Pros: Easy to setup and store, variable resistance levels.
Cons: Not enough resistance for bikes geared low, a little on the expensive side.
----- A Quick Introduction To Trainers -----
Training is a crucial element to the success of any athlete, and with anyone working to lose weight or work on a healthier lifestyle. Cyclists have two choices once the cold winter season sets in and outdoor riding is impossible. Your first option is to pay for a health club membership and train indoors in a spinning class or work out on an excer-cycle. The other choice is to purchase a trainer and use your own bicycle in the comfort of your home. Trainers are designed to support the rear wheel of your bike and apply resistance to the tire or rim. This allows you to pedal just like you would outdoors and feel the resistance as if you were riding on the road or down a trail.
The most popular trainers fall into three categories: Rollers, Tire Drive, and Rim Drive.
Rollers are the hardest to use, and are simply four rollers shaped like rolling pins and allow you to ride in one place. They will spit you off if you don't keep your balance, and injury is possible. Rollers also won't allow you to ride a mountain bike or any bike with knobby tires.
Tire Drive trainers are a different breed, and are noticeably easier to use. They require you to mount your bike in the trainer by clamping the rear axle between two cups. This suspends your bike off the ground and rests your rear tire on a roller. This roller is connected to a magnetic or hydraulic flywheel that provides the resistance. This system is cheaper than a Rim Drive trainer, and works very well with all types of road bikes and comfort bikes. As with the Rollers however, you cannot use mountain bikes and hybrid bikes unless you change to bald tires.
Rim Drive trainers are the most expensive, easiest to use, and best system for your bike. Rim Drives utilize two rubber wheels attached to spring loaded arms. When activated, these arms press towards the center of the trainer and rest on your wheel rim. One of the rubber wheels is attached to a magnetic flywheel using a belt or gear system. The Rim Drive system allows you to use any bike with any tire style or size, as long as your bike has a rear wheel. :)
----- My Comments on the Minoura 850 Mag -----
I asked my local bike shop quite a few questions about trainers, and finally decided to purchase the Minoura 850 RDA Mag model. It is functionally the same as the 850D version, just with the Rim Drive feature instead of roller drive. Since I have two mountain bikes and one road bike, I wanted to use all my bikes without having to change tires.
Setting up the trainer at home is very easy, and my bike shop did what little assembly there was before I picked it up. Simple unfold the collapsible legs to their extended position, and place the trainer on a level surface with enough room for your bike. Now you can roll your rear wheel in between the axle cups and tighten them firmly. Make sure your bike is not in the cups crooked or you could fall off the trainer. After you're finished, check to see the rubber wheels are lined up with your rim face (the shiny silver part your bike brakes rub on). If they aren't, you'll need an allen wrench to loosen and adjust the wheel brackets. You will need to adjust these every time you switch from a road bike to a mountain bike, since the rim design is different.
One last thing to do is to set the resistance level with the lever on the magnetic housing and pedal away. If you have the RDA 850R you can use the handlebar remote to change the resistance. I did not want this feature since I rarely change the resistance on the trainer. Since I have a nine speed bike with three front chainrings, I have 27 levels of resistance without adjusting the trainer itself! Remember you are on a trainer, so don't stand up and hammer away like you would outside.
The other benefit of the Rim Drive trainers is your tire life will be much better. Tire drive trainers work by pressing very hard on your tire to maintain traction. This puts an excessive load on your tire and may cause early failure or a tube to go flat.
There are a few drawbacks to the Rim Drive system, the biggest being the wear and tear to the rubber wheels. You will replace them about once a year if you do most of your training in the winter months. If you use your trainer year around, you may replace them more often. The other annoyance is the loss of traction you get every time you start to pedal. You can apply so much torque to the rear wheel that the rubber wheels lose traction with the rim face and you end up spinning your rear wheel wildly. This can be eliminated by making sure your rear rim is clean and starting at a slower pace until the trainer is up to speed. The last complaint I have is the limitation of only 8 resistance levels. With my mountain bike and its low gearing, max resistance and my tallest gear still don't provide as much resistance as I'd like for sprints and hill training. Road bikes have much taller gears and have a higher ultimate resistance threshold.
Make sure when you go to purchase your trainer, that you specify which version of the Mag 850 you want. They all look very similar and are even the same color.
If there is an 850 RDA on the trainer body it is a Rim Drive model. It it's just an 850 Mag it will be a Tire Drive trainer. Finally, if you find a long cable with what looks like a shifter on the end you're looking at the R model with the remote resistance adjuster. Which one you need is mostly up to you, what bikes you own, and what type of training you plan to do.
Minoura RDA 850R Trainer
Thanks for reading, and I hope I answered your trainer questions!