teetopkram

The LBS has a set of used Easton EC90 SLX low profile carbon tubulars for sale, with the R4 ceramic hubs. Took them out for a 40 mile test spin which consisted of VO2 and Tabatas work. For test ride they had heavy 105 skewers, heavy Vittoria Challenge tires (kevlar belt), stuck to rim with tape. So, I know this is not going to be as representative of a tubular race wheel with real glue and Vittoria Corsas and titanium skewers. Still...

Big surprise! The cornering was better, spin up was much faster, and comfort was better than my current clincher race wheels (SRAM SL30s). Once up to speed the wheels didn't seem to make much difference as they are not aero, but getting up to speed was much better...I actually felt like I had somewhat of a kick.

Surprisingly though, it seemed like the cornering and comfort was quite similar to what I experienced with my previous alloy clincher race wheels, HED Bastognes with the C2 rim. The HEDs are heavier by a good deal so they won't spin up as fast. But this experience unofficially and unscientifically lends some credence (to me at least) that the wider rim technology's claim about "tubular-like ride" does have some merit.

That I'm even more undecided, if that's even possible, about going clincher vs. tubular for my updated racing wheel set-up. I was pretty set on an alloy clincher set-up (HED Ardennes + HED Jet 60) to avoid tubular expense and hassle of changing brake pads, but dang those light Eastons were awesome (Easton EC90 SLX + Planet X/Boyd/Williams carbon deep dish).

That is all...thanks for reading these ramblings and sorry if you were bored...

carpediemracing 

You drank the Kool Aid. Congrats.

ridethecliche

Haha. Shortest CDR post ever!

ericm979

You know that the actual benefit from faster "spin up" due to lighter rims is miniscule, right?

"In a criterium race, a rider is often jumping out of every corner. If the rider has to brake entering each corner (no coasting to slow down), then the KE that is added in each jump is wasted as heat in braking. For a flat crit at 40 km/h, 1 km circuit, 4 corners per lap, 10 km/h speed loss at each corner, one hour duration, 80 kg rider/6.5 kg bike/1.75 kg rims/tires/spokes, there would be 160 corner jumps. This effort adds 387 kilocalories to the 1100 kilocalories required for the same ride at steady speed. Removing 500 g from the wheels, reduces the total body energy requirement by 4.4 kilocalories. If the extra 500 g in the wheels had resulted in a 0.3% reduction in aerodynamic drag factor (worth a 0.02 mph (0.03 km/h) speed increase at 25 mph), the caloric cost of the added weight effect would be canceled by the reduced work to overcome the wind."

(from https://en.wikipedia.org/wiki/Bicycle_performance)


I'm not sure why light wheels feel faster than the math says they are.

Creakyknees

I'll thank you to keep your "science" out of this thread. Toobies are better. Just ask Eddy.

teetopkram

My experience was that it was quicker for me to "get up to speed" so to speak, but I'll confess that after the first several pedal strokes it didn't feel significantly different. My initial thoughts were that the lighter weight would pay off with the constant jumping in crits, but your post doesn't seem to indicate so. Thanks for the input.

teetopkram

Just compensating for my ramble, me thinks.

caloso

Just wait until you ride nice tires on real glue.

Homebrew01

Clement Seta Extra

And whatever those hadmade French tires were ... Durdoigne (sp?)

merlinextraligh

^ dugast

kleinboogie

It was my understanding there would be no math in this thread.

carpediemracing 

I'm not a mathematician (I pretty much failed the medium advanced stuff in college) but here's a few things to think about when someone discusses "weight doesn't matter". I've said this before but since I haven't done a post on it I can't just link to it

1. When accelerating out of a turn I've counted pedal revs required to get up to speed. Significantly lighter wheels require 1-2 less pedal strokes. I'm resting or soft pedaling 6 pedal strokes away from the turn while others around me are still "pedaling hard".
2. I am not a strong rider individually. I absolutely rely on the draft. If I'm at my limit (200 watt average in the hardest crits gives me nothing for the sprint, 180w average lets me sprint, 170w avg may let me win) responding to moves, if I can save even a little bit, I can get on a wheel. Once I'm on the wheel my wattage requirements drop dramatically (like to 100w on a straight while at speed). If a heavier wheel requires me to pedal two extra pedal strokes at the limit, it'll take me a few laps to get shelled.

