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Thread: New wheels

  1. #1
    pan y agua merlinextraligh's Avatar
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    New wheels

    Zipp 808 rims laced to White Industry hubs. 24 spokes front, 28 rear.

    Haven't ridden them yet. But at least they make the bike look fast.





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    hors category TandemGeek's Avatar
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    Hmmm. They look good, but they would look even better on a Ferrari Red Robusta...

    Now, help me out here...

    If there a reason that you have your wife's cranks leading, or was that an unintended mis-alignment that happened when you installed your replacement belt????

    OK, and because I'm REALLY anal, you really should have your tire's labels lined up with your valve stems. By the way, how much effort did it take to mount the tires?

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    Looks really FAST!! Let us all know how they ride.

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    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by TandemGeek View Post
    If there a reason that you have your wife's cranks leading, or was that an unintended mis-alignment that happened when you installed your replacement belt????
    Inadvertence installing the new belt. Didn't really notice it until I looked at the pictures. One drag of the belt is I had to take the eccentric loose to reposition the cranks, given the "rolling" prohibition.

    Quote Originally Posted by TandemGeek View Post
    OK, and because I'm REALLY anal, you really should have your tire's labels lined up with your valve stems. By the way, how much effort did it take to mount the tires?
    The tires were comparitively easy to mount. Substantially more effort than getting the same brand tires on Rolfs, but not as bad as the Zipp 404's on my single bike, which are next to impossible without a tire jack.
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    The wheels look fast, are the basically intended for fast daily riding or for the times you entire some ofrm a racing?

    We just bought out tandem the end of last year so we are still on the stock wheels that came with the C'dale, what would you suggest would be the next step for us to upgrade to? We typically hop on the bike, pick a general direction, decide on a distance and go, point a back to point a, would your new wheels be something we might want to consider?

    Where did you buy them from?

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    Very nice! You guys should really see a nice boost up in the 30+ range.

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    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by tandemnh View Post
    The wheels look fast, are the basically intended for fast daily riding or for the times you entire some ofrm a racing?

    We just bought out tandem the end of last year so we are still on the stock wheels that came with the C'dale, what would you suggest would be the next step for us to upgrade to? We typically hop on the bike, pick a general direction, decide on a distance and go, point a back to point a, would your new wheels be something we might want to consider?

    Where did you buy them from?
    We bought them primarily as race wheels. We'll use them in the Co-Motion Tandem Stage Race next month, and then some time trials after that.

    We'll train on them enough to get comfortable with them, and likely do some fast group rides with them, that are almost like races anyway.

    But I don't think we'll use them as everyday wheels. I think you're probably pushing the envelop durability wise, and there an expensive option for everyday use if you break them.

    We got the wheels from Precision Tamdems. My understanding is they had them built by Dave Walker (the designer of the Paketa Tandem.)

    As for a wheel upgrade for more everyday use, I'd consider Rolf Vigor Tandem wheels, relatively light, relatively aero, and we've found them up to everyday use (although you might get some varying opinions on that).

    Topolinos, are a bit pricier than the Rolfs, probably less aero, but also noticeably lighter.

    Your other option would be a good handbuilt wheel.
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    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by Shayne View Post
    Very nice! You guys should really see a nice boost up in the 30+ range.
    Now the trick is to get to 30mph
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    Senior Member embankmentlb's Avatar
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    Those Zipps have allot of surface area. Do cross winds have much effect on control & balance?

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    yummmmm
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    Double Secret Probation R900's Avatar
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    Nice, you should order some custom orange Zipp decals... sweet!
    Time to Ride...

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    Senior Member rishardh's Avatar
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    Wow, that bike looks really fast with those wheels. Enjoy!!!

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    Very nice!! A couple of our tandems during this year's RAAM were using 505's laced to WI hubs, rather than 808's, with mixed results. Not sure if this was due to the wheels or their Calfee's geometry, but one team experienced significant speed wobble when they got above 60mph on a downhill run . It was bad enough that they replaced the front with our backup WI/Fusion wheel for the remainder of the race. The other team commented on the added weight during extended climbs. If you are using these primarily for TT's then you should be fine.

