# Does my frame have too much flex for speed?



## bwalton (Mar 18, 2010)

I own a 2007 Specialized Sirrus Sport. The Sirrus is essentially a road bike with flat handle bars or a hybrid. The frame is constructed with an A1 aluminum main triangle and chain stays with carbon fiber seat stays and fork. Both the seat stays and fork have zerk inserts to dampen road vibrations. The Sirrus has a very comfortable ride quality even with its 700 x 25 Continental Gator-Skin tires inflated to 105 psi. Pot holes are the only road defect that really jars me if I don’t get my tail feathers off the saddle in time. The frame is engineered to flex, which is great for comfort but not speed.
For the last two summers I participated in the Pyramid Lake Sprint Triathlon, which has a 14 mile bike route on a windy hilly road in the high Nevada desert. My first year I completed the 14 mile bike leg of the race in a little over an hour without much training and last year I completed it in about 55 minutes or at a little over 14 miles per hour with 4 months of training and a centaury under my belt. This year I would like to get my time down to under 50 minutes or around 17 to 18 mph. Clearly I need to do interval training on hills similar to the ones at Pyramid Lake but I also need to either buy drops for my Sirrus or purchase a road bike that has a stiffer BB shell, chain stays and seat stay in order to accomplish my speed goal. For example, I have a hard time pushing my Sirrus past 18 mph on semi flat roads without wind. Any head wind will slow me down on that same flat road by 1 ½ to 2 mph. I’m not sure how much drop bars would help my bike but it seems like some of my pedaling energy is being absorbed in the plush frame. I am 6’-3” tall and currently weigh 200 pounds so I’m not exactly an aerodynamic poster boy. My weight also exasperates the frame flex. 

I guess the advise I am looking for is; will I ride faster on a road bike than on my Sirrus without changing my current fitness and road riding skill level. If so, what kind of speed gains should I see between the two bikes--1 to 2 mph? If speed is more of a function of training and aerodynamics, installing drops on my Sirrus, losing 10 plus pounds and wearing spandex shorts and a jersey would be a more economical way to go.


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## locustfist (Feb 21, 2009)

Short answer: Yes, you will be faster on a stiffer bike with a more aero/powerful position. Most of that speed would be realized due to a more aero/powerful position rather than stiffness of the frame. At the end of the day most power improvements will come from training

If you want to put drop bars on it you'll also need new levers.

If you wanted a better bike situation I would sell it and buy a a different one.


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## kbiker3111 (Nov 7, 2006)

It is not the stiffness, it is the position. Unfortunately, there is no real economical way to get drop bars. Its a $300+ install on your Sirrus and more for a new bike. It will make you a heck of a lot faster, though.


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## JCavilia (Sep 12, 2005)

I think it's likely that the speed disadvantage of the Sirrus is almost all a matter of body position, and very little of it due to the small losses to the suspension elements.

But just putting drop bars on it may not be a very good solution. Its frame geometry is designed for the flat bars, and it may be hard to get a good position, reach, etc. if you modify it. It really sounds to me like you'd enjoy a road bike more, so the best solution may be to sell the Sirrus for as much as you can get for it, and buy a road bike, if that's in your budget. 

You will almost certainly go faster on a road bike. It's hard to predict how much, but the effect of the more aero body position is substantial. If you did the 14-mile course in 55 minutes, that's about 15.3 mph. I would think on a road bike the same effort would get you close to 17. Training will, of course, make a big difference.


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## icsloppl (Aug 25, 2009)

If you are flexing your frame to a noticable degree while seated your cadence is almost certainly far too low. It's probably worsened by your overly upright seating position.

Get a new bike that's fitted correctly if you are serious about going faster IMO.


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## bwalton (Mar 18, 2010)

My 07 XL Sirrus Sport has the following frame geometry and component specifications. Last year I replaced the OEM wheel set, tires and crank set with Mavic Akism wheels and 700 x 25 Continental Gator-Skin tires and a Sungino XD600 crank set. Aside from the chain, the seat post and the seat, all of the other components on the bike are stock. 

As you can see the XL’s frame geometry is based on a compact road frame with a slightly taller stack (i.e. center of bottom bracket to top of handle bars). For around $200.00 I can purchase Shimano 2303 drop bar shifters/brake levers, drop bars, cork tape and leverage cams for the V-brakes and have a road bike that mimics a plush road bike like a Roubaix. 


XS	S	M	L	XL

Seat Tube Length, Center to Top	400mm	445mm	480mm	515mm	565mm

Seat Tube Length, Center to Center	350mm	395mm	430mm	465mm	515mm

Top Tube Length (Horizontal)	510mm	530mm	545mm	565mm	590mm

Top Tube Length (Actual)	493mm	512mm	524mm	543mm	567mm

Bottom Bracket Drop	68mm	68mm	65mm	65mm	65mm

Bottom Bracket Height	277mm	277mm	280mm	280mm	280mm

Chainstay Length	430mm	425mm	425mm	425mm	425mm

Seat Tube Angle	76°	75°	74°	73.5°	73°

Head Tube Angle	70°	71.5°	72°	72.5°	73°

Rake	50mm	50mm	50mm	50mm	50mm

Trail	72mm	63mm	60mm	56mm	53mm

Front Center	595mm	597mm	600mm	611mm	626mm

Wheel Base	1015mm	1012mm	1016mm	1027mm	1042mm

Standover Height	715mm	745mm	782mm	814mm	855mm

Head Tube Length	135mm	150mm	175mm	205mm	240mm

Handlebar Width	580mm	580mm	580mm	580mm	580mm

Stem Length	90mm	100mm	100mm	110mm	120mm

Crank Length	170mm	170mm	175mm	175mm	175mm

Seatpost Length	300mm	350mm	350mm	350mm	350mm

FRAME	Specialized A1 Premium Aluminum, fully manipulated tubing, compact design, FACT carbon seatstays w/ Zertz inserts

