cyclezen

A Tale of Two Wheelsets - It was the fastest of times, it was the slowest of times.... OK, maybe I've gone over the edge...

anyway, I had a wheelset built by a renowned builder, local guy, great builder... Velocity A23 Rims onto a set of Bontrager hubs (not sure which models, but not cheapest, not most expensive) with DT Revolution spokes. He did a AB FAB job!
I luv the way they ride... but when I ride them, mostly on my ROubiax, I always feel like I'm working harder and goin slower, than normal. I rode em again this Saturday, and again felt 'slow' and workin hard...
On Sunday, for some reason I swapped out to my weekday training wheels - 5 years old, prolly 25K miles on this set of Shimano WH-R500 wheels - what great wheels for the money! Anyway everything seemed 'faster' on Sunday.
I always put these feelings to good and bad days and just lower my head and HTFU...
But this time I decided see how certain these feelings were. Rode on Monday, started on the Velocitys, did 12 mi and then switched to the WH-R500s and did the same 12 mi. - WH-R500 were .5 mph avg faster... DId this again on Tues and again Yesterday - same story...
So Today I decided to do a coast-down test on the road with the wheels under load (my weight).
The course is a section of my weekly hill climb called Old San Marcos Rd. The section was 1.2 miles long and 580 ft vertical drop, enough to get a longer coastdown, but not so long that I had to ride sections which required braking - so a clean coast from top to bottom.
Same bike - Roubaix, both wheelsets have same tires and tubes, set to same pressures, 95 frt, 105 rr. careful to set the skewer pressure to about the same.
No wind, not even a breeze, rode the same line each time, no auto traffic to deal with. Assumed the identical rider position to equalize aerodynamics for each test. No pedal turns, pedals at 3 & 9

I figured a delta of 1 to 2 sec might be chalked up to operator error.
Resutls
Bontrager/Velocity A23s : 1st run 2min 19sec, 2nd run 2min 18sec , max spd : 39 mph
Shimano WH-R500 : 1st run 2min 11sec, 2nd run 2min 11 sec max spd : 39.5 mph

That's a delta of 7 & 8 sec.

Quickie Calcs - Bontrager/Velocity avg spd was 32.8 mph, WH-R500s avg spd was 34.1 mph.
calc'd out at the finish, the Bontrager/Velocity wheels were 365 ft / 121 yds behind the Shimano WH-R500 ! HUGE!
The WH-R500s feel appreciably faster, everytime .

WHen you spin the Bontragers in your hands they feel silky smooth. WHeels are solid/ stiff, rims are true. Only thing I can think causing this is bearings which are just crap/done/ not rolling well under a rider load...

any other thoughts ???

I think I'm gonna rebuild the Hubs with the finest bearings I can find, and then do the test again. Think I'll 'test' all my wheelsets - be fun to see how the HEDS come out...

Anyone else do crazy shyt like this?
If your wheels feel 'slow' maybe they are ???

sbxx1985 

Test the HEDs.

Bah Humbug

Mmm... average speed.

Jed19

I've found that hubs of any kind requires a break-in period. Make sure this is not what is affecting the delta in how fast your two wheelsets roll.

Gluteus

Before the naysayers show up and start splitting hairs finding problems with the way you tested, I think what you describe sounds like a good field test.
Time for me to look again at the Shimano R500.

carpediemracing 

I think some wheels are faster than others but usually there's a significant difference in either weight or aerodynamics. It doesn't seem like either applies here. The only thing I can think of for weight/aero is if the Bontragers have a much higher spoke count (32H or similar).

How much do the two wheelsets weigh? That's the unknown here. You controlled tires, tubes, pressure, even preloading the bearings (skewer).

Interesting, I like it.

merlinextraligh

Yeah, the test isn't double blind, and you believe the one set of wheels to be faster.

Subtle, unintentional changes in your position would likely have more effect than differences in bearing resistence.

RT

I own a set of the R500's and absolutely love them. Of note is that my other bike features a set of hand-built wheels using old Alex hubs in great condition, Wheelsmith spokes and some old unbranded rims. The build is solid and appreciably heavier than the R500 (about 1,800g compared to the customs at 2,100g). The custom build has red nipples.

The custom wheels reside on the cross bike, and the best comparison I can think of is that the cross bike rides like a '59 Caddy and the R500 (road) bike rides like a Saab 900 Turbo. Can't afford them fancy wheels, so my comparisons are dated on purpose. The cross bike is about 7 mph faster as it features a 52t big ring and the weight certainly helps.

Glad to hear someone else likes the R500.

nhluhr

What spokes on your new wheels?

The R500 have 20/24 aero spokes. That right there could create a significant difference against a 24/28 or 28/32 with round spokes.

rogerstg

If the bonty hubs are a loose ball design, I'd fine tune the preload and run the test again. That assumes that you know how to do this. FWIW, there should be a bit of play in the axle when the skewer is loose, which disappears when it's tightened.

Otherwise, tell the builder about this and see what he advises.

rogerstg

Shhh. While folks think they are junk, you can often get a set of takeoffs on Ebay, with tires, for practically the price of a set of tires.

cali_axela

Seconded. My new Ksyriums were slower than my ~6mo old cheap Vueltas for the first few hundred miles at least, since the Vueltas were already broken in. The Vuletas would freespin for several minutes on the stand, while the Ksyriums wouldn't freespin more than about 20 seconds, at first. Once I rode the Ksyriums a few weeks and they broke in, they started spinning for longer, as expected.

