Damon Rinard's 2016 Cannondale CAAD8 105

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RyanH
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by RyanH

Hi Damon,

Not exactly related to your build, but seeing a chance to enquire about stack and reach since it's being discussed, I have a few questions. If I recall correctly, Cervelo brought stack and reach measurements to the mainstream. I assume that was around the time you were there, correct? Cervelos have nice linear progression through the S/R curve, which many manufacturers have trouble offering. The question is, does that come at a cost of handling or otherwise in the largest and smallest sizes? When I was looking for an aero road frame, reach figures are relatively long, especially for the smaller frames. Cervelo S5 had the shortest reach (the one I should have picked up) while the Scott Foil was longer, but relatively reasonable compared to the Madone, for example. My second question is, if a rider is on the cusp between a 48 and a 50, what things should they keep in mind when choosing between the two frames? With the Evo, as an example, what design choices went into designing the 48 vs the 50? I have this perception, and I may be wrong, that the smallest frames will ride differently than the middle of bell curve frames, so all else being equal, choose the next size up assuming you can make it work since it's closer to the intended handling characteristics (when discussing sizes smaller than 56, opposite for larger sizes).

DamonRinard
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by DamonRinard

Hi Ryan, good questions.

In the late 1990s, with a few exceptions frames were usually measured either center to center or center to top (of seat tube). Giant brought in "compact geometry" with sloping top tubes but the real innovation in frame dimensioning came from triathlon. With "funny bikes" and dropped top tubes the length of the seat tube no longer indicated as much about where your handlebars might end up.

So Dan Empfield started promoting stack & reach.

While I was at Trek, Lance retired (the first time) and in 2008 Trek was finally able to bring out a road bike with sloping top tube. Suddenly they had to decide how to measure it. With horizontal top tubes, Treks had always been measured center to top. So road product manager Tyler Pilger and I considered lots of potential measurement schemes, including a set of polar coordinates Gary Klein was pushing: the direct distance from BB to hand, and the angle that line made from horizontal. (Bikes are 3D, but if you ignore width then they're 2D, which means any two dimensions can fully describe where points fall in space. In polar coordinates it's a length and an angle, rather than two lengths as in Cartesian coordinates.) Long story short, Trek started reporting stack & reach. We smoothed out the zig zags in the old OCLV geometry and created H1 and H2. Later someone added H3. (And now it seems Trek's designers have forgotten stack & reach, as some of their trend lines have zig zags again.)

When I started working at Cervelo in 2008, they already had a nearly smooth S&R line. This was somewhat by luck, since HT lengths were the driver (100, 120, 140, etc.) and seat angle was a constant 73 degrees in all sizes. (Variable seat angle is what usually leads to zigs and zags if you're not at least watching S&R while designing.) There was only a kink around size 54 and 56, which no one remembers designing in. So when Gerard wanted to increase handlebar height I arbitrarily made the new geometry linear.

(By the way, in the GURU database with thousands of good fits, road riders from tall to small are happiest with a seat tube angle around 73.2 plus or minus a fraction of a degree, so Cervelo was right to fix seat angle there for all sizes. As far as I know, this is virtually unexamined and unknown outside a small number of insiders, and since seat angle has little effect on power output, and most of the world wants it to vary, many bikes still vary seat angle with size, even Cannondales.)

Trek didn't make a big deal out of stack and reach, it just showed up on the geo table. But Cervelo did, mostly in response to, for example, Pinarello dealers, who felt Cervelo's 6 sizes weren't enough compared to Pinarello's 13. But some had stack and reach points less than 5(!) millimeters apart, and lots of zig zags. So it made sense to market a rational stack and reach line to dealers. Still we knew there was no direct benefit to riders. Once you have your size, who cares what the next size is like? When buying a bike, look at stack and reach points, not lines.

To your question of handling, a good handling bike can be designed nearly without regard to how straight the stack and reach line is. Although they're both part of geometry, it sometimes helps to think of "fit" as separate from "handling." The dimensions that fix your feet, seat & hands, have only a secondary effect on defining steering response and weight distribution. Of course there are limitations, and smaller sizes often get screwed if the designer isn't paying attention. The usual crime is too much trail, which leads to understeer.

