This forum is a fountain of knowledge im reading lots of things and i know there lots of talk about who makes the most aero thing out there
however i feel as a lurker and someone who knows a fair bit about aerodynamics(for all you ALMS car fans out there yes im crapping bricks to see if the new car will perform this weekend)
i remember back before my interest in designing timetrial bikes was rekindled the zipp and lotus bikes (admittedly old technology now) and how quick they were
well to cut to the chase why does there seem to be alack of interest especially the tri sector of the market in modernising these designs and sticking them front centre as i go through the wind tunnel cfd etc process im starting to wonder if its market perception or rules and regs which are limiting the design aspects of bikes more than anything…as the data is certainly interesting to say the least
any thoughts on the topic would be great either positve negative or shut up stupid comments are equally welcome
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those designs are not UCI legal, limiting their market somewhat. they ARE legal for triathlons though.
those designs do well in low yaw conditions, so might be great in a velodrome but the current UCI legal designs outperform them at higher yaw angles, which you experience outdoors.
As a BPStealth rider I’d love to see some evidence that they do poorly in high yaw situations. I know mine feels like a sail when the yaw angle goes way up (15-20mph winds from the side) so my butt dyno sez that may not necessarily be true. I haven’t seen any serious windtunnel tests to say otherwise…
I think mostly it is marketing. While the Tri sector accounts for a large amount of sales, the fact of the matter is that most of the ‘public eye’ time occures during Time trial events in the Grand Tours.
There are still a few molds out there that make ‘beam bikes’ but for the most part they are a small part of the market. If Lance hasn’t got one, the publice don’t want one.
No, we’re not removing the top tube. We’re removing the down tube, and elevating the top tube such that it sits between the thighs and only minimally contributes to the side-on drag. The beam of the Zipp is proof that a narrow, aero tube can be used in this high load area. There is no reason that you can’t make a P3/P4 dimensioned downtube strong enough to act as a downtube with the removal of other frame members.
ah, your right I was imagining this all wrong in my head.
It is the seat tube we are removing, sort of, really just combining the seat tube and top tube into one.
But then the rear wheel is no longer shielded. Would it be faster to put a fairing in front of the rear wheel on a Zipp?
If so, you are part of the way up to the seat already.
So, there is no reason you can’t make a P3 dimensioned downtube strong enough for this kind of design?
You sure? why hasn’t it been done?
The
No, we’re not removing the top tube. We’re removing the down tube, and elevating the top tube such that it sits between the thighs and only minimally contributes to the side-on drag. The beam of the Zipp is proof that a narrow, aero tube can be used in this high load area. There is no reason that you can’t make a P3/P4 dimensioned downtube strong enough to act as a downtube with the removal of other frame members.
I’m not sure about the head angle/fork on that image. My 650c large frame does not bring the wheel anywhere near that close to the frame. My replacement design does though.
The only tube I have done at this time is the down tube. It is 32mm wide and 110mm deep. I need to have a steel head tube cut in the next few weeks, and that will get bonded into the down tube. I will be making the beam after that, I suspect, but it won’t be adjustable. Rear brake will be somewhat similar to the Fuji D6, but will be under (and behind) the BB. I am considering doing the whole rear end out of titanium.
those designs do well in low yaw conditions, so might be great in a velodrome but the current UCI legal designs outperform them at higher yaw angles, which you experience outdoors.
What are you basing this on? nobody has done and published a test comparing these old frames to new ones. from 0 yaw and especially from higher angles.
the few tests that were casually ‘mentioned’ by manufacturers on this board comparing the lotus/zipp to newer frames such as the P3C have suggested the opposite is true.
Thats only because you are comparing a 700 to a 650. The 700 front wheel does indeed come that close to the frame even with a Kestrel EMS fork. I have some serious toe overlap on my Large/large 700c 2001.
I spoke with a Zipp rep at Tri Fest and learned/relearned that there is still not much out there that comes close to the aerodynamics of the Zipp 2001. Say what you want…the Zipp frames were/are extremely fast. With the age of that frame technology you are still not giving up anything in aerodynamics when you ride the Zipp frames.
