Leaking Fluid 2 trainer

My trusty Cyclops Fluid 2 Trainer has started leaking.
There is Fluid under the resistance unit, I can’t see exactly where it is coming from.

It certainly still has fluid in it, I just did a ride and was doing Ebbetts fine.

But it is only a matter of time before the fluid all drains out.

Has anyone successfully service this unit, new fluid, gaskets?


Best to contact Saris and see what they can offer

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Saris is pretty good about replacing these if you are the original owner from what I’ve heard. I’ve had this happen to me but wasn’t the original owner. They sold me a replacement resistance unit for a discounted price.

I typically pointed a small floor fan at the resistance unit when using it. But forgot one day to turn it on and then it overheated which lead to a small leak (it was a really old unit). I upgraded to a direct drive smart trainer but still point a fan at the resistance unit out of preventative habit.


I rode mine while it leaked for quite awhile, a few drips every time I rode so I think it would take a long time for it to all drain out. Mine was old too, so it didn’t seem worth fixing. Something else broke on it and I eventually I just got a new one.

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I had the same thing happen about 8 years ago. They sent me a new resistance unit free of charge, Super easy. Great customer service.


I have contacted Saris USA, which I imagine will end with me being directed to the Australian supplier. I’m the original owner, but my chances of finding my receipt are nil!

I’ll see what they say. I will ride it as long as possible and then if it completely gives up the ghost I’ll open it up and see what happens.

Corona virus has resulted zero trainers available for purchase…and wiped my $$$ out.

I don’t know if it’ll work or not but find some high temp silicone or rtv and just “caulk” it all around the split line. See if that’ll help prevent more fluid leaking until you can get a new resistance until or trainer. Allow probably 24 hours to cure to be sure it is set.

These units are sealed using a rubber gasket and they eventually degrade and fail. Especially through repeated heat cycling. It be easier for longevity to permanently seal them by welding the thing shut or used an temperature resistant bonding agent to seal instead. But that adds costs to manufacturing.

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I think I have 2 leaks by the looks, it is hard to trace as the oil slowly moves around.
But there is 2 openings the bearing and the main 2 pieces for the unit.

It’s shrouding these haven’t been diy fixed more, there is surprisingly little info on the web.

Such terrible timing for me.

So…no reply from Saris.

I took the side off, the big O-ring is still looking good.

It appears to be leaking through the bearing which the shaft penetrates through.

Anyone with bearing knowledge know What forms the oil seal?

Just as info for anyone in a similar situation in the future.

  1. knock the shaft out and there was a small nick in the oil seal. Picked one up from the bearing shop for $10 (inclusive of new bearings)

  2. cleaned all up and put the seals and bearings back.

  3. leaks are all fixed up, resistance is a little lower due to the loss of oil.

Oil seal part number: Metric oil seal Viton M10X20X7V
Bearing: Ball bearing FBJ 10X30X9
image image image image image image image image image

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Your o ring looks fine. I only just noticed your post.

Measure the diameter of the drive shaft and start looking up mechanical seals/shaft seals. It could be proprietary. More likely an off the shelf part used in many other things.

Maybe Saris will help out. In my experience in Aus you’re on your own out of warranty.

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Look up the MSDS (material safety data sheet or something) for the Fluid2 which will list the actual fluid they use. Some type of Mobil fluid from what I recall. You might be able to buy that actual fluid to refill the resistance unit since it is an off the shelf type item it seems.

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I’ve found in another forum one user said he got the MSDS and it is Mobil DTE746 turbine oil.

Unfortunately I have to buy a barrel of it, it isn’t readily available anywhere.

I’m assuming it is the viscosity which I need to workout for this oil and match.

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What about a similar hydraulic oil? Like the stuff they use in excavators.
That comes in 20L containers and you could probably find a repair person who’d sell you a liter of it. They’d probably know which shaft seal the trainer uses as well.
Another good source of advice I’ve used in the past is chatting to the shops that sell the o-rings and seals.

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My Fluid 2 seal let go last year. I contacted Saris customer service and they sold me a brand new resistance unit for $100. My trainer was 15 years old (well past warranty) but bombproof to that point, so I was happy to replace the unit inexpensively and easily and still have my race warmup option and my back up trainer back available.


ISO 46 Hydraulic Fluid available in smaller quantities from Amazon, Tractor Supply, etc. ~$25 for a gallon. Google “ISO 46 hydraulic fluid”. Legit Mobile DTE 25 is ~$40 for a gallon on Amazon.

Anyone have luck sourcing the viton o-ring for a Cycleops Fluid 2? What are the correct dimensions? (Haven’t busted mine open yet)

I posted the pics above.
Cant recall the dimensions, but I replaced the bearings, seals, and fluid in mine.
All went fairly well. Went to a bearing shop with all the bits I pulled out and they sorted me out, very cheaply.

I found the biggest difference to the feel of the trainer after the fix up was the resistance which is altered easily with the quantity of fluid.



Follow Gary_Gumnut’s post
I disassembled Fluid2, found all the part numbers, and replaced them. The magic is that there is no leakage.
all the part numbers:

  1. O-ring: wire diameter 2.62mm; inner diameter 106mm, 1 pcs
  2. Bearing: original model GLOBAL 6200RS, 10×30×9, 3pcs
    Alternative model: NSK 6200VVCM NS7S, 10×30×9, 1pcs
  3. Oil seal: VITON (FPM) This fluorine rubber material can reach 250 degrees high temperature, 10×20×7, color brown, 1pcs
    Alternative number: SOG 115385 TC (with dust cover), in Taiwan
    4.Mobil 1 0W-20, 155cc

But after I loaded the liquid, I found the sound of air and liquid being agitated when the Fluid2 was rotating. I am not sure if the liquid volume is correct?


I’m no expert on the oil, the oil I used was antifoaming- doesnt get aerated. You might have a different viscosity. Do you know the ISO number of yours?

With the unit on its side and the cover removed I put almost as much fluid in until it was just below the rim.
I opened mine up another 2-3 times to adjust the amount of fluid in it, but that was to adjust the resistance feel.


Do you remember the past
How much liquid volume does Fluid2 need to load?
155cc? or 200cc?