Wheels

Thylacine said:

I love scientists and engineers. The never have a handle on the big picture (and by that I mean wholistically, not 'Big Bang Theory'. 🙄😉

Oh man. That clarifies everything.

Will the Mods please post a sticky saying that iffin' people are lookin' for the handle on the big picture that they should get hold of Thylacine? He got it goin' on. He's got The Handle.

Good, now we can put that whole science thing to rest and get back to doing all the things that were just right, like aging tubular tires, crankin' up tire pressure to the max and riding 19mm wide tires, and get everyone back on steel like they're supposed to be. Dang it: it's about time. 🙄

*laugh* Got Issues?

Thylacine said:

*laugh* Got Issues?

Got a sense of humor?

Gee, an example of an "absolute"...Newton sat under a tree, an apple hit him on the head, gravity is the culprit, seems pretty absolute to me, never been disproved. Unless, of course, Alienator has a different explanation.

Make my wheels light and to go, please.

I dunno, I looked back at all your other posts, and all I can really deduce from your last two posts is thinly disguised spite which you're now trying to dress up as humour.

If the popularist nature of my post offended you, please, resume the previous tome of this thread. You'll get no resistance from me.

Just don't expect anyone to find the juvenile "My PhD is bigger than your PhD" slinging match funny or informative.

Oop, look at that. Think I just had what they call it a 'micro sleep'. Must be boring myself already. Time to press a button.

Thylacine said:

I dunno, I looked back at all your other posts, and all I can really deduce from your last two posts is thinly disguised spite which you're now trying to dress up as humour.

If the popularist nature of my post offended you, please, resume the previous tome of this thread. You'll get no resistance from me.

Just don't expect anyone to find the juvenile "My PhD is bigger than your PhD" slinging match funny or informative.

Oop, look at that. Think I just had what they call it a 'micro sleep'. Must be boring myself already. Time to press a button.

Dunno about that thylacine and alienator, hard to keep track of these posts. They, apparently, aren't showing up in the same order as they are written. Makes it difficult to follow the thread. This one appeared before I responded to another, and alienator has several postings in a row, so it is difficult to follow what has been responded and to whom.

My contention and my only contention is that light wheels work. However, Science guy disagreed and said that they are unimportant in the total scheme of things. The rest of the thread is total nonsence as far as I'm concerned.

I agree, lets get back to aging tubulars (mine certainly qualify in that they are 25 years old!), and steel is real.

Listen to Alienator when it comes to wheels. newton may have been hit in the head by an apple, but what does that have to do with light wheels? 300g in a 75kg package is 0.4% of the total weight giving you even less of a speed gain talking about climbing, because (guessing from basic physics) it is much closer to horizontal than vertical and there are other resistances. Aerodynamic wheels will gain more of a percentage in speed (though it should still be very low) than weight, unless you are going slow up an 8%+ (steep) hill.

bobbyOCR said:

Listen to Alienator when it comes to wheels. newton may have been hit in the head by an apple, but what does that have to do with light wheels? 300g in a 75kg package is 0.4% of the total weight giving you even less of a speed gain talking about climbing, because (guessing from basic physics) it is much closer to horizontal than vertical and there are other resistances. Aerodynamic wheels will gain more of a percentage in speed (though it should still be very low) than weight, unless you are going slow up an 8%+ (steep) hill.

Well said. Nice summary. If there are disagreements, first attack the calculations and measurement methods before you attack the conclusions... When I do that, I often find that I was wrong.

For example, it was completely non-obvious to me that spoke tension has little to do with lateral wheel stiffness. Rather than reject the conclusion, I studied up on beam stiffness and material properties under tension. Then it became obvious that the conclusion was correct and my initial assumptions were wrong.

Or, we could get back to the rhetoric and polemics... That's probably more fun. 🙂

John Swanson
www.bikephysics.

