I’ve been using a wheel cover over a Zipp 404 for the past six years. Now I’m ready to get a disc. Very limited choices in 650c clincher: HED or Renn. Price and weight are similar, with the Renn a little less expensive and about 100 grams lighter.
The biggest difference between the two are the construction. The HED disc is a carbon skin (over the Jet 60), and (I think) a 23mm rim. (It’s a little hard to get the specs on the HED 650c disc, as it is not advertised on their website. I’m going off the 700 Jet disc specs.)
In contrast, the Renn is a true, structural disc constructed with a honeycomb core and a 21mm rim.
Due to my age, this will likely be the last wheel I purchase.
A couple of questions:
Based on the construction, which is the best choice? FWIW, if it makes a difference, I’m a lighter rider (about 120lbs). I will be racing on an NP3. Most of my races are on relatively flat courses with a few rollers and false flats. On my old bike, the switch from clunky training wheels to the the 404s with disc cover consistently led to 1 mph faster speeds.
The hub–I’m running 10spd and have no plans to move to 11. Should I get a 10spd hub if I can?
The RENN disc will make the whoop-whoop sound, so that is the one to buy.
More seriously, it may depend on the frame you are running. The flat Renn will work best with frames that shield the rear wheel very well (mostly recent fast frames). I am not familiar with the 650c Hed clincher, but if it has been updated to the widest rim like some of their other wheel, it may not fit in some older frames (like a p4 or a transition), Hed could probably help you out here if you contact them. Also, the wider the Hed rim will work better with the wider tires now offered, this will be good for 650c wheels because of the limited tire selection.
I would get an 11 speed if they are the same price. It will make resell easier and you simply need to run a small spacer to run a 10 speed cassette.
Probably the best arguments for the HED are, it’s a spoked wheel with a permanent cover. As such, it behaves like a spoked wheel. It’s laterally stiff, but more vertically compliant and it’s truable. It probably has a wider rim bed which would make it a better aerodynamic match with a 23c tire.
In contrast, the Renn is a “true” disc. It’s probably stiffer, vertically (less compliant/comfortable over long distances?) and might be a bit more flexy, laterally. Unless they’ve recently changed it, it probably has a narrower rim bed and, therefore, unless you run a skinnier tire like a 19c, you’ll have a tire that’s wider than your rim bed and the rest of the disc surface which may not be aerodynamically optimal. But I used to race TTs on a 650c Renn with 20mm Vittoria tires and it was a sweet setup.
I’ve ridden and raced both Renn and Hed discs. Never raced a Hed 650c clincher disc 'cuz I never knew they existed. I couldn’t tell you which one is faster. I doubt there’s much of any difference. On a more technical course, I think I’d prefer the Hed because it behaves like a normal bike wheel. Also, if I expected less-than-ideal pavement, I’d also lean towards the HED as it would be better suited to a larger tire and maybe a bit lower tire pressure.
The disc cover you have is the same shape as a disc. The wind has no idea what’s underneath the skin or how much you paid for the wheel. To be honest, your disc cover is as fast as a “disc” wheel. The HED wheel is the same as you are using now, a cover over a spoked wheel.
I think you will be bitterly disappointed at buying a new new wheel and finding it isn’t any faster. Spend your money somewhere else.
The disc cover I have now is 8 years old and cracked in multiple places–held together with electrical tape. It barely fits and I get rubbing in the lowest gear. There’s also a lip around the edge, even after taping it down.
I tried to replace it with a new one–which doesn’t fit at all.
An added consideration is the availability of 650c tires. As best I’ve been able to learn over the weekend, 650x23 is the only width still manufactured. There are still some Vitorria Open Corsa CX 650x21 available. However, current production of that tire is now only in 650x23. And rightly or wrongly, that tire has a reputation for short lifespan/flats.
There are some old HED and Mavic 650c structural discs still floating around used. Those are listed with 9 speed cassettes. Anyone know if I could swap out the freehub for something that I could run 10 speed on? I imagine those rims are probably 19mm. How will they play with 650x23?
10 speed and 9 speed fit on the same hub. I have been running a 23 tire on a 19mm Renn disc for over ten years. It doesn’t have the same bad effect that it would on the front. On the front I go with a Hed3 with a 20c tire. Look for a front Hed3 in 650c. You can probably find one on Ebay for a song.
If you are interested in running a tubular rear, I have a beloved disc (650 X 23) and 10 speed hub for you. It has been raced 3 X since I bought it and the new Cervelo P3 is equipped for 11 speed hub, so I have no use for it.
Please reach out if it can have a good home in your race stable. Meanwhile, I have to shop for an tubular, 11-speed hub 650 disc…sigh…
The Edco Monoblock 11 speed cassette will work on your old Zipp disc’s 10 speed hub. It’s not cheap at over $200 but it’s less than buying a brand new disc. https://m.youtube.com/watch?v=sj5E-hVDrMc
The Edco Monoblock 11 speed cassette will work on your old Zipp disc’s 10 speed hub. It’s not cheap at over $200 but it’s less than buying a brand new disc. https://m.youtube.com/watch?v=sj5E-hVDrMc
😘😘😘😘😘😘😘😘😘😘😘 Problem solved!