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Author: Subject: Carbon or Aluminium framed bike
hughpinder

posted on 25/6/14 at 09:34 AM Reply With Quote
Carbon or Aluminium framed bike

I am looking at buying a new bike, and have decided on a Giant Defy. I can buy the 2013 carbon bike at a good discount, which means it is 'only' about £100 more than aluminium frame of the same spec, so that seems good value. I have no experience of composite bikes.

However, I often transport my bike on one of those tow ball mount racks, where the bike is hung on by its top tube, and have seen many warning that carbon bikes should not mounted this way. Does anyone know if this is actually true? Are they really that delicate? What are the chances of breaking it if you fall off? Are there any other 'special issues' using a carbon bike?

Thanks for any help
Hugh

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Wadders

posted on 25/6/14 at 10:57 AM Reply With Quote
Don't claim to be an expert, but I have a Trek Madone full carbon road bike which is 10 years old and has done thousands of miles on our very poor roads, I always leave it hung up by the front of the seat when not in use. No problems so far.
I reckon 80 percent of my cycling club are now on composite frames and talk of failure is tiny, they don't fare so well if you have a big off, but thankfully that's a rare occurance.
If you're buying a new one you should get a warranty to cover manufacturing defects.
BTW I'm not claiming carbon is superior to ally, just different, there are plenty of very desirable steel frame bikes also.

Al.

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lewis

posted on 25/6/14 at 10:58 AM Reply With Quote
I have just upgraded to a carbon frame & love it,noticably lighter & feels stiffer,I don't see how the problem you mentioned could affect the bike? Have a look on YouTube about carbon/ally bike strength tests,you might be impressed....not to mention the cool factor





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hughpinder

posted on 25/6/14 at 11:52 AM Reply With Quote
Thanks for the comments so far. The problems I've read about seem to indicate the carbon tube is not especially crush resistant so strapping it down can damage the tubes/cause splits or start cracks. Most manufacturers recommend hanging by the seat/seat post rather than the frame it appears. I've also seen comments about it being easy to overtighten things and damage the tubes or pull bushes out of the frame etc. It probably isn't a big issue, but I want something that will be durable so was tapping the knowlege on here.
Thanks again
Hugh

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Daimo_45

posted on 25/6/14 at 12:01 PM Reply With Quote
Hello,

If the rack you use has them rubber straps I wouldn't even worry about; the clamps for handlebars and seatposts are metal and they don't fail. Handlebars and seatposts always give you the max NM to torque the clamp so maybe apply to your straps as the max.

Carbon is pretty durable and if you fall off you never hit the frame, just the crank arm, derailleur or handlebars. Carbon is much stiffer but provides good dampening and responsiveness. Make sure you go for a monocoque frame and not lugged as our roads are dreadful.

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chris-g

posted on 25/6/14 at 12:45 PM Reply With Quote
You can get towbar mounted racks where the bike sits on its wheels. I have one like that and prefer it the type where the bike hangs off its frame.
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nick205

posted on 25/6/14 at 01:50 PM Reply With Quote
Can't add any experience with composite or ally, both my bikes are Reynolds steel






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MikeRJ

posted on 25/6/14 at 04:10 PM Reply With Quote
quote:
Originally posted by nick205
Can't add any experience with composite or ally, both my bikes are Reynolds steel


Proper frames then, and will doubtless be providing excellent service long after the daft composite things are landfill.

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iank

posted on 25/6/14 at 04:48 PM Reply With Quote
Carbon fibre while having massive tensile strength really doesn't like point loads, so you need to be aware while strapping it down down and/or putting stress into the middle of tubes. While it's unlikely to be a problem 99% of the time if there's a bare metal tube in the middle of the cross bar there is the potential for damage.





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Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous

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mac1ZR

posted on 25/6/14 at 05:04 PM Reply With Quote
I bought a Giant Defy 2 last year. Havent had any experience of a carbon frames, but cant fault the Ali frame
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nick205

posted on 25/6/14 at 10:22 PM Reply With Quote
quote:
Originally posted by MikeRJ
quote:
Originally posted by nick205
Can't add any experience with composite or ally, both my bikes are Reynolds steel


Proper frames then, and will doubtless be providing excellent service long after the daft composite things are landfill.


Well the first one has had 20 of years of of road abuse and shows no signs of giving up. The second is only a few hundred miles old but was bought to last at least the next 20 years.






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Jenko

posted on 26/6/14 at 05:46 AM Reply With Quote
I've just bought a planet x pro carbon, and it is absolutely fantastic....cost £799 with tiagra components, and weighs 8.5kg....only had it for a few weeks but am a complete carbon convert.....





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hughpinder

posted on 26/6/14 at 07:12 AM Reply With Quote
Thanks chaps, I think I will go for the carbon one, and look at a diy adapter for my current tow ball rack to spread the load where the frame mounts (the load arms have rubber bits wher the tubes mount anyway)/allow it to mount via the seat.
I'll probaby stick with the Giant defy - I got a defy3 aluminium for my missus for christmas and the geometry is perfect for me. I've been cycling to work (21 miles each way) mostly on my bike, but once on her bike, and compared to my old steel one I get there 10% faster for 20% less effort. Also the carbon forks soak up a lot of vibration from the road - the last 7 miles are so rough I literally can't feel my hands when I get to work on mine!

As a side issue, I believe you should torque down everything on the carbon bikes- does anyone know what the lowest torque setting is likely to be. I have a 1/4 drive one down to 5Nm, but most of the bike specific ones seem to go down to 2 or 3 Nm - do I need that extra bit on the bottom of the range?

Thanks all
Hugh

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02GF74

posted on 26/6/14 at 04:29 PM Reply With Quote
Go for carbon.

Figure out how to transport it safely and job done.

You may need padding round the tubes or a different rack.

As said C is stong in certain directiond and can be fragile when impacted.

If you are buying new the guarantee may cover this... more likely not.






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