Edwin says:Damon, Asked this question on the forum but want a definitive answer. What is Cervelo's stance on clearance for 25c tires. I have a R3 Team with the SL Fork, Zipp 101, and Michelin PRO 4 Service Course 700x25 tires. Clearance is great in the rear but I'm having some issues with clearance with the front fork. Is there something I can do to help this out, but more importantly should that fork be able to clear 25c tires. Thanks as always for your help Edwin

Damon Rinard, Cervelo Engineer says:Hi Jussi, The FK30SL is a few tens of grams lighter than the FK30 fork. Stiffness and strength are the same so there's no difference in the ride. A few forks are available by special order - please check with your Cervelo retailer. Cheers, -Damon Rinard, Cervelo Engineer

Damon Rinard, Cervelo Engineer says:Hi Sam, No rider weight limit. We design with 240 pounds in mind and include large safetyy factors so you should be fine riding and racing hard. When the R3 was introduced in 2006, it was the lightest frame and was ridden by the heaviewst rider in Paris-roubaix. We still test to the same hgih standards now for all our frames. It's a Cervelo thing: we don't compromise performance or strength even in our lightest frames. Cheers, -Damon

Jussi says:Hi Damon, I have 2011 R3, absolutely lovely bike, stiff and comfortable ride! I'm thinking of changing the fork to FK30SL. What are benefits of FK30SL compared to FK30? Is it even possible to purchase FK30SL separately? Thanks in advance.

Sam says:Hi Damon, looking at getting either an R3 or an R5 - is there a rider weight limit to these frames please? I weigh 210 and race pretty regularly. Many thanks.

Damon Rinard, Cervelo Engineer says:Hi Bruce, Very good points, they illustrate how simple the engineering meaning of modulus really is - and reminds me how complex bike companies can make it! Cheers, -Damon Rinard, Cervelo Engineer

Bruce Rudolph says:From what I have seen most the manuafacturers don't seem to understand the term "Modulus" or how it applies to the final product. Modulus or elastic modulus can be measured by placing a carbon fibre sample in a rheometer and appling a strain and measuring the stress. The modulus measured in Dynes/cm2 will vary depending on the orientation, the type of primary and secondary phase materials (the carbon and the epoxy) the degree of cure as well as the interfacial bonding between the two. Modulus is geometry independent. The aerospace manufactuers and suppliers test their composites extensively using rheoleogy but I am not so sure the bicycle manufactuers do any rheology at all. I hope that helps your customers understand a little more about modulus

Gibson says:Damon. You've done it again thank you so much for your insights. And this is why I'm a cervelo buyer for life. No matter what. Thanks guys

Damon Rinard, Cervelo Engineer says:Hi Gibson, You ask a good (and frequent!) question, and you already know the complete performance difference: the R5 VWD is lighter than the R3 Team. In every other performance aspect (comfort, stiffness, aerodynamics), they are the same. The second part of your question is what both bike geeks and marketing guys love: “but what makes it lighter?” Bike geeks love it because we’re fascinated with the technical details; marketing guys love it because they get to write words that magnify the importance of those details. Of course, the “how” is irrelevant while riding, but I have to admit I still love knowing about it. That said, here are the details: As you guessed, the carbon fibre types are different, but as mentioned in the main article above, it’s not as simple as “more 60T”, it’s the engineering knowledge, simulation and physical testing that enables us to place those higher modulus fibres in just the right places, orientations and amounts to maximize performance while minimizing weight. This lay up knowledge comes from the lessons we learned in Project California; the R5 VWD in particular uses a lot of the technical knowledge that we transferred directly from the Cervelo R5ca. You noticed another difference which is the carbon cable guides and front derailleur mount on the R5 VWD, which together save about 5 grams. You also mention drop out material, but in fact a similarity is that the dropouts are carbon on all current R3s and R5s. A small difference you’ll notice if you build the bike yourself is the bottom bracket: they both accept normal BBright PressFit cups, but the R3 has the interface molded directly into the left and right walls of the bottom bracket lug, while the R5 VWD has a separate carbon tube bonded between left and right walls. There is no weight or performance difference, just different manufacturing preferences in the different factories we work with. One last difference: the seat cluster. On the R3s, the top tube and seat stays are connected to the seat tube using a tube-to-tube style overwrap, but on the R5s the top and seat tubes are formed together in the mold, with the seat stays secondarily bonded and overwrapped using a typical mortise and tenon joint in the seat stays’ mono stay area. Cheers, -Damon Rinard, Cervelo Engineer