REAR SHOCK	N/A

FORK	Specialized FACT carbon, bonded carbon legs, Zertz inserts, fender mounts

HEADSET	Specialized Mindset, 1 1/8" integrated threadless, sealed bearings, alloy 40mm cone

STEM	Specialized 3D forged 6061 alloy, 31.8mm bar clamp

HANDLEBARS	Specialized Event, A1 Premium Aluminum alloy, 580mm width, 31.8mm

TAPE / GRIPS	Body Geometry Comfort II, triple density gel

FRONT BRAKE	Forged 6061 alloy, 85mm linear pull, multi condition pads

REAR BRAKE	Forged 6061 alloy, 85mm linear pull, multi condition pads

BRAKE LEVERS	Shimano EF-50, EZ Fire, integrated w/ shift lever

FRONT DERAILLEUR	Shimano T301, 31.8 clamp, bottom pull

REAR DERAILLEUR	Shimano Sora, long cage

SHIFT LEVERS	Shimano EF-50, EZ Fire

CASSETTE / FREEWHEEL	Shimano HG50, 8-speed 12-25t

CHAIN	KMC Z72, 8-speed

CRANKSET	Sugino XD, five arm, polished arms w/ chainguard

CHAINRINGS	48x38x28T

BOTTOM BRACKET	Sport cartridge, square taper, 68 x 113mm 

PEDALS	Composite body, alloy cage w/ toe clips and straps

RIMS	Alex R500, 700c, alloy double wall, machined sidewalls

FRONT HUB	Specialized forged alloy, 32 hole, double sealed bearings, QR

REAR HUB	Specialized forged alloy, 32 hole, double sealed bearings, QR

SPOKES	Stainless 14g

FRONT TIRE	Specialized All Condition, 700x28c, wire bead, 60TPI w/ Flak Jacket

REAR TIRE	Specialized All Condition, 700x28c, wire bead, 60TPI w/ Flak Jacket

TUBES	Specialized standard presta tube

SADDLE	Body Geometry Milano Comfort Max

SEAT POST	Forged alloy, 27.2mm

SEAT BINDER	Specialized CNC, alloy

NOTES	Chain stay protector, chain catcher, clips and straps, derailleur hanger, clear coat, owners manual


The road course at Pyramid Lake is not flat by a long shot--it is riddled with lots of hills. These hills are steep, so you either drop into granny gear and spin up hills at 8 mph or you get off your seat and mash up the hills at 10 mph. The downhill runs is where you can make up some time but your downhill speed is limited by self preservation and how much vibration your body can withstand from the very rough AC. So aerodynamics will only come into play on downhill runs at Pyramid Lake not uphill grinds at 10 plus mph. Having said that, I’m not sure if a stiffer bike would be faster on a beat up paved road. Maybe I should run 90 psi in my tires and buy dropped bar ends (without brake levers—yikes)!!


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## AndrwSwitch (May 28, 2009)

That's some crazy geometry for a bike sold with flat bars.

If you can live with it, here's another frankensetup for your bike, that'll be a lot cheaper.

Get the drop bars, tape, and some long-pull drop bar brake levers. While your shifters aren't meant to go on something with the diameter of a road drop bar, you can probably jury 'em on. You'll have a good brake setup, which is more important, and the riding position. You'll just have to plan ahead for your shifts a little more.

Or clip-on aero bars and call it a day, but I'm the first to admit that I don't know about what extra problems you might run into trying to put them on the current handlebars, and dealing with whatever geometry you already have. It would certainly put the bike in the running for an appearance in BSNYC.


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## looigi (Nov 24, 2010)

AndrwSwitch said:


> ... Or clip-on aero bars and call it a day, but I'm the first to admit that I don't know about what extra problems you might run into trying to put them on the current handlebars, and dealing with whatever geometry you already have. It would certainly put the bike in the running for an appearance in BSNYC.


Agree. You'll have to noodle out the details to make it work but it should be possible and not cost a lot. 

But as others have pointed out...it's more about the motor. There are lots of good books on training. Any of the popular titles from Carmichael or Friel will clue you in.


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## AndrwSwitch (May 28, 2009)

^^^
Very true. Especially on a hilly course.

Still, since it's legal to address one of the major power losses in this case - why not? I suck at running and hate being in the water, so you won't see me doing a triathlon. But if I were time trialing and wanted to beat some people, I'd probably be looking at aero bars.


