Cracked Carbon Wheel

[3WHELZ]

I am starting to rethink this idea of carbon wheels, at least for the front. About three miles into my morning ride today, I hit a small patched area of asphalt heading up an incline at 25 mph (after coming down another hill). It was enough to jar one of my bottles loose, but I did not think much about it until I applied my front brake and detected an odd high spot. After closer observation, I noted a bulge in the sidewall on both sides of the carbon rim. The carbon fiber had definitely been compromised and was now soft in the affected area of the sidewall. Rather than continue another 30 miles and chance total failure, I decided to return home.

The affected wheel is a HED Stinger-6. HED has a decent repair program, but I think it may be time to discuss options. On a metal rim, the worst outcome that I would have expected would have been a pinch flat. At 6'2" and 185 lb, maybe the front drive wheel is just being subjected to too much force when it comes contact with irregularities in the road.

I would welcome your thoughts. Thanks, Dean

 

[RAR]

What size tire ?

 

[3WHELZ]

Gatorskin tubular tire 700c 25mm, approximately 90psi

 

[paco1961]

I am 6’1” 195 and have thousands of miles on DFs w assorted carbon wheels. Never had this happen and I rode most of those miles on 23s at 120 lbs. should never happen. I’d guess a mfg defect.

 

[benphyr]

That must have been some serious impact. Since you mention no injuries I am very glad to hear that you are ok and the only casualty is the wheel.

That rim looks trashed - am I seeing both sides with significant cracking, looks like from a major impact with either sealant or glue evidenced around the area on the one side? Seems like the tire pressure was too low to provide any protection for the level of impact it experienced. What kind of tire, tube/tubeless/tubular, tire pressure, and spoke tension before/after?

210 lbs bike+rider at 25mph (40km/h) carries quite a lot of momentum to slam into a road cut or sharp transition edge though I don't know how to quantify it. The deeper the "v" of the aero rim the stiffer it is (ie. more efficient aero and more efficient rolling on perfectly smooth BUT less give to absorb impact without breaking.) That would go for any material I think. Keep us posted if you find anything further out.

 

[3WHELZ]

Thank you. It was a depression in the asphalt from prior utility work, not unusual for the roads in this area -- far less of a sharp edge than a pothole.

I have no idea about the spoke tension, but there seems to be no change in tire pressure and the spokes do not seem to have reduced in tension. As previously mentioned, the tire is tubular Conti Gatorskin and inflated to about 90 psi, as recommended by HED. There is appears to be no damage to the tire.

I may have more information after speaking to HED. I suspect that they will steer me towards their JET wheel design, which is a hybrid metallic/carbon wheel.

 

[jond]

Ouch that’s very disappointing and expensive but you were not hurt.

I think personally a strong training wheel set with 32 spoked aluminium are worth their weight in carbon. I have an enve carbon wheel set and they are strong too but ..........the roads I ride are fraught with irregular surfaces and potholes.

I save the carbon rims for going faster on specific selections. Gives me a boost.

You could run higher pressures and absorb the poorer ride or fit larger tyres.
I duly note most of my flats on the vendetta seem to be on the front. Probably a good reason for that like fallible measure of memory.

 

[super slim]

I have seen too many Carbon bike and a few carbon wheel, riders on the ground on "Tour Down Under", 7,000+ riders Community rides, to EVER think of going Carbon, unless there is Titanium in the middle of it(Silvio suspension)!!!!

 

[bladderhead]

The wheel stayed in one piece. Lucky. I think carbon is scary. How much are the Silvio's carbon components stressed?

 

[super slim]

The wheel stayed in one piece. Lucky. I think carbon is scary. How much are the Silvio's carbon components stressed?

Very lightly stressed as the Front chainstay suspension only takes the rider chain loads, and the rear only takes rear braking loads Fore /Aft.
The chainstay/rear lower arm, is VERY flexible in the vertical direction, as only 5 Kg/10 mm of movement, so with a broken top flexible suspension plate, the rear wheel stays on the ground when you lift the frame to go up a 150mm (6")curb.
But VERY stiff in a horizontal as I rode 30 km with a broken top flexible link, so the bottom CF+ titanium keep the rear wheel vertical through some fast bumpy corners, when dropping from 500 m to 40 m elevation.
The carbon fibre chainstays are 23mm*7.4 mm with I am assuming a 20*1.6 titanium core, so the CF is mainly used to stop the thin Titanium collapsing under the axial loads of braking or rider chain tension!

 

[bladderhead]

So my Silvio has more Ti in it than I thought.