Gibson says:Damon, What is the real difference between the R5 VWD, and R3 Team? I know the main difference between the R5 VWD and R3 Team is weight, but what makes it lighter? What is the difference in the carbon layup? 40T on the R3 versus 60T on the R5? And are things like dropouts, cable routers, and derailleur hangers carbon on the R5 as opposed to aluminum on the R3? I know the bikes are very similar, and have a very similar ride, but I would just like to know what makes the R5 stand out from the R3. Plus I'm trying to justify if I should scrounge up some extra funds to make the leap to the R5. Thanks as always for you time and response Damon.

Damon Rinard, Cervelo Engineer says:Hi Terry, As always, we make small running changes as we learn more. But you are correct, there are no major changes to any model year S2. Cheers, -Damon Rinard, Cervelo Engineer

Terry says:Are there different carbon layups and or materials used on 2010, 2011 and 2012 S2's? As far as I can tell there was not a significant redesign.

Damon Rinard, Cervelo Engineer says:Hi danny, The Cervelos that don't have BBright were designed before BBright was invented. We'll design BBright into each model as we update each one in time. That said, the stiffness of current frames is certainly adequate: The Cervelo S2, RS and P models have all been raced by the top pros at the higest levels of racing. That's more than enough stiffness for any of us mere mortals. In fact, BBright brings so much extra stiffness, Cervelo engineers can "spend" some of it by reducing wall thickness, thus making a lighter frame. Cheers, -Damon Rinard, Cervelo Engineer

danny says:why no BBright for the S2, RS, and P models? are the bottom bracket area of these less stiff than one w/ BBright? are there rider weight limits to any cervelo frame?

Damon Rinard, Cervelo Engineer says:Hi sausskross. All tubes in the S5 VWD have a different layup than the S5 Team, not just the main triangle. VWD engineers took an extra two months molding and testing different layups to meet all stiffness and strength requirements while removing every gram of excess material. Cheers, -Damon Rinard

sausskross says:One more question. Are different fibers and / or lay outs for S5 Team / V.M.D used in all tubes or in the main fraim? Thank You Damon!

Damon Rinard, Cervelo Engineer says:Hi Forschung, A few years ago when commercial FEA software for composite analysis wasn't as good as it is now, we wrote our own FEA pre-processor code, C-TOP, to speed analysis iterations in the design phase. C-TOP really helped us accelerate the number of trials we could analyze using existing FEA software in those days, which is one reason Cervélos perform better - we went through more trial and error before making frames for sale. Things are different now - as part of Cervélos Project California we surveyed and chose newer FEA software developed for aerospace and F1 racing that's much more capable and user friendly than in the past, so we now use "standard" analysis tools. I say standard in quotes because it's standard in advanced composite industries such as aerospace and F1 but only one other bike company that I'm aware of is even close to a similar level of in-house analysis capabilities, in fact some companies advertise that they've outsourced such advanced analysis because their own engineers don’t have the skills. In the meantime, the same Cervélo engineers that designed the R5ca also develop the laminate schedules for every Cervélo model, so all Cervélos benefit from the advanced know-how of Project California, only sometimes using less exotic fibers to reduce cost. Cheers, -Damon

Ramón says:[URL=http://imageshack.us/photo/my-images/11/dsc07561m.jpg/][IMG]http://img11.imageshack.us/img11/7112/dsc07561m.jpg[/IMG][/URL] Uploaded with [URL=http://imageshack.us]ImageShack.us[/URL] The mith?? i´ve a S1 with paint problems since 6 months after i bought it. You are not responsible, i have three cervelos good bikes but warranty is very bad. What mith??