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## philbennett (Jan 20, 2012)

I have that exact bike for around town, as well as two high-end carbon frames and a Cervelo s1 alum. bike for bad weather...
Sirrus frame is EXTREMELY stiff, and those wheels are two. stiffness is not the issue... def. its the position, as everyone says.
nothing wrong with the frame if you can make the geometry work with lower bar setups discussed.


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## bwalton (Mar 18, 2010)

I explored the idea of putting my Shimano Alivio flat bar shifter/brake levers on dropped handle bars last year. I learned though the Sheldon Brown link below that the diameter of drops is 15/16” and the diameter of flat mountain bike handle bars is 7/8”. Unfortunately, you can’t open up the aluminum clamps on mountain shifters and brake lever up enough to accommodate 15/16” diameter drops without fracturing the clamps.

Handlebars for Touring and Commuting

Anyway the other Frankenbike bike idea I was looking at last year were these Origin 8 Dropped bar ends to my flat handlebars for $16.00. The thing that spooks me about these bar ends is that they lack brake levers. I could probably mount Dia-Comp V-brake drop brake levers on these ends but I would need to abandon my integrated flat bar brake levers. It sure would be nice if a brake “Y” cable union was available because it’s nice to have your fingers next to brake levers when the unexpected happens.
Amazon.com: Origin 8 Bicycle Drop Bar Ends, Black: Sports & Outdoors


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## JohnStonebarger (Jan 22, 2004)

It might be counter-intuitive, but frame flex doesn't really cost us any speed -- the frame works like a spring, and energy we "lose" flexing the frame is largely given back to us when the frame springs back (if this wasn't true, our frames would get mighty warm with all that flexing). However, marketing speak loves frame stiffness, because stiff is so easy to feel on a test ride. Simply put, stiff frames sell bikes, but they don't make you faster.

You might be a bit faster on a road bike, but I can't imagine it would add up to a lot of free speed compare to the Sirrus. On the other hand, if dropping coin on a new bike motivates you to lose those ten pounds, then yes, you will get faster...


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## bwalton (Mar 18, 2010)

My post boils down to my lack of practical experience with road bikes. Ideally if I could ride a back to back time trial on a road bike and my sirrus than I could put my original question to rest. 
I commuted to High school on a Univega road bike 28 years ago and commuted to college on a Schwinn Sierra mountain bike. Fifteen years ago I got into mountain biking and been riding dual suspension rigs ever since. Five years ago I began to commute to work and purchased the 07 Sirrus because the flat handlebars, the semi-tall stack and the carbon fiber fork and seat stays made this hybrid feel like a mountain bike on thin tires. The concern I have with a road bike is that I won’t ride it because they are not built for comfort. The only type of road bikes I would consider is ether a plush bike like a Roubaix or a cx (cyclocross). Both of these type of bikes are essentially a Sirrus with drops.


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## MR_GRUMPY (Aug 21, 2002)

It's the legs, baby......Not the bike.
.
.
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.


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## AndrwSwitch (May 28, 2009)

Test ride a few road bikes.

I rode mountain bikes and hybrids for years before I got my first road bike. A lot of mountain bikers are under the misapprehension that they're not built for comfort. They're built for efficiency, though, and an uncomfortable rider is an inefficient rider. You should be able to match the relationship of your saddle and pedals on a road bike to that relationship on a mountain bike. Then, put the handlebars wherever you want them to be. A lot of people on the internet upload pictures with a lot of drop from the saddle to the bars. It's pretty, and a tall spacer stack is kind of ugly, but the reality is that you get as much vertical adjustability as you do on a mountain bike. My road bikes mostly have their bars just a little bit below the level of the saddle. Cycle tourists sometimes put them higher. While you don't get the aero benefits that you would from a more extreme position, you should still present a narrower face to the wind, which helps quite a bit.

Bottom line: if you can't make a bike with drop bars more comfortable than a bike with flat bars for continuous-pedaling riding, either you've got some other anatomical problem, maybe an arm that was broken and reset oddly, or you're not quite getting something. But many of us do have to let go of the slammed stem and high saddle aesthetic to make them work well. Sometimes you need to choose a frame that runs to a shorter top tube and taller head tube to get the handlebars in the right place, although I also question the setup of a rider who needs to land the handlebar clamp more than an inch or two higher than the saddle. The riding position should be balanced over the pedals, same deal as a XC bike.

Since you're doing a triathlon, though, you should keep in mind that people race on drop bars because they handle better than aero bars (according to those I've read, I don't have ride time with aero bars) and because UCI and USAC rules define a massed start bicycle in a way that doesn't permit aero bars. Aero bars and the accompanying riding position are certainly the gold standard for efficiency on a conventional bicycle. International and USA triathlon rules don't permit recumbents, and some other extreme setups.

The other big difference in comfort between road and mountain bikes is the tires. IME, this is much, much more important than the frame. However, some road frames can only clear 23mm or 25mm tires. For a bigger person, a person riding on rougher roads, or a person making some off-road forays, this may not be acceptable. Tire pressure in a road bike is really more similar to tire pressure in a mountain bike than different - sure, it's almost always more. But it's still about what feels, tracks and handles the best. A lot of people place much more faith in the sidewall recommendations for road tires than they should, even if they happily run less than the minimum pressure on their MTBs. For the sake of comparison, I'm at 170 lb right now and have 95 psi in my rear 23mm tire.


