Other use for cyclocomputer

[dabac]

Hi guys,
I'm thinking of using a cyclocomputer together with my inlines, so I'd appreciate your help with a few questions:
1) Which makes / models would accept non-bike wheel dimensions? (dia 84 mm to be precise)
2) For wireless units, what is their range? (Polar claims 50 cm / 20 inches which is a bit on the short side for my use)
3) for wireless units with cadence sensors. The CS must have a greater range than the speed sensor, so is there any way I can trick a cadence sensor into acting like a speed sensor? (I assume their pickups are basically similar)
4) Has anybody experimented with the size of the magnet? Given the wheel design of inlines I'd like to recess as small a magnet as possible into the wheel.

Cheers,

dabac

 

[John M]

Wouldn't this be quite inaccurate because most of the time one foot is off of the ground and with that foot's wheel speed not matching that of the foot that is on the ground. I think that a GPS is probably the way for you to go.

 

[garage sale GT]

See Sheldonbrown.com. His info is geared towards helping people recycle old cyclos but you can use it to infer which ones have a decipherable means of calibrating your device to your wheel size.

 

[dabac]

Wouldn't this be quite inaccurate ...

That remains to be seen. First, the spin-out rate of the wheels is fairly low so I don't think they're slowing down that much during their hover time. Second, each "stride" a skater takes is angled away from the direction the skater is travelling in, so the skate is probably following a longer path than the skater. Maybe the time spent in the hover phase and the offset angle of the skate's path will compensate for each other to some extent. Third, I've seen skate computers before. But they worked by replacing the wheel in its entirety which is a more cumbersome solution - but still enough to give some hope that this would work.

Besides, if the loss is consistent it can always be handled by calibration.

I think that a GPS is probably the way for you to go.

I'm not against GPS, but:
-they're quite expensive compared to cyclocomputers
-the one I'm most likely to get (a PDA/GPS) will have trouble logging a full run due to limited battery life.

 

[impakt]

The polar rs800g3 comes with a GPS. and measures heart rate, calories, downloads..ect..

 

[CJ Smith]

I was skating 12 miles per night on smooth to semi-rough paved surfaces. I rotated and replaced wheels frequently and because of that and the concept of having to recess & probably epoxy a small magnet combine with factoring that the diameter of the wheel is changing more rapidly than, let's say, a 700c wheel does... well you get the idea... Add this all into the equation and I will side heavily with the G.P.S. vote. If you must be insistant on going by the way of the magnet. May I at least offer this as a suggestion. Use a Dremel tool with a flexible shaft (I use this one: http://www.dremel-direct.com/acatalog/Dremel_Flex_Shaft.html) or a bench top grinder (I will advise wearing safety glasses and gloves). I've ridden with a Dremeled magnet siliconed to an Aerospoke wheel for years it worked out fine, but that was years before the G.P.S. technology that now exists.

Bottom line of this reply is I hate seeing people wasting time. Also consider that with the G.P.S. you can hook it up to your computer and get all kinds of cool stats to log, without having to manually do all that much.

Best Regards,
CJ Smith

PS: Keep It Simple Skater

 

[dabac]

Hi all,
A few weeks ago I found a Sigma 800 cyclocomputer that would accept the roll-out value of my 80 mm wheels and installed it on my inlines. A small piece of aluminum and some double sided tape was enough to position the pickup at a suitable slot in the rail.
The magnet was a laughingly simple squeeze fit between the spokes of a wheel. It stays in place during riding and a poke with a pencil is sufficient to get it out when the wheels are shifted around.

I've done more than 100 miles with it now, and its consistently showing <3% mismatch when compared to a GPS. At that performance I don't think I'll even bother trying to adjust the roll-out value.

Top speed recorded is 36 km/h, which appears reasonable enough, so there don't seem to be any problem with the contacts "floating".

Not too bad for an investment of $12/ EUR 9 and half an hour of tinker time!
(It'll run for years on the same battery too!)