Forschung says:Damon Does Cervelo use an off the shelf FEA like NEi Nastran FEA or is it a proprietary in-house program? Thanks

Damon Rinard, Cervelo Engineer says:Hi Ron, Great question, with a really simple answer. First of all, we do not change the way a rider sits on the bike: the saddle height and setback are the same as a normal 73 degree bike with a typical 20mm offset seat post, so the seat is in the same biomechanical position. It may help to imagine a "virtual" seat tube line directly from the bottom bracket to the seat at 73 degrees. What's different with the S5 is that the structural elements of the frame's seat tube follow a curved and angled path from the bottom bracket to the seat, similar to our P4 and P4 triathlon bikes. Like the tri bikes, this arrangement helps the S5 reduce aero drag: the seat tube covers more of the leading edge of the rear wheel. So with the seat in the same position, there is no change in rider position, but you still get the advantages of the S5's unique design. As for the different trajectory when raising or lowering the seat, the S5's seat post has two optional clamp positions, one forward and one aft of the traditional clamp. -Damon Rinard

Ron says:Hi Damon, I was recently looking at the seat tube angle on the S5 and noted a unique difference (at least for a road bike,/ non TT bike) that the virual straight line from the seat post does not pass through the bottom bracket. The seat post real angle is more up right than the virtual angle in the specs (73 deg) So this leads to the question why this was chosen? The real centre is significantly behind the BB., as well when someone changes the seat post height it does not affect the set back to the same degree as would be the normal case. As well how was the 73 deg angle determined since the post height would impact this vitual number. Thanks

Damon Rinard, Cervelo Engineer says:Hi again Mig, I was wrong in my earler answer to you, and for that I apologize. Richard Matthews, our senior composites engineer and author of the blog post on this page, corrected me via email from our factory where he's working now. Here's the correct answer to your question, and again I apologize. "In the comment on November 7 [Damon] indicated that the 60T, 40T and 30T designations were for fiber strength. That is incorrect: those values are for fiber modulus. So, 60T fiber is stiffer than 40T fiber, which is stiffer than 30T fiber. Those 'tonnage' numbers are generally referring to stiffness. However, it is not really clear because a 'ton' could mean anything. Some of the fiber names (T600, T700) were derived from the material strength, which is maybe where the confusion came from." Cheers, -Damon

EdwinFabre says:Damon, What are the R3's stiffness numbers and how do they compare to the R5ca's of 101 Nm/degree & 70 N/mm?

Damon Rinard, Cervelo Engineer says:Hey S.L., I'm sorry, but I mistyped the numbers in my reply to you (below). The EVO measured 107 Nm/degree & 53 N/mm; the Cervelo R5ca measured 101 Nm/degree & 70 N/mm. The EVO is still 6% stiffer in torsion, but the Cervelo R5ca is 24% stiffer in the bottom bracket. The resulting conclusion is still correct. Cheers, -Damon

Damon Rinard, Cervelo Engineer says:Hi Mig, 60T, 40T and 30T refer to the strength (not stiffness) in tonnes of each fibre type. Generally high strength carbon fibres have lower stiffness and vice versa, so 60T is probably low modulus, 40 and 30T probably higher. But what is more important is how much of each type is used, whether it is placed in the right areas in the frame (or fork), whether there are other fiber types used as well, where and what are they, what orientation and resin systems are used, etc. etc. So while 60T is a small technical description rather than marketing speak, it is a very small part of the engineering inputs that make a good carbon bike. For example, the cross section geometry of the various tubes and bottom bracket dimensions both make an equal or greater difference to the real performance of the frame. (We describe some of this in "Materials and Shapes" part 1 & 2 here: http://cervelo.com/en_us/engineering/tech-presentations/ . I suggest in addition to learning about the "ingredients" so to speak, remember to taste the cake too: compare the lab test numbers, go for a test ride, use your own experience! Cheers, -Damon