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## Scott in MD (Jun 24, 2008)

*Trick Sirrus -v- race Bike?*

*Most of this what follows is my opinion"
I have the same Sirrus except 2008, and I enjoy riding it. I have it tricked out a little, and use it to commute to the neighborhood pool; as a buddy-bike loaner, and riding with my wife while she is on her Specialized Vitae. Otherwise, I ride about 3000 miles a year on my Spesh Tarmac mostly, and race about three or four times per year on my Cannondale Slice. I consider myself a pretty serious Tri racer for an age-grouper ... every minute counts. I agree with your opinion ... the Sirrus is a great bike, and fast for a flat bar bike. But here's the thing: drop bars are more comfortable (more hand positions) and faster (more powerful and aero position. I would not hassle with replacing drop bars on the Sirrus (although I have thought about it on mine). You can make it a little more comfortable by adding Ergon or similar bar ends, to give you another hand position perpindicular to the flat bar. You could also drop the stem/bar a little lower, which would help a little. Or.... you could use a clip on aero bar on your Sirrus ... which might have a 25.4mm diameter bar (not 31.8), since it is a 2007. This would not be an absurd idea, but you will have the only one in the race. Yes, you will be 1-2 MPH faster on a road bike, or especially 2-3 MPH faster on a tri bike ... most of the difference between the roadie and the tri bike base on aerodynamics. I don't think you are flexing your SIrrus all that much ... and if you are, your riding style is hurting your race time. Triathlon is easy duty for a bike ... get up to race pace, then stay there nice and steady. No lung-busting sprints or crank-stomping climbs in Triathlon. So, I guess my recommendation is: If you are only racing one race per year, stick to the Sirrus, maybe with some upgrades like bar ends and lower the handlebar bar. Maybe get some faster 25mm tires ... Gatorskins have their place but it is not at the start line of a triathlon. GP4000s or Specialized Turbos would be a better choice for racing. Then if you start riding more .... hang on to your Sirrus and get a road bike or a tri bike after you get your annual mileage up over 1000 miles per year. See you out there!


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## bwalton (Mar 18, 2010)

Scott in MD, nice looking 08 Sirrus. Currently, I ride (one) Century and participate in (one) Sprint Triathlon per year. With young children I limit my bike training to a 25 to 40 mile pavement ride on Saturday and a 20 mile mountain bike ride up very steep and rocky trails on Sunday for a duration of about 3 months. The only bike training I do on the weekdays (year-round) is 6 mile commute back and forth to work three to four times a week on my Sirrus. Commuting on flat handlebars works great where there are a lot of stop lights. It is hard to justify dropping 1 to 2 grand on a new road bike that may be ridded on the weekend three months out of the year and that is why I’m exploring the idea of converting my Sirrus to drops. Do you think your 08 Sirrus would be as fast as your Tarmac road bike and your Cannondale Slice Tri-bike if it was equipped with the same handlebar setups?


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## AndrwSwitch (May 28, 2009)

That's not a lot of volume and it's odd distribution.

Also, just because some people choose to spend a thousand or two (or ten) on a road bike doesn't mean you have to. I bought my last one for $450. Since you're not doing any massed start road racing, you really only need something you can maintain and that puts you in the right riding position. I've had enough older bikes that I don't want to deal with something that predates 8-speed cassettes anymore. But that leaves about twenty years worth of bikes to choose from.

You're not the only person on the board or who has a life, or young children. (I only have one of those things at the moment, but I hope to maintain this when I have both...) My notional training schedule right now is that I have a nice long mountain bike ride on the weekend, intervals on my road bike on Mondays, either an easier road ride on Wednesday, a track night on Thursday, or both. I also commute by bike, and have run/walk workouts on Tuesday and Thursday mornings and on Saturday. I only ride my bike on one weekend day because I wouldn't get to hang out with my fiancee if I insisted on doing it on both. (And then she might not be my fiancee anymore...)

I think that those midweek rides are important to maintaining fitness for whatever kind of competition I'm doing. For a while, I was saying I'd make Wednesday a mountain bike ride, but I'm probably only doing one or two MTB races this year and since I'm trying track this season, I'd like not to shoot myself in the foot. If I was doing mostly longer events, I'd probably drop the intervals and make Monday a tempo ride and Wednesday a medium-length ride. I'd also do a couple months of build weeks beforehand, so I was at a nice, high volume.

I think three "real" workouts a week, commuting, and possibly a leg-openers ride or something the day before a race are enough for me. Maybe not to cat up in the near future, but to race well within my class. At least, if I'm actually following the schedule. Doesn't do anything when I'm taking a partial differential equations class, that torpedoed everything else.

The point of this being, if all you want is to finish your Century and your Tri each year, whatever. You can already do that, with your current equipment. If you want to be faster, you need to figure out how to ride your bike more. There are all kinds of options - "taking the long way home," using a trainer, getting up a little earlier, figuring out a different distribution of child care, giving up some hours at work maybe...


