Daan Posted July 20, 2015 Share Posted July 20, 2015 Daan, how would you suggest measuring the max speed other than with GPS?Inspired by Esaj, I just bought a Cateye urban wireless speedometer ($45) -- it works! (actually, it does not -- see the posts below) Just a bad wireless range and I cannot keep the speedometer display in my pocket but need to attach it to the wheel; not sure yet how to do that nicely . The actual sensor magnet had a screw attached which I sawed off to make it flat, and I glued it to the wheel. The wireless sensor is glued to the outer shell -- looks quite nice but of course, with glue it is permanent I tested just a little but it seems to work well and I got a top speed of 18.7 km/hr. Link to comment Share on other sites More sharing options...
esaj Posted July 20, 2015 Share Posted July 20, 2015 Inspired by Esaj, I just bought a Cateye urban wireless speedometer ($45) -- it works! Just a bad wireless range and I cannot keep the speedometer display in my pocket but need to attach it to the wheel; not sure yet how to do that nicely. The actual sensor magnet I glued to the wheel, and the wireless sensor to the outer shell -- looks quite nice but of course, with glue it is permanent I tested just a little but it seems to work well and I got a top speed of 18.7 km/hr.My original plan was to get a backlit wireless computer, so I could put the computer inside my helmet visor to see the speed & trip-odometer without having to turn my head, but abandoned the idea, as hobby16 told me the wheel motor gives off too much RF-interference for the computer to work over longer distance (or even over short distance, but apparently it works on you at least to the top of the wheel). So I ended up using my old computer from my bike. The computer itself has a stand to which you sort of twist it into, and twist it the other way to take it off. I was originally thinking if I should glue it, but as I wasn't sure if I'll use for longer period, I just ended taping it, but have since been using it all the time (it's easier to know when to turn back home by looking at km's travelled, and knowing the usual ranges I get, than trying to guess from the battery display).Not bad top speed, I thought Xtreme's were limited to 16km/h? Or was that downhill speed? Now you can also get accurate measurements for the battery range. Link to comment Share on other sites More sharing options...
Daan Posted July 21, 2015 Author Share Posted July 21, 2015 as hobby16 told me the wheel motor gives off too much RF-interference for the computer to work over longer distance (or even over short distance, but apparently it works on you at least to the top of the wheel).Ah, that explains the abysmal range I guess I am lucky it works at all :-) I want to keep track of the total miles that I ride the wheel so I need to figure out a nice way to attach the speedometer; for now I attached it to the head light but it is not ideal.Not bad top speed, I thought Xtreme's were limited to 16km/h? Or was that downhill speed? Now you can also get accurate measurements for the battery range.Yeah, I was surprised! good speed -- this was flat terrain but I just rode a little bit so I need to do more testing. Nevertheless, I already feel a higher max speed would be great, say 14 mi/hr (~22km/hr) would be great. I would like to do a new range test but it harder here in the Seattle area with all the hills... Link to comment Share on other sites More sharing options...
Daan Posted July 21, 2015 Author Share Posted July 21, 2015 Just to complete the story for others who buy the Cateye urban wireless, I managed to attach the display quite nicely; I drilled two tiny holes in the display holder through which I could put a tie wrap /zip tie and attach it semi-permanently to the handle. Only drawback is that I cannot read the display while riding ah well.(btw. the upcoming blue tooth app may actually support measuring speed, distance etc. so all this work may prove to be useless lol ) Link to comment Share on other sites More sharing options...
Daan Posted July 21, 2015 Author Share Posted July 21, 2015 Well, darn! hobby16 was right -- the speedometer stops working when I draw too much power (like uphill) no matter how close I hold it I just bought another cateye but wired this time --now let's see if I can remove the glued sensor... ouch Link to comment Share on other sites More sharing options...
esaj Posted July 21, 2015 Share Posted July 21, 2015 Sorry, I probably should have mentioned the possible problem with wireless computers, before recommending using a bike computer... Link to comment Share on other sites More sharing options...
Daan Posted July 21, 2015 Author Share Posted July 21, 2015 No worries Esaj I got it off pretty well; just a blackish mark but that's ok. I installed the wired speedometer instead -- not as pretty but not too bad. And now it works perfect -- I got a top speed of 19.4 km/hr today -- I wish it would go faster still but it is definitely capable of going faster than the 16km/hr in the specs. (of course, one is not supposed to keep leaning in when the tilt-back happens so do this at your own risk). btw. sorry Sam for somewhat hijacking your excellent review thread with speedometer issues; I'll stop now . Btw. watched your videos now and you are very skilled! (warning: the way the sensor is attached here is wrong since it is not orthogonal to the magnet -- see below) Link to comment Share on other sites More sharing options...
