For downhill carbon fibre is best avoided

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If you are into downhill or rough enduro and you expect to knock yourself and the bike a bit, avoid carbon fibre.

Unless of course you have loads of money to spare or you are sponsored.

I won't say how I found that out but I assure you it has become very clear to me. 

It's a bit like holding an extremely expensive wine glass while taking part in the cooper's hill cheese rolling race.

Cheers

Post edited at 13:10
11
 summo 09 Apr 2021
In reply to Dago theruinmargalef:

Ouch!?

I think it's fine if you are spending £5-10k, but if it's a cheap Chinese knock off frame, with a few shiny bits added on a £1k bike, then folk are potentially risking their life. 

2
 nniff 09 Apr 2021
In reply to Dago theruinmargalef:

Alternatively - https://www.pinkbike.com/video/243228/

In reply to summo:

It is a Trek, chain stay got knocked on a rock, Arrrrggghh...

In reply to nniff:

Thanks for the link.

Interesting... The carbon frames do not bend as the aluminium do at lower loads in normal loading conditions or areas designed to take those loads, they burst completely when failure loads are exceeded, as you can see in the test. 

Point loads however, in areas which are not designed to take those loads can well exceed failure forces on the carbon and it will shatter like glass (my case- expensive bike hitting a rock) where as aluminium will bend, so the aluminium bike will still be rideable but with an ugly dent. 

On the other hand you can repair carbon fibre, though not sure how reliably, by slapping on some new carbon fibre. The replacement parts are much more expensive than the aluminium counterparts.

 Myfyr Tomos 09 Apr 2021
In reply to Dago theruinmargalef:

Yeah. Downhill bikes need to be quite robust...   youtube.com/watch?v=nsNnGZZusiQ&

 gethin_allen 09 Apr 2021
In reply to Dago theruinmargalef:

Just repair it, it's easy, especially on a DH bike where all you want is strength and  you don't have to worry about fancy carbon layups. The only thing is warn you about is to be very careful when handling the uncured resins and when sanding and finishing as exposure can result in sensitisation and a whole load of unpleasant side effects.

 HammondR 09 Apr 2021
In reply to Dago theruinmargalef: my Orange 5 is tough as old boots and made from scrap filing cabinets. It's the future.

In reply to gethin_allen:

Thanks , I did, I wrapped it (3 layers), sanding was interesting, used an ohm meter to find out if I had got to the carbon fibre. You are right, itchy stuff. I had a thermo retractable tape to get bubbles out. Left it to cure for over 10 days.  Seems to work well, but worried I might hit more rocks.

Cheers

 Dax H 09 Apr 2021
In reply to Dago theruinmargalef:

I too learned to stick with metal bikes, I'm fairly sure I was the first person in the UK to break the head tube on the new thermoplastic GT StS back in the mid to late 90's. Waited ages to get one, built it on the Saturday, broke it on my first race on the Sunday. Back to the shop on Monday who replaced the frame with a aluminium GT downhill bike that I abused the crap out of for years. 

1
 Yanis Nayu 09 Apr 2021
In reply to Dago theruinmargalef:

Not sure what the advantage would be anyway- or do you have to ride up first?

 Alkis 09 Apr 2021
In reply to Dago theruinmargalef:

Yeah, there is no way in hell I would be riding such a bike without accident insurance that covers off-road damage. Sucks, man!

PS: Even if you don't have explicit insurance, I would check what's included in your household contents insurance, you'd be surprised sometimes.

 Myfyr Tomos 09 Apr 2021
In reply to Dago theruinmargalef:

A recent offering from the Athertons.  youtube.com/watch?v=FbVR2WDrWno&

 petegunn 09 Apr 2021
In reply to Dax H:

I loved my GT LTS 1000 DS

In reply to Myfyr Tomos:

It it wasn't for the embarrassing walking up hill supping red bull sponsor BS that would be really good!

1
 Myfyr Tomos 09 Apr 2021
In reply to Simonfarfaraway:

Aye. Agree, but I suppose it pays the bills.

 wbo2 09 Apr 2021
In reply to Dago theruinmargalef:  if its any consolation I've seen plenty of metal framed bikes destroyed by crashing and hitting sharp objects , storing in the piping. 

 Pre hydrometer Al were horribly sensitive to side hits. I recall a friend dropping his cannondale on the floor, hits a wall on the way down and bye bye 

In reply to Dago theruinmargalef:

Interesting that Trek's latest Session DH bike only comes in aluminum.  Were they thinking of you?

In reply to Myfyr Tomos:

That's a great little video.

I'll happily put up with a little bit of product placement if I get to watch things like that for free.

 mondite 09 Apr 2021
In reply to wbo2:

> if its any consolation I've seen plenty of metal framed bikes destroyed by crashing and hitting sharp objects , storing in the piping. 

Yup. Remember one particularly amusing incident where someone stacked at low speed and despite them and the bike be undamaged decided in their anger to throw their bike away.

Right into a handily place root which stove it in so badly it was unrideable.

 Dax H 10 Apr 2021
In reply to petegunn:

> I loved my GT LTS 1000 DS

Even better when I replaced the bushes with bearings. 

In reply to Simonfarfaraway:

> It it wasn't for the embarrassing walking up hill supping red bull sponsor BS that would be really good!


It was painfully embarrassing.

 artif 10 Apr 2021
In reply to wbo2:

DH isn't for shallow pockets. Back in the 90's I wrote off loads of metal bike bits on their first outing, one set of forks lasted less than a minute after folding them, half way down a dh course. A friend tore the back end off his intense M1 on its first run.

If your not crashing you're not trying

1
 afx22 10 Apr 2021
In reply to Dago theruinmargalef:

I’ve cracked, snapped, bent and dinted many frames, made from all sorts of materials, back in my days of racing (XC, then DH).  

Carbon can be especially prone to side impacts, but that shouldn’t be a surprise and non-carbon bikes are not immune to this.

 SAF 10 Apr 2021
In reply to Dago theruinmargalef:

When my, 10 stone, brother was racing elite downhill he use to destroy at least one frame a year regardless of what it was made of.

It worked out well for him as they were always covered by either his sponsor or by warranty and meant that most years he could sell it on as nearly new at the end of the season as it had recently been replaced.

In reply to Myfyr Tomos:

Brill


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