  14. #14
    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by vc_rider View Post
    Very nice!! A couple of our tandems during this year's RAAM were using 505's laced to WI hubs, rather than 808's, with mixed results. Not sure if this was due to the wheels or their Calfee's geometry, but one team experienced significant speed wobble when they got above 60mph on a downhill run . It was bad enough that they replaced the front with our backup WI/Fusion wheel for the remainder of the race. The other team commented on the added weight during extended climbs. If you are using these primarily for TT's then you should be fine.
    I'm surprised that people would have difficulty with 505 rims (which are the rims on 404's) I ride 404's on my single bike, and have never had any handling issues with them in winds below 30 mph.

    The 520's (808's) are deeper, and I can tell in just riding them once that they're going to be a bit more susceptible to cross winds. I doubt we'll be using them in very windy conditions, and we'll see how they descend.

    As far as weight is concerned, I believe these wheels are around 100-200grams heavier than our Rolfs. Given that they are dramatically more aerodynamic, I think the Zipps are going to be faster on most any course that isn't a pure hill climb.
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    pan y agua merlinextraligh's Avatar
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    We've ridden them 3 times now, and are really enjoying them. Several observations:

    1) They feel fast. With no power meter, I've got no way to quantify that, and readily admit there's a placebo effect from having a new toy. Subjectively, they feel as fast, if not faster, than the HED Trispoke/ Rear disc cover combination we were using to time trial. My guess is that these wheels might be worth 1/4 to 1/2mph compared to ROLF's once you get above 25mph.

    2) Handling in cross winds doesn't appear to be a big issue. We've only ridden them in moderate winds, (10-15mph) but so far cross winds don't seem to be a problem. I think the inherent stability of a tandem resulting from the long wheel base may help here. I use 404's on my single bike, and I would say that the 808's on the tandem are not significantly more difficult to control than the 404's on the single bike. Caveot here is that I'm pretty big (6'1" 200lbs). Lighter captains might have different experiences.

    3) They are very stiff. I never really appreciated the degree of flex in ROLF tandem wheels. When we got the ROlfs with our new tandem, the whole package was such an upgrade handling wise, I think it obscured the flexiness of the ROlfs. By comparisons the Zipps are extremely stiff. The feeling cornering at speed is much more confidence building, and I think we'll be faster cornering on the Zipps because of the confidence factor. Trade off is that the ride is slightly more jarring.

    4) We didn't really notice a loss of acceleration. These wheels weigh approximately 200 grams more than ROLFS. The claimed weight is 2047 grams. I would have thought that you would feel that weight difference accelerating. However, we really didn't notice it. My thought is that a tandem already doesn't accelerate quickly, and 200 grams on a tandem wheelset is a smaller percentage of the total equation than it is on single, that a difference in wheel weight that would be noticeable on a single, is less noticeable on a tandem.

    5) These wheels are expensive. We got them from Precision Tandems. They were new old stock, and with a shop credit, ended up costing $1800. I noticed today that the Precision Tandems website is listing them now for $2800.
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    Quote Originally Posted by merlinextraligh View Post
    We've ridden them 3 times now, and are really enjoying them. Several observations:

    1) They feel fast. With no power meter, I've got no way to quantify that, and readily admit there's a placebo effect from having a new toy. Subjectively, they feel as fast, if not faster, than the HED Trispoke/ Rear disc cover combination we were using to time trial. My guess is that these wheels might be worth 1/4 to 1/2mph compared to ROLF's once you get above 25mph.
    <snip>
    What does the stopwatch say?

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    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by conspiratemus View Post
    What does the stopwatch say?
    Without a power meter, there's really no way of telling. Whatever speed you measured with a stopwatch would depend on the amount of power put to the pedals, and the prevailing wind.