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## Scott in MD (Jun 24, 2008)

Bdalton, to answer your question ... No. Adding road bars (thus also adding road shifters, plus new 2x10 RD and FD) would make the Sirrus faster but not as fast as my Tarmac. And definitely not as fast as my Slice. I am always surprised, even after three years and a dozen races, how much faster my Tri bike is than my road bike .... It's easily 1.5 to 2 MPH. Nevertheless, the vast majority of my road miles come on the Tarmac. It is much more enjoyable to ride than my Sirrus or my Slice. I have about 1000 miles on the Tarmac so far this year, and only a few hundred on the Slice. 

Also, don't forget that your Sirrus has cross-style cantilever brakes, not standard dual pivot road brakes, so this factors in to plans for upgrading to a road bar.


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## bwalton (Mar 18, 2010)

Scott in MD, let’s say that you add dropped handlebars, road shifters/brake levers, a road crank set with 39 & 52 chain-rings, an 11-25 cassette and a double chain-ring front derailleur to your 08 Sirrus and setup the bike with the same reach (center of BB to the handlebars) and offset (center of BB to the top of handlebars) as your Tarmac. Given these hypothetical modifications, what exactly makes the Tarmac faster than the supped-up Sirrus?

I have read, that a Tri-Bike positions your knees in front of the pedal axles when the crank arms are orientated at the 3 o’clock (right arm) and 9 o’clock (left arm). This changes your pedal stroke from a vertical up and down axis to a slightly tipped forward axis where your diaphragm does not get pinched as much when your upper torso is bent forward with your forearms resting on the aero-bars or your hands on the low drops. Is this why your Tri-bike is 1.5 to 2 mph faster than your Tarmac? How do you balance your diaphragm movement with the aerodynamic drag you create in a more upright position.

Unlike the rest of us, Professional bikers are limber enough to bend their lower backs at a near right angle so they can reach the low drops while pedaling in a vertical axis without restricting their diaphragms movement. Somehow they can squeeze/contort their intestines, liver and spleen in such a way to allow their diaphragms to contract down freely. I wonder how many years on a saddle it takes to train your muscles and guts to adapt to this racing position?


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## Scott in MD (Jun 24, 2008)

Bwalton.... are you kidding me? Intestines, liver and spleen? What are you talking about? 


But ... to answer your question.... look at your earlier post: You asked: "Do you think your 08 Sirrus would be as fast as your Tarmac road bike and your Cannondale Slice Tri-bike if it was equipped with the same handlebar setups? " - Handlebars >>>>No, I don't think so.

Then you asked your your new question, above: "...let’s say that you add dropped handlebars, road shifters/brake levers, a road crank set with 39 & 52 chain-rings, an 11-25 cassette and a double chain-ring front derailleur to your 08 Sirrus and setup the bike with the same reach (center of BB to the handlebars) and offset (center of BB to the top of handlebars) as your Tarmac. Given these hypothetical modifications, what exactly makes the Tarmac faster than the supped-up Sirrus?" >>> Gee, You left out wheels .... but yeah, if you added expensive wheels with fast tires instead of Alex hoops with 28mm Armadillo tires to all that other stuff.... then yeah, the Sirrus would be as fast as a Tarmac on smooth, flat roads, but perhaps not on rougher roads or hills, where the incremental benefit of the Tarmac carbon frame would still give it a little advantage.

Then, if you swapped out the Sirrus frame on the Sirrus with a Tarmac frame, I think the Sirrus would be exactly as fast as the Tarmac.


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## bwalton (Mar 18, 2010)

Scott, take a look at the following frame geometry of a few 07 Specialized road bikes below: Sorry about the column misalignment but the Sirrus measurements fall in-between the racy Allez and the comfy CX Tri-Cross.

Element(s)	58 cm Tri-Cross--61 cm Tri-Cross--61 cm Sirrus--61 cm Roubaix--61 cm Allez
Seat tube (ST)	580	610	565	570	580
ST (CL to CL)	520	530	515	520	530
TT (Horz.)	575	595	590	600	600
BB Drop	67	67	65	70	67.5
BB Height	282	282	280 272.5
ST Angle	72.5	72	73	72.5	72.5
HT Angle	72.5	72	73	72.5	72.5
Fork Rake	47	47	50	49	43
Fork Trail	61	58	53	53	53
Front Center	607	616	626	628	612
Wheel Base	1038	1047	1042	1038	1013
HT Length 170	195	240	235	220
Handlebar 440	440	580	440	440
Stem	110	120	120	120	120
Crank Arms	175	175	175	175	175
27.2 Seat Post	350	350	350	350	350

Certainly my handle bars are too wide.

Here is my Sirrus all decked-out with commuting gear:

View attachment 257556


View attachment 257557


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## the_don (Mar 23, 2008)

Why are you fighting about this?

You obviously really like your Sirrus.

If you want road drops, then you have 2 options,

1) buy all the parts you need and add drops to your bike.

2) get another bike,

If money is an issue, then sell your bike and get a used bike, there are lots of great used options out there.


