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Author Topic: High Pressure Sensors  (Read 475 times)
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I am looking for a high pressure sensor that is a type of pad. I want to measure the rear suspension on a race motorbike to ascertain travel. I am yet turn anything up? Ideas?
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pressure and travel are 2 different things. Why not just measure travel. Give more details.
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This is the bike in question. We need to get the data whilst the bike is racing so everything had to be rock solid and I have not seen a way to measure travel that I feel would stand up to race conditions...


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I might want to look into and research load cells or strain gauges, they are available in all sorts of ranges. They are rugged and accurate but do require good low level amplification as most are designed to be wired into a Wheatstone bridge circuit.

Lefty

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How on earth would you hook up a pressure sensor the rear suspension?  I guess you could put it in place of the nitrogen filler or provide some sor of 'y' fitting to get both on there at the same time.  However, you would then have to do a lot of calculations on the raw data to determine rear wheel travel from the pressure.  Some things you would have to take into account are:

Pressure
Temperature of shock gas
Volume vs. shock displacement
rising rate of suspension linkage

It wloud get complicated

In my opinion you'd want to use a linear displacement sensor.  Something like this: http://www.pennyandgiles.com/linear-displacement-sensor-pd-109,3,,.php

It would make your life very much easier.
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How on earth would you hook up a pressure sensor the rear suspension?  I guess you could put it in place of the nitrogen filler or provide some sor of 'y' fitting to get both on there at the same time.  However, you would then have to do a lot of calculations on the raw data to determine rear wheel travel from the pressure.  Some things you would have to take into account are:

Pressure
Temperature of shock gas
Volume vs. shock displacement
rising rate of suspension linkage

It wloud get complicated

In my opinion you'd want to use a linear displacement sensor.  Something like this: http://www.pennyandgiles.com/linear-displacement-sensor-pd-109,3,,.php

It would make your life very much easier.

Haha. I never imagined it would be easy. Thanks for that link. I will look further into it, that might be just what I am after.
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I have not seen a way to measure travel that I feel would stand up to race conditions...

The commercial race logging systems I've seen all used position sensors to measure suspension deflection. Trying to infer it from pressure/force does not strike me as a promising approach. Depending what you're trying to do with the log data, you might find that you could achieve it from accelerometer data. However, if suspension deflection is what you ultimately want then deriving that from inertial forces would not be a good way to go imo. The sensors for some of the commercial systems seem extremely expensive to me, for what they do - I suspect buyers are mostly paying for convenience rather than technical complexity. I had good results from a set of cheap home-made string pots (measuring aerodynamic lift and drag in the 50 - 150 mph speed range) and, while my cheap and simple string pots were too obviously DIY to be shown in public, I feel sure that you could come up with something similar that did the job.
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Depending on the travel distance of the suspension, maybe mount a linear pot on the side of the shock/spring assembly.
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