Secondhand carbon frames - ?

[kingrollo]

My friend John buys non branded carbon frames onto which he builds his time trial bikes ......
Quality kit, Toray product.
He rides them for 2 TT seasons .......
Then cuts them up and drops them into the BIFFA bin at work ...
Like me he is an Aerospace Engineer with many years of working with carbon structures in primary, secondary and tertiary stress applications.

Have to say i agree with him.

Exactly - your an Aerospace engineer working with carbon structures. You are going to be more aware of the limitations and failures. A bit like people who work in a+e who won't ride a bike - because they see injured cyclists on a daily basis.

For most people 2nd hand carbon frame will be fine. Sure it's a risk - but imo a small one.

 

[cougie uk]

My friend John buys non branded carbon frames onto which he builds his time trial bikes ......
Quality kit, Toray product.
He rides them for 2 TT seasons .......
Then cuts them up and drops them into the BIFFA bin at work ...
Like me he is an Aerospace Engineer with many years of working with carbon structures in primary, secondary and tertiary stress applications.

Have to say i agree with him.

Do two seasons fine - three seasons dangerous ? And they are his TT bikes - he would know if he's knocked it. Seems a bit OTT.

 

[Cycleops]

Can never understand why cyclists go so mad for CF frames when the advantages are minimal and cost is higher.

 

[davidphilips]

Can never understand why cyclists go so mad for CF frames when the advantages are minimal and cost is higher.

Only my view but perhaps its because of money spent in advertising, an average cyclist with a 12k bike must be a lot faster and better than some one on a bike thats a few years old. (said in jest)

 

[Landsurfer]

Do two seasons fine - three seasons dangerous ? And they are his TT bikes - he would know if he's knocked it. Seems a bit OTT.

I agree .. but John feels that the possibility of him selling on the risk would not be fair ....

 

[IanSmithCSE]

Good morning,

Can never understand why cyclists go so mad for CF frames when the advantages are minimal and cost is higher.

I have a used one because I wanted to find out if they were better and decided that for me the improvement over a 531c frame was noticeable, but not the ride changing experience that I was expecting.

The points that the improvement were most noticeable were when a hill started to level out or on short steep hills especially when ridden in a too high a gear. These would be the points when I would be riding out of the saddle at maximum effort. This suggests to me that at elite level, where the power output is much greater than mine they could easily be essential if everyone else is riding CF.

I have CF forks on an aluminium framed bike as well and for me the forks seem to be a very big step forward over the non-alloy steel or 531 forks that I have used on various steel bike. They just seem to keep the front wheel in proper contact with the road. I haven't put a steel fork onto the Alu bike to be sure, but I have ridden a lot of steel bikes including a proper track bike on the road as the basis for this comparison.

I probably wouldn't buy another CF frame as it seems to me to be race tech, but I would need some special reason to go back to a metal fork, such as carrying luggage on a rack mounted on the fork.

I know nothing about CF manufacturing, but in around 2013 Halfords started to offer some Carreras with CF forks as were Specialised on the entry level Allez and Secteur. The lack of publicly reported failures and the fact that they are still doing this has given me the confidence that a CF fork is safe.

It may be that at the bottom end of the market forks are easy to make as they have a very simple lay-up that is hard to get wrong. Yes there probably have been more CF fork recalls than for metal forks, but a lot of those seem to be for elite level rider components, where a newish material/design would be expected to have issues.

After all most disc braked bikes have CF forks, so misunderstanding disc brakes will result in a fork recall and these forks will coincidently be CF. Don't forget we got thru-axles on road bikes because of an argument that Q/R wasn't secure enough under certain circumstances with discs even though "everybody" said I've never had Q/R undo on my disc braked bike.

Bye


Ian

 

[Cycleops]

Only my view but perhaps its because of money spent in advertising, an average cyclist with a 12k bike must be a lot faster and better than some one on a bike thats a few years old. (said in jest)

I’m sure there’s quite bit of ‘that’s what the pros use so that’s what I’ll use’ thinking involved when it comes to buying, particularly if you’re a ’serious’ cyclist.

 

[Dogtrousers]

And the brakes will probably be faulty and you will crash horribly.
And it's probably nicked.
And when you go to pick it up the seller is probably a serial killer and your body will never be found.

 

[Landsurfer]

I’m sure there’s quite bit of ‘that’s what the pros use so that’s what I’ll use’ thinking involved when it comes to buying, particularly if you’re a ’serious’ cyclist.

I’ll stick with steel ....

 

[Dogtrousers]

I’ll stick with steel ....

After all, it was good enough for Eddy Merckx

 

[Peter Salt]

Well, it's one of these things where technically it's true but not a big deal. Especially if you're a 'casual' buyer - it's a lot easier to inspect a steel/alloy frame for dents/defects/cracks. CF is a bit trickier but not to an extent where one could say that it's a significant risk.

 

[Milkfloat]

I personally think that CF frames are easier to detect for damage. CF cannot dent so you are looking for cracks. The walls of the material are so thin that any crack in the CF will show in the paint.

 

[bonzobanana]

I personally think that CF frames are easier to detect for damage. CF cannot dent so you are looking for cracks. The walls of the material are so thin that any crack in the CF will show in the paint.

You can have internal cracks and voids etc on CF admittedly they would be more likely there at the time of manufacture but over time as the frame is used they can get worse. However it should be pointed out CF forks are far more dangerous than CF frames due to the way they fail which is much more life threatening. An aluminium frame with CF forks is far more dangerous than a CF frame with steel forks but of course no one produces a CF frame with steel forks. Typical failures on CF frames could be the one of the stays, maybe at the top of the seat tube or at the bottom of the seat tube in the bottom bracket area, those are the most common by far and mostly you can still ride safely to a stop (mostly) but CF forks basically fail and can face plant you in the road at high speed for a HGV to go straight over you. It's much more deadly.

If safety is your main concern pretty much steel forks is the way to go.

 

[IanSmithCSE]

Good morning,

You might find this " interesting" https://www.cyclechat.net/threads/broken-steel-i-guess-i-was-lucky.273776/ My steel frame that literally split into two parts whilst exiting a roundabout, fractured downtube and top tube pulled and twisted out of the seat stay lug held together solely by the rear brake cable.

I have also broken a new 501 frame where the downtube fractured at the downtube/headtube

Whilst I understand that CF fails differently from steel and I remember when Trek introduced OCLV Optimum Compaction Low Void. In other words they were advertising "Properly Made"!!!

The problem that anyone who wants to advance the CF is high(ish) risk has is that CF forks have been on commodity bikes for over a decade and they are still being sold. Yet we aren't seeing The Sun running headlines such as I Carreraed into a ditch when my broken Halfords bike broke its forks.

https://www.halfords.com/bikes/road...ad-bike-2020---red---s-m-l-frames-348526.html

At £450 many of the buyers will just be looking for a bike and they won't be treating their bikes gently, yet Halfords are still happy to offer them CF forks.

Bye

Ian

 

[simongt]

If that rag told me the sky was blue I wouldn't believe it. Don't waste your time on it.

Just sayin' - !