So I have a bunch of wheels and different tires. Is there any easy and reliable method for figuring out which combo is fastest on my bike?
I am thinking of something like creating a strava segment on a mild straight downhill, starting from basically a standstill and letting gravity do its work - then seeing if any particular wheel set/tire combo was appreciably faster.
I would guess strava is not all that accurate for these purposes, but starting and stopping a stopwatch at prescribed places would be subject to inaccuracy as well.
I don’t want to just pedal a flat course, and that would be limited by keeping my effort constant. I don’t have a power meter so I can’t use it for measurement purposes.
I am not sure how wheel weight would factor into my proposed method. I understand that aero trumps weight, but I also want to figure out which of my wheels gives me the best aero/weight blend for climbing - and I can’t figure out how to test climbing without just riding the same hill over and over again and hoping that by doing it enough at a similar effort, a trend would emerge.
Choosing a course that is only going downhill might not help you with the decision. A heavier wheel might be an advantage while going downhill as there is more mass that is accelerated (while having same aerodynamic resistance). So even if this was the fastest wheelset downhill, it would probably not be the fastest on a regular training course. And as the differences between the wheelsets might be very small, you will need to choose a long segment to determine which one is better. If you go 10 seconds faster on a 2 mile segment that could be caused by many factors. Fatigue, different power, bad day,…
You should go ahead and start riding them for a few rides and choose by how they “feel”. Since there are many mags trying to figure out features like speed and acceleration, you might also start searching for tests on the internet.
if you have an android phone, this still might work.
If you measure the weight of the wheels, you should be able to subtract that effect from the overall. -J
I’m afraid a power meter will be the only way to gather empiric data about your wheels then. No matter how repeatable you will choose your course and the conditions under which you ride it will always be sort of guessing which one is the more efficient.
if you do downhill rolling tests, then equalize the weight with a partially full waterbottle. In theory downhill testing should work, n practice it doesn’t very well. You have to keep everything equal and due multiple runs to tease out small differences.
I have had pretty good luck with roll-down tests in the past, but the GPS speedometers are way too inaccurate. You need a real cycling computer that counts wheel revolutions (About 25$ at Performance or add a sensor to the Garmin 500 for about 80$) and I like to mount mine on the back wheel. A slightly better solution is to mount multiple magnets and reduce the tire circumference measurment. I go from a standing start and roll down a hill where my top speed will be about 30 mph. I hold as consistent a position as possible (including foot and pedal position) and look down at the computer only as I get to a marked location at the bottom. Then I record the terminal speed for each run.
You can test whether roll-down tests will work (i.e., can you hold a consistent enough position) by trying a couple sets (I do about 3 or 4 per set) of roll-downs using a road helmet versus an aero helmet. The difference between helmets tends to be in the 5-15 watt range, so I would expect about a .3-.6 mph difference in the average of your terminal speeds with the different helmets.
If you can detect the difference in helmets, you can probably detect significant differences in wheels (3-5 watts). I would suggest starting with only the front wheels (assuming you put the computer on the rear wheel) and use your slowest wheel/tire combination (training tire, butyl tube, non-aero wheel) against what you think is your fastest wheel. Switch wheels after each roll-down and see if you are consistently faster in the “fast” wheel. If that works, move on to more similar wheel/tire combinations. At some point there will be too much noise to easily pick bewteen wheels. At that point you can probably consider weight, handling… when choosing wheels/tires.
A lot of people poo-poo roll down testing, but it has worked well for me and it is about as cheap and easy as it gets. The hill I use is right outside my front door, so I can test anytime the wind isn’t howling. If you are consistently faster on a roll down, then you will be… faster. You can’t control everything, but adding more runs allows you to get more accuate results.
I have been trying to collect good data to do the Chung method over the last week and so far I haven’t gotten anything very useful.
I have been trying to collect good data to do the Chung method over the last week and so far I haven’t gotten anything very useful.
You need a way to record second-by-second speed. The best way is to have something like a Garmin to record the speed but with a dedicated wheel sensor for speed.
I was going to try that this weekend, but I am shoveling snow instead. I was curious if the Garmin picked up the speed from the hub or if it was still using the GPS signal. My guess is that latter, given that I noticed some odd speed values when going very slow.
P.S. Thanks for all the work you have done. I was also curious if the R code was to do the analysis was available.