Which size?
If you can fit two sizes according to stack and reach, then look next at saddle position. Sometimes the STA gets really steep on smaller sizes. Team Estrogen Forum women have spotted that, and share sources for seat posts with more setback to fix it. Also consider water bottle space & standover.

As for "intended handling," ride what feels good. Don't compare handling to the medium size; compare it to other bikes in your size. It should handle alright to *you.* But don't get hung up on handling: after a few corners, most people can adapt to most bikes. These days it's pretty hard to buy a bike with "bad" handling. Back in the 1970s however...!

One of the cool things we've done at Cannondale is make a fork with adjustable offset. Within seconds you can be riding anywhere from 38 to 78 millimeters offset. We pass the fork around, so different people (on different size bikes) all get a chance. The usual response is "Yeah, it feels different, but I can ride 'em all!" That's not to say handling doesn't matter, just that it's not a big point to get hung up on when choosing a model or size.

One example: In preparation for Paris-Roubaix, we supplied Roger Hammond with three forks. Various combinations changed head angle, offset & trail. After riding them all for a few months on his familiar training routes in Belgium, during the January training camp in Portugal Roger summed up his impressions of how they each handled differently. But it didn't make sense based on the dimensions. After discussing with him for a few minutes (and a quick sketch on the box Thor's new bike had come in), he realized he'd gotten it backwards! That's how close most handling is. (He's a degreed engineer so was able to follow my description of the physical effects of gravity on flop and of rolling resistance on trail, etc.)

So choose what you like, but don't sweat the small stuff.

Cheers,
Damon
Last edited by DamonRinard on Wed Aug 10, 2016 12:29 pm, edited 2 times in total.
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

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gravity
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by gravity

Hi Damon,

Whenever I see your new post on WW, I'd get excited. Thanks for your very insightful views. Keep em coming.

Cheers.

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Calnago
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by Calnago

Damon, such a great post! It should be the basis for a thread of its own. Years ago when I built some frames from scratch I thought about designing a hub somehow that would be able to simulate different fork offsets to experiment with. Would love to see a pic of that fork you're talking about. And perhaps you can help me understand the reasoning behind Treks decision to go with very small fork offsets (relative to most others) and pair it up with a steeper headtube angle (again relative to most others). They end up with similar trails and I can ride both and they both feel great. And I can't say which is better.
For example, I know Colnagos very well. And for a long time now I've thought Treks sizing and geometry was really well done (at least in my size frames). Their 60 Emonda/Madone is virtually identical in geometry to my 61 Colnago. Same effective TT to the mm at 586mm. Same seat tube angle 72.75 vs 72.8. And trails are almost the same but they get there in two different ways re HT angle and Fork Offset. Comments?
And yes, seat tube angle is something I look at really just for an end aesthetic, to predict where (given that I know where my saddle needs to end up in space) the seat post clamp will be clamping the rails of my saddle. Really don't like it when the saddle rails are being clamped at either extreme end of the saddle rails, even though the "fit" may be the same.
Thanks
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

DamonRinard
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by DamonRinard

@gravity: Thanks!

@Calnago:
No photos, but it's inspired by the fork Bill Holland made while we were developing steering geometry for the tri bikes he was making. That would have been around 1988 or so... The smaller 650C (not 650B) wheels meant traditional head angle & fork offset geo handed down for 700C wheels wasn't quite right, so he brazed a pair of Gipiemme horizontal rear dropouts into a steel front fork to experiment. Worked great and we dialed in the fork offset. At the Long Beach Interbike show, Richard Cunningham told me his rule of thumb for adjusting mountain bike steering geometry for 24" wheels, which matched our experiments.

Image

Bill chose Gipiemme, not Campagnolo dropouts, because they lacked the triangular window and Bill knew they'd be strong enough to braze into the fork blades by just the seat stay tab (not both tabs).

