carleton

It's been discussed a lot and I'd like to know your thoughts.

I see people get caught up in numbers and fret over grams. Then I hear,

- "Weight doesn't matter on the track."
- "You aren't climbing hills"
- "But weight does matter in mass start races with multiple speed changes"
- "Weight is momentum"

Then in my experience, there aren't that many light track bikes. Of every bike I've owned, guess what the heaviest was the 2010 Felt TK1 with Mavic Io/Comete, SRM with Easton EC90 bars coming in at just over 20lbs. It was 3lbs heavier than my Tiemeyer which was 17+ lbs with the same kit. I didn't notice any performance difference on the track (I was still slow, hahaha) (more on that later).

I've grabbed a 57cm BT and it felt heavier than any bike that I've ever handled. I think it was @taras0000 old bike...the one with the unique paint job, right? (cycling is a small world)

Check this out...I recently borrowed TheBlackBullet's 61cm Snyder Cycles steel bike and guess what...it was only 1lb heavier than my 58cm Tiemeyer. I did not expect them to be so similar in weight.


On a related note, I think relative weight of bike to rider is more of a factor than absolute weight. Think about that for a sec. Example:

Rider A:
- Body weight + clothing, shoes, helmet, etc... 140lbs / 63.5kg
- Bike weight 15lbs / 6.8kg (UCI minimum)
- Bike is 10.7% of the rider's weight.

Rider B:
- Body weight + clothing, shoes, helmet, etc... 200lbs / 90.7kg
- 10.7% of 200lbs / 63kg = 21.4lbs / 9.7kg

So, for Rider B to have an equivalent bike/rider ratio as Rider A, Rider B could ride a bike that is 21.4lbs / 9.7kg.

So, what's your take on all of this? Is my logic sound? Thoughts on the other stuff above?

Is a nice rule of thumb that a bike that is 10% of your body weight a fair target to shoot for?

carleton

The converse of that is:

Rider B:
- 200lb / 90.7kg body weight
- 15lbs / 6.8kg bike
- Bike is 7.5% of body weight.

Rider A:
- 140lbs / 63.5kg body weight
- 7.5% of 140lbs / 63.5kg = 10.5lb / 4.8kg bike!

dunderhi

I agree it's all relative to a degree and maybe proportionality is a good measure, but I think where the weight lies is also really important. It's easy to rotate between two sets of wheels and feel a difference. So saving 100 grams of tire or rim weight is far more important than 100 grams in the seatpost or seat. The question I ask myself when selecting components is if a part weighs/costs more or less than another component what are the differences in stiffness, durability, and overall performance. Take carbon vs aluminum bars for example: It appears this would come down to lightness vs stiffness? Do some models have both advantages, but maybe at a higher much cost? Is the money for those bars better spent elsewhere like ceramic bearings? Then again, people might just buy both.

carleton

Of all upgrades, it's been shown that ceramic bearings provide the least benefit per dollar spent. The benefits over normal quality steel bearings are negligible and could probably be lost in measurement margin of error.

dunderhi

I haven't heard of this before. So, are you saying that spending an extra couple of hundred bucks on a lighter seatpost and seat will get you more than a minute in a 40km time trial? For me, a ceramic BB pays for itself in longevity alone since even Dura Ace bearings only last a single road season for me.

bitingduck

Weight doesn't matter on a track bike because you can easily get below 6.8 kg without trying, and then you have to start adding weight back on somewhere.

I've never been a weight weenie and had some of my best results on an old steel pinarello frame that they didn't even weigh at nats-- the official picked it up, looked at me and chuckled, and then moved it onto the track. I've had a couple of bikes since then that I had to add tens of grams to (electrical tape was enough).

If you're going to play games with where you put the weight, minimize what's near the OD of your wheels (rims, tires). If you're still under 6.8 kg, put any extra weight high up on the frame (though it will hardly make a difference out of the total weight or angular momentum anyway).

carleton

maintenance - Real measurable benefit to ceramic bearings? - Bicycles Stack Exchange

Note the guy who replied. "R Chung" is probably Robert Chung (a scientist I think).

More from Chung: https://anonymous.coward.free.fr/watt...direct-cda.pdf

I think he's a member here too.

carleton

I agree with both of you about trying to keep the weight away from the circumference of the wheels.

taras0000

Weight matters for acceleration, but a balance of power transmission/weight has to be taken into account. Light but flexy is at one end of the scale, heavy and rigid is at the other. The key is the balance point for each rider somewhere in between. If rigidity can be maintained while losing weight, then it does matter.

You're climbing a hill every time you get ready for a sprint, F200, or an attack in a mass start race. It matters there.