Actually, now it has Ti pulleys.

 

[3WHELZ]

I spoke with Christin from HED this morning. I found her to be very helpful and friendly. Based on her input, this may have been a fluke failure. Regardless, I plan to switch to a JET-6 that has an aluminum embedded rim for the front wheel. They are working up a price for the swap.

I am also considering purchasing a FLO wheelset, a FLO 60 Aluminum + Carbon. I spoke to Chris from FLO this morning, and it appears to be a good compromise between structural strength and aerodynamics. Plus there is an option to run a tubeless clincher rather than a tubular tire.

 

[RojoRacing]

If you had hit the same hole with an alloy rim you'd most likely be buying a new rim. From my experience alloy rims walls will bend twice as easy as a carbon rim will crack, they just aren't strong enough in that respect because they have to try and compete with the weight of carbon. I double pinch flatted over a sharp edge pot hole two weeks ago on my DH bike. Front rim was alloy mid grade training wheel so not super lightweight and I bent both sides of the rim enough to easily see it when spun. The super lightweight enve carbon wheel and tire also pinch flatted in the exact same why as the front but with zero damage to the rim. If you hit something and damage a wheel it's not the wheels fault for failing, it's you fault for hitting the object, not pointing fingers just stating facts. What we do on carbon in the mtb world proves just how strong carbon is but just like anything if you push something the correct way it'll fold no matter what it is.

 

[bazzawill]

I agree with @RojoRacing I damaged a DT Swiss alloy rim, the rim dented which definitely prohibited running tubeless, but also I didn't want to run it with a tube for too long either , hence the upgrade to carbon.

 

[3WHELZ]

I will be the first to agree that cracking the rim was my fault. I was paying attention the car coming along side of me and did not dodge the patched area quickly enough despite having passed it dozens of times previously. However, you will not convince me that alloy wheel is as fragile as a carbon wheel. After riding 10s of thousands of miles over the last 50+ years, I have hit my share of patches of rough road. For example, I only had to true the front wheel of my Silvio 1.0 alloy wheel only once in nine years of riding.

I just look at it as a cost of enjoying the sport and thought that it may be of interest to others. The HED team has offered me a discount on replacing the entire wheel, which is greatly appreciated!

 

[jond]

I agree with @RojoRacing I damaged a DT Swiss alloy rim, the rim dented which definitely prohibited running tubeless, but also I didn't want to run it with a tube for too long either , hence the upgrade to carbon.

It’s just that overall strength of the wheel is related to spoke count. Most carbon wheels are built below 32 spoke count. My enves are 24. I know the results of breaking a spoke on a 24 enve and a 16 scandium and 32 alloy. The 32 was ride on the 24 was slow down the 16 was limp home and pray. Id rather train on a cheaper decent alloy 32 spoke training wheel and save the purposed carbon wheels for events.

I run rim brakes so my experience is influenced by this.

I guess the lesson is don’t hit anything. Yeah right.

As carbon wheel technology has matured so the alarmist overblown nightmare stories have diminished.

Still given the choice I would in a situation rather have alloy rim dinged dented or bent than carbon cracked. Safer cheaper repairs on side road maybe possible . With 32 spokes.

If I .....when I move to discs it may be different. By then I will have won the lottery.

 

[super slim]

It’s just that overall strength of the wheel is related to spoke count. Most carbon wheels are built below 32 spoke count. My enves are 24. I know the results of breaking a spoke on a 24 enve and a 16 scandium and 32 alloy. The 32 was ride on the 24 was slow down the 16 was limp home and pray. Id rather train on a cheaper decent alloy 32 spoke training wheel and save the purposed carbon wheels for events.

I run rim brakes so my experience is influenced by this.

I guess the lesson is don’t hit anything. Yeah right.

As carbon wheel technology has matured so the alarmist overblown nightmare stories have diminished.

Still given the choice I would in a situation rather have alloy rim dinged dented or bent than carbon cracked. Safer cheaper repairs on side road maybe possible . With 32 spokes.

If I .....when I move to discs it may be different. By then I will have won the lottery.

If you win the lottery, are you going to share the Cruzbike upgrades with your fellow "AUSSIE" Cruzbiker mates????

 

[Don1]

we will all be too old to joy them, alas

 

[jond]

If you win the lottery, are you going to share the Cruzbike upgrades with your fellow "AUSSIE" Cruzbiker mates????

Yes and also move to Adelaide

 

[super slim]

Yes and also move to Adelaide

That would be great to have another Cruzbike to chase me, especially when climbing hills!!!