jond
Zen MBB Master
double sided bear tape works for me.
yes I think event specific is the way to go long term in terms of a disc wheel using monokote
How to make your Vendetta as fast as possible
- Thread starter Tor Hovland
- Start date
double sided bear tape works for me.
yes I think event specific is the way to go long term in terms of a disc wheel using monokote
Frito Bandito
Zen MBB Master
jond, and GetBent, I agree. For multi-day events when keeping it taught with a hair dryer is impossible, it might be good to use it until it starts flapping, and then remove it since you can peel it off easily. Kind of expensive but....
I haven't tried Dyma wheel covers yet Adrian, but what I have in mind is very similar to it. I bought some thin material that is more like vinyl than plastic, but getting it to stick to the CF wheels with 2-sided tape doesn't seem to want to stay put well enough for me to trust it. The tape sticks fine to the CF, but not the vinyl. I don't want to glue it either. It looks great and can be trimmed to fit perfectly for fit and the thickness is perfect so that the air doesn't trip when passing from the brake tracks to the CF. So, the search for some plastic material that resembles the "For Sale" type mentioned earlier continues.
I haven't tried Dyma wheel covers yet Adrian, but what I have in mind is very similar to it. I bought some thin material that is more like vinyl than plastic, but getting it to stick to the CF wheels with 2-sided tape doesn't seem to want to stay put well enough for me to trust it. The tape sticks fine to the CF, but not the vinyl. I don't want to glue it either. It looks great and can be trimmed to fit perfectly for fit and the thickness is perfect so that the air doesn't trip when passing from the brake tracks to the CF. So, the search for some plastic material that resembles the "For Sale" type mentioned earlier continues.
I'll probably try the Dyma at some point. My Yoeleo wheels are in transit. Hope to get them next week. I will ride on them as is for a bit to get a feel for them and also get some CdA data on them with MyWindsock... then I might try a wheel cover with them and see what difference that makes. If it makes little difference, I would not bother with the hassle. I mean they are 88mm deep already. Not sure how much extra benefit closing the middle will make.
Another thing I was thinking about.... If I make a custom rear race case style thing. I was wondering if I bridged the gap between the case and the frame to cover the top half of the wheel. Would that have a similar effect to a disk wheel? You would basically be covering the top half of the spoked area. Of course that is also the half that is behind the seat so probably in slow moving air anyway. But I am not sure if the drag reduction from a disk is from stopping the spokes moving through the air or another effect. If you covered the wheel as I suggest, the air inside the cover is still not moving relative to the rotating spokes... so still drag there. With a disk, or cover, presumably the air inside the wheel moves with the spokes, so not much drag.
Another thing I was thinking about.... If I make a custom rear race case style thing. I was wondering if I bridged the gap between the case and the frame to cover the top half of the wheel. Would that have a similar effect to a disk wheel? You would basically be covering the top half of the spoked area. Of course that is also the half that is behind the seat so probably in slow moving air anyway. But I am not sure if the drag reduction from a disk is from stopping the spokes moving through the air or another effect. If you covered the wheel as I suggest, the air inside the cover is still not moving relative to the rotating spokes... so still drag there. With a disk, or cover, presumably the air inside the wheel moves with the spokes, so not much drag.
Thanks for the tip on Dyma.
Also consider this, less expensive, but probably less durable. https://wheelbuilder.com/aerojacket-disc-cover/
My criteria were: simple, light and cheap. I have looked into commercial shrink wrap used in the packaging industry, for shipping equipment, and covering boats. That stuff is much thicker than Monokote and most likely would hold up better. The problem is I would need to buy an entire roll of 500 to 2500 feet - there goes cheap.
Also consider this, less expensive, but probably less durable. https://wheelbuilder.com/aerojacket-disc-cover/
My criteria were: simple, light and cheap. I have looked into commercial shrink wrap used in the packaging industry, for shipping equipment, and covering boats. That stuff is much thicker than Monokote and most likely would hold up better. The problem is I would need to buy an entire roll of 500 to 2500 feet - there goes cheap.
I think Dyma and aerojacket are similar, but I think some users here were having trouble getting aerojackets. Not sure if they were out of stock or something. I am in Australia and Dyma ends up cheaper for me (the prices on their web site are AUD which means the base SL Dyma is only about US$68 plus delivery). I think either would give a similar result... and the cost is not that much more than monokote if considering that you may need to repair monokote a few times after punctures and presume these covers are more robust?
It would be at least a couple months before I do anything with a rear disk wheel though.
Using MyWindSock, and also other tools (bikemetrix), I get quite low CdA figures... always under 0.2 which seems too good to be true. I still can't work out if I am just very lucky to be quite aerodynamic... or my power meter reads low resulting in unrealistically low CdA. The reason I mention this, is because I wonder if I will see much difference in making changes such as wheel optimisation being at a low starting level?
It would be at least a couple months before I do anything with a rear disk wheel though.
Using MyWindSock, and also other tools (bikemetrix), I get quite low CdA figures... always under 0.2 which seems too good to be true. I still can't work out if I am just very lucky to be quite aerodynamic... or my power meter reads low resulting in unrealistically low CdA. The reason I mention this, is because I wonder if I will see much difference in making changes such as wheel optimisation being at a low starting level?
