Suspension linear potentiometers

[imdying]

These are priced from reasonably pricey to hideously expensive. I can understand why having an item like that that strokes at a high cycle rate, over millions of cycles, whilst still giving a clean signal, isn't the easiest thing in the world to manufacture, but it still surprised me a bit.

Any advice on places to find them? I really don't need to drop $600 a piece on Bosch Motorsport ones, to me the data will only be personal interest rather than mission critical, although I would give the traces to Ohlins dude when he revalves the bike.

[tigertim20]

These are priced from reasonably pricey to hideously expensive. I can understand why having an item like that that strokes at a high cycle rate, over millions of cycles, whilst still giving a clean signal, isn't the easiest thing in the world to manufacture, but it still surprised me a bit.

Any advice on places to find them? I really don't need to drop $600 a piece on Bosch Motorsport ones, to me the data will only be personal interest rather than mission critical, although I would give the traces to Ohlins dude when he revalves the bike.

Build your own. make it a project. if its only for personal interest, doesnt matter if it takes you a while to get it dialled in

[bogan]

These guys do good and cheap high res digital rotary encoders. It looks like they do an incremental optical linear encoder, which might work? Depends on how you are datalogging and how much time you are willing to invest in making up a case etc for it.

[Robert Taylor]

These are priced from reasonably pricey to hideously expensive. I can understand why having an item like that that strokes at a high cycle rate, over millions of cycles, whilst still giving a clean signal, isn't the easiest thing in the world to manufacture, but it still surprised me a bit.

Any advice on places to find them? I really don't need to drop $600 a piece on Bosch Motorsport ones, to me the data will only be personal interest rather than mission critical, although I would give the traces to Ohlins dude when he revalves the bike.

Its not only that its the resolution of your data logging. Most of the affordable stuff on the market is only 200 hertz, and with suspension you really miss a lot of data at that very low frequency. Ideally you need 1000 hertz and upwards

[imdying]

Its not only that its the resolution of your data logging. Most of the affordable stuff on the market is only 200 hertz, and with suspension you really miss a lot of data at that very low frequency. Ideally you need 1000 hertz and upwards

Sadly, it'll only be 100hz max. There were (few) higher sample rate options in my price range, but they dropped too many of the other features that are of greater importance (to me)

[imdying]

Build your own. make it a project. if its only for personal interest, doesnt matter if it takes you a while to get it dialled in

It is possible, although I really have lots of other projects that my time would be better spent on One of which is to make a rudimentary supplementary logger (no outputs, few inputs, no UI, just an SD card and a stop/start button) with a sample rate as high as I can manage... to log the suspension traces.... it's a never ending round and round circle of tinkering

[Robert Taylor]

Sadly, it'll only be 100hz max. There were (few) higher sample rate options in my price range, but they dropped too many of the other features that are of greater importance (to me)

In reality there is an enormous amount of data that you will miss at that frequency. It will be useful though.

[imdying]

In reality there is an enormous amount of data that you will miss at that frequency. It will be useful though.

Indeed!

But on the flip side, in practice I'll still have an enormous amount of data compared to what I'm getting now (i.e. nothing).

As to exactly how much that missing data matters, once I have collected sufficient 100hz and 1khz trace data sets, I will be able to quantify that (for anyone that cares).

How much are you flogging the linear pots for?

[Robert Taylor]

Indeed!

But on the flip side, in practice I'll still have an enormous amount of data compared to what I'm getting now (i.e. nothing).

As to exactly how much that missing data matters, once I have collected sufficient 100hz and 1khz trace data sets, I will be able to quantify that (for anyone that cares).

How much are you flogging the linear pots for?

We are not selling them ourselves, we have to purchase

[bikaholic]

These are priced from reasonably pricey to hideously expensive. I can understand why having an item like that that strokes at a high cycle rate, over millions of cycles, whilst still giving a clean signal, isn't the easiest thing in the world to manufacture, but it still surprised me a bit.