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## Scott in MD (Jun 24, 2008)

Your Sirrus is pretty cool. Assuming you remove the rack and pack for races, you have it set up as fast as any Sirrus can be, except perhaps you could drop the stem a little (get the bars a little lower), and get some faster tires. Those changes might make a slight difference in a Sprint triathlon if you are a strong rider. But you do need pedals. Clipless road or mountain pedals would make a difference. A big difference ... much more efficient. Anyways, my buddy Greg could beat the tar out of me in a race on your bike versus me on my Cannondale Slice tri bike even with my $2000 aftermarket deep dish carbon wheels, latex tubes, and expensive tires.... because mostly it's about the Indian and not the arrow. No way I would add drop bars to it ... but yes, in my opinion, it would be a little faster because you could get into the drops, and that is a faster place to ride. Would it be as fast as a Tarmac? Who knows? I didn't notice anyone racing in TdF on a tricked out 2007 Sirrus, though. But even if you did you would then have a slightly goofy 22 pound Specialized Secteur, and a lot of left-over parts in your garage, instead of a slightly cool Sirrus. If it were me, I'd spend the $200 on a set of shoes and pedals or a good racing wetsuit. It's a shame to upgrade a bike with less than a few thousand miles and fully functional parts ... is what I think... but if your existing group is wearing out, then probably is a good idea.


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## bwalton (Mar 18, 2010)

My Sirrus has Shimano PD-A520 clip-less pedals. They are classified as a one-sided SPD touring pedal with a wide platform. I use these pedals with my size 49 Shimano SH-M087G-E shoes. This setup works great for road riding because they are super easy to clip in and out of and the SPD shoes are great for walking.

View attachment 257581


A few years ago I rode my friends 2004 Cannondale Road bike around the neighborhood and I have to say it was the most uncomfortable bike I have ever ridden. The CAAD aluminum frame rode incredibly harsh even on smooth AC. And I felt like my upper torso was stretched-out and reaching for my toes just to grab the tops of the drops even though the frame was one size too small for me (56 cm). The TT seemed ridiculously long and the top of the drops were about 3” below the top of the seat. After that ride, I concluded that if I ever got a road bike I would get one with a more relaxed fit like a CX or a plush bike like a Roubaix. Having said that, does the top of the drops need to be 3”+/- below the saddle in order to get your body in an optimal aerodynamic position (i.e. elongate and contort my upper torso forward to cut through the air in order to go faster)? If so, setting up a new road bike with the top of the drops level with the seat (like my Sirrus) would not yield any significant speed gains over my current setup uless I moved my hands down in the drops. Is this assesment correct?


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## AndrwSwitch (May 28, 2009)

No.

First - setup makes a bigger difference than frame stiffness. Your friend's Cannondale had too much air in the tires and the wrong riding position for you. If the frame's too big, there's not much you can do about it. Otherwise, the right reach and the right tire pressure should be able to make it as comfortable as your Sirrus.

Second - there's more to aerodynamics than this... but getting lower isn't the whole story. Drop bars also make you narrower. This would apply even if you kept as upright a position as on your Sirrus. It wouldn't make as much of a difference as having a TT bar, but it would still help a little.

EDITED because I left a few words out typing up with my thumbs the other day.


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## foto (Feb 7, 2005)

I have a similar question. Right now, I can only go 10mph, but when I try to go 15mph, I am so strong, I flex the frame right in half, and it saps all my speed.

Should I get a new bike with a beefier bottom bracket? (I am currently on a CAAD5, and teh bottom bracket isn't beefie at all). I heard that alumnium frames are bad for going 15mph, or riding more than 20 miles at a time. Should I get a carbon bike, or should I just go custom steel to accomadate my massive leg strenght, and help me win the triatholon?


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## bwalton (Mar 18, 2010)

My Sirrus is setup with a Sugino XD 600 crank-set and a Shimano 68 x 113 UN-54 BB. I can rotate the left crank arm alongside (parallel to) the left chain stay (CS) and visibly see the crank arm along with the left side of the BB move about 1/16”(-) in closer to the CS when I wrap my finger around the CS and push the end of the crank arm with my thumb. I do not observe any visible flex/deflection on my mountain bike’s FC-M770 XT (2-piece) left crank arm when performing the thumb push test. I’m not sure it the UN-54’s plastic non-drive side BB cup is compressing or the BB shell. Given that the thumb load is being transmitted axially through the end of the CS it seem more likely the square tapper set up or the BB itself is the culprit. Too bad Shimano doesn’t sell the UN-72 anymore with its aluminum left side BB retaining cup. I can also get my hands on a Problems Solver #54 aluminum BB retaining cup for $20.00, but I’m not sure if it would fix the problem.


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## the_don (Mar 23, 2008)

Sounds to me like you should just go out and buy another bike.

If you want a lower price stiff frame, get an old Klein, They are very light and stiff.


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## bwalton (Mar 18, 2010)

OK I think I get it, my bike accounts for 25% of the aerodynamic drag and my body accounts for the other 75% of the air friction. Generally, a road with its thin profile tubes will not be as stiff as a mountain with its large tube sections. Therefore; a road bike predominately relies on rider aerodynamic efficiency for speed. Which means the rider needs to tip his or her pelvis forward so the spine/back is straight (not hunched over) and angled off the horizontal at a minimum of 45 degrees with the arms stretched forward 90 degrees off the torso when positioned on the top of the drops. And of course the rider’s pelvis and back need to tilt more forward when the hands are grabbing the hoods or the drops.