Daan Posted July 22, 2015 Author Share Posted July 22, 2015 Darn -- it still doesn't work well -- today it seemed to about double the speed & distance I wonder if the magnets in the wheel cause this??@esaj: I think that once a wheel is somewhat inflated such that it doesn't 'fold' or 'slip', any full turn means the wheel traveled the circumference, regardless if it is pushed down or not. Link to comment Share on other sites More sharing options...
esaj Posted July 22, 2015 Share Posted July 22, 2015 Darn -- it still doesn't work well -- today it seemed to about double the speed & distance I wonder if the magnets in the wheel cause this??Check that the sensor doesn't give off the signal twice when the magnet passes, on mine, it does this really faint "click"-sound when the magnet passes, and at first it was giving off two "clicks" when the magnet passed and showed all the values doubled (like the wheel would have made two turns when it did just one). Turning the magnet 90 degrees on the rim solved it (probably it was reacting to both poles of the magnet separately).@esaj: I think that once a wheel is somewhat inflated such that it doesn't 'fold' or 'slip', any full turn means the wheel traveled the circumference, regardless if it is pushed down or not.I beg to differ, consider the following (exaggerated) image:If the tire pushes in evenly at the ground contact point all the way around the turn, the real circumference it travels over one turn (red) is less than the circumference without weight on top (black)... but I'm not 100% sure if this is true, it's just my conclusion. Anyway, a 1% or less error on the numbers is very low, consider for example the speed of 20km/h, if it's showing 1% too much, the real speed is about 19,8km/h, big deal? Still way more precise than what I was getting with GPS giving me sometimes numbers jumping between 20-28km/h when I was riding steady maybe around 25. With the same 1% error, if the trip meter is showing 10km, in reality it's around 9.9km etc. If you use high pressure, the tire doesn't even push in much at all, so using the circumference measured without weight is probably giving much less than 1% of error... I've used the table-value for 16" tire circumference (1272mm) on my computer, which is lower than what the real circumference without weight is (1310mm), but I expect that with weight on top it gets pretty close to the table value (haven't ever bothered to measure the circumference with weight on top). Link to comment Share on other sites More sharing options...
dmethvin Posted July 23, 2015 Share Posted July 23, 2015 To support what @esaj said, it turns out that some tire inflation warning systems in cars take advantage of this effect. If the tire pressure gets too low, the electronics in the car notice the difference between the number of revolutions in some tires and can tell that one is underinflated. Link to comment Share on other sites More sharing options...
Daan Posted July 23, 2015 Author Share Posted July 23, 2015 Check that the sensor doesn't give off the signal twice when the magnet passes, on mine, it does this really faint "click"-sound when the magnet passes, and at first it was giving off two "clicks" when the magnet passedYes! that was it. Changing the magnet direction didn't help because the sensor was not 'orthogonal' enough to the magnet. So I repositioned the sensor (on the other side of the wheel since it didn't have enough clearance on the first side due to the air valve) and now it finally works at least, on my short test ride today... pfff, well, third time's a charm Hmm, I have to still disagree with your argument about pressing in the tire... if the wheel does not slip (or fold) and makes a full turn, the entire outside of the wheel is the distance travelled. No matter how much I press or not. Right? @dmethvin: I think on a car the underinflated tire has more resistance and thus a tendency to go slower than the other wheels. Link to comment Share on other sites More sharing options...
dmethvin Posted July 23, 2015 Share Posted July 23, 2015 Okay @Daan I'm gonna have to go all Wikipedia on you! https://en.wikipedia.org/wiki/Tire-pressure_monitoring_system#Indirect_TPMS Link to comment Share on other sites More sharing options...
Daan Posted July 23, 2015 Author Share Posted July 23, 2015 Okay @Daan I'm gonna have to go all Wikipedia on you! https://en.wikipedia.org/wiki/Tire-pressure_monitoring_system#Indirect_TPMSOkay, I give up (but still -- what is wrong with my argument about the distance travelled being the outer perimeter of the tire...??) Link to comment Share on other sites More sharing options...
SirGeraint Posted July 23, 2015 Share Posted July 23, 2015 @Daan, maybe this would help. Picture that the tire is completely flat. Then I bet you could see that the diameter would be the wheel plus the thickness of the rubber of the tire. Then it might make it clearer that increasing the pressure in the tire would also increase the diameter (and therefore the circumference) of the tire until there was no give in the tire and the diameter would be the diameter of the tire with no weight on it. Link to comment Share on other sites More sharing options...
Daan Posted July 23, 2015 Author Share Posted July 23, 2015 Regardless of circumference, I had a great off-road forest ride today; I continue to be surprised how far you can take these wheels; amazing! and so fun. I just hope my new speedometer is dust-proof Link to comment Share on other sites More sharing options...
Daan Posted August 4, 2015 Author Share Posted August 4, 2015 I finally disassembled the wheel and tucked away the wiring neatly inside the shell; read about it here: Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.