Someone posted about J-disk's and got me wondering as I used a j-disk in last years ironman canada. It was the first time I had used one since 1994...................I love them as they are extremely light and I'm not a super strong rider (I rode 5:05 approx this year......... by strong I mean big gear masher..........I have chicken legs). But how aerodynamic are they? It was a pb for me on the course, and I'm wondering if I can chalk it up to the wheel, as I've used various set ups of wheels. We have a Renn disk coming, but will I notice a difference in terms of speed? I remember that wheel covers were not very succesful, but j-disks have been used in the past by many world champions.................Were they wrong?
Triathlon Forum
Login required to started new threads
Login required to post replies
Re: j-disk aerodynamics [canwi]
[ In reply to ]
"I remember that wheel covers were not very succesful"
Amazingly there is a $.98 solution to this problem. When Cobb aero tested them he rightfully noted that they don't usually form a complete seal with the circumference of the rim. This allows air underneath and defeats the aero advantage. Just use black electrical tape around the circumference of the cover and let it bond from the cover to the rim, avoiding the braking surface area. I tried it and it works well enough to easily complete a tri. In fact if done right you can get quite a few miles on it before the tape needs replacing. Disc covers are selling for about thiry bucks or so on ebay. Makes a pretty cheap and fully functional disc. I would assume that if they had been aero tested this way, they likely would have been as aero as anything else.
Amazingly there is a $.98 solution to this problem. When Cobb aero tested them he rightfully noted that they don't usually form a complete seal with the circumference of the rim. This allows air underneath and defeats the aero advantage. Just use black electrical tape around the circumference of the cover and let it bond from the cover to the rim, avoiding the braking surface area. I tried it and it works well enough to easily complete a tri. In fact if done right you can get quite a few miles on it before the tape needs replacing. Disc covers are selling for about thiry bucks or so on ebay. Makes a pretty cheap and fully functional disc. I would assume that if they had been aero tested this way, they likely would have been as aero as anything else.
Re: j-disk aerodynamics [cerveloguy]
[ In reply to ]
How i the heck do you put air in the tube without having the thing fall apart? I just found that it took to much time!
Re: j-disk aerodynamics [canwi]
[ In reply to ]
I emailed John Cobb about the J-Disk in the fall. He responded that so long as the mylar is "good and tight", it really is a pretty good wheel, and not far off from where a traditional disc wheel is, aero wise.
For what it's worth,
Philbert
Dr. Philip Skiba
Scientific Training for Endurance Athletes now available on Amazon!
For what it's worth,
Philbert
Dr. Philip Skiba
Scientific Training for Endurance Athletes now available on Amazon!
Re: j-disk aerodynamics [denewone]
[ In reply to ]
"How i the heck "
The disc wheel covers I had were made by CH Aero. They had a cut out for the valve stem. I taped over that as well to improve aerodynamics.
The disc wheel covers I had were made by CH Aero. They had a cut out for the valve stem. I taped over that as well to improve aerodynamics.
Re: j-disk aerodynamics [canwi]
[ In reply to ]
What world champions used them, I've heard PNF and Pigg.. Any truth to that?
Re: j-disk aerodynamics [juha-pdx]
[ In reply to ]
yes, those pro's and karen smyers.............she was still using a newer looking one as recently as maybe a year or two ago as I saw her in St. Croix with one................though she may have had trek make her one as I didn't see j-disk stickers
Re: j-disk aerodynamics [canwi]
[ In reply to ]
Any tips on keeping the mylar tight and servicing the wheel?
Re: j-disk aerodynamics [canwi]
[ In reply to ]
One for sale on ebay http://cgi.ebay.com/...8&category=36144
Re: j-disk aerodynamics [cerveloguy]
[ In reply to ]
Interesting site - make your own disc cover.
http://www.angelfire.com/...isc/wheel_cover.html
David K
http://www.angelfire.com/...isc/wheel_cover.html
David K
only way I know is with a hair dryer..............as for servicing things.............you'd have to get the mylar off somehow...........if you are real handy you could just buy some mylar and recover the disk...........bit of a painin the ass though