Damon Rinard, Cervelo Engineer says:Hi S.L., We are always cautious when reading about performance ranked by a ratio: by changing either the first or second number, you can adjust the ratio, but even if the ratio is “better,” it doesn't mean you have the *optimum* first number, nor the *optimum* second number. For example, a heavy yet very stiff bike could have a higher STW ratio, but it's probably not what you or I would like best. So, while STW can be useful, it's not the whole story! Therefore at Cervelo we look at weight and stiffness separately, and also consider the STW ratio afterwards as well. That said, you can see TOUR's comparison of several frames including both EVO and Cervelo R5ca in the current issue. EVO has torsional stiffness and BB stiffness of 107 Nm/degree and 53 N/mm, respectively, while the Cervelo R5ca has 101 and 53. While EVO’s 107 is indeed 6% more than Cervelo R5ca’s 101, both are quite high. And the Cervelo R5ca’s 57 is 21% more than EVO’s 47, so overall, while both frames are very good, on balance the R5ca is stiffer. For weight, TOUR reported 1084g for the Cervelo R5ca and 1188g for the EVO: again the Cervelo R5ca has a more optimum number. In the end of course, the frame must perform on the road. Team Garmin-Cervelo riders on R5ca had great results this year, starting immediately when the bikes were made available to them. I understand EVOs were introduced at the Giro but only one rider rode only one EVO, for only one stage. So riding is important! If you can, please test ride a Cervelo and see for yourself how good it is with your own experience. Cheers, -Damon

Damon Rinard, Cervelo Engineer says:Hi Edwin, All 2011 and 2012 R3 frames have the same lay up. In 2011, some R3 bikes came with the FK30 fork and some R3 bikes (and the frameset) came with the FK 30 SL fork. This lead to some confusion over which forks came with with frames. In 2012, the R3 Team always comes with the FK30 SL fork (as you mentioned), while the 2012 R3 always comes with the FK30 fork. Paint color is one other difference, with black being lighter than white. Cheers, -Damon

Damon Rinard, Cervelo Engineer says:Hi Chakies, any modulus fibers can be unidirectional (UD) or woven. Modulus is a property of the fiber (it's stiffness), while uni or weave are simply how the ifbers are positioned relative to each other. So you can have unidirectional in high or low modulus, and woven in high or low modulus - modulus and weave are independent. Cheers, -Damon

Mig says:Good info, thanks. How about the differences in 60T, 40T and 30T carbon fiber?

S.L. says:It is claimed the R5ca is the lightest and stiffest frame, but Cannondale claims the SuperSix EVO has the best stiffness-to-weight that is slightly stiffer than the R5ca with a chart. Below is a short reference they've provided: 695 grams and 142.3 nm/deg/kg.* *zedler fahrradtechnik, 4/11, 56 cm, ultimate frame, normalized to tour magazine test standards.

Edwin Fabre says:Damon, What if any difference is there between the carbon lay-up used for the 2011 R3 (black and red with the SL fork) and the 2012 R3 team. They seem very similar to me but I would love your insight as to what makes them different. Thanks Damon. Edwin

Chakies says:whether all unidirectional carbon classified as high modulus carbon? and woven carbon is low modulus carbon?

Damon Rinard, Cervelo Engineer says:Hi Nick, Yep, all Cervelo frames are made primarily with unidirectional carbon fibers of various moduli and strength. Of course, where it makes sense we also include a little woven carbon. For example, where holes will be drilled, we often add a small patch of woven on the inside and outside since woven carbon produces fewer splinters when drilled. Also in small areas where stress concentrates in many directions a layer of woven cloth can be appropriate. As always, it's not only what material is used, but that it's used appropriately and intelligently, with real engineering experience, analysis and testing to back it up. Cheers, -Damon

Nick says:Great info! I always wonder what's this 'high-mod' thingy! Question, so does ALL the Cervelo frames use Unidirectional fibers?

Damon Rinard, Cervelo Engineer says:Hi Sausskross, Good questions. First, a chambered down tube only becomes important if the walls begin to buckle, otherwise the internal brace is just wasted additional weight. Along with stringent CAD & FEA design and lab testing, Cervelo's SmartWall(TM) helps avoid buckling, so we don't want to add the extra weight. To your second question, a larger lower headset bearing does make sense in some cases, and it's important, as you mention, to balance all the characteristics including stiffness, weight and aero to achieve the best performance. The S5 uses normal headset bearings top and bottom, in order to reduce the aerodynamic drag and as you can see in the low measured drag values, it works to keep the S5 the fastest road bike in the world. Cheers, -Damon

sausskross says:Uups .. and/ore 1 3/8 is the question, thanx in advance.

sausskross says:A very nice insight! How are the chances to improve the frontend stiffnes for the S series with a chamber downtube and/ore 1 1/3 lower headtube bearings, would this ideas work well ore compromise wight and aero too much?