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Crit bike weight - does it make a difference?(37 posts)

Crit bike weight - does it make a difference?outofthesaddle
Jan 20, 2004 3:21 PM
I'm wondering about the impact of bike weight in a standard industrial park 50 min crit (1.3 mile course). I have two bikes one is about 16 pounds and the other about 18 to 18.5. I've never weighed them but I'd guess that 2 to 2.5 pounds is about the relative difference between them. Does the additional weight make much difference in a 50 min crit? It seems like having to accerlerate the additional 2 pounds or so out of every turn might make a difference by the end of the race. (I understand that I could also just stay in the first 5 for the entire race and avoid this issue but assume that I've dropped to the middle of the pack for a while...)

More on the bikes if it matters. Set up: Bike A is an '03 5900, full DA, prima bar/stem with Ksyrium wheels and Veloflex Pave clinchers. Bike B is a '99 5200, 105 cranks, DA shifters, Ultegra bb & derailleurs, Icon bar/stem with Vector Pro front wheel and Vector Comp rear with Conti GP3000 clinchers. Pedals and shoes are the same for both.
My vote for the stiffest setupspincircles
Jan 20, 2004 3:58 PM
Lots of discussion about this. I believe analytic cycling will let you compute based on wheelset weights and total bike weight the relative advantages. Crits have little elevation gain so linear weight tends not to be that big of a deal. If the heavier setup is significantly stiffer in the BB/wheels/etc. that will more than make up for the weight. Not sure about the rotating weight diff, but the vecs are not that much heavier than the K's and more aero. I'd rather have a 20 lb. rock under me than a 15 lb. noodle come the bunch sprint.
See Kraig Willett's Articleasgelle
Jan 20, 2004 5:52 PM
http://www.biketechreview.com/archive/wheel_theory.htm

He's already considered weight, drag, inertia on Crit performance. Bottom line: weight makes almost no difference, being more aero does.

Regarding stiffness, as long as the deformation is in the elastic range, does stiffness really make a difference? See Sean Kelly's results on a Vitus.
He factors inertia but...outofthesaddle
Jan 21, 2004 11:34 AM
I can't determine from my inadequate math background whether he considers the effect of repeated acceration. He shows an ave power output for the crit 323 watts and he factors the force needed to accelerate the mass but also identifies something like 28 accelerlations.
He factors inertia but...asgelle
Jan 21, 2004 12:32 PM
One of WIllett's examples uses the power profile from a 50 minute P,1,2 Crit, so the results from that case would have as many corner and pack accelerations as might be expected from such a race.
I see that he shows the power and velocity profile from a crit..outofthesaddle
Jan 21, 2004 3:11 PM
but I can't tell from his equation whether he's accounting for the change in velocity (0 mph to the ave speed of 28 mph) one time or whether he accounts for it each time that it occurs (more like 20 mph to 30 mph for every corner) 28 different times. If he hasn't accounted for this then he's grossly underestimated the impact of weight (wheel weight and/or total bike weight).
Power is calculated from Velocityasgelle
Jan 21, 2004 4:45 PM
In the article, Willett uses the velocity profile measured in the crit and calculates the power to produce that speed (he uses the measured power to validate his model). So when speed changes in corners or from attacks (shown in the velocity profile in Appendix D), Willett's model includes the power needed to accelerate the bike and rider (it's the Delta V/Delta t term in his equation in Appendix A). So yes, he has accounted for the 28 accelerations out of the corners.
Ahhhhh - thanks - (nm)outofthesaddle
Jan 21, 2004 7:13 PM
Ever seen the diff between P/1/2 and Cat 4 crit?lonefrontranger
Jan 25, 2004 9:59 AM
The pros don't brake in the corners. Nor do they even slow down noticeably. From what I can tell, there's virtually no "yo-yo" effect in their fields, regardless of whether you ride forward or at the back.

Here's an interesting comparison. Last year, I got the chance to read the PowerTap and SRP outputs from 3 different riders, from the same crit course. All 3 finished okay, tho the pro didn't make the breakaway and the Cat 3 dude made top 10 in the field sprint.