This morning while riding into work, I tilted my pelvis forward while trying to keep may back straight (angled at 45 degrees) and rode into a headwind at 18 mph with a backpack. The flat bars on my Sirrus tilts my back forward at roughly 30 degrees off the vertical, which creates a lot of air friction on my upper torso. So if I want to increase my mph, than I need to reposition the upper half of my body in a more aerodynamic profile. This will take time for my 45 year old body to adapt to because 1. I am not accustomed to riding in an aerodynamic position for any lengths of time and 2. I am not that limber. Training my hip abductors, hamstrings, back muscles, triceps and neck trapezoids will be a gradual process so I need to start off in a more upright position and gradually tilt my upper body down at steeper angles over time. In other words, I need to start off with a Roubaix, Secteur or CX type comfort road bike and work myself into a racing type road bike like a Tarmac.


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## AndrwSwitch (May 28, 2009)

I would say you're starting to get it.

I'm not sure if the numbers are right, but the idea behind them - that your body pushes the most air - certainly is.

The stiffness thing is a little bit of a fetish among some road (and mountain) cyclists. Most energy that goes into deforming your bottom bracket/chainstays area is returned. If a significant amount was absorbed, the frame would wear out very quickly. Also, the amount of force you're putting into the crank should be relatively small - power is torque*frequency, and cyclists pedal a pretty high frequency - so the ability to deform your bottom bracket area or crank a little bit when you exert a lot of force out of plane with how it's supposed to operate isn't that meaningful. I'd say that as long as you have enough stability from the bike to sprint without weirdness, climb without weirdness, and descend with stability, it's sufficiently stiff. In other words, don't sweat it. The old aluminum bikes with narrow-gauge tubing weren't problematic because of energy loss due to flex. They were problematic because they scared people to descend on and they suffered metal fatigue from too much deformation.

As far as starting with an endurance road bike and then moving up to a real racer - meh. Choose one or the other and stick with it. While a shorter head tube might force you to use a taller spacer stack and higher-angled stem to get the same handlebar position, you can probably still do it. If not, you can probably get the lowest position you'll ever want on an endurance bike by slamming the stem. I really don't think that you need a start road bike and that you'll graduate from it later. At least, unless you buy the wrong one to begin with. If you wanted one and you could afford it, whatever, but as far as getting some free speed in your tri and your century is concerned, any correctly-fitted drop bar bike will be better than what you've got and the difference among different road bikes is going to be pretty minor. If comfort was a big goal of mine, I might still be looking at the endurance class because they tend to have clearance for bigger tires. And that makes a big difference IME. So get the bike that handles the way you like, as long as it'll fit a big enough tire for you, and be happy. If you were to graduate to another bike, for tris it would be a TT bike anyway.


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## bwalton (Mar 18, 2010)

As someone who has been riding dual suspension mountain bikes for the last 13 years up very steep rocky grades, I can say that the rear triangles, the BB shells and the BBs have been steadily getting stiffer with each new refinement. For example, the pipe style BB axle is noticeably stiffer than the tapered axle BB when climbing up a hill out of the saddle. The 2-Piece crank sets with larger pipe axels and outboard BB’s are even stiffer. Likewise, the lateral stiffness of soft-tailed frames have been improving from one generation to the next as well. This stiffness can be felt when pedaling up a hill in granny gear. Drive-train and rear triangle stiffness translates into easier pedal strokes, which means you can shift up one or two gears and increase your speed by 1 plus MPH. Stiffness is less noticeable when riding a mountain bike on a flat seated. I guess a road bike does not need to be as stiff as a mountain bike because the rider needs to stay seated and somewhat stationary in order the reap the benefits of a reduced aerodynamic body profile. How does a road bike’s geometry help a rider up a steep hill, with its narrow drops (reduced pulling leverage), tall gears (which forces the rider to stand on his pedals and mash down on the pedals) and a light weight semi-flexi frame and wheel set?


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## Local Hero (Jul 8, 2010)

JohnStonebarger said:


> It might be counter-intuitive, but frame flex doesn't really cost us any speed -- the frame works like a spring, and energy we "lose" flexing the frame is largely given back to us when the frame springs back (if this wasn't true, our frames would get mighty warm with all that flexing).


Is this true for everything? 

Flexy crank arms, flexy wheels, flexy stem, flexy screwdriver, flexy pry bar, flexy drive shaft on the Buick...

they are all essentially springs with very little energy loss?


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## AndrwSwitch (May 28, 2009)

Hysteresis costs a little energy in any real-world spring.

When suspension gets involved, in which there's a significant amount of travel and a component specifically placed in the system to absorb energy, there's more energy loss. To my mind, that's when it starts to matter.

Improvements in mountain bike technology are making FS bikes suck less. My aspirational bike is still a hardtail, though.