The fork we have here at Cannondale follows the same concept, but with larger horizontal aluminum dropouts bonded into an existing carbon fork. Intern Josh Hursh followed my instructions to design and cut the dropouts from plate stock, then bond them into an old Synapse fork we had lying around. Design engineer Andy Schmidt designed and turned a thin aluminum cone to adapt the fork for 1-1/4" tapered frames, so anyone (at CSG) can use this fork on any recent Cannondale or GT rim brake bike. Josh figured the best angle for the slot, not really "horizontal," so that when you move the hub forward or back there's negligible change in brake reach. You can set your brake shoes to fit the rim at all points along the slot and you're off for a fun experiment on your lunch ride. Design engineer Darius Shekari made the cool digital laser X-Y bike geometry measuring jig Josh used to confirm the offset range.

Cheers,
Damon
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

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Calnago
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by Calnago

Interesting, but I'm not sure about the actual engineering principles that actually combine offset and headtube angle together and how they all interrelate. The example above only allows you to change offset. But the headtube angle is held constant. Over my head. I once designed a spreadsheet that showed constant "stability indexes" across a combination of different headtube angles and offsets for a 700c wheel. The "stability index" concept was from the book "Bicycling Science" and is a great book to have if you're into that sort of thing. Anyway, bit of a diversion from your build but thanks for sharing. Very interesting.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

DamonRinard
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by DamonRinard

Yeah, you're not alone Calnago - very few people in the world are really up to speed on the true physics of bike steering.

Luckily, there are a couple of schools of thought with practical models which explain differences within a fairly narrow range of traditional geometries, and they work well within their developed envelope, but they often fall apart when applied outside that parameter range, for example recumbent tandem bikes, etc. For us road bike geeks they're fine.

More advanced, Dr. Bill "Lord of the Chain Rings" Patterson used to teach a class on vehicle dynamics at Cal Poly SLO. I met him at the San Diego Velodrome when I competed in the HPV race there on my homemade carbon fiber bike around 1995, and had him and George & Carol Leone over to my house for lunch afterwards. He used to design fly-by-wire control systems for fighter jets and explained the force feedback they programmed into the stick. They couldn't get "real" force feedback 'cause it was all electronic, but they found the force was an integral part of the pilot's control. In his class every student had to build an experimental vehicle, and of course many of them were based on bikes. Cal Poly's HPV always handled well.

Perhaps even more advanced, Dr. Jim Papadopoulos and Andy Ruina are some geniuses who made the news recently about the math behind bike handling. Here's a link to that article: http://www.nature.com/news/the-bicycle-problem-that-nearly-broke-mathematics-1.20281
Even though we've spoken in person, I confess I still can't follow his explanation!

Cheers,
Damon
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

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mythical
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by mythical

Great thread. Very informative. Speaking of feedback, it reminded me of these experiments where the steering on a bike was reversed. No one used to a normal bike can ride it because the brain cannot adapted quickly enough.

Anyway, decent daily bike, Damon. It seems to have quite a tall but long front end. Is there a specific reason you prefer this particular position on the bike? For example, I'm 1m83 and my ideal fit is a 54cm Cannondale with a 130mm stem slammed and 100mm reach bars, while my seat height is about the same as yours.
“I always find it amazing that a material can actually sell a product when it’s really the engineering that creates and dictates how well that material will behave or perform.” — Chuck Teixeira

DamonRinard
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by DamonRinard

Yes! The reverse steering bike. I think it might have been "Downtown" Jarrod Brown who made the one Trek had. One year at the company picnic I spent the whole day learning how to ride that thing. That was harder than the day I spent learning how to ride a unicycle.

Thanks mythical, glad you also like my CAAD8. My high handlebar position is just where I've ended up over the years. Despite being a bike fitter from way back (when C.O.N.I., the Guimard formula and the N.E.C.A. Fit Kit were the most advanced fitting tools in town), today I have an outlier position. I suppose there are several factors.
- The slammed stem trend was just getting started after I was already pretty happy with my traditional position.
- I have a humped back, so my upper spine slopes down toward the neck, making it harder for me to hold my head up if my bars get too low.
- I come from an era when riders actually rode in the drops for a significant portion of the ride. I remember racing crits with guys on their hoods and me in my drops.
- I learned a lot about saddle pressure distribution and I want to have at least one riding position where my weight is primarily on my ischial tuberosities, not my pubic symphysis.
- There's so little science around saddle-to-bar drop.