    You'd have to do a series of time trials on the same course, alternating back and forth between wheels.

    And you couldn't do just one test each because of the fatigue effect.

    Probably the best way to measure without a wind tunnel would be a series of roll down tests, alternating wheels. However, it would be a lot of effort, and I also have no desire to limit the value of the placebo effect.

    Zipp claims 808's are 81 seconds faster in a 40k TT, with 300 watts power, over a conventional set of wheels with box section rims, which is about .6mph.


    How that translates to a Tandem would be subject to some extrapolation. The speed increase compared to Rolfs would probably be a little less, because the Rolfs are semi aero. However the Speed increase compared to a 36 or 40 spoke tandem wheel would likely be noticeably more.

    Also the aerodynamics of the Tandem would come into play. Given that tandems time trial at higher speeds, than riders of equal strength on a single bike, a tandem team would likely see greater benefit from aero wheels, than they would see from aero wheels on their single bikes, because aerodynamic drag increases geometrically with speed.

    However, given that the drag coming from the wheels has to be a lower percentage of the total drag of the riders, bike, and wheels on a tandem, than it would be on a single bike, that would argue for less speed gain with aero wheels on a tandem than on a single bike. Also the air hitting the rear wheel on a tandem is "dirtier" than on a single bike. Which one of these effects predominates in adjusting the claculated speed gains up or down in extrapolating single bike data to a tandem, without a wind tunnel, or some really extensive modeling, would be anybody's guess.

    Thus I'm sticking with 1/4 to 1/2 mph above 25 mph as my SWAG.
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  18. #18
    Elite Rider Hermes's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    Without a power meter, there's really no way of telling. Whatever speed you measured with a stopwatch would depend on the amount of power put to the pedals, and the prevailing wind.

    You'd have to do a series of time trials on the same course, alternating back and forth between wheels.

    And you couldn't do just one test each because of the fatigue effect.

    Probably the best way to measure without a wind tunnel would be a series of roll down tests, alternating wheels. However, it would be a lot of effort, and I also have no desire to limit the value of the placebo effect.

    Zipp claims 808's are 81 seconds faster in a 40k TT, with 300 watts power, over a conventional set of wheels with box section rims, which is about .6mph.


    How that translates to a Tandem would be subject to some extrapolation. The speed increase compared to Rolfs would probably be a little less, because the Rolfs are semi aero. However the Speed increase compared to a 36 or 40 spoke tandem wheel would likely be noticeably more.

    Also the aerodynamics of the Tandem would come into play. Given that tandems time trial at higher speeds, than riders of equal strength on a single bike, a tandem team would likely see greater benefit from aero wheels, than they would see from aero wheels on their single bikes, because aerodynamic drag increases geometrically with speed.

    However, given that the drag coming from the wheels has to be a lower percentage of the total drag of the riders, bike, and wheels on a tandem, than it would be on a single bike, that would argue for less speed gain with aero wheels on a tandem than on a single bike. Also the air hitting the rear wheel on a tandem is "dirtier" than on a single bike. Which one of these effects predominates in adjusting the claculated speed gains up or down in extrapolating single bike data to a tandem, without a wind tunnel, or some really extensive modeling, would be anybody's guess.

    Thus I'm sticking with 1/4 to 1/2 mph above 25 mph as my SWAG.
    You could probably run a test at the track (velodrome). Ride the tandem in the pole lane and do a couple of different efforts. A flying one lap for max speed and a Kilo or 2K pursuit for a longer duration data point. However, fatigue may be a factor. I have been testing different gearing for the last two weeks with back to back efforts and it is not too bad. The assumption is that you have access to a track and they will let you do it. If it were here, we would let you on the track for a test as long as you stayed in the pole lane.

    Besides the aero nature of the wheels traveling horizontally, there is less spoke surface area i.e. the deeper the carbon rim the closer you approach a disc so less power is required to just spin the wheels when the bike is standing still.

