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Frame stiffness on a dually


the.flying.al's picture

By the.flying.al - Posted on 03 January 2012

Recently I upgraded by road bike from a lowish spec alloy/carbon to a high spec full carbon bike and have been gobsmacked by the difference it makes. I had always imagined that mere mortals wouldn't pick much of a difference and only the elite riders would notice the incremental benefits of the higher spec bike. The difference is not so much weight, but the power transfer and acceleration resulting from the stiffness of the frame and bb you end up with rocket like acceleration and awesome climbing.

Which takes me to my question about mountain bikes. My conclusion has been if you are spending around $3K on a dually you are better off sticking with the alloy frame with higher spec components than a carbon frame with lower spec components (and you probably have to shell out an extra $1K for the carbon frame anyway).

Although the carbon frame will be stiffer what benefit does this give with the intrinsic floppiness of a dually? Yes you can use a lockout, but although lockout might help in longer climbs I don't see how lockout is very useful for short pinches or accelerating out of corners.

So how much does frame stiffness matter with a dually? would I notice a big difference if I moved to a carbon frame dual suspension bike?

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Little-Ditty's picture

I have never used a carbon framed bike, so take this opinion as that, mere opinion.

I would have thought there would be little difference noticed on a dually mtb, as your bike moves and sways and pitches much more as your are riding on a slippery, in-tractable surface, rather than concrete or bitumen.

Unless you are going racing, where you will notice the benefit of a much lighter frame over a given longer distance, I don't see there being much difference to a weekend warrior rider. If you can afford it, I would still buy carbon over an alloy rig, at least for XC/AM purposes.

Regarding the price/component spec trade-off, you would be best buying the highest spec'd carbon frame bike you can afford then upgrade the components at a later date. Even the higher spec'd alloy frame bike will need its components upgraded eventually anyway, and I reckon you would have your carbon framed bike with the components you want within 12 months anyway.

Damo5's picture

I just upgraded from a 2010 Trance x2 to the full carbon xtr 2011 Trance sl x0 & the difference is amazing , it feels so responsive cornering u can feel the stifness ,such a pleasure to ride !

Flynny's picture

The thing with carbon is you can engineer it to do what you want. You can make it flex in directions where flex is good and stiff in directions were flex is bad.

When carbon is done good it's hard to beat

hawkeye's picture

When I passed my much-loved 2005 Jekyll down to my son and upgraded myself to the Rize, I noticed a significant improvement in how "planted" the bike felt, especially on the slow, tight, rough stuff.

The forks are identical (the Jekyll got an upgrade to a PBR fork off a Rize year before last) but supposedly the big difference with the Rize was the one piece machined/cast/whatever seat tube/bb/suspension pivot assembly, where it's manufactured out of a single piece of metal rather than lots of little bits welded together.

Whatever they changed, it definitely stood out on the first ride with the new bike, and again yesterday when I went for a ride with jacojoco on the Jekyll.

So yes, I think improved frame stiffness is noticeable on duallies.

I'm still not convinced about carbon mtbs... too many fatigue failures. A secondhand alloy mtb is reasonably safe purchase, I don't think I could say the same about a secondhand carbon one.

the.flying.al's picture

That sounds pretty convincing, similar to my experience with road bikes. But is the difference from the wheels, since everyone says wheels have a huge influence on the ride.

hawkeye's picture

Big difference between the entry-level XM117s and the Crossmax SLRs... chalk and cheese.

The CrossLands which are my general duties wheelset are somewhere in between but closer to the CrossMax once I tensioned the spokes properly. Nice freewheels which take up quickly make techy riding much more manageable than the entry level hub on the XM117 wheelset.

The SLRs roll noticeably faster, accelerate faster, are definitely stiffer and less compliant for better precision and control, but have noticeably less grip due to the narrower rims compared to the wider, more trail-oriented CrossLands. Nor are they as tolerant of being bashed around by my crap riding skills, so these days they only come out of their bags for events.

Antsonline's picture

As they say "buy the worst house in the best street".
Its like buying a car, a low spec BMW is still a different experience to a high spec'd Hyundai.

As almost everyone has said, the carbon frame is a fair bit better. Certainly better than the downgrade difference between components.
Componentry wears out - regardless of quality, so its always worth getting the red hot frame with the low spec, and when things break, upgrade them.

Wheels and Frame, followed closely by your contact points (bars/grips, saddle and pedals) - they are the key things to get right. Getting an XT over an SLX front mech - that wont change a thing.

Yes - carbon frames are perhaps a bit more fragile, I have broken a few and know a few that have broken that werent mine, but if you buy well you will always be looked after. Most manufacturers will replace broken frames with no questions asked.
I have also broken Alu frames (went through a Niner or two) and some steel frames.
MTB riding is hard on kit, things break regardless of material. Carbon (or whatever composite material your frame is actually made out of) is the way forward. I am certain in years from now we will all look back and fondly remember 'welds' on frames in the same way we look at 'lugs' today.

the.flying.al's picture

Next frame I get I will make sure its a carbon frame. Given my experience and the comments above. After the first couple of bikes it all gets mixed in - I don't think my next bike will be out of the box, but rather a new frame with a mix of the good components I already have plus upgrades. So at some point in the next year or so I will be on the lookout for a carbon frame upgrade.

Damo5's picture

Yeh better wheelset & the bike is about 1.5kg lighter ,but it somehow feels like more than that,so agile & responsive ,it go's where u want it to if that makes sense .I think a combination of everything (frame,wheels & spec )make a difference to a bikes performance but I think stiffness & carbon r a big part of it ! Go the carbon I say !

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