fujiraf

Hi all, why a premium carbon,or high modulus carbon is so much more expensive than an average carbon? Example,BMC SLR1 vs BMC SLR2. The SLR1 is 1200€ more expensive than SLR2 (same components).
Same with every other company.
Is it stronger,or just lighter? If it's stronger,then I would consider to pay, but, if is to save 200 or 300 grms only,...Can anyone enlightens me on this?
thanks

redfooj

1-marginally lighter
2-because people will pay for it

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Campag4life

Its partly marketing. Because they can charge more and large bike brands universally do for higher modulus carbon fiber. The fiber filaments are more expensive because they are stronger pure unit volume...higher tensile strength by cross-section which allows a lower volume/thinner tube which reduces weight which is mostly the point of higher modulus carbon fiber. This puts greater onus on carbon lay up integrity...which is largely human involvement until AI robots assume this thankless job in likely less than 10 years from now.

A lower modulus carbon fiber bike doesn't have to be softer aka greater force/deflection than a higher modulus carbon fiber bike. By increasing wall section aka more low modulus carbon fiber, a low mod carbon fiber bike can be made stiffer than a high mod bike with enough wall thickness, but would weight a fair amount more like a pound or so. Difference between an Emonda SLR 700 series frame...not incl the fork which weighs just under 700 grams and an excellent 500 series SL6 Emonda which weighs a decent 1000 grams...is 300 grams or 3/4 a pound. All for the princely sum of $1000 more the SLR frameset. In terms of stiffness, they are pretty darn close. Keep in mind a 150 lb rider may not be able to feel or detect a stiffness difference between these frames but Tom Bonnen out of the saddle will be able to...but there isn't a whole lot of stiffness difference between the two. Real benefit is weight because the stiffness target by the designers is achieved for both bikes. They can make either bike stiffness by tweaking what is called section modulus of frame tube members locally. Keep in mind mechanical properties like bending aka stiffness is a function of material chemistry aka modulus + shape of the tube. Nobody wants a bike as stiff as the old Scott Foil or first gen Cervelo S5...both rode like cattle trucks so tweaking frame shape/tube cross section is done asymmetrically to achieve flex for ride quality and stiffness for performance.

Hope above makes sense. Part marketing, part labor intensity of getting the carbon layup just right on the thinner wall higher mod carbon frame and partly the higher cost of the carbon fiber material itself...higher modulus carbon fiber being more expensive because carbon filaments have higher strength per unit area.

Kimmo

One thing to bear in mind is that high modulus carbon is more brittle.

So it's quite possible that a hi-mod part will be lighter and stiffer than an equivalent low-mod part, but actually not as strong.

noodle soup

Most people don't take this into consideration when they make their buying decision. Lower -end CF bikes are often the better choice, because they are far more durable.

Racing Dan

High modulus and high strength is not the same thing.

noodle soup

correct. High modulos CF is stiffer, not stronger.

Racing Dan

Elvir

Your choice depends on what your goals are. I have a 2014 Cannondale Supersix Evo (NON-himod) I have so far put just under 10,000 miles on it. I thought it was the best thing since sliced bread. After 3 years, I ended up buying a Trek Emonda SLR 700V frame, with just over 3,500 miles. The two bikes cannot even compare. Emonda is significantly stiffer and lighter by 2 pounds. To me that is important because I love climbing and I did not realize how much more effort I have to dish out and how much higher fatigue levels I have after I am done riding with the Cannondale. On my Cannondale, I can literally see when looking down how my bottom bracket and crank flex. The bike is very fast riding consistently, but If I need to jump out of the seat, its useless to me. I don't take it to any group events or races, its used as my back up bike at the moment. I thought about selling it but decided that (N+1) is worth it when the other bike is in the shop.

Also, while the carbon bikes "MAY" have a life span to them, Trust me its not one of those ride it one year and trash it. You will be able to ride if for a long long time, so much so that you have a better chance of flat out wanting to upgrade to another bike just for the sake of having something different than actually needing a bike because your carbon one failed.

Also, If for some chance your carbon bike does fail, a reputable manufacturer will always replace it.

maartendc

If it is stronger, they will use less of it and thus it will be lighter for the same strength. If that makes sense?

It is all about the design of the frame. You can build a strong frame out of a weaker material, it would just be very heavy. Similarly you can build a weak frame out of a strong material, if you don't use enough of it. It is all about strength/weight ratio.

I would assume for example that BMC build their frames for the same load capacity for the SLR1 and SLR2, so the SLR1 would just be lighter, same "strength".

rgconner

How do you like your S-glass frame?

noodle soup

The lifespan of a CF bike is not usually determined by fatigue, but by the possibility of it being damaged(impacts or crashes) Higher-end frames are more susceptible to damage due to using stiffer material, and less of it.