There are lots of threads on tires. If yours don’t show up on a list, flat resistant features like kevlar belts probably slow you down. There are also charts with wheel data, often from manufacturers, go figure. If your wheels don’t show up, maybe you can make some guesses comparing wheels that are visually similar.
The differences are likely to too subtle to make any accurate conclusions from timing yourself over known distances.
I was also curious if the R code was to do the analysis was available.
You’ll want to verify that the speed signal is coming from the wheel and not GPS. Especially when you don’t have power but are doing coast downs, all of the analytical weight rests on the speed signal – so it better be as good as possible.
The functions are available but not very friendly because there’s no documentation. I was just talking to a friend who encouraged me to put them together into an R package, with some examples.
I have been trying to collect good data to do the Chung method over the last week and so far I haven’t gotten anything very useful.
You need a way to record second-by-second speed. The best way is to have something like a Garmin to record the speed but with a dedicated wheel sensor for speed.I beg to differ.
If the dude has to ask, chances are he can’t do it.
I suggest doing rolldowns together with a buddy with similar ‘profile’ (build, aeroness, nerdiness).
Do a bunch of shoulder-to-shoulder launches down a hill that averages out to 20-25mph.
Swap wheelsets between bikes every run. Somehow record the difference between buddies. One could measure time or distance differential at a finishline, distance between stopping points or recorded peak velocity, if accurate.
Compare how wheelsets affect difference.
Repeat until certainty. Winning wheelset stays in the tournament, bring on the next contender.
The best part is that these comparisons are immune to conditions and gear, to a degree.
I beg to differ.
If the dude has to ask, chances are he can’t do it.
I suggest doing rolldowns together with a buddy with similar ‘profile’ (build, aeroness, nerdiness).
Good point. If you can find someone like that, that would work and it does control for many of the other variables.
However, for me, it’s easier to buy a piece of equipment than to find a compatible buddy. (And that’s less a statement about my checking account balance than about the quality and quantity of my friends).
Thanks. I am running Conti 4000s and Vittoria Open Corsa 320s with latex tubes. I have seen the charts, but was interested in comparing them myself when on my wheels and with my bike (an S2) - in particular because there may be some aero effects of each tire and wheel combo that my in some cases trump or magnify the Crr data.
As for wheels, this is more for road riding - I have some Hed Adrennes (wide rim), Easton EA 90 SLXs and some carbon clincher Reynolds MV 32 C ULs - so there isn’t a lot of aero data out there for such wheels - and each wheel is unique in that the hubs may have some variance.
In any case, this thread isn’t meant to speculate on which wheel tire is best, but rather how to design a test to determine that question for oneself for any wheels or tires.
I have been trying to collect good data to do the Chung method over the last week and so far I haven’t gotten anything very useful.
You need a way to record second-by-second speed. The best way is to have something like a Garmin to record the speed but with a dedicated wheel sensor for speed.I beg to differ.
If the dude has to ask, chances are he can’t do it.
I suggest doing rolldowns together with a buddy with similar ‘profile’ (build, aeroness, nerdiness).
Do a bunch of shoulder-to-shoulder launches down a hill that averages out to 20-25mph.
Swap wheelsets between bikes every run. Somehow record the difference between buddies. One could measure time or distance differential at a finishline, distance between stopping points or recorded peak velocity, if accurate.
Compare how wheelsets affect difference.
Repeat until certainty. Winning wheelset stays in the tournament, bring on the next contender.
The best part is that these comparisons are immune to conditions and gear, to a degree.
Thanks for this thought - sounds good. Just FYI, I am a trained (non-practicing) engineer that at one point used Fortran to attempt to model turbulent flow (didn’t work very well), so I am ok with this sort of thing. I just don’t want to reinvent the wheel so to speak.
Now I’m picturing digging up a bunch of old hot wheels tracks and using them for a control. Kidding but from years ago those things were pretty repeatable.
You are wasting a tremendous amount of energy and time to figure out things, that are well known and not highly important. My take on the wheel thing: Get sturdy training wheels, get any good racing wheels, get fast tires. Stop worrying about that aspect of your game.
Testing 808s against Jet 9s is simply irrelevant, both are fast wheelsets, as are most discs and most trispokes. Just pick and stick.
My combos (Front + Rear):
Triathlon: Hed Jet Disc + Hed 3
Road: Sram S60 + Flashpoint 40mm
Training: Some old training wheel with a powertap + some old training wheel