Uhhm, my head hurts😄
In motorcycle roadracing, we decreased wheel/tire weight as much as possible. A lighter wheel will cause the bike to turn in & straighten up out of a corner quicker, easier & is more stable on turn in. Acceleration & braking also changes for the better but I'm talking speeds a bicycle will never see.

Lionfish said:

Uhhm, my head hurts😄
In motorcycle roadracing, we decreased wheel/tire weight as much as possible. A lighter wheel will cause the bike to turn in & straighten up out of a corner quicker, easier & is more stable on turn in. Acceleration & braking also changes for the better but I'm talking speeds a bicycle will never see.

To quote Enzo Ferrari: "Aerodynamics is for those who can't build engines". Cyclists are very engine limited and have to pay a lot of attention to aerodynamics. Weight, not so much. Consider that a motorcycle weighs much more than the rider and a bike weighs much less than the rider. Weight is a much bigger concern for handling for the motorcycle for that reason.

John Swanson
www.bikephysics.com

Thylacine said:

I love scientists and engineers. The never have a handle on the big picture...

Funny, I've made my living as a systems engineer for the last 20 years. My entire career has been a question of looking at the big picture, the interactions and the tradeoffs associated with different technologies, algorithms and components. It's exactly that perspective that made it so clear why a couple of hundred grams of weight on a bicycle, rotating or in linear motion are all but neglible compared to 70 to 80 kg of total mass. Sure it could be the margin of victory for one of the top competitors, but how many light weight wheelsets are sold to folks finishing in the middle or lower half of the field? How many weekend warriors agonize over a hundred grams of weight because it's out at the rim and is going to kill their 10 hour century time. The folks marketing wheels must laugh all the way to the bank when a cyclist weighing in at 20% body fat plunks down a grand or more for their ultralight wheels. Your point about the psychological value of light gear is valid, the placebo effect can be very powerful, but the extreme measures some folks have taken to lose a few grams here and there are crazy. I started racing during the "drillium" days where everything from brake calipers to seatposts and steering tubes looked like swiss cheese, yeah I saw a lot of those parts broken some with disasterous consequences.

Mercian said:

Gee, an example of an "absolute"...Newton sat under a tree, an apple hit him on the head, gravity is the culprit, seems pretty absolute to me, never been disproved. ..

In addition to physics, you might want to brush up on history. The story of Newton being hit on the head by an apple and having a gravity revelation is a myth, a convenient story to introduce concepts to grade school children. It never happened!

Alienator and the others are right, physics is anything but absolute. Physicists regularly make simplifying approximations where higher order terms are dropped for convenience. A great example is Bernoulli's equation which describes forces and energy in flowing fluids which is key to understanding aerodynamics in cycling. Terms that are sufficiently small are simply dropped for convenience sake. It's done all the time in various physics problems.

In engineering we take a step further and introduce tolerances to account for the lack of absolute repeatability. We do things like montecarlo analysis to investigate the randomness of manufacturing processes and thermal variations. In my field (radio frequency propagation) we work in stochastic processes which are randomly time variant and can only be described statistically. I can't tell you the exact signal strength at your cell phone at any given moment in time regardless of how well we try to define the environment, but I can give you coverage statistics useful for planning the network and determining if we need additional power or cell sites or different antenna configurations. That's a long way from cut and dried absolute answers but a realm many scientists and engineers work in every day.

-Dave

Mercian said:

...I can see this is proceeding into absurdity with the assertion that a heavy mass doesn't take more work/force/energy to accelerate than a light mass. You should tell that to my legs when I'm accelerating my sub 16 lb race bike vs my 21 lb training bike. ...

No one is arguing that the additional weight doesn't require additional energy to accelerate or to lift up a hill. The question is whether it takes enough addtional energy to be worth caring about. If you flex your fingers occasionally during a ride it also takes additional energy relative to keeping them still but do you worry about it?