This is true for the original owner, and only for failure, not damage. Some manufacturers off a crash replacement discount, but it usually isn't a great deal.

Elvir

That is kind of the point. If you buy a lemon car, you can return it. If you buy a car and 3 years down the road you crash it, don't expect your insurance to pay out brand new car value. They will pay what your car is worth. Its kind of common sense.

noodle soup

It might be common sense to you, but your post was misleading, and the comparison to a lemon car is inaccurate.

Even if the the frame has a defect, if you aren't the original, most manufacturers won't replace the frame..

Campag4life

The Emonda SLR is a bike I would like to personally own. Good post. I casually keep an eye out for one on ebay with the right group and wheelset and in my size.
No, I don't like the single seat post bolt nor do I have any love for BB90, but the bike itself is simply outstanding.

May I ask what size Emonda you ride and what your body weight is?

Have a pic?

Thanks.

Campag4life

No, his post isn't misleading. He speaks truth. You are blowing any significant difference in high mod versus more generic carbon fiber out of proportion.
Most will prefer a high mod carbon frameset...why they are sold on the highest level framesets from all manufacturers. Difference in crash performance is 'incidental'...a non issue. I have crashed high mod carbon bikes and got off the ground, clipped back in and rode away. Many thousands of happy miles.

Most will take an Emonda SLR all day long over a SL6. Both are outstanding. Many will take almost the pound savings and enjoy the punch of the high mod bike.

noodle soup

We disagree then.

I work for a framebuilder that also does CF repair. We are thankful that Hi-Mod CF frames are popular now, because we always have a dozen or more frames waiting to be repaired.

Any wreck that you simply "got off the ground, clipped back in and rode away" obviously was much of a wreck.

79pmooney

Well, sorta. If it is stronger and they use less of it, then the wall thickness of the tubes is thinner. Say Material A is 20% both stronger and stiffer than material B. Wall thickness of the tube with A is now say 90% of tube B and the stiffness is up 8%. But, the strength of the tube for impacts (say the bike falling over and the tube hitting something) is dependent on the material strength and the wall thickness squared or 1.08 X 0,9^2 = 0.87 or 87% of the tube of material A. So tube A is 8% stiffer and 13% more prone to breakage from impacts. (This is sophomore year engineering. Nearly a 1/2 century ago, I haven't used this in 30 years and am not being either graded by on the way to a diploma I am paying big money for nor am I being paid here, so I haven't checked my figures.)

Ben

Campag4life

High mod bikes maybe 'fractionally' more crack prone, but this hasn't been verified. Your rash of high mod bikes maybe for example based upon strong racers ride high mod carbon bikes hard and crash more racing them then fredly 50 something who rides the MUP at 15 mph on his mid level carbon bike. Have to be careful about extrapolations.

Suffice to say, crash performance or longevity will NOT be on the radar of a prospective high mod carbon owner. This type of owner will pay the $1000 penalty for a bike they know to the lightest and highest performance. Trek has a lifetime frameset warranty. There can also be a philosophical argument that frames that are crashed by their owners deserve to crack. If they don't they are overdesigned which has a companion weight penalty. Highest mod carbon frames are racing frames or meant for those who want performance above all else.

noodle soup

Often they are purchased by affluent cyclists, that would be better served spending a little less on the frame.

Elvir

Well, from experience, I would rather have BB90 than BB30. So far, I can get 3000 miles out of BB90 where as with BB30, I am lucky to get 800-900 miles.

I Ride a 58 H1 Frame. I prefer to ride compact set ups for more race oriented geometry. I am 6'3" and 185lbs.

Here is a pic of it. I Currently am riding on stock wheels for the past two months as I keep snapping the rims on the Comet wheels. Good thing I got a custom set on order, but that is a long wait as well..

Campag4life

By some of your comments, I had a feeling you were a big boy who could generate some power out of the saddle. I am a slightly shorter and probably older version of you. at 6'1" and 180 lbs. I like to ride more stretched out and with less drop than you. I am surprised you have enough reach on a 58cm H1 with that length stem. With pro level drop, I would think you would prefer to stretch out a bit more to get the power down with your long body.

Congrats on a beautiful and uber light bike. I like the purity of the design. No BS. No integration, pure function. Would love to have the SLR...but I need the H2 head tube length. B!tch getting old

Elvir

The bike did indeed come with a longer stem. But after playing around couple weeks with it, I got refitted with a shorter one and found it to be ideal for me.

Kontact 

The tensile strength of high modulus fiber is higher than lower modulus.

You're referring to something more like toughness, not strength. And that has to do with how much plastic ductility the material has between exceeding its tensile strength and actually fracturing. More ductile materials will deform first before breaking.

noodle soup

that’s a damn fine looking bike. I wish my proportions and flexibility would have allowed an Emonda, but my very long legs & short torso are much happier with a Domane H2 fit.