The power outputs (for the bulk of the race, disregarding things like prime sprints and attacks, which show as sharp spikes) for the 3 different riders showed some fascinating trends. The pro guy's power graph for the most part was a very smooth and gentle sine-like curve, with several periods of very high output where he was attacking or chasing, and periods of next to no output, like 10 watts or so, when he was just cruising in the field. His speed was very consistent for long periods of time -- high, but very consistent. However, the key was that you really could not tell where the corners were on the course. The Cat 3's power graph, by comparison, looked like a roller coaster, and each corner was clearly marked by a "0" power coasting spot before each one, and a subsequent power surge coming out. The Cat 4's graph had far longer coasting (or braking) periods going into the corners, with much more marked power peaks after as he sprinted madly to close the gaps coming out of the corners. It looked like a saw blade. The corresponding speed changes for this poor guy were wild swings, so despite the fact that his average speed was quite a bit lower than the pro's, in the end, it seemed that he expended a lot more effort. The most interesting part to me was that the Cat 3 guy mostly hung out in the middle to the back of the bunch, where you'd think he'd have a bigger yo-yo effect, and the Cat 4 was constantly riding in good position (top 10 to top 20), so positioning in this case wasn't saving the Cat 4 much effort -- it was probably his inexperience (first-year racer) that was causing him so much grief.

Both the 3 and the 4 race finished in a bunch sprint, but the Pro/1/2 race (as they typically will) evolved a break that stuck about 3/4 of the way through.

The eventual point to all this meandering is that 2 lbs difference in bike weight really isn't going to matter a hill of beans if you are an inexperienced crit racer. Your technique (or lack thereof) and ability to be efficient through the corners will be the thing that helps or hurts you the most. Most people, regardless of how fit and strong they are, will get dropped in their first few crits from sheer lack of technique.

Ride the bike you least care about trashing and have fun.
the return of the voice of reason n.m.shawndoggy
Jan 26, 2004 11:42 AM
the return of the voice of reason n.m.asgelle
Jan 26, 2004 1:32 PM
Unfortunately, the data doesn't support this. The data for speed, heart rate, and power from the Bario Logan P,1,2 Crit, http://www.biketechreview.com/archive/appd.pdf shows a cyclical rather than constant profile. So while the Pro's might be smoother than lower cat's they still show the same qualitative profiles.
the data don't support that a skilled rider on a heavy bikeshawndoggy
Jan 26, 2004 3:57 PM
will be more efficient than an unskilled rider on a light bike? C'mon man. We all know the dude who "just rides" who shows up to the local time trial on a cross bike and throws down a smokin' time. But put him in a crit, regardless of equipment, and he'll probably get tooled.

Personally in a crit, I've never caught myself thinking, damn, if I had just bought those carbon bottle cages, I'da won.

In fact, my wreck of a bike is probably 21 lbs. I run old school spds because they are compatible with my mountain shoes. But the frame is stiff and the wheels are stiff and I can't think of much else that counts in the sprint.
Huh?asgelle
Jan 26, 2004 5:01 PM
I was responding to lonefrontranger's assertion: "The pros don't brake in the corners. Nor do they even slow down noticeably. From what I can tell, there's virtually no "yo-yo" effect in their fields, regardless of whether you ride forward or at the back."

If you look at the data I referenced, you would see a noticable periodic pattern for a rider sitting in the pack of a P1,2 crit. with respect to speed, heart rate, acceleration, and power. So while experienced riders might be smoother through corners, even at the highest level, there is noticible acceleration. I never disputed the importance of not wasting power slowing and reaccelerating through corners. Sorry if there was confusion.

Now as to your claim "But the frame is stiff and the wheels are stiff and I can't think of much else that counts in the sprint." Where do you think aerodynamic drag fits in and what do you think controls the speed of your sprint?
um, I think you missed the pointlonefrontranger
Jan 26, 2004 5:34 PM
you said:

>>> So while the Pro's might be smoother than lower cat's... <<

That is exactly the point I was trying to get across.

All power downloads from any circuit course will show a cyclical profile (yes, even the pro's power had a sine-wave type, cyclical profile). All courses have max/min power sections, especially if there's a hill or headwind section. Plus I am not talking about the spikes where attacks or prime sprints occur, merely the long "tempo" sections that occur in every crit where the field is pretty much cruising through the laps.

What I was talking about was the radical difference in *amplitude* of those long periods of cyclical (sine-wave) sections on each rider's chart. A more efficient rider (the pro in this instance) has much less amplitude, UNTIL AND UNLESS he decides he needs it - i.e. to bridge, cover a break, attack, whatever. The term is "burning matches" and as you are aware, you only have so many to burn.