So, yes, on paper lighter weight shouldn't make much of a difference. In real life I think it makes a difference. I can't prove it. Please, some math/physics major try and prove it using numbers and such.

carpediemracing 

At work, eating lunch, thin staff (1 other person here), and lots of people walked in.

Fat Boy

fmb ftw.

caloso

Thank you to this thread for reminding me go out to the garage and check on my race wheels today rather than Saturday morning before rolling out to the first race of the season.

I seem to have buggered up the valve on one of them. I knew I was having issues with it late last season, but it the pressure was holding it in place. Now it's just pushed all the way through and I can't get enough air in it to hold it against the inside of the tube. So, a quick trip to the LBS for some cement and I'll be back in business. Good thing I had a spare stretched out.

mollusk

What is the difference between getting a gap and pulling the group?

mollusk

Oh, and today I was riding a 20+ year old tubular wheelset (Front: Campy C-Record, Mavic GEL 280, 32, 3x, Back: Campy Record, Mavic GP4, 36, 3x) for an easy Z2/"hard" Z1 ride. Doing it old school.

kleinboogie

When we would do sprint workouts at Fiesta Island I'd usually ride the 404s but a couple times I rode the 58mm and 38mm tubulars and it sure felt like it required less power to kick in the first few strokes but it could be a placebo. I have 38, 58 and 88 mm tubulars and each smaller size feels snappier than the larger. But again, could be all in my head.

ericm979

A possible test protocol would be to have a rider do multiple jumps with different wheels while using a power meter and Garmin with speedometer, then go through the data to find the jumps and determine the accelleration rate in each, compensating for the variations in watts put out by using one of the well known standard models. It'd have to be a blind test with the rider not knowing which wheels he's using. At the same time subjective impressions would be recorded.

In order to keep it a blind test the rider would need to be blindfolded and the test done on a trainer. That would also eliminate wind as a variable and would eliminate wheel aerodynamics also. Actually a trainer would only use the rear wheel. You'd want to include the front too as it also has to accellerate. Maybe a special trainer that turns a roller that rotates the front wheel. Since you'd be looking for differences beween the wheels, the inertia of the test rig would not matter, other than wanting it to be similar to real life so it feels right to the rider.

But I expect that you'd find that the results matched the model in the wikipedia page above- it makes a difference but it's small. You'd get more benefit from wheels that are aerodynamic but heavier. I think that most pro road sprinters use aero wheels. Cavendish certainly does.

merlin55

when sprinting, if you reduce the weight of each rim/tire by .5 lb/wheel, the improvement in your sprint would be if you lost 2 pounds of bodyfat based on basic high school physics....on rotational inertia

king-tony

I address the acceleration issue by rarely racing crits. Life is so much simpler this way.

carpediemracing 

Test protocol - have a moped rider go down a road at a given normal crit staight line speed (30 mph?). Bike rider waits on a cross street (clipped in, held up, and in some standard gear like 53x17), pulls out when moped goes by or just before or some consistent time. Rider has to get 500 meters down the road (or 300 or 400 or something) as fast as possible. Different wheels, different weights, different aero. Repeat ad nauseum. In WKO (that's the only one I know of), highlight each effort. Check avg wattage, peak, etc. I think PowerTap has a way of measuring "matches burnt", that would help too. I think that the overall effort required to go a given distance would be much higher for a heavier wheel. I think that you'd burn a match much quicker with the heavier wheel, meaning if the moped went 35 mph, you may not get on. At 20 mph it wouldn't make much of a difference.

This would take into account pure acceleration, drafting (or not), and the energy required to get into the draft. By having the moped go fast it forces the rider to go into aero-wheel territory.

