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Pages: 1 Pintsized journeyman Reged: 02/27/05 Posts: 90 Loc: Corvallis OR 24 hole drilling and powertap hub: advice, please? #6560 - 09/10/05 06:20 PM (24.22.126.42) Edit Reply Quote Hey all, There is a brand new powertap sl on ebay right now at a not so bad price. No one has bid yet, and I think I know why. The catch is that it is a 24 hole drilling. Now I gather this is not a bad bet for a smaller rider like me, and so am contemplating a bid. But that is only my assumption. Does anyone know more? This auction runs 3 more days, so I have some time to investigate. Here's the other, probably bigger, catch. If I bought this system, I'd have to get a 24 hole rim in a 650 c size and so clearly my options will be limited. One rim that appears to fit the bill is the Velocity Aerohead rim. The regular one. I understand that the O/C rim is designed for hubs with dish and I don't know whether a Powertap hub has that. I don't know, either, whether the O/C comes in 24 hole (it does comes 650 c)., but if the "dish" thing is not an issue, I don't need to worry. As usual, the lady is over her head. The only dishes I have ever heard of are the ones on the roof that get you the tv channels. Can anyone shed some light ?P.S. I have a Shimano drivetrain, not Campy, in case this is relevant to anything. Thanks, y'all. Post Extras: flythebike captain Reged: 08/26/04 Posts: 272 Loc: N. Virginia, USA Re: 24 hole drilling and powertap hub: advice, ple [Re: Pintsized] #6574 - 09/12/05 08:13 PM (66.7.29.138) Edit Reply Quote Dear Pintsized I can say that the offset it just makes the spoke length different. It isn't any kind of compatibility issue. Rather than have the holes in the middle of the rim, the holes are on one side a bit more than the other. The idea is that it helps make the wheel a bit stronger. I think Sun might also make rims in 'odd' drilling sizes. Of course Zipp makes 24 spoke drillings, too, and I would also check DT Swiss. Powertap's internals are kind of low quality from what I hear, but probably fine for training on and watts are the way to go, I think, for many types of training, and for tracking progress. Hubs with dish - that is any wheel that has a cogset - not a fixed gear or singlespeed wheel. To make room for the gears, the wheel is not centered over the hub's axle, but offset. For elucidation on these types of things, Sheldon Brown's site is usually 'the bomb.' www.sheldonbrown.com Post Extras: Pintsized journeyman Reged: 02/27/05 Posts: 90 Loc: Corvallis OR Re: 24 hole drilling and powertap hub: advice, ple [Re: flythebike] #6590 - 09/16/05 01:39 AM (24.22.126.42) Edit Reply Quote Thank you for the filling in; very helpful. In fact, I did get the powertap and so am looking forward to a rip roaring good time next season. Good thing I have an indulgent husband . They'll build it on a simple Aerohead rim --start simple, start cheap--and see how it works out. I can always rebuild it if I need to with something more bombproof but I'm betting I won't have to. Post Extras: flythebike captain Reged: 08/26/04 Posts: 272 Loc: N. Virginia, USA Re: 24 hole drilling and powertap hub: advice, ple [Re: Pintsized] #6594 - 09/16/05 01:25 PM (66.7.29.138) Edit Reply Quote Yep. Glad you got it. Check this out from a local coach: We actually have done some research on pedal stroke economy at Fitness Concepts and have found that improving pedaling technique will have a large influence on overall economy. We tested a category 1 cyclist. The cyclist worked extensively on her pedal stroke. We loaned her a pair of Powercranks and also had her do extensive sets of tempo tension - mid zone 3 at 40-60 rpm with specific concentration on either the downstroke, backstroke, or upstroke. She also spent almost an hour a week doing legspeed tempo - riding at the highest cadence she could maintain smoothly in her easiest gear. As expected during preparation and base periods, her maximal oxygen consumption, and therefore energy expenditure, decreased. Her oxygen consumption at LT was exactly the same. Look at the changes in her pedaling economy at all three thresholds in the results below. Wattage increased significantly at both LT and max without any increase in energy expenditure - just by making her more efficient. How would you like 25 more watts at exactly the same energy expenditure at LT? What we see is that VO2 at aerobic threshold has increased, at LT it is exactly the same, and max VO2 has dropped slightly. Just as would be expected during base period. Improvements at all three thresholds were dramatic ... 5.2% at aerobic threshold, 12.2% at LT, and 13.3% at max. October January Change Aerobic Threshold VO2 2.07 2.23 + 7.7% Aerobic Threshold Wattage 150 170 + 13.3% Aerobic Threshold Econ. (W/L) 72.46 76.23 + 5.2% Lactate Threshold VO2 2.88 2.88 0 Lactate Threshold Wattage 205 230 + 12.2% Lactate Threshold Economy 71.18 79.86 + 12.2% Peak VO2 3.63 3.45 - 5.2% Peak Wattage 260 280 + 7.7% Peak Wattage Economy 71.63 81.16 + 13.3% A cat 1 cyclist is not likely to improve max VO2 by 13.3%, but she could improve power to that degree with consistent, specific work on pedal stroke mechanics. I understand that this is not a controlled study, but we have seen similar results with many of the athletes we work with. Adam Adam R. Coon USACycling Expert Coach Joe Friel's Ultrafit Associate ACE Certified Personal Trainer www.Fitness-Concepts.com www.OptimumFitnessResults.com www.evolutioncycling.org Post Extras: Pages: 1

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