springy', riding it is a revelation - much smoother, less vibes through the bars, less overall rod shock even at 70/80psi pressures. Before it felt a bit 'dead' to ride, now it feels altogether a bit more lively.
It weighs 250g less too!
£120 well spent.

 

[Illaveago]

I removed the fork this morning . I attacked one side of the fork to find out what was going on. There are a lot of layers of paint before you get to a layer of thin carbon fibre . I think the paint layers are primer , black , white ,black ,white , grey. They could have saved weight by not using so much paint . Filler was used to blend the transition between the carbon fibre blade and the fork crown .It is the filler which I think cracked . There is some slight corrosion , dark ally at the edge of the end of the carbon fibre which might have caused the filler to crack .

 

[wafter]

I removed the fork this morning . I attacked one side of the fork to find out what was going on. There are a lot of layers of paint before you get to a layer of thin carbon fibre . I think the paint layers are primer , black , white ,black ,white , grey. They could have saved weight by not using so much paint . Filler was used to blend the transition between the carbon fibre blade and the fork crown .It is the filler which I think cracked . There is some slight corrosion , dark ally at the edge of the end of the carbon fibre which might have caused the filler to crack .

Good work - would be interested to see some pics

 

[Illaveago]

 

[Illaveago]

Sorry for the poor quality of the picture . I've been rubbing down the paint where it has bubbled up with corrosion . It looks like it is repairable .

 

[wafter]

Sorry for the poor quality of the picture . I've been rubbing down the paint where it has bubbled up with corrosion . It looks like it is repairable .

Paint maybe; crown to fork interface perhaps not so much. If you value your teeth / higher brain functions I'd suggest relocating that to the bin..

 

[Jameshow]

Paint maybe; crown to fork interface perhaps not so much. If you value your teeth / higher brain functions I'd suggest relocating that to the bin..

Why when the interface is intact.

Much like condemning a steel bike that has a knock on it!

 

[wafter]

Why when the interface is intact.

Much like condemning a steel bike that has a knock on it!

I was under the impression that there was a "defect" along the CFRP / ally interface; which implies something not right there; maybe just local oxidation lifting the paint; maybe the beginnings of adhesive failure. Not a chance I'd be willing to take tbh - as I think you've already alluded to, composites are a lot less predictable than metals.

While dinged steel is predictable and by extension acceptable, composite showing any obvious signs of degradation should be nuked from orbit tbh.