Although the differences may be small, for me, doing 3 jumps a lap, it's the difference between doing 5 or 6 or 7 laps and doing a full race (same course, same competition, pretty much same me). I believe the physics of the difference in weight thing (meaning I subscribe to the math) but I think there are other factors in play here, most significantly the draft, a second factor the burnt matches or fatigue thing.

One difference between say me and the pros is that they typically have fewer accelerations in their real races, their focal ones. They start at a much, much higher speed. Although they jump hard, they're starting at speeds (I'm guessing 35-38+ mph for some of the field sprints, based on the fact that the last couple leadout men are going flat out, so fast that no one else can move up) where having non-aero wheels would be a huge handicap, forget about starting the actual sprint. For many years I wondered why they didn't use aero wheels more regularly.

asgelle

Or instead of reinventing the wheel with a more or less suitable protocol every time a question comes up, acknowledge that the equations of motion for cycling have been well developed and verified and put them to work.

The question of acceleration out of a corner has been treated at analyticcycling, https://www.analyticcycling.com/Wheel...rner_Page.html and the results for 6% heavier, 2% more aero wheels show the heavier wheel 18 cm ahead after 100 meters. Other cases of interest can be easily calculated.

Quel

I think a lot of the "comfort" and "ride quality" difference is just from latex versus butyl tubes. Some Vittoria Open Corsas with latex tubes ride much differently than GP4000s with butyl.

I won't get in to the spin up issues. But regardless of reality, if you think they help you out, they probably will.

carpediemracing 

I plugged in some more realistic values, for something like a hairpin turn. Starting speed 15 mph (6.67 m/s), I left the drag for the Standard Rider the same (assume 32H box section wheel profile), lighter (not as light as a Reynolds KOM but safely 500g lighter per wheel (500g + 250g for front but used 846g, 500g + 250 + 300 for rear but used 1271g), peak power 1000w for half a second, avg power 400w.

Based on this the non-aero rider with the lighter wheels is half a foot ahead of the aero wheel guy after 100m. I don't know how they'd compare meter by meter for the first 20-30 meters.

Some things I don't know how to account for:
- Realistically the aero wheel (Test Rider) should be maybe a bit less aero but much lighter. I'm thinking a 1400g pair of wheels, with 250g tires, and a 300g cassette. I don't know if the cassette weight is calculated as a central weight or if it's part of an average for the whole wheel. In other words is it affecting acceleration calculations as much as a 300g tire?
- The power numbers are a bit off. A decent jump out of a turn in a crit for me, when it really counts, is 1100-1200 watts, and I've averaged both higher and lower numbers. Lower is better (I jump out of corner, get on wheel, soft pedal). Higher is more impressive but I can't do it repeatedly (jump out of turn, get on wheel, hammer because guy in front is flying).

Hm I ran more models. Say that hairpin turn was just before the finish line. If I do a sprint (I know most of my numbers well enough), I'm jumping at 1250w on a good day (1 second at power), holding 1100w avg for 20 seconds, with the above weights/aero/etc. I expected the aero rider to be way ahead, based on acceleration and the fact that there'd be a top speed element coming into play. Instead the non-aero rider is .59 meters ahead.

It seems that if I do a lower power average the aero wheel goes ahead, but as I put more power into the equation, it seems that weight becomes a factor (since it really affects acceleration).

If there was a drafting model then I could see how losing 6 inches or a foot or whatever would affect overall power needs to maintain a speed or to accelerate from one speed to another.

If I look at my Jet 6/9 wheels (the aero clinchers that I don't like using), their weight is about 1125g for the front and 1700 for the rear, so about the same as the aero wheels in the calculator. Using those slightly lighter weights puts the aero wheels down 0.51 meters instead of 0.59 meters (assuming the Jets are as aero as TriSpokes).

Ultimately, for the first 190 meters or so, the lighter wheel seems better. After that the aero wheel picks up, surpassing the light wheels by 370 meters.

Question is how long do you want to be at 1100 watts average. If you hold it for 10 seconds the light wheels are better. If you hold it for 25 the aero wheels are better.

It's a cool tool though.