It's a little challenging for me to get the bars that high with some frames, but so far I've managed by keeping a lot of spacers and sometimes flipping the stem up. Very non-pro, I know. Every other summer as I gain fitness and speed I try to go with the trend, look a little more pro and get a little lower, but then there's always one really long ride where, near the end, my neck and crotch are killing me and I say to myself, fashion be damned, just put the bars back up where they were! LOL.

Cheers,
Damon
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

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mythical
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by mythical

There are plenty of pro riders with high bars. Lance also had his quite high. Ever since building up my first road bike in 2000, a 6.8kg Giant TCR with Dura-Ace, I too always end up in the same position on each bike I build up for myself. It's just what works best for our bodies I guess.

My problem is getting my bars low enough, otherwise I'm cramped and too upright, and my neck starts feeling uncomfortable on longer rides because my spine isn't relaxed. Due to my ape arms and tall shoulders, my stem needs to be slammed.

Once time I tried one of Jan Ullrich's bikes and one of Lance's in close succession. Ullrich's position is long and low, with a rather extreme seat height for his build, while Lance sits quite short and upright. Coming from mountainbiking, my bike fit used to resemble Ullrich's. It would've required a TT length of a 58cm frame with the HT length of a 54cm, but then I gradually acclimatized to a higher pedal cadence (>100rpm) and started favoring a shorter position with a more rounded back where I can still ride comfortably in the drops.

Here is a photo of one of my old bikes (the quickest one I found). Sidenote: I switched to a lower stem later on because this 130mm Ritchey still put the bars too high for my liking. Albeit heavier, the lower stem was noticeably stiffer, which I preferred.
Bike2.jpeg

My bikes have always felt like I can relax on long rides but also really attack a corner in a race. I like to think my position on the bike gives me a greater aero advantage than the expensive aero bikes other riders buy. Especially during races, it keeps surprising me that my bike rolls on farther than others.

Don't feel pressured by trends, Damon. Let's leave fashion to the fickle. :wink:
“I always find it amazing that a material can actually sell a product when it’s really the engineering that creates and dictates how well that material will behave or perform.” — Chuck Teixeira

DamonRinard
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by DamonRinard

Calnago wrote:...the reasoning behind Treks decision to go with very small fork offsets (relative to most others) and pair it up with a steeper headtube angle (again relative to most others). They end up with similar trails and I can ride both and they both feel great.


Trek had already developed their steering geometry before I got involved. So when we updated stack and reach to H1 & H2, we asked about steering geometry. Every bike company hears this when they ask dealers and riders, and Trek heard it when they asked: How's our geo? People loved it, said the bikes handled great, it's perfect, don't change a thing, etc. etc. (Heard the same at Kestrel, Cervelo, Cannondale...)

So that's why we kept it (mostly) unchanged.

And you're exactly right: The scientists say trail isn't the right model for bike handling, and they're right. Even within the trail model, trail isn't the only parameter. But within a reasonable range of head tube angles and wheel radii it is the main one. So Colnago and Trek can both ride well, despite different combinations of head angle and fork offset, as long as trail is about the same.
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

DamonRinard
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by DamonRinard

I crashed a few weeks ago, on only my second ride outside this year. I'm happy to say there's only minor damage to both me and the bike. :-)
I'm healing up well, and now that my skinned knuckles don't hurt so much, I'm willing to put on mechanic's gloves and start fixing the bike.

Image

I fell on my right side, so the derailleur had a gouge that I easily smoothed out with a hand file, and the hanger was bent. @Colnago, you'll appreciate this: when I tried to straighten the hanger, it broke! Okay, my CAAD8 isn't an EVO Hi-MOD like we were talking about before, but as you mentioned at the time, good practice is to have a spare, and I did. :-) Also happy to have this replaceable hanger break, so the frame is still good.

Like most brands, Cannondale has a few different hanger interfaces. The CAAD8's hanger is single-sided and has proven to work very, very well. This hanger is so well-liked we use it on lots of Cannondale models, obviously my CAAD8, but also the Slice triathlon bike and the Cannondale Quick hybrid bikes. We sell so many Quicks every year, I have to believe spare hangers can be easily found in most major Cannondale dealers.