F=M(A). Consequently, (A), acceleration is affected by mass. This cuts both ways, when trying to speed up, and slow down with the group. The less Force required to achieve the desired acceleration, the better.

True. How effective this is, I don't know. Like your ceramic bearing example in an above post, I believe that there are other aspects of the rider/bike set-up that have a greater effect on speed than momentum. More effective when it's a flywheel effect than a linearly travelling mass. Although it's costly to accelerate that same flywheel. Most likely a net loss in the end.

It was my bike and it's now WHITE! So heavy! But you can't flex that thing if you tried, it's so overbuilt. Although they have gotten lighter (in some cases, like the UKSI or FES bikes, very close to the UCI Limit), most high end track bikes geared for sprinting are still built with a nod to stiffness over weight. Weight matters more now than it used to when it came to sprinting because sprint tactics have changed. It used to be that most of the cat and mousing took place high up on the track at slower speeds with a rapid acceleration steeply down the bank. Now we have high speed rolling start drag races where most of the moves are initiated closer to the stayers line, with a more horizontal progression, therefore less gravity helping with your acceleration.

Volume of material. Lot's of aluminum in the Tiemeyer compared to any steel bike (except Darryn Hill's, and yes, I am absolutely in love with that frame).

At 10%, I would be riding a 22# bike, so it's reasonable, but if I could ride something as stiff as my old Cyclone at 17 lbs, then I would definitely go for that. My road bike was 19# with two full waterbottles on it and a full 105 group, so with today's tech available a mass produced carbon track machine strong enough for sprinters should easily come it at 17# and still be reasonably priced.

dunderhi

I've some seen several 5-10 Watt measurements and as a scientist myself (Dunderhi Ph.D.) I know that a 5 Watt difference is a 5 Watt difference whether or not it is perceived by a rider. As I said previously, I do prefer ceramic bearings in the BB for their sigificant durability advantage, but given my current capabilities, I haven't put them in my wheels. I've bought Aero goodies instead. Now, if I was racing at the top level, ceramic wheel bearings would be well worth it to me performance-wise. It's a heck of a lot easier to "buy" 5 Watts of savings than to "train" 5 Watts more of strength, especially at my age.

carleton

Taras,

What do you think about "Momentum" during time trials. So, whatever I spend getting the bike up to speed, I get to use at the end of a 500M or Kilo when I'm fading. Thoughts on that?

Yeah, Mr. Tiemeyer took my weight as strength into consideration when he made my frame. He said he used thicker tubing even though it looks the same as others from the outside.

I'm not disputing you. This is sort of a theoretical question: Where is the point of diminishing returns with a lighter bike? Let's say an 185lb omnium guy. When will a lighter bike start being detrimental? 13lbs, 10lbs, 5lbs, 3lbs? Or is "As light as possible" always the answer (assuming that everything is safe and performs as expected)?

It's difficult to separate the wheat from the chaff when it comes to this stuff because a lot of it is marketing hype to sell stuff and a lot of it is over-zealous buyers who must have the "lightest and fastest (tm)" thing (i've done this)

Let's say I ride a 11.5" flying 200 on a 20lb bike. Would that same effort be faster if the bike were 15lbs?

I also like the idea of buying speed where you can. I think that ceramic bearings aren't worth it. Mainly because they are not a sure thing as the results aren't nearly as conclusive as with skinsuits, aero helmets, etc... But, my wallet is *definitely* and *conclusively* several hundreds of dollars lighter

5 watts is under the +/- 2.5% wattage margin of error that power meters have. Any time differences you may experience would be insignificant. I think it's a placebo, in my humble opinion. It's a way to get an extra $250/wheel (Zipp's MSRP) from the "buy speed" triathlon customers. If I'm looking for that last thing to fine-tune after I've already bought everything, that $500 could go towards wind-tunnel testing being that wind, not friction, is our biggest enemy

dunderhi

I'm not sure what is inconclusive about the data, since even the link you provided stated nothing different that what I have read in the past: 5-10 Watts. Anyway, the data is out there for everyone to consume, so do whatever what works the best for you. I wouldn't dream of dropping 4 bills on a set of carbon handlebars, but some people do in the belief that that is a critical place to spend the extra bucks.

gtrob

Plugging random numbers into Analytic Cycling, Interactive methods for estimating cycling performance., setup a 1:03 kilo, if you add 5kg, or 11lbs, it adds roughly half a second.

Half a second is a lot in a kilo at that level, however 11lbs is a LOT weight. Throw that on a roadie and hes now getting dropped on a climb vs leading it out.

