new Trek Speed Concept Blendr Duo Base and Computer Mount and Device Mount Location

[gte534j]

Hi,
I have a new Trek Speed Concept Blendr Duo Base and Computer Mount and wanted to know what to select for Profile 4- Device Mount Location (Handlebar, Stem, Remote Wind Sensor, or Front Mount)?

Below are some pictures of the mount. On the bottom you can attached the GoPro mount to attach the Aeropod.
https://www.trekbikes.com/us/en_US/equi ... t/p/42018/

Pick of mount w/ highlighted gopro mount location

mount.jpg (37.55 KiB) Viewed 13561 times

Some good pics of the mount-
https://www.bespokecycling.com/build-ga ... -concept-3

Also- do you think this mount will be stable enough?
Thanks!

[Velocomp]

I think this mount will be fine; where your PP/AP attaches is very close to where the mount connects to your handlebars.

You can select "stem" for the location; when you do your calibration ride everything will be corrected as needed.

[gte534j]

Thank you John. I have the Trek Speed concept mount all setup and working now. See the 3 photos below. I will start working on collecting data with this setup soon-

TT-3.jpg (125.92 KiB) Viewed 13467 times

TT-2.jpg (84.99 KiB) Viewed 13467 times

TT-1.jpg (130.87 KiB) Viewed 13467 times

[Velocomp]

I can't tell from the photos how the mount is attached to the handlebars. If the mount is stiffly attached the handlebars this is fine; if the mount is attached to the aero bars this won't work correctly, because the aero bars flex.

Please show photos showing how mount is attached to bike handlebars.

[gte534j]

Hi,
The mount attaches to the aero extensions. See the two photos. Do you think this is ok?

front2.jpg (78.81 KiB) Viewed 13454 times

front1.jpg (108.77 KiB) Viewed 13454 times

[Velocomp]

You can try using this setup, but because the mount is attached to the aero bars, it is very likely that the aero bars flex, and will cause problems for AeroPod.

The best place to attach AP is underneath the stem. We have a mounting solution for this configuration; email technicalsupport@velocomp.com for details.

[mamilian.bike]

Is there a way to tell if the level of vibration is problematic?

I have been using a very similar setup (one one short metal extension from the Bontrager mount instead of two) on my Speed Concept. The bar setup on the new Speed Concept is very rigid. Nothing is moving as far as I can tell. I would prefer not to stick a go-pro helmet mount to the bottom of the base bar if I can avoid it.

[Velocomp]

Is there a way to tell if the level of vibration is problematic?

I have been using a very similar setup (one one short metal extension from the Bontrager mount instead of two) on my Speed Concept. The bar setup on the new Speed Concept is very rigid. Nothing is moving as far as I can tell. I would prefer not to stick a go-pro helmet mount to the bottom of the base bar if I can avoid it.

The problem is not vibration; the problem is flex. Aero bars flex up/down under loading from the cyclist's arms. When AP is attached to the aero bars, flexing alters the angle of the AP relative to ground, and causes extraneous power readings.

[mamilian.bike]

Thanks. Conceptually there will be some flex in a standard road bike bar/stem, just as there is some flex in the base and bars on a TT bike. Both configurations put rider weight on the bars through a lever. There are a lot of factors that will determine how much the bar/stem of either bike will flex (i.e. materials, design, rider weight, rider position, etc). I imagine that's why the configuration dialogs require rider weight and hand position. Some road bikes (e.g. Domane & Roubaix) are even intentionally designed to provide explicit front suspension. Are these types of bikes unsupportable? Is there a way to tell if the level of flex is problematic, or within the AeroPod's compensation algorithms?

The base towers and bars of the 2022+ Speed Concept up to, and including, the Bontrager mount are made from thick aluminum. The extensions are the only part made from carbon.

I would prefer not to modify the bike in a way that reduces it's aerodynamic efficiency when I'm not using the AeroPod. It would great if there was a way to support this configuration.

[Velocomp]

Thanks. Conceptually there will be some flex in a standard road bike bar/stem, just as there is some flex in the base and bars on a TT bike. Both configurations put rider weight on the bars through a lever. There are a lot of factors that will determine how much the bar/stem of either bike will flex (i.e. materials, design, rider weight, rider position, etc). I imagine that's why the configuration dialogs require rider weight and hand position. Some road bikes (e.g. Domane & Roubaix) are even intentionally designed to provide explicit front suspension. Are these types of bikes unsupportable? Is there a way to tell if the level of flex is problematic, or within the AeroPod's compensation algorithms?

The base towers and bars of the 2022+ Speed Concept up to, and including, the Bontrager mount are made from thick aluminum. The extensions are the only part made from carbon.

I would prefer not to modify the bike in a way that reduces it's aerodynamic efficiency when I'm not using the AeroPod. It would great if there was a way to support this configuration.

AP measures slope changes as little as 0.05%--that is a half foot of vertical travel over a distance of 1000 feet.