Any advice on places to find them? I really don't need to drop $600 a piece on Bosch Motorsport ones, to me the data will only be personal interest rather than mission critical, although I would give the traces to Ohlins dude when he revalves the bike.

what is the output required, or the datalogger input, do you need linear or rotary pot( a bit like a tl1000 rotary dampner conversion i'd imagine, to make them work).

[imdying]

what is the output required, or the datalogger input, do you need linear or rotary pot( a bit like a tl1000 rotary dampner conversion i'd imagine, to make them work).

0-5v, linear.

[Ocean1]

0-5v, linear.

Doesn't really matter, you can get widgets to change most signal feeds to 0-10v or 4-20mA. That scan frequency is a bit limiting but as you say you'll at least get the basics.

Couple of years ago someone started making elastomeric linear transducers, rubber bands that accurately varied resistance throughout a stretch range. How cool would that be, bung a rubber band around your swingarm / frame, plug in a dataloger and you're off. Haven't heard anything from them since but the prototypes were apparently functional and reliable.


Must admit I'm surprised someone's not offering a transducer / logger set for rent, after all not many people need this gear for more than a week or two while they tune shit. Is there a market, there?

[LBD]

Could you not use a rotary pot with a drum, coil return spring and a cable (string) to where ever you wish to measure the travel?

[imdying]

Doesn't really matter, you can get widgets to change most signal feeds to 0-10v or 4-20mA. That scan frequency is a bit limiting but as you say you'll at least get the basics.

Yup to all that

Couple of years ago someone started making elastomeric linear transducers, rubber bands that accurately varied resistance throughout a stretch range. How cool would that be, bung a rubber band around your swingarm / frame, plug in a dataloger and you're off. Haven't heard anything from them since but the prototypes were apparently functional and reliable.

Heh, that's phat.

Must admit I'm surprised someone's not offering a transducer / logger set for rent, after all not many people need this gear for more than a week or two while they tune shit. Is there a market, there?

I don't know if there's much interest here. To be honest I don't actually need one, all I need are the data traces. My main interest is in the software possibilities; think of it like an 'expert system'. I expect that not actually being able to decipher that data is a portion of what holds people back from using them. I have developed something from the data from my existing 10hz logger, but obviously that rate doesn't take you far if you're doing any sort of in depth analysis... good for tuning via a wideband though, assuming you collect sufficient data.

A guy I know wants to make his own traction control unit, maybe I could provide him with some useful info to make his life easier, maybe not. I'll be able to offer at least.

Of course, a track bike festooned with electrical sensors looks trick as you like (to my eyes at least ), so if nothing else I'll get that

Could you not use a rotary pot with a drum, coil return spring and a cable (string) to where ever you wish to measure the travel?

I'm not sure. I don't know enough to answer that. I expect it'll be years (at my current rate of progress) before I could tell you that (unless you donate such an item in which case I'll run the two types at the same time for a direct comparison). So when in doubt, stick with that everyone else uses


It's cheaper to dick about with loggers than superchargers... what can I say, I'm a tight wad. Plus it'll give me something to do over the Christmas holidays.


/edit: Sorry that doesn't make much sense without an explanation... an expert system in this instance would be something like a program that can suck in the data traces, analyse them, and then recommend changes to the bike. I have rudimentary one I built for the wide band, but the power commander auto tune does basically the same thing so I've lost interest in something that simple. Was good learning exercise though. Ideally I'm heading towards something that can take say RPM, TPS, airbox pressure, air temp, detonation, EGT, and AFR, and help with the tuning of a two stroke. Ultimately it's just a stepping stone towards an EFI 250 two stroke project, but now I'm getting waaaay ahead of myself. Plenty of melted pistons await before I can even think of that. A VJ23 with electric start and EFI would be kinda neat though.

[Ocean1]

an expert system in this instance would be something like a program that can suck in the data traces, analyse them, and then recommend changes...

You'll be aware there's existing systems that go a very long way down that path. You'll also not want to invest that much.

These guys use a fairly heavy duty multi-channel system: http://www.solidstate.co.nz/ They've got a long history with dataloggers too.