Cheap carbon vs aluminium - which do you prefer

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thelawnet
Posts: 2736
Joined: 27 Aug 2010, 12:56am

Cheap carbon vs aluminium - which do you prefer

Post by thelawnet »

(Please, no 'steel' or 'titanium' replies, I'd prefer to limit this particular discussion to standard mass-market 'road bikes' which often have alloy frames down the range and carbon above it, essentially the respective merits of the two materials in that context)

I was just reading a review (https://road.cc/content/review/257212-m ... isc-carbon) of this:

https://www.merlincycles.com/merlin-cor ... 27943.html (£1279)

This particular bike is bang-on trend having the supposed 'sweet spot' 2019 groupset, new R7020 105 hydraulic, though I think it doesn't like mudguards, which might well cancel out the supposed advantage of the discs.

The frame one presumes is straight out of a catalogue in Taiwan.

It's available on its own (with fork & headset) for £450 https://www.merlincycles.com/merlin-cor ... 06064.html (as an aside the wheels are £200 on their own, the groupset £650, the discs a whopping £80, and the other finishing bits about £80, so there's a reasonable saving for the compelte bike)

The review includes a few words about 'buzz', and this sort of damnation with faint praise

The Cordite's frameset is impressive. The overall quality looks and feels to be great, from the paint through to how it rides. Some cheaper carbon frames can feel 'plasticky' and resonate a huge amount, but while the Cordite does let some buzz through it is damping the majority. It feels like a really sorted aluminium alloy frame; if you've ridden some of the latest alloy offerings you'll know what I mean.


It seems that a higher quality alu disc brake frameset is around 1350 grams (e.g., Specialized Allez Sprint Disc), or Canyon Endurace Al. There are some lighter frames, such as the Emonda Alr, which is just 1112 grams, but I think this is at the extreme end of lightness.

A cheapo alu frame is more like 1550 grams. https://www.planetx.co.uk/i/q/FRPXRT58A ... d-frameset

Cheap carbon is e.g. 1.1kg https://www.planetx.co.uk/i/q/FRPXPCEVO ... o-frameset though the Merlin here is a bit higher spec at 1kg

Anyway, you are saving perhaps 500 grams for around another £300 on the cost of your bike. Which is about 60p/gram, and in that sense better value than say speccing Ultegra rather than 105 (200 grams for £200, more-or-less).

But is the alu frame better in other ways (durability, ride, etc.)? Conceptually there could be considered to be three choices here: 'cheap alu', 'cheap carbon' or 'good alu'. The good alu and the cheap carbon presumably costing about the same. And that's of course before you get into the question of whether 'good carbon' requires a fancy brand name. Or indeed whether 'good alu' is one that has a fancy brand name on it, or if a a generic (and cheaper) one is just as good.
Jamesh
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Joined: 2 Jan 2017, 5:56pm

Re: Cheap carbon vs aluminium - which do you prefer

Post by Jamesh »

I prefer carbon to alu but there isn't much in it tbh
My older carbon supersix is bullet proof but a bit heavy by today's standards.
My Scott CX bike is light weight alu both feel fairly similar in ride if the same wheels are used.

I think high level alu ie caad10+12 and equalvalent are prone to cracking. Same may be true of hi mod carbon?
thelawnet
Posts: 2736
Joined: 27 Aug 2010, 12:56am

Re: Cheap carbon vs aluminium - which do you prefer

Post by thelawnet »

Jamesh wrote:I prefer carbon to alu but there isn't much in it tbh
My older carbon supersix is bullet proof but a bit heavy by today's standards.
My Scott CX bike is light weight alu both feel fairly similar in ride if the same wheels are used.

I think high level alu ie caad10+12 and equalvalent are prone to cracking. Same may be true of hi mod carbon?


I think the Caad12 and the Emonda ALR are quite similar, both weigh ~1.1kg, which is about the same as a new model open mould carbon frame. The super-light carbon frames are about 700g. A super aero frame is about 1kg.