Adding 5 pounds as in your 16 vs. 21 pound example starts to get noticable assuming you're relatively light. That might represent a 3 or 4 percent change in total weight but couple of hundred grams is pretty insignifigant compared to the total weight you have to accelerate or lift for most folks. You complained that folks digressed into aerodynamics, but you have to consider all the forces you're trying to overcome and at higher speeds aerodynamics dominate. There's a great example over at analyticcyling where they compare a heavier aero wheel and a lighter box section wheel coming out of crit corners. Even in that case where acceleration is key the heavier aero rim wins out in the first hundred meters. Check it out: analyticcycling.comWheelsCritCorner Page.htmlOpen ↗

Sure weight matters or we'd all be riding around on fifty pound road bikes. The question is whether small weight changes are worth the tradeoffs (less aerodynamic as a rule, often less stiff, often less durable). If you want to save weight leave your water bottles home for a long race on a hot day. You could save a pound or two that way, is it worth it?

Thylacine said:

I dunno, I looked back at all your other posts, and all I can really deduce from your last two posts is thinly disguised spite which you're now trying to dress up as humour.

If the popularist nature of my post offended you, please, resume the previous tome of this thread. You'll get no resistance from me.

Just don't expect anyone to find the juvenile "My PhD is bigger than your PhD" slinging match funny or informative.

Oop, look at that. Think I just had what they call it a 'micro sleep'. Must be boring myself already. Time to press a button.

What PhD ib bigger than your PhD slinging?

There is good information and bad inforamtion. If people point out errors in bad information, what is wrong with that?

For a while now bicycle and component manufacturers have pushed the "light is right" mantra, and to a large degree, buyers have bought into that idea. Buying light components because you want to because it's interesting to make your bike light as possible or because you're just a gearhead is one thing, but buying light stuff because you're new to the market and have been lulled by the hype is entirely different.

Since you enjoy reading past posts, do a search and see how many times some new person has asked about buying light wheels or a lighter crankset or a lighter frame because they mistakenly believe that said light bits will offer a distinct performance advantage. Scientific explanations help show the fallacy in that "distinct performance advantage." Moreover, I can't think of any scientists or engineers that have posted anything that suggests there isn't a psychological component to riding and that said psychological component can't trump any very small advantage from a wheelset that is 200g lighter or a frame that is 2lbs lighter.

The nice thing about the scientific explanations is that if you don't like 'em, you don't have to read 'em. It's pretty simple, really.

Spite? Really? I'd call it sarcasm, exactly the same stuff you displayed in your little slap at science. No different at all.

The only way that things are shown to be myths are via science. That's it. Now, maybe it would be better for people to blithely go about their daily doings with all their myths and misconceptions in tow.....well that's always an option.

[quote="...... If you flex your fingers occasionally during a ride it also takes additional energy relative to keeping them still but do you worry about it? QUOTE"]

Now THAT'S funny! And, a well put illustration I might add! (well, now I DID add)😄

...though I LOVED a quote in the march issue of Bicyclist Mag. "Don't buy upgrades; Ride upgrades." SO true...and very relevant to keeping $1000.00+ upgrades in perspective. The Motorcycle industry rams "Faster-Lighter" down everyones throat meanwhile the skill level of riders remain unchanged making any upgrade as unnessesary as the bike they're already on. In my cycling, I'll focus on "Me" rather than the bike for improvment. Once I run out of Breath or Legs then any upgrades I've paid for are useless.

Going back to the OP's question. In relation to stiffnes, are there significant differences between wheelsets that are worth worrying about?

I have seen on a website that people have linked in the past [see below] containing data on the stiffness or more specifically the lateral flex, of various wheel sets, but what does this mean in real world terms? How much power is lost via this flex? Are there a handling differences you can notice? Thoughts, comments, opinions....or even facts?

http://www.rouesartisanales.com/article-4934445.html

Tapeworm said:

Going back to the OP's question. In relation to stiffnes, are there significant differences between wheelsets that are worth worrying about?