Covering the top of the rear wheel with a case would direct the airflow away from the top of the tire, which would have otherwise been moving towards that air. If you look at many of Morciglio designs including Magic, he tries to shield the front tire this way. Jan Heine's claim that fenders are faster is similar; however, he lengthened the front fender considerably over a stock fender.
A disc is a little faster from 0 degrees to 10 degrees of apparent wind yaw but much, much faster in cross winds due to sail effect. I would guess 20 grams of drag in the 0-10 degree range but perhaps 150-200 grams advantage at 20 degrees. As a rule of thumb, 50 g of drag = 0.5 s/km = 5 W = 0.005 m^2 CdA = 0.0005 Crr at bent speeds. I read that from Andrew Coggan on a british TT site.
A small piece of cardboard or even tape could divert the airflow away from the top of the rear wheel like on these two very fast bikes. Note area under seat, too.
A disc is a little faster from 0 degrees to 10 degrees of apparent wind yaw but much, much faster in cross winds due to sail effect. I would guess 20 grams of drag in the 0-10 degree range but perhaps 150-200 grams advantage at 20 degrees. As a rule of thumb, 50 g of drag = 0.5 s/km = 5 W = 0.005 m^2 CdA = 0.0005 Crr at bent speeds. I read that from Andrew Coggan on a british TT site.
A small piece of cardboard or even tape could divert the airflow away from the top of the rear wheel like on these two very fast bikes. Note area under seat, too.
M.J
Well-Known Member
After I put my disc cover on I went out to a 2.5 mile Strava segment that I had tried a bunch of times with a strong tailwind and had come up short of the KOM. I set a new best time with a 5mph crosswind and the disc cover, so I definitely buy the "sail effect" explanation.
Frito Bandito
Zen MBB Master
A great idea GetBent. I wonder if you could find a company that does industrial heat shrinking and probably get a few meters leftover from a job.
Mathew Fy
GRU
Every once in a while I review Cruzbike’s wind tunnel results that showed a significant improvement by using carbon disc wheels. I’m riding Enve 4.5AR, and adding disc covers would probably shave 5-10 watts. Not enough for my kind of riding, but if I ever try racing, I’ll be all in. I’d probably try Jason’s approach:
https://forum.cruzbike.com/threads/rojoracing-style-diy-carbon-wheel-covers.12075/
https://forum.cruzbike.com/threads/carbon-fiber-fun.10937/page-6#post-126609
DavidCH
In thought; expanding the paradigm of traversity
Looks like someone has done their homework but I would not want to ride it on a windy day
I am not sure I'd want a front disc either.
I tried to measure the sail effect on my Two Spoke front wheel. I found a day with a strong West to East cross wind and did 10 miles North and 10 miles South using the 2 Spoke and then repeated it with my 60mm Flow front. And repeated again (ABBA testing). The 2 spoke was very clearly needing less power than the 60mm Flo whereas normally it is just a little faster. (rear wheel was covered on all trials)
BTW: by my guesstimates, those two are two of the three fastest road going bents ever. I think the homemade one is the fastest
ccf
Guru
Here are some thing's I've done:
1. Wheel covers: can use on on the front when wind is less than 12 mph
2. 650B rear wheel: lowers my head
3. Short cranks (145mm): legs and feet sweep through a smaller area
4. Mid-foot cleats: raises feet
5. No seat pad above the waist: lowers head
6. TT brake levers: eliminates brifters that stick up (also improves visibility)
7. Curved slider: lowers bars and hands (also improves visibility)
8. Moose pack: reduces frame drag underneath
1. Wheel covers: can use on on the front when wind is less than 12 mph
2. 650B rear wheel: lowers my head
3. Short cranks (145mm): legs and feet sweep through a smaller area
4. Mid-foot cleats: raises feet
5. No seat pad above the waist: lowers head
6. TT brake levers: eliminates brifters that stick up (also improves visibility)
7. Curved slider: lowers bars and hands (also improves visibility)
8. Moose pack: reduces frame drag underneath
I've asked this before.... where can you get these short cranks other than cutting down long cranks? I'm talking about something that will support 2X11 front rings. Shimano don't seem mto do anything shorter than 160mm (in 105). I have 165 now. It does not seem worth the effort for a 5mm reduction.
ccf
Guru
Mine are Cobb cranks. https://speedandcomfort.com/products/alloy-short-cranks
Rotor makes 150 cranks, you might have to order them online.
BJ686
Well-Known Member
here’s another option….BBK from Australia….I have a set of these
https://www.ebay.com/itm/194306075275?hash=item2d3d8b6a8b:g:56kAAOSw~vpaAScF
chicorider
Zen MBB Master
And these...
https://crupibmxracing.com/collections/cranks/products/rhythm-expert-cranks?variant=4728624261
They work great as a 2x setup. Standard Shimano 24mm bb, with pinch bolts on the non-driveside arm (which I prefer over the SRAM GPX style). I wouldn't worry much about the 165lb rider weight limit; I doubt that us recumbent rider are as hard on cranks as BMX riders). Availability could be an issue, but that almost goes without saying these days.
https://crupibmxracing.com/collections/cranks/products/rhythm-expert-cranks?variant=4728624261
They work great as a 2x setup. Standard Shimano 24mm bb, with pinch bolts on the non-driveside arm (which I prefer over the SRAM GPX style). I wouldn't worry much about the 165lb rider weight limit; I doubt that us recumbent rider are as hard on cranks as BMX riders). Availability could be an issue, but that almost goes without saying these days.