    I raced at the track in the 2k pursuit and other races Sunday. Today, I did a morning track session. Sunday, I used the HED Trispoke / Zipp 900 combination and today I used the Planet X 50 mm carbon wheelset.

    Out of curiosity, I may get motivated and do some testing between the wheelsets because the HED / Zipp combo seemed much faster than the other wheels. I have seen data published by HED, Cervelo Zipp and others, but I would like my own test results.

    Those are going to be a great set of wheels and you will soon be spoiled and not want to ride anything else.

    Edit: I may have to rethink a flying one at the track but a fast effort would be okay. The concern would be the amount of Gs you would generate and the lateral forces on the wheels.
    Last edited by Hermes; 07-07-09 at 07:31 PM.

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    Quote Originally Posted by merlinextraligh View Post
    Without a power meter, there's really no way of telling. Whatever speed you measured with a stopwatch would depend on the amount of power put to the pedals, and the prevailing wind....blah blah blah.
    So you're saying that there is no need to keep track of time in the Tour de France, or in your local club's evening time trials? We should just look at the equipment that everyone's riding and figure out the winner that way?

    Relax, I do hear what you're saying. And I understand the practical difficulties of designing a proper experiment that controls for effort, wind, fatigue, etc. The reason the experiment has to be done with careful controls is that the "effect size" from the wheels is going to be small, and easily swamped by random variation unless diligent effort is made to control for it. Science is hard work and it's easy to mess it up. You and I both know how difficult it will be to demonstrate any meaningful (if you're not racing for a big purse) speed advantage objectively, i.e., in good old time-over-distance hard numbers, if one even exists. And what you said later says it all: you really don't want to dissolve the placebo effect anyway after spending that much money on fancy wheels.

    Nonetheless, in the spirit of critical thinking, it's worth making at least one paired observation over a course you do frequently and know from experience to be fairly reproducible. A longish loop without stop lights that normally takes an hour or so at your (both of you) usual vigorous but comfortable effort, say. I'll bet you know within a minute or two how long it normally takes, (or what your average speed is) and I'll bet it doesn't vary all that much under different wind conditions. If your normal weekend ride is 2-4 hours, you could, for this experiment, certainly do two laps of the one-hour course at close to the same pace on each lap without fatiguing on the second lap.

    Get up early, when the wind is lightest. Then do one lap with the new wheels and one with the old ones. Repeat the experiment the next morning reversing the order, just in case fatigue does play a role on the second lap.

    Now, if both trials show as much as two minutes faster over the hour, you might be on to something real and it would be worth it, for the sake of science, to design a better experiment (which means, practically, many more trials) to see how large the "wheel effect" really is. My mention of "two minutes" represents an educated hunch about how much of a time saving is likely to be real and not merely due to random variation in wind, effort, amount of wine consumed the night before, etc. etc. With a well-designed experiment it would be possible in principle to detect a much smaller "wheel effect" but smaller effects would be unlikely to convince me the new wheels were worth it for ordinary pleasure riding. So I wouldn't bother looking. But if I was racing for money, even a few seconds of real time saving would be worth it.

    Next section is for statistics geeks only:
    If you are interested in pursuing this, you need to figure out how many trials you need to do (2?, 10?, 100?) in order to be reasonably sure of detecting an effect size from the new wheels of x seconds, if it in fact exists. The smaller the effect size (two seconds vs. two minutes) you are hoping to find, the more trials you have to run to reduce the chance of missing it. The more scatter there is in the time it takes to ride the course with the same wheels, the more the two "bell curves" (new wheels and old wheels) will overlap, and the larger the number of trials it will take to tease them apart and discover a difference. A statistical test of "significance" (e.g. Student's t-test) would tell us how likely any observed difference in times between new and old wheels could occur from chance alone.

