The Low Down on Carbon Bike Tech.

[MrSteve]

This expert shares his broad knowledge about carbon bicycle frame repair,
carbon composite airframes, carbon building, carbon grades, corrosion
and more!
He's Australian, so there's a bit of an accent for Anglo ears.
By the way, he rides the carbon bikes he built for himself.

 

[Robert Holler]

Interesting. I personally know one of the head composite engineers from Boeing and he wouldn't ride a carbon fiber bike if you paid him.

 

[trapdoor2]

Yah, interesting indeed. Same old story though: properly made = good, poorly made = bad. Similar learning curve when aluminum frames hit the market. I like the idea of having a carbon frame scanned for defects. Wouldn't surprise me if manufacturers started including a 'scan' sheet or similar provenance with each bike. Could even require annual (or regular) scans to maintain warranty, etc. If I were an insurance company, I'd probably stipulate a regular scan for a CF bike (or car!).

 

[DavidCH]

That was a bit of an eye opener. Makers like specialized and giant with Quality control issues due to bubbles because of humidity when gluing. Quite incredible technology. It was interesting to about having alluminium next to carbon causes acidity if the aluminum gets wet. (Acts like a battery). Oh yea and if you are selling a carbon framed bike it will cost a$320 approx. if a bike works for you then why not keep it?

It was interesting too hearing that the guy worked on airplane systems. Very fascinating

 

[ratz]

For the newer generation of forum members that haven't seen these before.
If you ride something carbon; inspect your frame 2-3x as often as you think you should.
Doesn't mean other materials don't fail but Carbon tends to be catastrophic. I'll spare you my x-rays.

Below is what the police handed my wife; when she showed up at the scene; by then I was long gone in the ambulance by then. Didn't realize it was so long ago that STI was state of the art; and I was tracking HR with a polar watch strapped to the handle bars. Oh look an iphone2 mount.

 

[super slim]

Ratz did you hit something, or just a bump in the road?

During the Tour Down Under Community race with 5,000 to 7,000 riders, I see at least 2 CF bikes on the side of the road with broken frames, and sometimes ambulances depending on the speed at time of fracture!!!

I will stay with Aluminium OR Titanium!!!

 

[ratz]

Ratz did you hit something, or just a bump in the road?

During the Tour Down Under Community race with 5,000 to 7,000 riders, I see at least 2 CF bikes on the side of the road with broken frames, and sometimes ambulances depending on the speed at time of fracture!!!

I will stay with Aluminium OR Titanium!!!

The only thing I hit was the wind cresting a hill at about 28mph and accelerating. The entire bike was inspected no evidence that I hit anything, I gave it back to the manufacturing so they could study it and learn from it. It was 6 years old at that time (2004 bike, 2010 crash). All I remember was pedal pedal pedal - big white flash - and waking up on the ground with medical people over me.

 

[super slim]

The only thing I hit was the wind cresting a hill at about 28mph and accelerating. The entire bike was inspected no evidence that I hit anything, I gave it back to the manufacturing so they could study it and learn from it. It was 6 years old at that time (2004 bike, 2010 crash). All I remember was pedal pedal pedal - big white flash - and waking up on the ground with medical people over me.

Was the frame replaced under warrantee?
Did you learn a lesson and stop riding CF DF bikes????

 

[Robert Holler]

The Boeing engineer we know has said to us before "CF is not appropriate for things like bikes and cars" due to so much notch sensitivity. I won't ride one. One that could hold my weight would be heavy as the week is long to begin with - so whats the point. Plus they are loud and have horrible ride qualities. No thanks. Too much money for something that can fail so spectacularly so suddenly.

I sat on a Lightning R84 once and thought I was going to break it in half. I didn't ride it.

 

[ratz]

Was the frame replaced under warrantee?
Did you learn a lesson and stop riding CF DF bikes????

That would be NDA.....

