Tsdz2 under reading speed

[Bogmonster666]

Is it just me or does the tsdz2 massively under read speed? Might just be poorly adjusted speed sensor but I don't think so. I've been suspicious and meaning to check but held off as was fitting a new rear tyre. The tyre is 26 X 1.75. I believe that is a 25.75 inch diameter overall so the default 26 inch setting is only a few percent out when you calculate circumference. I believe my speed is reported 15 % higher. I did a quick test with a phone GPS speedometer app. My '26' mile ride today is reported as 22 miles by Google maps, again about 15 % out. Sure, I can try and compensate by bodging the wheel size setting to something like 24". Feels like a real bodge...anybody else found this?

I believe osf allows more fine grained control but I'm on stock fw.

Will have a better attempt tomorrow...

 

[Simon Knight]

Is it just me or does the tsdz2 massively under read speed? Might just be poorly adjusted speed sensor but I don't think so. I've been suspicious and meaning to check but held off as was fitting a new rear tyre.

Depends on how you define massive. My trike has 20 inch wheels all fitted with Big Apple tyres i.e. large balloon tyres. Initially the TSDZ2 was over reading by approximately 10% when compared with both my Garmin GPS and Sigma cycle computer. I played with the diameter setting and if I remember correctly 19 inch diameter gives a speed that more closely matches the two other devices. Who knows which is the closest to truth?

S

 

[Bogmonster666]

Depends on how you define massive. My trike has 20 inch wheels all fitted with Big Apple tyres i.e. large balloon tyres. Initially the TSDZ2 was over reading by approximately 10% when compared with both my Garmin GPS and Sigma cycle computer. I played with the diameter setting and if I remember correctly 19 inch diameter gives a speed that more closely matches the two other devices. Who knows which is the closest to truth?

S

Well, for such a simple calculation it feels a long way out

A 22" wheel setting should get me in the right ballpark I've just calculated. My GPS Speedo measurement was quite quick and only displays to the neatest mph so I'll play later.

Edit: set to 23" and that appears much closer, that would put it at ~12% under reporting. At least it is very easy to compensate for.