CdA measurements in profile 4 can distinguish between wattage changes as fine as one watt; that translates to a slope change of more than 0.05%. So, when the aero bars flex (and they do) the slope change can be a few percent. This renders CdA measurements somewhat worthless.

The under-bar mount we recommend is very small, and I find it difficult to believe it will measurably affect your overall aero efficiency.

[mamilian.bike]

The under-bar mount we recommend is very small, and I find it difficult to believe it will measurably affect your overall aero efficiency.

It's hard to see how adding a GoPro helmet mount to the bottom of the basebar wouldn't cause air to detach, or at least not flow the way Trek intended. In either case that would cause aerodynamic inefficiency. Is that a measurable thing? I don't know. I do know that it's ugly and I'd rather not put it on my bike. I also suspect that there's risk of paint damage that Trek will not warranty if I do it.

I am asking if there's a way to measure that flex to know if it's an actual concern or something theoretical. It sounds like the answer is "no". There isn't a way to measure that data, or tell if it's any different from the acceptable amount of flex that I will see on my road bike. That feels like the kind of thing that should be surfaced.

I understand what you're saying, but I am struggling to see how the flex that you're concerned about is different from the flex that has to exist in a road bike. It's the same kind of leverage system, just configured a little differently.

I bought the AeroPod to play with. I am finding out that it's a very complicated toy that is very hard to use. For e.g. I went out today to try to calibrate it, and couldn't remember what all the different blinking light combos were trying to communicate, had to stop several times to look that up, it wouldn't go to 100W, and I got frustrated and turned it off. I'm sure there's value here, but I'm not confident that the value is worth modifying my bike in a way that might damage it or dealing with the UX limitations to extract it.

[Velocomp]

The under-bar mount we recommend is very small, and I find it difficult to believe it will measurably affect your overall aero efficiency.

It's hard to see how adding a GoPro helmet mount to the bottom of the basebar wouldn't cause air to detach, or at least not flow the way Trek intended. In either case that would cause aerodynamic inefficiency. Is that a measurable thing? I don't know. I do know that it's ugly and I'd rather not put it on my bike. I also suspect that there's risk of paint damage that Trek will not warranty if I do it.

I am asking if there's a way to measure that flex to know if it's an actual concern or something theoretical. It sounds like the answer is "no". There isn't a way to measure that data, or tell if it's any different from the acceptable amount of flex that I will see on my road bike. That feels like the kind of thing that should be surfaced.

I understand what you're saying, but I am struggling to see how the flex that you're concerned about is different from the flex that has to exist in a road bike. It's the same kind of leverage system, just configured a little differently.

I bought the AeroPod to play with. I am finding out that it's a very complicated toy that is very hard to use. For e.g. I went out today to try to calibrate it, and couldn't remember what all the different blinking light combos were trying to communicate, had to stop several times to look that up, it wouldn't go to 100W, and I got frustrated and turned it off. I'm sure there's value here, but I'm not confident that the value is worth modifying my bike in a way that might damage it or dealing with the UX limitations to extract it.

Attached are the instructions for attaching AP to your bike. These instructions specifically state that AP should not be attached to the aero bars.

Aero bars are cantilevered beams, much like a cantilevered swimming pool diving board. Both are rigidly attached at one end to a solid, non-flexing base. But at the unsupported end of the bars, your hands are applying varying amounts of pressure out near the edge of the bars, analogous to jumping up/down out at the end of the diving board. When you apply pressure at the end of the beam, THE BARS/BOARD WILL FLEX.

Here is a video we made four years ago, showing precisely why AP should not be mounted to aero bars:

https://youtu.be/ZjcVGtdjqDk

If you believe the aero bar flex problem is theoretical, please watch the video a few times.

There is no way to measure aero bar flex, because there is no way to know how much pressure you are applying to the bars, no way to know how bumps/perturbations in the road are giggling you and the bike and the aero bars up and down, and no way to know how stiff your bars are.

AeroPod is a very precise device, measuring wattage differences as little as 1W in order to extract CdA information. AP does require care in its setup and usage--as does every aero sensor device on the market. And, frankly, CdA measurement is no less challenging in a wind tunnel, even with lots of technicians assisting with setup/measurement/data interpretation.

We have tried to make the instructions clear and complete, we have made videos to assist with calibration steps, and our AeroPod 2.0 app makes data collection simple and automatic.

But if you don't follow the instructions and don't mount AP correctly, most definitely we cannot promise AP will provide the results you are seeking.

[mamilian.bike]

Here is a video we made four years ago, showing precisely why AP should not be mounted to aero bars:

https://youtu.be/ZjcVGtdjqDk

If you believe the aero bar flex problem is theoretical, please watch the video a few times.

Sorry, I don't think I ever implied, stated, or said anything that would suggest that flex is theoretical. Flex is an inherent part of any loaded system. There are many ways to design systems, even with the same materials, to promote or reduce flex. A very simple example of this is the difference between a round and D-shaped seat post.