Two years later I was healthy enough to ride a trike the rest is history. The long version is over on my "information tab"
http://cruzbike.com/forum/members/ratz.4093/

Plus they are loud and have horrible ride qualities.

bad ride; good race; but after they are 4-5 years old you gotta wonder what you are riding especially if you ding it. I miss the feel of Steel. As for Titanium please don't make a V20-T my wallet can't survive that.

 

[DavidCH]

big white flash

I had a big white flash when driving around a country corner much too fast when I was a teenager. We came head to head with a bus. My friend ducked underneath the dash and I did too. There was a huge white light and somehow we missed it???? Still don't get it. Perhaps God gave us a second chance??? There wasn't a scratch on the car either.

Have you seen the film Passengers?

I wonder where on a carbon fiber bike is the most likely place for it break?

Might be worth after 5 years just to replace the forks on a safety issue.

 

[super slim]

The only thing I hit was the wind cresting a hill at about 28mph and accelerating. The entire bike was inspected no evidence that I hit anything, I gave it back to the manufacturing so they could study it and learn from it. It was 6 years old at that time (2004 bike, 2010 crash). All I remember was pedal pedal pedal - big white flash - and waking up on the ground with medical people over me.

Ratz were you wearing a skid lid at the time of the "White Flash"???

 

[hamishbarker]

Lack of ductility is the problem. But given the weight advantages, there is surely a case for investing in tech to improve that.

my vendetta frameset seems pretty heavy, never had it stripped down to weigh, but read on a french website that the fork, chainstays, boom, main frame and seat are over 5kg. I'd appreciate a couple of kilos less than that! Of course, comparing to a df would require including seatpost, seat, stem and fork in the frame weights, so maybe 2kg is best possible? Given the inefficiency (in terms of material use) of a beam (the V frame) compared to triangulated DF, and the fact that the structural part of a DF is also the drivetrain support, whereas on a vendetta/silvio, the front part of boom and chainstays are extra weight used only for the drivetrain, maybe 5kg isn't too bad.

Anyone ever weighed a bare vendetta frameset (incl. seat but not wheels, handlebars, or groupset)?

Hey, aren't many of the comments about not riding a carbon bike coming from individuals who I am sure are riding vendettas and silvios with carbon seats?
(wish I could put the carbon seat on my vendetta 1.5. With 2-3mm of aluminium seat pan at least I have a bit of protection from rhinos charging from the rear...

 

[castlerobber]

Ratz were you wearing a skid lid at the time of the "White Flash"???

He was. But a helmet won't prevent a broken neck...

Two years later I was healthy enough to ride a trike the rest is history. The long version is over on my "information tab"
http://cruzbike.com/forum/members/ratz.4093/

It's worth going to that link and reading the whole story, but here's a key snippet:

"I was on a solo ride on a summer day. I crested a small hill, and was accelerating back down it. That is when the forks on my bike simply failed.

They cracked halfway up on both side; and at 28mph my front tire was gone and the concrete was there. The crash was over in a second, and so were my upright road biking days. My helmet saved my life; it shattered; my skull did not."

<snip>

"In the end, my neck had two fractures at C1 and C2 at the base of my skull. In my case they are non-operable injuries."​

That would be NDA

NDA = Non-Disclosure Agreement. One presumes the very large bicycle company "forked over" much more than a replacement frame, with the stipulation that Ratz isn't allowed to talk about the settlement.

 

[MrSteve]

I realize that real information based on actual experience will never change anyone's mind on anything ever.
(Unless you live and breathe the Scientific Method!)
Especially if the information has been posted on a public site by someone you will never meet and is presented by
someone that you may never have heard of and whom you will also likely never meet.
This is the internet....
The context of presenting this information on this site?
Some people were -and probably still are- desiring a racier/lighter/blingier V20.
I stumbled onto this vid. and thought of youse guys:
information is useful.

My opinion?
I agree with the carbon repairman in the video:
I build composite structures for my own use because I can trust them.
Carbon composite bike frames are for individuals and teams with deep pockets.

Finally, the carbon composite seat pans that Cruzbike uses are fine:
They're both stronger and prettier than my fibreglass/epoxy composite seats.