The crit I saw the downloads from happened to be a 7-corner, dead flat course on a day when we had little to no wind.

The thing that impressed me most in the differences between these graphs was that, for long periods of time, the pro's data was extremely smooth, i.e. he would go 4-5k (6 or 7 laps) at a time with only about 30 watts variance, and almost no speed variance (less than 1 mph). He also had quite a few long periods where he was putting out astonishingly little power despite the fact that his speed stayed consistently high (this meant he was in superb field position, riding well protected, and expending ~50 watts at most)

The most notable part was that on his graph I had a *very* difficult time telling where any of the corners were, much less all 7.

Contrast that with the 3 and 4. There were 7 repetitive, distinct "lumps" or peaks on each of their graphs, that represented deceleration and subsequent acceleration out of each corner. The amplitude of the Cat 3 guy's peaks weren't nearly as extreme as the Cat 4's - i.e. the "roller coaster" vs. the "saw blade" analogy. I think the 4 had mass-start raced (yes, he is a crossover triathlete) maybe all of six times, and never on that technical of a course, so he was struggling and his output really showed it.

The point I was making is that your TECHNIQUE, not your bike, is gonna save you the most significant amount of effort on a large majority of crit courses out there. If you're smooth, efficient at riding well protected in the pack, and not jamming the brakes going into every corner, then your speed becomes much more consistent, you AREN'T accelerating / decelerating a lot, and therefore the whole light vs. heavy bike debate becomes effectively moot (assuming a flat crit course). "Flat" to me indicates not more than 30' of elevation change over a lap of not more than one mile in length.

I personally feel it's far more valuable for a rider to work on their technique and riding efficiently in the pack than to blow effort and cash on having some unobtanium bike. I won plenty of crits on a 26.5 lb cyclocross bike, by the way. Save your nicer bike (and/or the extra $$ in upgrades) for hillclimbs and hilly road races. Or better yet, use all that spare cash for coaching and entry fees.
Crit bike recipelonefrontranger
Jan 26, 2004 5:56 PM
Recipe for a perfectly good crit bike:

Search the classifieds or the local swap meet for a gently used Giant TCR (aluminum) or Cannondale R1000 (or similar) frameset (~$300). There are so many of these out there that you can often find one in your size that has little to no use at all for that price. Put Ultegra or Centaur (your preference) on it. This level kit sans hubs is available on the 'net for ~$500. Add ITM alloy bars /stem /seatpost and an Excel Cirrus Light wheelset (virtually same weight as Ksyriums at half the price). I highly recommend a hand-built, easily-serviced set of box rim clinchers with non-aero spokes for Cat 4 level crit wheels because these days you can build them surprisingly light and they're not too expensive if (when?) you trash them. Plus I've found that aero' type wheels have a depressing tendency to become a sail (in a bad way) in crosswinds. Also, when you decide to go racing in East Jesus Tennessee and happen to break a spoke or tweak something, it's always good to have something the pit mechanic or Podunksville LBS can service in 5 minutes flat (this would be a good case against using Campag, tho' I'm a dedicated Campag user). Use a Wheels conversion cassette if you want to run Campag.

This recipe builds you a light, durable and serviceable racing machine for under $1500. It might not incite mad frenzies of bike lust in your peers, but you're also not going to waste any grief on it if you break it in half on a curb.

Using this rationale with recommendations from yours truly, a friend of mine found a brand new, never been used 2003 Trek 2300 frame and full Chorus groupset at Veloswap last fall. He got a killer deal on the grouppo and a nice light set of box rim clinchers, and built himself a super sweet light crit bike for less than a grand. YMMV
Thanks for the recipe.treebound
Jan 27, 2004 11:08 AM
Good basic (somewhat upscale at $1500 but good none the less) format for a crit bike. Thanks for the parameters to consider.

And on your comments about smoothness, absolutely dead on accurate.

Have a good season.
$1,500 is the absolute upper end you should expectlonefrontranger
Jan 28, 2004 7:57 PM
I kind of threw that figure out there as a worst-case, assuming you had no spare parts from other bikes / build projects lying around to bogart for it.

As I noted, with a little dedicated digging around, you can significantly lower that number. More so if you already have decent parts lying around (which many of us older roadies do, check with your club / teammates for bargains).