My question was how the flex in an aerobar system is different from the flex inherent in a road bike setup - which is subject to mostly the same pressures.

That bike (2018?) is not my bike (2022). That bike has a very, very different configuration. It's arguably the absolute worst design for aerobar stability; Trek probably learned something there.

The thing demonstrated it that video is akin to saying because one tire does X, all tires do X, but we know it doesn't work that way. It's a worse case scenario.

Is it possible that all aero bars are a problem? Yes it's possible, but if we can't measure it we can't say that with certainty. That's what part of what I'm struggling with here.

Aero bars are cantilevered beams, much like a cantilevered swimming pool diving board. Both are rigidly attached at one end to a solid, non-flexing base. But at the unsupported end of the bars, your hands are applying varying amounts of pressure out near the edge of the bars, analogous to jumping up/down out at the end of the diving board. When you apply pressure at the end of the beam, THE BARS/BOARD WILL FLEX.

On an aerobar most of the weight should be loaded on the back, weighting the tip of the bar (the diver in your e.g.) creates instability. On my bike, my weight is loaded almost entirely straight over the two 52.4mm x 17.4mm aluminum towers (the fulcrum). Each elbow is supported by its own 52.4mm x 17.4mm squared-oval of aluminum. There is a cross-beam between both bars. That part is all heavy aluminum. I don't think it's accurate to claim that it will behave like the bike in that video.

Road bars are also cantilevered beams, but all the forward weight is at the front (and sides). That's much closer to the system you described. I also struggle with how this is OK, and every possible aerobar design is not.

There are at least two road bikes with built in front suspension systems (I mentioned these before). It sounds like there is no way to compensate for, or support, these bikes, and that's fine as long as it's documented.

AeroPod is a very precise device, measuring wattage differences as little as 1W in order to extract CdA information. AP does require care in its setup and usage--as does every aero sensor device on the market. And, frankly, CdA measurement is no less challenging in a wind tunnel, even with lots of technicians assisting with setup/measurement/data interpretation.

We have tried to make the instructions clear and complete, we have made videos to assist with calibration steps, and our AeroPod 2.0 app makes data collection simple and automatic.

I'm guessing this is a response to my comments around UX. I'm not disagreeing that AP is doing a complicated thing, I think that's clear. I figure out complicated things for a living. Part of making a complicated thing simple to use is in how it communicates to users. UX matters. I don't think the blinking lights and colors are simple or clear. I think that you would sell more of them, and they would be more useful to your customers, if they surfaced more diagnostic and state data in a way that is consumable without a decoder ring.

But if you don't follow the instructions and don't mount AP correctly, most definitely we cannot promise AP will provide the results you are seeking.

There is a significant level of complexity and room for "user error" present. I completely agree. Like I said before, I bought it to have a play. Playing should be fun. I'm still trying to figure out what kind of fun this is.

Next time I will roll with the decoder ring taped to my bike... Maybe I'll come around.

[mamilian.bike]

There is no way to measure aero bar flex, because there is no way to know how much pressure you are applying to the bars, no way to know how bumps/perturbations in the road are giggling you and the bike and the aero bars up and down, and no way to know how stiff your bars are.

What if they put the bike on a smart trainer with a fan on? Mostly just spitballing, but very few things are impossible. Most things can be solved with money and time .

Air speed would be mostly constant. Power and cadence would be easy. Speed might be problematic if AP doesn't support trainer speed. Then move around the bike. Weight the bars. Weight them unevenly. Track the telematics. It might not be perfect, but given all the variables that AP is guessing around when using it as intended, it might be good enough.

[lorduintah]

I am not sure that the AeroPod or PowerPod are that useful when on a trainer.

The inertial sensitivity is compromised by the lock down of the bike, so I suspect that almost all power to the drivetrain will not be detected.

What wind resistance could possibly be converted to any impact on power?

[mamilian.bike]

I am not sure that the AeroPod or PowerPod are that useful when on a trainer.

The inertial sensitivity is compromised by the lock down of the bike, so I suspect that almost all power to the drivetrain will not be detected.

What wind resistance could possibly be converted to any impact on power?

The smart trainer provides a power/cadence/speed and the fan provides "wind". All of these things would effectively be constants (or close enough). The air movement would be constant (+/- AC voltage variations), the other numbers are products of mechanical measurement + algorithms, and as you note the bike is mostly locked in place.

In this model we would expect the CdA to be effectively constant as well. If there were wide variances in reported CdA when changing how the cockpit is loaded then something cockpit loading related is the most likely cause for that. This model would need to be validated with a variety of bikes, obviously including some road bike (because we know those are fine), and ideally some floppy TT bikes like the one in the video.

But, as I mentioned before that is just me spitballing an idea. Without more information about how AP actually works, it would be difficult to create certainty around a testing protocol.