What am I doing wrong?

This topic contains 1 reply, has 2 voices, and was last updated by  jetblackcoach 2 years, 1 month ago.

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May 4, 2015 at 7:06 am #387


Just bought a Jet Black fluid trainer. I want to practise long climbs but can’t find a way of using the small ring plus large rear cog, no matter how far I “dial up” the pressure on the rear tyre. On the old magnetic trainer I had to use the large ring plus a small cog to exert enough pressure to simulate a long hard climb and had hoped the fluid trainer would allow me to use a combination that better simulates climbing, ie, small front ring plus large rear cog. What am I doing wrong?

May 6, 2015 at 3:36 am #389


Hi, I hope you find some useful information in this reply

The beauty of fluid trainer is they progressively get harder the faster you go, this simulates the progressive effects of wind and tyre resistance. So in your case and like with any brand fluid trainer I would suggest use the large and match the gears to find the power matched with cadence that simulates climbing a hill.. Most fluid trainers will simulate a between a 0~2% slope, this may vary depending on the weight of the rider and many other factors .. For the user to simulate a hill climb this is easy, you ignore the speed and gear you are actually in and simply focus on matching the required power and cadence you feel when climbing a hill. You match the power and cadence by adjusting the gears until you find the sweet spot. To get more technical on this you can review calculated powers for climbing different hill slope/grades on a site like this:


You should keep the trainer at max PSI and at 1.5 turns of pressure onto the roller, see below important notes:

See also notes on fluid resistance below.

Relevant section from this web link to instructions is pasted below:



Do not ride your trainer with less than 1.5 complete turns (three half turns) of the roller adjustment knob after the roller first makes contact with the tyre. It is important that the tension between the tyre and the roller is set correctly every session for two reasons. (1) It ensures that the tyre will not slip on the roller which could cause permanent damage to the trainer and your tyre. (2) It ensures the resistance of your trainer is consistent for every training session allowing you to track performance. The trainer base power curves used in the JetBlack app are measured on a bike using 700x23c slick road tyres at 110psi with exactly 1.5 complete turns (three half turns) of the roller adjustment knob after the roller first makes contact with the tyre. If your setup is different you will have a slightly different resistance, but as long as you keep the setup identical between each training sessions you will be able to monitor your performance. The proprietary fluid in the JetBlack Z1 PRO Fluid increases resistance exponentially, the faster you spin the harder it gets. Correct use of your bicycle’s gears will allow you to fine tune any training session without having to manually adjust resistance. To make your indoor workout as quiet as possible, set the trainer on a JetBlack Trainer Mat and use a rear tyre with a smooth tread pattern. Once attached, the bicycle slopes downward slightly. To level, use the optional JetBlack Riser Block under the front tyre.


1. Increasing the tension of the roller from our recommended 1.5 turns to 2 full turns will increase the resistance approximately 10-15%. So if you are using the trainer for tracking your power performance, you should resist adjusting the roller up to 2 full turns.

2. For every 20 psi your tyre deflates you will lose approximately 5% resistance. You must check your tyre pressure before every ride making sure it is inflated to whichever comes first the tyre manufacturer’s maximum recommended pressure or 110psi if your tyres will allow.

NOTE: Fluid trainers require a warm up period of between 5 to 10 minutes. This is also great time for you to do your own warm up. Once the trainer has been running for 5 to 10 minutes the resistance will be easier and the resistance will be stable. Trainer power curves for the fluid trainers are measured after the trainer has sufficient time to warm up. You should avoid monitoring your performance during this warm up period as resistance fluctuates until the resistance unit is adequately warmed up.

Happy riding

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