If the Bontrager hubs are still very new, just keep riding them... they will break in and spin better soon enough.

rangerdavid

try testing two GOOD wheelsets.

FusionOne

I remember doing a pancake flat road race once in my stupid carbon weight weenie non-aero wheels that were soft as butter and seemed like they must have sported 68 spokes. In truth, it was probably a 28/32. I absolutely SUFFERED during that race, and I've never felt slower. I sold those wheels the very next week because the disadvantage on the flats wasn't worth whatever perceived advantage I might have been getting on the climbs in other races.

I have always felt faster on stiffer, low-spoke, aero wheels even though I know how much low-spoke gets a bad wrap. My Rolf Prima Vigors, for example, when I used to own a set, felt like they screamed. I also noticed that, even as a lighter rider, I would fly downhills on my Bontrager Race X-Lites in comparison to most of my other wheelsets in relation to whomever I was riding with.

In your test, I would imagine spoke counts make more of a difference than bearings on coasting speed.

nhluhr

Still waiting to hear if OP's new wheels have round spokes or aero...

howsteepisit

Are the tires same make/age?

canam73

Bontrager hubs? Were they used? I didn't think they sold loose hubs.

Carbonfiberboy 

You could also just read the wind-tunnel tests. All the faster wheels have aero spokes. The bearing drag doesn't much matter. Very small compared to wind resistance. Rim design is more complicated than one might think.
https://www.tour-magazin.de/services/...ge104.html#/98

chado445510

I'm pretty sure the aero/non-aero spoke idea isn't really all that effective. The difference between 20/24 aero spokes and 28/32 round spokes is ridiculously small, and would not account for even one tenth of the speed change.

I would suggest, however, that DT Revs are notoriously flexy, and could cause that slow feeling.

Not sure why there is a 7 second difference, though.

cyclezen

some further info to Q's posed...

Both wheetsets are 20/24, the shimanos are about 5 yrs old, so they are the older model which has round spokes.
As for weight, I need a new power brick for my scale, so I will get current full wheel weights some time next week - the new wheels are lighter than the WH-R500s.
Bontrager hubs came off a wheel set which both rims had been trashed. Again, I believe they are mid-line hubs - sealed bearing. Not sure how many miles they have on them (not new), but certainly less than the 25k+ that the WH-R500s have. They look clean and could be virtually new.

Double blind - Don;t think I can talk anyone into being my test pilot for this... yes there's always the subconscious tendency, but I made a real effort to take 'me' out as a variable - after spending some relatively solid bucks on the set, I was hoping the coast-down test difference would be undiscernible - and I would not have been disappointed to find my 25K+ mile Cheepie Shimanos were a bit slower...

Tires, in this case the Shimanos had PerfBike Forte Pro DCs (200g) on them. I took the Conti's I had on the Velocitys off and put on another set of Forte Pro DCs (these are Kenda Kalientes). The set on the Shimanos have about 750 - 800 mi, the set on the Velocities have (sat 40 mi, sun 55 mi, Mon 14, Tue, 14, Wed 14) 137 mi at the time of the test.

Dt Spokes - John builds a very stiff wheel, I would be afraid to tension a wheel as much as he did - but he does know his craft. Radial frt, 2x both sides rear - they feel very stiff. I have a bit over 1K mi on the velocity wheels. I will keep riding them, and maybe the hubs will feel a bit more 'free' as the mileage goes up.

I'm not tryin to sell Shimano wheels.
"good wheels" - a wheelset which goes for 25k+ mi and still rides pretty well, has required very little maintenance (replaced 2 spokes over these 5 yrs, retensioned the wheelset once...) is a good wheelset in my book. AT 170 lbs, I'm not a hvywght, but still 10 heavier than I'd like and 5 heavier than I've been recently. WOuld these wheels give 25K mi to a Clydesdale? don;t know...

Thanks for all the thoughts - maybe the hubs need more miles, maybe the spokes are flexy, maybe its the rims. between Conti GPs and the Forte Pro DCs, it's likely not the tires...
When time allows I will try coast-downs at different tire pressures, maybe tire pressure has a real affect on these new 23mm rims?
now that I have a 'base', I will be testing other wheelsets, to see how they come out... just curious

BTW: found a nice 'post' on Old San Marcos Rd, the first 5 pics show the section I was using. Start of the coast-down was almost exactly from where pic #5 was taken. Pic #1 shows the 'bridge; which has a concrete/tarmac joint which is usually the start for timing the climb, and in this case was the descent 'finish'.

DiscTruckerMF

interesting test. it would be more interesting and probably reliable using a powermeter on a set of rollers
also, for all you know the wind was blowing gently at 5mph behind you on one test and into you on the other. It's hard to get those variables out of a test.

JaceK

You may want to try going some distance to average out variability, a mile or 2 mins really is not meaningful.
Secondly 2 runs is a random occurrence, 100 or so runs is a pattern, 1000 is a representative sample.
Really can not make any valid claims with your data.

DaveWC

At least you can definitively say that the difference is not nutrition!

RT

wphamilton

I think it's a good test! You're not writing a scientific paper for peer review - you're just trying to find out the facts and, I suspect, without investing the time and resources necessary for a rigorous study. Simply disregard the pickier objections. I do suggest making several runs with each configuration, and doing all of the tests on the same day in the same conditions, but even that is just a suggestion and not objecting to what you're doing. You're getting good data, within a certain range of accuracy.