I suspect you are right in that super-light alu (i.e. 1.1kg) is 'not for everyone' any more than super-light carbon is.
tim-b
Posts: 2091
Joined: 10 Oct 2009, 8:20am

Re: Cheap carbon vs aluminium - which do you prefer

Post by tim-b »

Hi
I generally buy at around the £1000-1200 price point, and only in the sales :)
I'm more than happy with alu frames, but always with a monocoque CF fork. I have a distrust of alu steerers with CF blades because the two materials together corrode badly should poor QC be an issue.
I'd rather have a better-quality alu frame than cheap CF, but I don't think that alu is a good fork material (if that makes sense)
Regards
tim-b
~~~~¯\(ツ)/¯~~~~
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The utility cyclist
Posts: 3607
Joined: 22 Aug 2016, 12:28pm
Location: The first garden city

Re: Cheap carbon vs aluminium - which do you prefer

Post by The utility cyclist »

My ex conti pro team frame (don't confuse frame with frameset which includes forks and headset) from 2013, made by KTM is 1085g for a 60cm, it's a lovely ride, the newer variant after it was better by all accounts but it didn't have BSC threading and I was happy with what I had so ...

The Spesh Sirrus Carbon Pro Ltd frame made with the same carbon modulus as bikes used in World Cup Downhill from 2010 (FACT 9M) weighs 1354g in a 58.
A Scott CR1 SL I had, more a 'sportive' enthusiast frame type rather than an out and out race frame, 930g in a 61, the Tarmac was even lighter.

My Principia Rex was in the 1450g bracket and my RS6 was a bit lighter, the RS6 pro and the Evolution models were in the 1150g range, impressive considering the RS6 pro was around some 16 years old from first production. The Rex was a superb alu framed bike, very nice to ride and the Isaac carbon forks excellent and surefooted, the RS6 was a ridiculously responsive rocket ship, well loved by crit riders.

The weight of the product in itself isn't always an accurate measure as to if the product is 'cheap' or not or indeed if it's any good, it could be an open mould but maybe not Taiwanese, could easily be from China were they are significantly cheaper.

One thing your post highlights is the massive inequity between disc brake groups and rim brake groups. The 5800 (105) rim brake group from Merlin is £324 with R7000 cassette, Ultegra FD and BB (£315 if you use topcashback) and the R7000 rim group is £400 (£388 with TCB)

if there's no tyre advantage of the disc frame, a question to ask could be, do I need a disc brake frameset because it's heavier and the components far costlier?

That PX alu frameset is okay for commuting/light touring I suppose but wouldn't be my choice for much else, the 1540g weight is for the small, you're more in the 1650-1700g range for the medium, a 600g carbon fork even with alu steerer is pretty chunky, that's about the same as the massive 55mm tyre accepting carbon forks (with alu steerer and V pegs) on my Spesh Globe Pro, that's a 2007 fork!

Would I say that having only c.200g difference in the frame of the PX alu frame made it similar to the Principia Rex frame, not a chance, I don't even need to ride the PX to know they won't be remotely similar, add into which the 340g Isaac full carbon forks will be completely different to the 600g ones on the PX, only 460g total difference but I'd pay £800 more for the Prinny frameset over the PX (and the retail price was even more than that and rightly so in mine and others opinion)

Of the bikes you have up, I wouldn't choose either, least of all the disc carbon bike from Merlin which IMHO is ridiculously overpriced, it's flogging a dirt cheap frame with a decent group, the £450 for the rim braked variant is an insult, £300, maybe at a push would be closer the value going by market prices.

If you're going to spend £1200 buy a higher end alu framset with a decent carbon fork, CAAD 10/12 for example as mentioned, You can get a new Tiagra CAAD 12 for £750
thelawnet
Posts: 2736
Joined: 27 Aug 2010, 12:56am

Re: Cheap carbon vs aluminium - which do you prefer

Post by thelawnet »

The utility cyclist wrote:One thing your post highlights is the massive inequity between disc brake groups and rim brake groups. The 5800 (105) rim brake group from Merlin is £324 with R7000 cassette, Ultegra FD and BB (£315 if you use topcashback) and the R7000 rim group is £400 (£388 with TCB)

if there's no tyre advantage of the disc frame, a question to ask could be, do I need a disc brake frameset because it's heavier and the components far costlier?


AFAICT there's not a significant weight difference in current disc brake framesets, just an ounce or two. The components themselves are significantly heavier (around 300 grams more, with actually a bigger weight penalty on Dura-Ace than 105) and indeed much more expensive, but the framesets not so much.

The Emonda SL (cheaper carbon) is 1091g rim and 1149g disc, while the ALR is 1112g rim vs 1131g disc. The Emonda is supposed to be lightweight, but the SL just isn't particularly.

Of the bikes you have up, I wouldn't choose either, least of all the disc carbon bike from Merlin which IMHO is ridiculously overpriced, it's flogging a dirt cheap frame with a decent group, the £450 for the rim braked variant is an insult, £300, maybe at a push would be closer the value going by market prices.


I wasn't particularly suggesting any of them, just some vague ballpark figures for weights. I didn't spot that that wasn't the disc frameset btw....
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