There are two hanger lengths: short and long. The short version (about 25 mm) is used with road derailleurs. The long version (about 29 mm) is used with mountain derailleurs. They're interchangeable on the frame.

The CAAD8 comes with road derailleurs and the short hanger, but my spare is the longer length.

The longer hanger means the derailleur is farther away from the cassette. Generally that also means the jockey pulley is farther from the cassette teeth, meaning the derailleur has less control over the chain's lateral position (the length of chain between the pulley and cassette is longer, so more flexible).

For Shimano road derailleurs with a spring in the B-pivot (most of them), the longer length can be a significant contributor to poor shifting if the extra distance can't be adjusted out by loosening the B-tension screw.

For SRAM derailleurs, and the newest Shimano derailleurs that no longer have a spring in the B-pivot, the B-screw can usually adjust the derailleur to close the gap to the specified distance.

Image

SRAM recommends 6-8 mm for the gap, which is easy to judge by eye because a chain link is about 6-8 mm tall.

I assembled the new hanger on my bike, using a 2.5 mm allen key. Super convenient: the SRAM rear derailleur limit screws are also 2.5. :-) After aligning the hanger and adjusting the derailleur as usual, I'm good to go!

I'll keep an eye out for a short hanger and switch back to save, what, maybe two grams or so.
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

SixThirteen
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by SixThirteen

A little bit of thread necromancy...

How's the CAAD8? Anymore changes in the couple of years?

Always interested to see what folks do with their 'Dales. As per sig I had a Six13, plus a CAAD2, and currently a CAAD9 and for daily beater use, a CAADX.

A couple years ago I got an S series Cervelo (mabye that should now be LordVelo?) and thought I'd sell the CAAD9, but no, it just fits sooooo nicely.

Cheers from DownUnder

Six13

DamonRinard
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by DamonRinard

Hi SixThirteen,

Great username! Good collection of Cannondales you've had over the years. Like you, I like the CAAD series for "beater" bikes.

LOL at LordVelo. Jane named her first Cervelo "Sir" Velo. And now that they sponsor the Brits... Ha ha!

After several years now, my trusty CAAD8 has settled in to a stable configuration these days. It's still built with SRAM eTap (still 11 speed), alloy bars & seat post (I was changing saddles and took off the carbon post to drop in a different saddle and I've just stuck with it), same alloy clincher wheels with PowerTap hub and Kinlin rims.

Good handmade Vittoria tires sure are nice, but since it's winter and turbo training season here I've put on some vulcanized tires. Still nice ones: I had a Vittoria Rubino Speed and a GP4000 S2 lying around so installed them. Tires make a huge difference in comfort, speed and handling. Life's too short to ride bad tires. :-)

Note: Only use vulcanized tires on a turbo trainer. On a cold-bonded handmade tire, the heat generated in the tire can delaminate the tread.

I'm still quite happy with this bike. My position is still the same, I still appreciate the frame having plenty of stiffness, handling is totally predictable, and thanks to the saddle I've settled on (surprisingly enough, it's the OEM Cannondale "Stage Ergo"!) comfort is quite good.

Cannondale CAAD bikes in general are good, honest, hard-working race bikes. This may be my keeper! Even great to travel with, since all the cables are external. That means the handlebars aren't tethered close to the bike; they're free to swing over to wherever they fit nicely in the travel case. And if cables get damaged on the trip they're quick and easy to replace. (This actually happened to me one year on holiday in France: I was snipping the zip tie to unpack the bike and accidentally cut the front derailleur cable as well! Local bike shop sold us a cable and we were shortly off to enjoy our vacation.)

Cheers,
Damon
Damon Rinard
Engineering Manager, Road Bikes
Cycling Sports Group, Cannondale
Ex-Kestrel, ex-Velomax, ex-Trek, ex-Cervelo

bm0p700f
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by bm0p700f

Dr. Jim Papadopoulos has written a very good book. Bicycling science. It goes into more detail than you hope for. sadly no work in wheel physics.

by Weenie


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