01 September 2013 ~ 9 Comments

Battle of the Bikes (carbon fiber vs. titanium)

In April of 2010 I purchased a new carbon fiber bicycle, a Rocky Mountain Prestige 70 CR. I had previously owned bike which was made from hybrid materials — part aluminum and part carbon and was looking for something with a better ride. This new frame was 100% HM Monocoque Carbon with other carbon components like a carbon fork (with a carbon steerer tube) and carbon cranks. The handlebars were alloy, which I prefer anyway. Rocky Mountain (based in Canada) is most noted for their mountain bikes, but they also carry a small line of road bikes too.

After two years of hard riding, this frame developed some hairline fractures (report here) and I consequently got a new frame under warranty. Because of this problem I decided to look at getting a titanium frame as they are more durable. During the summer of 2012 I found a used Seven Ti frame (Axiom SL). The geometry was just right for me with a 61cm top tube (1 cm longer than my carbon bike). I was hoping this would be my new long distance bike as Ti frames supposedly never wear out. Later that fall (due to the delays in manufacturing at Zinn), I built it up with new handlebars, new seatpost, saddle, custom 190mm extra long cranks from Zinn and new Shimano drive train & derailleur.

To make a long story short, in June of 2013 I finished my “long ride of the season,” a 1200km (750 miles in three days) brevet, called The Gold Rush, in northern California. My butt suffered big time, like my early days of cycling, before I converted to suspended leather saddles. During 2012 I used my carbon fiber bike (with an alloy seatpost) with the same saddle and wheelset which I used on Gold Rush and had zero saddle issues. Some two weeks after Gold Rush, I had a 600km, in which I switched back to my carbon bike and once again, had no problems.

My conclusion: My carbon fiber frame yields a more comfortable ride than my double-butted Ti frame. Are all carbon frames similar? The Rocky Mountain Prestige is an average, run-of-the-mill Chinese-made model  ($3,000 MSRP including a $600 Ksyrium Elite wheelset which I only use for training rides). Could the longer cranks on the Ti frame be causing me butt pain?

Possible solutions? Add a carbon fiber seatpost to the Ti bike? Or a suspension seatpost (urrgh, the extra weight)?

Specs — 2009 Rocky Mountain Prestige 70 CR / 2000 Seven Axiom SL
Frame sizes (seat tube length, cm): 60 / 61.5
Horizontal tube tube (cm): 60 / 61
Head angle (degrees): 73 / 74
Seat angle (degrees): 72.5 / 72.5
Head tube length (each has 30-40mm extra height with spacers, cm): 23 / 20.5
Wheelbase (distance between axles, cm): 101.5 / 102.0
Chainstay length (cm): 41.8 / 41.3
Fork rake (mm): 45 / 41 (frame was designed around a 40mm rake, I am using a Alpha Q carbon fork on the Seven)
Wheelset: DT Swiss 1450 alloy with Continental 4000 S 700 x 25c tires inflated to about 100 PSI
Saddle: Gilles Berthoud Aravis suspended leather with Ti rails
Pedals: Shimano A520 / Shimano A600 road touring pedals
Aerobars: Syntace C2 / Syntace C3 mounted to alloy 44cm wide bars
Cranks (mm): 175 FSA carbon fiber / 190 Zinn

9 Responses to “Battle of the Bikes (carbon fiber vs. titanium)”

  1. Jim Bondra 1 September 2013 at 4:08 pm Permalink

    Richard:

    My guess might be that the longer cranks force you to use a lower cadence and be more planted on the saddle. Also at double the distance your body gets beat up more. Think back about the ride a year ago and try to compare if you possibly stood more and spun more. I ride a Litespeed Arenberg which had been really comfortable on brevets. Unless you were using the exact same saddle (not the same model on another bike) that you used previously the year before, it is another variable added to the mix. I found this out last year (rode a Fizik Arione on a fleche ride with no issues, saddle developed a crack so I bought a new Arione and rode a 400k and it felt like I was sitting on a hatchet.

    Most of the riders that I know say that they prefer ti over carbon because there is some give/spring which reduces the road vibration. I have ridden a carbon seatpost and an alloy post and felt the carbon reduce a little of the road buzz.

