Question on Pro Twin front forks

[Pussy]

There in fact would still have been variance, just less obvious. And this was because of precision remachining on the damper rods to actually get them to sit on the same centreline as the fork tubes! Thereby giving less bypass, but this adds to the cost, inevitably.

It was worth the coin though, Rob. Those forks performed great!

[Robert Taylor]

Yeah that rear shock on the SV must really be a hard on to get right in winter with the exhaust and engine heat. Its temp range must be huge compared to the front. Rear shock heater would be a necessity to get it even close to working right.

Please beat me with a stick if you havent thought about it in this way, plus to clarify for all those reading this thread;

1) Forks will run at ambient temperature or slightly below due to being in the cooling airstream, having relatively light damping which lessens any heat build up, ''generous'' oil volume and lots of highly heat conductive alloy to carry heat away, etc.
The ideal trick is to engineer the forks so you can run as light an oil viscosity as possible, light viscosity oils are much less affected by temperature variance compared to heavier oils. Sadly the cost of re-engineering many oem forks to run very thin oils can be a chequebook exercise.
Dont use cheap oil! Because among other reasons the flow characteristics with cheap oil has a much greater variance than with more refined / sophisticated oils.
More and more we have been using Ohlins oil as we have found fork performance is much much better at low temperatures than anything else we had previously used...and we always selected on quality and performance as opposed to cost. Craig Shirriffs will verify.
There must be something with this Ohlins oil, they make a big number of snowmobile shocks which obviously get operated at cold temps, neccessitating oil with great cold flow characteristics. Sorry if this sounds like a commercial plug but we have conclusively proven the performance of this oil.

2) Rear shocks have much more aggressive damping and typically in a road / road race shock the oil capacity may only be 150 to 200mls. Also operating behind a hot engine / exhaust that all means a recipe for heat build up.
The first outing of the day will start with a relatively cold shock which means slightly lethargic performance. ( Excepting if the damping is already weak meaning youd want to keep that shock chilled! )
If you can therefore pre-heat that shock with a warmer ( I dont want any moronic suggestions about using heat guns or a kettle ) then you will have achieved first laps performance a lot closer to how the shock will ''temperature stabilise'' a few laps in.
Again, running a high quality oil and ensuring that the oil is as air free as posssible is an obvious. Shocks with gas bladders ( oem ) require much more frequent service than floating piston type.
Nothing magic about all this, its just physics and sitting down and thinking about it.

[GSVR]

Quite a difference with winter vs summer. Havent really given the suspension warmup times any thought but have heard it mentioned at race meets.

So the front end doesn't need any warm up as the temp of is components stays pretty close to ambient. Little confussed now over those fork leg warmers people sell.

And the back I can see gets a big workout. And can start from cold and get hot from various sources which stangely it isn't sheilded from nor is there any ducting to supply cooling to this area.

Front forks are like overkill and its a wonder wishbone suspensions aren't more common on bikes as they seem to have advantages like only one shock to tune.

[Pussy]

Front forks are like overkill and its a wonder wishbone suspensions aren't more common on bikes as they seem to have advantages like only one shock to tune.

I reckon weight and complexity might be a factor. Forks have come a long way in the last 20 or so years. On my wishlist is for a system to be invented for damper rod forks to upgrade the compression AND rebound performance... sort of like the present emulators, but with a controlled rebound too

[Robert Taylor]

Quite a difference with winter vs summer. Havent really given the suspension warmup times any thought but have heard it mentioned at race meets.

So the front end doesn't need any warm up as the temp of is components stays pretty close to ambient. Little confussed now over those fork leg warmers people sell.

And the back I can see gets a big workout. And can start from cold and get hot from various sources which stangely it isn't sheilded from nor is there any ducting to supply cooling to this area.

Front forks are like overkill and its a wonder wishbone suspensions aren't more common on bikes as they seem to have advantages like only one shock to tune.

In fact quality shocks with excellent thermal expansion characteristics and QUALITY shock oil are calibrated to run at high temps. The right rear shock on a Toyota racing series car runs at close to 120 degrees celsius because it is right next to the exhaust muffler. As long as high quality oil is used they can run a full season of racing. High temps like this are common in Formula cars as many damper installations are on top of the gearbox which runs very hot.
I suspect fork warmers are there purely for some people to make money, its a little akin to thermal barrier coatings on two stroke exhausts, technically its a crock. Its also a bit like those low crotch hanging pants that homies wear, they make think its fashionable but just how stupid and impractical they are!
We are not seeing wishbone front suspension en-masse because the reality will be that the market wont accept it en-masse, despite the technical benefits, albeit it with some shortcomings ( but Im not of sate of mind to get into that one! ) For example the early 90s GTS1000 Yamaha.

[Robert Taylor]

I reckon weight and complexity might be a factor. Forks have come a long way in the last 20 or so years. On my wishlist is for a system to be invented for damper rod forks to upgrade the compression AND rebound performance... sort of like the present emulators, but with a controlled rebound too

Dont hold your breath on that one.