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## bwalton (Mar 18, 2010)

Aside from my first fork, none of my mountain bike components or pivots were isolated or dampened by rubber bushings or elastomers. Given the elastic nature of properly designed brass bushing/sealed bearing suspension pivots, hysteresis would be very difficult to measure or qualitatively feel. The employment of cold forged frame pivot bearing supports with large sectioned chain stays, seats stays and pivot bolts have stiffened up the rear ends of dual suspension bikes considerably. They are not as stiff as a rigid hard tail but they are getting close.


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## AndrwSwitch (May 28, 2009)

Looking at the presence or absence of elastomers and rubber bushings is missing the elephant in the room.

Your suspension fork and shock are designed to absorb energy. That's their job.

I feel like this is quite a tangent, though. Even if you're riding a really lossy frame, on the road, it's still pushing air that makes the biggest difference. Even on a tempo climb. Sooner or later, of course, you spend more energy fighting gravity, but it takes a pretty slow climb. There are sites that break down this stuff; I don't remember the numbers off the top of my head and am too lazy to hunt them down. Although I guess it was Local Hero who was wondering about stiffness anyway, and I think he tries to win massed-start races.

Given the funky geometry of your Sirrus, if you'd ride a road bike with the same top tube length, a drop bar conversion seems feasible. Since your two events are a century and a time trial, I really think any road bike new enough to have 700C wheels and a freehub is going to give you both good service and a little "free speed." There are probably a few serviceable bikes in that group that would cost less than putting drop bars on your Sirrus. And since you like your Sirrus as it sits, I'm not sure drop bars for it would be a good plan anyway.

Or just do the TT extensions and be happy.


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## foto (Feb 7, 2005)

I think the conservation of energy in bike frames is kind of a waste of time, since it isn't really energy that determines how fast you go, its the power. And yes, flexy parts reduce total power transfer. Maybe there is some energy recycling in the bike/frame/body system, but that energy that came out of your legs isn't being used to propel the machine forward, it is energy that is wasted, even if it hasn't gone anywhere.


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## AndrwSwitch (May 28, 2009)

It's still used to propel the machine forward. You can see it as taking the scenic route.


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## foto (Feb 7, 2005)

AndrwSwitch said:


> It's still used to propel the machine forward. You can see it as taking the scenic route.


I though this was about going faster, not staying fresh on a recreational ride around the lake...


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## bwalton (Mar 18, 2010)

What I was trying to say in my previous post, is that I have firsthand experience with power loss caused by rear triangle flex. Granted the old dual suspension mountain bikes I rode flexed a lot more than any rigid (hard tail) rear end so I could really feel the flex and associated power loss through each pedal stroke. Likewise when I climb a steep hill (or ride on a flat above 18 mph) on my Sirrus, I feel a similar strain in my leg muscles during a pedal stroke that I felt with the old flexi dual suspension mountain bikes I used to ride. The free speed I will gain out of a road bike with drops will be from less aerodynamic drag because my torso will be stretch forward leaning down cutting through the air more efficiently. However pedaling up a steep hill in a tall gear will force me to get off my seat and stand on the pedals—so unless the new road bike has a stiffer rear end and BB I will not see any speed gains riding up a steep hill.


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## bwalton (Mar 18, 2010)

This weekend I test rode a Specialized 2012 Roubaix and a 2012 Allez. Both frames were 58 cm and the Allez handlebars are approximately 1”+ lower than the Roubaix’s handlebars. I was surprised how comfortable I felt on the Roubaix with my hands on the hoods and the drops. The Allez handlebar position was a little too aggressive for me because after a quarter mile I could feel the stain in my lower back, shoulders, arms and hands. Even though the aluminum Allez had a tapered BB with Shimano FC2300 compact cranks, it accelerated faster than the carbon fiber Roubaix with it’s outboard bearing BB and compact Tiagra crank-set. The Roubaix absorbed all the irregularities in the road very well while the Allez amplified them. There’s no question in my mind that I would get more free speed out of an Allez but I don’t think I would ever ride it unless started to do a lot of core training. Note both of the bikes tire’s were inflated to 110 psi.


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## AndrwSwitch (May 28, 2009)

I feel like you're not quite getting this - you can put the handlebars on a road bike at whatever height you want them, within a fairly broad range. Same as a mountain bike. And both the width and the height of your riding position matter in terms of air drag.

You can probably raise the handlebars on the Allez another inch if you want to. That's a non-issue if you liked the Roubaix better - just buy it and be happy. But if you liked the Allez better, see if the shop will raise the bars for you, and give it another shot.


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## foto (Feb 7, 2005)

Every one knows the main cause of the "free speed" is the "crank", regardless of how you "tweak" the cockpit. Seriously, though there are better "meth"ods for deciding on what to get for a new bike, this once beats picking out the first thing you see, peering through the "glass" of the shop window.

(that last one was a stretch)


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## foto (Feb 7, 2005)

Just curious if you are faster yet.


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## bwalton (Mar 18, 2010)

I read in Bicycle Science that aerodynamic drag starts to really take a toll on your speed at 7 m/s or 15 mph. Add headwind into the mix and your body become a sail. Riding in drops reduces your total area that pushes against the air, which equate to “free speed” without any extra power input from my legs. I will also join a group ride on Tuesday nights to improve my power output.


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