To that, I think weight is a lot more perception than actual speed on the track. Even in wheels. I love love love the weight my race wheels feel because they feel like they spin up faster, they are smoother, etc etc. But in reality, its probably the rolling resistance of the tires and the fact I ride so much, that 2% faster feels like a lot. I think a 20lb bike vs a 16lb bike will feel a lot slower, but in the end likely isn't much slower at all, even in those fast accelerations of attacks, standing starts, etc. But perception can translate to speed too.


FWIW, my Aluminum 58cm Cervelo T1, Zipp 900, carbon pursuit bars, was only 1lb over minimum weight.



And I agree that all the data out there is very skewed, very bias, and written specifically to sound more than it is. Not saying its not true, but this is an industry that relies on selling us new stuff constantly. They are marketing the new sram wireless derailleurs as an AERO benefit. Seriously, imagine the power savings of not having a 1mm wide, 6in cable sticking out of the chainstay, so much speeedz! So many seconds saved in a 900km TT!!

Baby Puke

Re: Ceramic bearings, they don't have to be that expensive. Go straight to the bearing manufacturer, Zipp posts the dimensions of the bearings right on their website. I just ordered a set for my 900, about $60.

TurtleRacer

As the first law of thermodynamics says - "there's no such thing as a free lunch". The momentum that you get isn't free - it's just energy you spent earlier. All else being equal, being lighter will always be as fast or faster - depending on the event.

Longer events that have more accelerations / decelerations are going to cost more energy for heavier bikes (you don't want to have to waste energy spinning up/down that excess mass).

Weight wouldn't matter for an event like a flying 200 (provided the bike wasn't so heavy that you couldn't get it up to speed for your effort): an f200 is an all-out max anaerobic effort - and the acceleration to get up to speed for your f200 doesn't really sap that power*. So if you could do a flying kilo with a few easy aerobic laps to get up to speed, that momentum would be beneficial.

If the stiffness/aeroness are equivalent, a lighter bike would be faster, of course they aren't and that makes this difficult.

I'm not sure about the benefits of ceramic bearings- but it should be easily scientifically testable/provable. Does anyone have any links to any papers demonstrating their superiority?

*I could be wrong about this, I'm a noob

taras0000

I don't really think that any of the things we're discussing are super critical in the differences they can make. They're really only applicable in situations where you are chasing the next 0.001 of a second (a masters rider who is getting a bit slower every year and looking to hang onto every second he can, or an elite who is maxing out his training/physical capabilities). I believe that lighter is better, but I also would only take lighter weight if strength/stiffness weren't sacrificed.

I'll approach this purely from a physics standpoint, cuz I hate to listen to the marketing BS. As far as the overzealous gearheads, they can use whatever reason they want to justify their purchases. It's their satisfaction and their money. If they get some fulfillment and/or a psychological benefit from owning the equipment, then they are better off.

The momentum thing seems to make sense on paper, but it won't help you at the end of your TT, it helps you in the middle. People think of flywheels and how long it takes a heavier flywheel to slow down, but a flywheel isn't used to prolong energy in a system, it's used to make a system more efficient when it's at operating speeds. A cyclist's operating speeds is during the "meat" of a TT, when they are cruising. Also, that flywheel doesn't have to deal with wind resistance the way a cyclist does. The flywheel effect is helpful only when you have the energy available to keep your speed constant, ie: you are still fresh enough to overcome the wind resistance on your own. It helps you through the dead spots and lessens how sharply you have to apply force to the pedals each time around. As long as you didn't waste too much energy getting it up to speed, it should make your cruise more efficient, therefore prolonging the time it takes you to die. If you are dying near the end of a TT, it won't help you because now you are going slower, or are having to apply more force (perceived) to keep the same speed. This means you are dealing with negative acceleration while expending more energy. In this instance you are now doing what you did at the beginning of the TT, trying to accelerate a heavier mass. Lighter equipment is more beneficial at the start and when you are dying. In a short 500/Kilo TT, you are dealing with trying to accelerate the whole time, from start to finish. Flywheel is detrimental in this situation.

To answer your theoretical question for the 185 omnium guy, when the power transmission losses are greater than the performance gains due to weight loss. So we kept taking material away from his bike, lets say 100g at a time. He got faster each time but the bike got noodlier. We took away another 100g, but this time he went slower than last time. You went one step too far in the weight game. This point will be different for each rider.It would also be different for each piece in the equipment puzzle.

In the F200 scenario, I would guess that your time would be the same, but that's dependant on how you accelerate. If you were to jump on the 15# bike like you did on the 20# bike, then I would think you would be slower.