    But you first need to do a statistical power calculation to figure out how many trials you need to run (i.e. how much of your weekend time together to devote to this project), and for this you need to have some estimate (even an educated guess will do) about the standard deviation of the times you usually rack up on the course you're going to ride for the experiment. And you need to have an a priori judgement of how much time saving is worth it. There is nothing worse than executing an experiment that is "underpowered" to detect what it set out to find. If you really are going to be happy with finding 5 seconds, get set to do a lot of trials or don't bother starting. If you are only interested in finding a "slam-bang" effect of say 10 minutes on the hour (we wish!), then you don't need statistics at all -- it just jumps right out at you. (Or someone is cheating, which is what slam-bang effects in science nowadays are usually due to.) But that's why I suggest doing at least a crude one-off experiment with a single comparison. Who knows?: you just might be pleasantly surprised at how much faster they are.

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    If it were me, I'd just ride it like I stole it all the while wearing a cheesy grin.

    Enjoy the placebo effect, tell yourself you are faster riding them and know a lot of us are very jealous.

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    Quote Originally Posted by conspiratemus View Post
    S
    Nonetheless, in the spirit of critical thinking, it's worth making at least one paired observation over a course you do frequently and know from experience to be fairly reproducible. A longish loop without stop lights that normally takes an hour or so at your (both of you) usual vigorous but comfortable effort, say. I'll bet you know within a minute or two how long it normally takes, (or what your average speed is) and I'll bet it doesn't vary all that much under different wind conditions.
    Merlin lives in FL, and that means two things 1) the conditions are different [and I don't know how] from my experience; and 2) the spring vs summer effect is much less. That said, we have a Sunday morning - go to church ride that has varied from 1:01 to 1:30, with the key variable being wind and how far into the season we are. If the wind isn't bad, and it's later in the season I expect to bring it under 1:00 (chain trouble last time when we did 1:01). But the 1:30 was real, and only half the distance was exposed and upwind (the other half cross-wind, but not exposed). It was early season (2nd or 3rd Sunday morning), which probably accounts for :10, perhaps :15, but that leaves a good 25% in variability. I was surprised, and maybe it's out at the 95th percentile or beyond. But unless the ride is sheltered, I'd guess that knowing an hour's ride within a minute or two isn't going to happen, at least not where I ride.

  22. #22
    pan y agua merlinextraligh's Avatar
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    Given that the predicted advantage is 81 seconds for an hour's effort, I'm pretty sure variables like wind, and just how you felt on a given day would be at least as great as the effect of the wheels comparing times on a regular loop done on different days.

    And I'm with Tandem Dude, I don't want any empirical data killing the placebo effect.
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    Quote Originally Posted by merlinextraligh View Post
    Given that the predicted advantage is 81 seconds for an hour's effort, I'm pretty sure variables like wind, and just how you felt on a given day would be at least as great as the effect of the wheels comparing times on a regular loop done on different days.

    And I'm with Tandem Dude, I don't want any empirical data killing the placebo effect.
    Well, OK, if you really don't want to know, fine. But you should acknowledge that an experiment could be designed that would show whether or not the predicted advantage of 81 seconds really does happen on your tandem out on the real road. If you do enough trials (old wheels vs. new wheels) you can measure a difference (if it exists) even if you are "pretty sure" that random variation would swamp it. In fact it won't: you just have to do enough trials.

    (It also helps to try to tighten up the random variation. Real-life researchers do this by using genetically identical in-bred lab rats, for example, or by testing new drugs in relatively healthy patients with stable, mild forms of disease who aren't taking a whole bunch of other drugs.) If there is a lot of scatter in those variables -- and thanks to WebsterBikeman for his quantitative contribution about his Sunday morning ride -- you will need a lot of trials. But if the the new wheels really are faster, they will make every trial with them faster, and the difference will eventually emerge from the background noise. Small differences are hard to detect when background noise is loud.

    More to the point, it is even harder, statistically, to prove that a small difference like 81 seconds doesn't exist....which is what the manufacturers of such equipment are counting on when they deal with disappointed customers smarting from buyer's remorse. The placebo effect does eventually wear off....

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