I have seen on a website that people have linked in the past [see below] containing data on the stiffness or more specifically the lateral flex, of various wheel sets, but what does this mean in real world terms? How much power is lost via this flex? Are there a handling differences you can notice? Thoughts, comments, opinions....or even facts?

http://www.rouesartisanales.com/article-4934445.html

Lateral wheel stiffness measurement is very is to make as it is a static measurement. There isn't a correlation of power lost through flex, but it is helpful to have sufficient lateral stiffness so that your brake pads don't rub and/or any spoke go slack and not support the rim. (The wheel isn't the only thing that flexes. The frame also flexes and the combination will impact how much relative movement there is towards or into the brake pads. Power loss can be significant in instances where the rider is out of the saddle and pedaling up hill, throwing the bicycle side-to-side and having the pads rub with each pedal stroke... I haven't looked into what happens on disc brake bicycles in this situation.)
Rider weight will effect how much the wheel will flex and conditions the rider subjects the wheels will also have impact on the amount of deflection. Most rim deflection comes in the radial direction and is due to rider weight.
There are a lot of ways to increase lateral stiffness:
increas number of spokes
increase spoke gauge
increase rim weight
increase hub flange spacing
increase rim height
Comprimises must be determined for aerodynamic performance, durability, matching the rider's range of applications, priorities, safety, etc.
Like any other parameter, it must be looked at in combination with others to make an informed decision.

this is another good link to similar stuff

http://www.biketechreview.com/archive/wheel_review.htm

I haven't read all of it yet, but I think the above is an updated version of this:
http://www.biketechreview.com/archive/wheel_theory.htm

Tapeworm said:

Going back to the OP's question. In relation to stiffnes, are there significant differences between wheelsets that are worth worrying about?

I have seen on a website that people have linked in the past [see below] containing data on the stiffness or more specifically the lateral flex, of various wheel sets, but what does this mean in real world terms? How much power is lost via this flex? Are there a handling differences you can notice? Thoughts, comments, opinions....or even facts?

http://www.rouesartisanales.com/article-4934445.html

I'm not sure of the relative magnitude of energy losses in wheels with low lateral stiffness. However, it should be obvious that energy loss will be greatest when power output is greatest. At these times, the bike is being thrown back and forth (climbing and sprinting). My inclination is to think that the energy loss is pretty small. Of course in the extreme where the wheels move laterally enough to contact the brake pads, the magnitude of energy will be much greater.

I think the biggest impact from a lack of lateral stiffness in wheels is in how the bike feels. High speed descents through twisties might be less than inspiring on wheels that are laterally flexy, with the bike possibly not feeling planted in corners. I think this will definitely be the case in bumpy corners. Bumpy, fast corners are challenging enough with the optimal bike, and even the most laterally wimpy wheels won't deflect enough to act as a suspension member and improve control through bumps. In such bumpy corners, lateral movement of whippy wheels is likely to increase vague front end feelings and possibly actually make control more difficult.

It'd be interesting to see some numbers.

I'd rather race on laterally stiff heavy wheels then mediocre light wheels. I am primarily a sprinter so it is my preference. My R500s are on the weighty side but they feel 'light' uphill because they are reasonably stiff (after retensioning to get it 100% even and dished properly etc. etc.). The Neuvation R28 aero are nasty, even though they are 300g lighter.

I also have a fixed gear conversion mtb which weighs aroun 10kg, and 3.5 of that is in the wheels. It is still a very fast, efficient ride for what it is. Having a 3.5kg set of tyres and wheels doesn't make it feel any slower than my XtC during an uphill sprint (possibly attributed to the lower overall weigh and fixed-gear drivetrain efficiency but..)

Alienator and Science is Cool plus DRwyoming have summed it all up perfectly. Start listening to them and stop listening to {insert wheel manufacturer}'s marketing department.

BTW. Ksyriums suck.