Momentum = MV or Mass x Velocity.
Acceleration, A=V/t
F=MA, therefore A=F/M
Ft=MV
More acceleration means more velocity for the same time period. To double velocity requires 4x the energy. More momentum, requires more mass/same speed, same mass/more speed, or less mass/much more speed. All mean more energy expenditure (power), much more energy expenditure. When power is finite, I think more is to be gained from lessening the effect of energy expenditure on speed, and that is most effectively done by becoming more aerodynamic.

carleton

Thanks, guys! These are definitely perspectives that I'd never heard.

(I'm going to have to re-read these a few times for them to sink in)

Oldan Slo

If you look at power data from a f200, peak power is generated in the acceleration phase before the timing strip so that max velocity is generated soon thereafter (ideally so that the speed crossing the start/finish timing strips are identical.) A lighter bike would accelerate to a higher speed given the same power profile which would result in a faster time.

Oldan Slo

The solution is simple. Rider B will be faster on a 6.8 kg bike than a 9.7 kg bike. If I'm Rider B, my goal is to beat Rider A within the rules.

A fair target is that the bike should weigh 6.8 kg for riders of any weight.

Oldan Slo

A heavier bike is a detriment at all times in a TT. If you're analysis was true, then the hour record attempts would be ridden on very heavy bikes since the acceleration phase is short compared to the cruise phase.

TurtleRacer

So I did some reading on bearings, and I spoke with a mechanical engineer who works in machining - ceramic bearings are advantageous in high load, high temperature settings - neither of which apply to cycling. Also, bearings come in grades- and a higher grade bearing will perform better than a lower grade bearing in a bike (regardless of material). From what I read full ceramic bearings are superior (ceramic bearings and races) but they are not common since the races can fracture when being used in press-fit applications.

TLDR: it's not just the material used, but the fabrication matters as well. Just like frame construction trumps materials.

Ball (bearing) - Wikipedia, the free encyclopedia
ABEC scale - Wikipedia, the free encyclopedia

dunderhi

Thanks for the update, but I guess it comes down the definition high loads. I have destroyed BB and rear wheel bearings on almost an annual basis, so I would suspect my bike bearings are subject to high loads. I have found the steel bearings in Shimano Dura Ace hubs hold up quite well to my loads, but many others don't. On the other hand, Shimano Dura Ace BB bearings don't last a year for me. I have found the same to be true for SRAM, FSA, and Trutativ steel BBs. I have had much better success with ceramic BBs. Now none of the may apply riders in the <220lb range, but it is an indication of the overall limit of the system.

carleton

I had a set of Dura Ace training wheels from 2010 till a few months ago when I traded them to my good friend. They held up fine. Always smooth. I'm 240lbs and ride on a bumpy track (DLV) and rode those wheels every track day for training and warmup on race days. In all of those years I can only recall cleaning and repacking them once...when I was bored one day.

I'm not doubting you, I just wonder why those bearings are failing under you but not me. Could it be the atmosphere of your region? Do you live near water?

Also, I don't think ceramic bearings are stronger than steel. I actually think they are weaker or more brittle.

dunderhi

As I've already posted, I've done well with Dura Ace hubs. So my experience is not counter to your own. FSA, Mavic, White, & Fulcrum hubs have not held up too well for me, but I'm not talking about hundreds of training/warm up track miles per year. I'm talking about a 5-10k mi/yr rider who, with serious dieting, is almost down to a "svelte for me" 240lbs. I have weighed as much as 350lbs (325lbs on average) and my local rides have ~80ft/mi of climbing. To help quantify that number, my ride today had about 3100ft of climbing maxing out at a 12% grade, so I put some serious stress of my equipment. (Yes, I plan to do a few road races this year.) Frames, chains, crank arms, pedals, BB axles, bearings, rims, spokes, hub flanges, seatposts, and seats have all failed for me at one time or another. Does this make a difference to sub-200lb rider? Not at all, but as guy who has tested bicycle parts to the limit of failure, I feel pretty good about my knowledge of what is stronger or weaker. I haven't had a ceramic BB fail yet, so I am going out on a ledge and drawing the conclusion that ceramic BB bearings are not weaker or more brittle in real world usage.

TurtleRacer

Just curious - have you inspected your bearings to see how/why they failed? Or were they worn? deformed? One big advantage ceramics have over steel is corrosion resistance (and low friction in the absence of lube). Do you ride a lot in wet conditions? I don't doubt your experience - and I'm a big believer that anything that keeps your bike on the road and out of the shop is a worthwhile investment.

BTW The 'high loads' my mech eng friend was referring to was in the thousands of lbs of force, multi-thousand rpms, or hundreds of degree temperatures - so not your typical (or atypcal) biking conditions.