  2. Lonnie 1 September 2013 at 9:35 pm Permalink

    Richard,

    I believe that your conclusions may be flawed, based on the methodology of your “study”. Comparing different frame materials in which the bikes have different set ups and components is an apples and oranges thing. Consider the different well known “established qualities” of these frame materials. Carbon is known for its light weight and stiffness. Ti is known for its light weight and compliancy, which is a combination of ride quality and efficiency. Steel on the other hand is known for its great ride quality and durability. Modern carbon frames are trying to mimic the ride quality of steel by incorporating more flexible stays and even forks in their design. That tells me that even the makers of carbon frames acknowledge that the harsher ride quality (generalization)of carbon frames is not ideal. They are trying find a better ride quality by modifying their designs to mimic the ride quality of steel.

    Your conclusion that a carbon frame offers a better ride (generalization) than a Ti or other frame material does not bear out the established wisdom on the topic. I can only conclude that other issues were a factor.

    It is still amazing to me that many riders will spend many thousands of dollars on a harsh riding carbon frame, which will probably need replacement in 3 years, when they could have a custom steel frame, which may be only ounces heavier but will yield a generation of comfortable riding. I am on my fourth wheel-set on my Pegoretti, having worn out the previous ones. I do not know of many carbon frames that will ever need more than a second wheel-set under normal circumstances. Modern lightweight carbon frames simply are not that durable.

    My 2008 Colnago Master X-Light (steel) weighs 19 lbs, with SPD pedals and cages. Campy Athena 2×11, Brooks saddle, no carbon whatsoever! It is the most amazing bike to ride that I own! It is not a Rando set up, but then I have my own ideas of what I want in a Rando bike. Weight for me in a Rando bike is less of an issue, comfort is foremost!

    Have you ever weighed your bike before a 600 or 1200k event. I mean on the starting line, with all of your gear. Your superlight carbon bike might still weigh 25 or 30 lbs with all your baggage! Add in all of the crap in your camelback or back pockets and the weight benefit of a certain frame material seems less important.

    Okay, I’ve rambled on long enough. I’m not trying to persuade you of anything. Each of us have our own values and preferences in what we ride. I sold my only carbon frame and now only ride steel or Ti. I am happy with that choice, and with the knowledge that my bikes will still be going long after I am gone. I may buy another carbon bike sometime in the future but I will have no illusion that it will be more than few years of use to me.

    Lonnie

  3. Richard 1 September 2013 at 9:56 pm Permalink

    Hi Jim,
    On last years 1200k I was using the same exact saddle as this year (I have moved it from bike to bike). Last year was riding with three others for three of the days and consequently was drafting more than perhaps on this years 1200k. There was heavy rain for the first 24+ hours on the 2013 1200k, but the saddle didn’t seem to suffer any ill effects during the ride.
    Lonnie,
    I REALLY wanted the Ti frame bike to work. I am just reporting my results. I used the Ti frame on all my spring rides, so I should have been accustomed to it (but it still hurt a little on 300k and 400k events, unlike last year on a “plastic” frame). It is only about 1/2 pound heavier than the carbon bike which is, as you say, is nothing in the rando world. Because of the compact geometry of the carbon frame, more of the seatpost is exposed, provided more flex in the rear part of the frame and/or post (as reported by others that have ridden behind me), compared to the traditional Ti frame with a horizontal top tube.

  4. Jim Bondra 11 October 2013 at 12:53 pm Permalink

    Richard:

    In thinking about this more, I think that the more compact frame with the longer seatpost feels better because of the flex in the seatpost which has more exposed area than on the ti frame. The other difference is the longer wheelbase on the carbon frame when you add the front center probably being longer with the slacker head tube and the .5cm longer seat stays probably is at least 1cm longer.

    Hope your shoulder is healing.

    Jim

  5. Rando Richard 1 July 2014 at 2:30 pm Permalink

    Update: See my post on the Specialized CG-R seapost, which I added to this bike during the summer of 2014. What a difference in comfort!

  6. Fred 19 August 2014 at 3:53 am Permalink

    Hi, Richard

    I am a day late and a dollar short but I have another hypothesis regarding the stiffness of the Ti frame: since Sevens are all custom made, yours may have been design for a much heavier individual which could possibly make it too stiff for you. I am glad. To hear that you have found a seat post which makes the ride better.

  7. Rando Richard 19 August 2014 at 8:14 am Permalink

    I bought it from the original owner — he was a young and lean cyclist. My guess is that the geometry is for a racer. This past weekend, I spoke with another person who used to have a Merlin X-Tra Light. She hated it as it was as stiff as aluminum.

  8. NeiL 13 January 2015 at 11:26 pm Permalink

    gents, looking for a long distance ti bike. Something a little longer and less impactful on my neck and backside.

    would also like to sell the BMC sloq. too racer style for me.

    Would it help anyone to get my bmc sloo1. only 1000mils on it.