The friend I was talking about in the previous reply (former BMX pro-turned-MTBer looking to start racing crits this season) built his crit bike for just a shade under $950 all told. Granted, my coach gave him a screaming deal on a full Chorus grouppo, but that's the kind of gig you need to try to snag - always try to leverage that friend-of-a-friend kind of thing, it works out more than you'd imagine.

My own personal beater-cum-crit bike cost me all of $400 bucks. I bought my Morgul Bismark frame and fork literally out of a random box of junk at Veloswap. I had all the other parts for it lying around (a mix of late-model Campag 10 stuff). Okay, I take that back, it cost me $470 because it had some stupid non-standard seatpost diameter (26.8) so I splurged on an Easton CF post. Like I said, YMMV
Yes I didasgelle
Jan 26, 2004 5:58 PM
I think we agree on almost everything. The difference seems to be in how we describe the magnitude of the oscillations in the P,1,2 race. I don't dispute the importance of smooth riding.

The reason we got on this subject was that I referred to the computer model for rider power to show weight had almost no impact on performance and someone questioned whether the model took account of accelerations out of corners. I replied that the model did in fact treat them. The question was not how important corner acclerations were relative to other factors, only did the model include these acceleration.
Will you be braking a lot?Kerry Irons
Jan 20, 2004 9:01 PM
Each time you brake, you burn up the kinetic energy of you and your bike. Then you have to accelerate that mass up to speed and you've lost the energy forever. However, if you're coasting into the corners, then you and the bike will slow down less due to the extra KE of the higher mass bike. In this case, you "get back" the energy you put into accelerating things in the first place. There's a slight metabolic penalty because you have to work at a tiny bit higher intensity during acceleration. If you are losing sprints by inches, then the lighter bike is possibly significant. Otherwise, it's not about the bike.
The answers I was afraid of...outofthesaddle
Jan 20, 2004 10:51 PM
I raced the 5900 last year but I guess the 5200 is a better choice for crit racing - I'll cry less if I toast the 5200.
"I'll cry less if I toast the 5200"treebound
Jan 21, 2004 6:11 AM
That's your answer.
I was going to suggest taking both bikes on different days and doing a sort of a timetrial crit just by yourself against the clock on a known course with limited traffic. Then analyze the results and pick the better handling or faster time bike.
But the bottom line in crits does seem to come down to the crash potential aftermath: "I'll cry less if I toast the 5200". Then you'll still have the other one as a backup to finish the season with should worse come to worse. 8|
What got me thinking was a big crash at the Early Bird crits...outofthesaddle
Jan 21, 2004 9:41 AM
30+ riders in the final corner. Larry Nolan (USPS Masters) called it "the worst crash I have ever seen in 17 years of racing my bike!" Roughly 1 rider in 3 went down in that crash. You always think it'll be someone else but when the odds look like that it makes you think twice.
Yep, makes one thinktreebound
Jan 21, 2004 9:51 AM
I was just given a heads-up about an early season road race I was thinking of. Fast, flat, early in the season, lots of crashes. I was then referred to a time trial around the same time. I'm thinking that sounds much better for my delayed conditioning program this year.
Agreed - Don't wreck your favorite bikebimini
Jan 22, 2004 6:34 AM
The differences between the two bikes are minimal and the risks of wrecking are fairly high in a crit.

Aggressiveness, willingness to take chances, and letting the other riders know that your going to hold your line come hell or high water are important in a crit. If you are afraid of wrecking your favorite bike, ride the bike that you are willing to toast.

I have a friend that has turned into a real wennie in races since he got his new Trek (and a lot of the folks know it and take advantage of it).

It's kind of like finding a spot to change lanes on a freeway. You find a nice shiney expensive looking car to cut in front of, never ever cut in front of the old beater or Taxi Cab, they got nothing to loose.
Yes.No_sprint
Jan 21, 2004 10:43 AM
I really don't care what the theoretical numbers say. When I run crits, which is what I do exclusively, I want stiff and light. I don't give a rats @ss about aero. I'll get more aero advantage of riding directly behind the guy in front of me than the 3 spoke Corima compared to my 38mm carbon tubies. I don't care what the numbers say, when doin' a 4 corner crit or 7 corner and feelin' a mushy, frame and/or wheelset every time out of 7 corners over and over again, you'll be zapped more than anything.

I go stiff and stiff and stiff and light. Period. I'll take my non aero tubed, spoked QPro at 16 lbs and stiff and f&*king rail over my aero tubed Italian jobby with Rev-Xs or any other aero wheel any time of the day.