 

[ratz]

NDA = Non-Disclosure Agreement. One presumes the very large bicycle company "forked over" much more than a replacement frame, with the stipulation that Ratz isn't allowed to talk about the settlement.

Actually I'm a pretty easy going guy. I assume that no one set out to build a fork that was going to fail and try to take me out. As an owner of a business I understand when people seek to profit from back luck. In the end I was approached by several people who thought I'd make a lot of money from it. Not my style. It's not like I ever thought to inspect the bike. nope never,

Instead I contacted the manufacturer directly; and after I convinced them I wasn't out to sue them; I got the bike delaminated and studied by their engineers and I got a copy of the report; a construction process was change based on the findings. So my mission accomplished; I'm cool if I survive something like that; I'm not cool if the same thing happens to my kids 15 years later because it was swept under the rug with money. I was compensated for the bike that was basically deconstructed and analyzed and I don't get to say who made the forks, and I admit that I don't know if I actually hit something. In the end todays fork are probably safer and whether or not there was a recall I'll leave that for speculation.

 

[Robert Holler]

A bare V20 frame - no seat/boom/etc - just the frame is 3.7lbs. That is stupid light for a recumbent frame I don't care what material it is made out of. The rear stays of the V20 are as thin and light as you could possibly make them before you run into durability issues and/or eliminating everyone except horse jockeys from riding it.

The same bike in CF would be far heavier. AND (my opinion) would ride like a POS in comparison.

Having ridden many CF recumbents other than the R-84 (albeit briefly on most) I have never been on one that felt smooth. Maybe its a great race day or track recorb machine but thats about it. That makes no financial sense to produce.

 

[ratz]

A bare V20 frame - no seat/boom/etc - just the frame is 3.7lbs. That is stupid light for a recumbent frame I don't care what material it is made out of. The rear stays of the V20 are as thin and light as you could possibly make them before you run into durability issues and/or eliminating everyone except horse jockeys from riding it.

When I did the diary I weighed most of the parts out of curiosity. Everything from this end users' perspective is pretty optimal but I had a small list where you can shave weight. For cross references a $2.5k mountain bike carbon frame with no fork, post, handle bars, etc. is about 5lbs and that's considered feather light, but has similar structural challenges as a Recumbent.

Things only an owner of the bike can do:

1. Owner Cut the headrest poles down once optimized
2. Owner Cut the boom to the minimum you need (hinders resale) would be nice to know what the minimum "insert length" should be.
3. Owner switch to carbon handle bars if you could find some with the right flare. (probably a unicorn)

Beyond that I just don't see how you get it lighter.

1. As soon as you add aero wheels the weight goes up.
2. As soon as you put water on board the weight goes up.
3. As soon as you put a few tools on it so you aren't a noob on the side of the road calling for a ride home it gets heavier. Etc.
4. As soon as you put a traditional recumbent seat on it the weight goes up.

With the current design assuming you want it to remain affordable. The front fork is a beast; but that's the heart of the drive train; getting that lighter without weakening it would be an interesting engineering challenge; maybe you make that out of titanium; carbon in my opinion (for obvious reasons) might be a really bad idea; mostly because I think it shortens the longevity of the bike and is asking for trouble on 8-10 year old frames.

If the chain-stay cup clamps got designed out of the equation then we could use lighter stiffer BB30 cranks which are readily available in shorter lengths too. Maybe make the boom out of something different but the size and diameter is part of the function of aluminum do you make it tiny in titanium to save 0.25 lbs and wreck the Look and the lines of the bike?

If it was me I'd be analyzing the front triangle to goal remove the cup clamps meanwhile required that that goal of the new design is lighter and equally stiff. The boom and handlebars secondary related issues. But given that 24mm GXP is waning I suspect (I know nothing real) that is where the next iterations come from in a year or 3.

In the mean time; I'm just going to loose 4 lbs of fat and declare it a win.

 

[mzweili]

I'm just going to loose 4 lbs of fat

At no cost, and on top of that it improves longevity!

 

[ccf]

Do the concerns about carbon frames extend to carbon wheels?

-Cliff