Yes, then there is the don't race it if you can't replace it thing. That is likely many of our first priority.
I'd consider cutting back to two cups of joe a day...shirt
Jan 21, 2004 12:35 PM
But I agree with you. When handling is all-important, which it is in most crits, I'll take the stiff, stiff, stiff, light combo over aero.

Like you, I don't care what the numbers say, because the numbers don't account for railing around corner-pokes on bad pavement, which you spend a large % of your time ("your" is hypothetical, of course) doing in a crit. The goal is to carry as much corner speed as possible in bad conditions, and not be the Seven-mounted dumb-ass braking for 90 degree corners like they see a stop sign. I also consider tubulars an essential part of the crit package, and mine are as aero as an oak tree.

Cheapo Cannondales are popular crit bikes for a good reason.

/shirt
LOL! More Dales in crits than any other manu.No_sprint
Jan 21, 2004 2:35 PM
and as you say, for good reason.
Could anything change your mindasgelle
Jan 21, 2004 1:34 PM
No_sprint writes, "I really don't care what the theoretical numbers say." and won't even consider the anecdotal evidence from the results of Sean Kelly, one of the most succesful pro sprinters who rode one of the worlds most flexible frames.

So I have to ask, is there anything anyone might say to make you at least consider that you might be wrong.
Please consider one thingNo_sprint
Jan 21, 2004 2:34 PM
I'm not talking about the aero advantages of darts vs. blocks.

I'm talking about things like comparing non-aero tubes on my QPro vs. aero tubes on *fill in here's* frames. I'm talking 38mm vs. 48mm rims spoke, etc.

Yes, there are surely times when aero plays a part, however, I'm not going to throw a disk on the back for my next crit. John Doe will be more aero sprinting with open pros and in the drops vs. deep dish aero rims and the hoods. Will John Doe be that much better in a 100 yard sprint with deep dish and in the drops? I'd say insignificant vs. the open pros.
Could anything change your mindSquint
Jan 21, 2004 3:32 PM
Don't try to change his mind. I love it when everyone shows up to a flat crit with their climbing wheels.
Please define climbing wheels, help me out.No_sprint
Jan 22, 2004 9:54 AM
Is that Jan's definition? Your definition? Lance's definition? Please direct me to an authority where the definition is published so that we all may learn.

Are my 38mm carbon tubies with low spoke count weighing in less than Zipps (around 1100 grams)climbing wheels? If so, why, and who says, if not, why not and who says?

I climb with them, I ride on hills and flats with them, I ride them in crits and on training rides, I'm going to be doing road races on them too. Those races have hills and flats.

What about my Nucleons? What about my 420s? What about my Sun semi aero? What about my Rev-Xs? What about my true French Open Pros with non-butted spokes and no ceramic? Man, I've climbed hills with all of them and done crits with all of them.
Please define climbing wheels, help me out.Woof the dog
Jan 26, 2004 5:52 AM
Mavic gel 280s on american classic hubs are definitely not a crit material. They are just that: climbing wheels made for smooth roads.

as;lfdkjasdl;fkjasdfojkasd
woof.
Sean Kelly is completely, totally and utterly irrelevantshirt
Jan 21, 2004 5:24 PM
Great rider, sure. Manly. Beefy. No whining.

But Sean Kelly didn't specialize in 50 minute industrial park crits with bad pavement and enough bots dots to shake your teeth out.

Light and stiff AL and CF is the way to go for these. If you're a manly-man like No_sprint, anyway. Or a little turd like shirt.

/shirt
Sean Kelly is completely, totally and utterly irrelevantSquint
Jan 21, 2004 6:04 PM
So how much power do you waste re-accelerating a heavy frame in a crit and how much does a flexy frame "rob"?

Wouldn't suspension deal with bad pavement and bots dots better?
Flexy frame gives the energy back.Spunout
Jan 23, 2004 7:15 AM
If you were to flex a BB a few degrees off and it stayed there, well, you would have lost energy. Never seen that.
Flexy frame gives the energy back.Woof the dog
Jan 23, 2004 9:15 AM
if you spend your energy flexing the frame to the side when powering it up to speed, it will flex back, but it will do nothing to propell you forward because we are talking different directions for flexing vs riding here.

god.
It seams to me that a crit comes down to one acceleration...TFerguson
Jan 22, 2004 2:47 PM
and when that criitical time comes, it's up to you, not the bike.

TF