Buying a smart trainer: direct drive or wheel-on?
A smart trainer is a device you see in your living room every day and that shapes your training. So it should fit your bike, your space and your budget. Here you see what matters, without having to memorise models.
- Direct drive is quieter, more accurate and more convenient, but more expensive and heavier.
- Wheel-on is cheaper and more flexible, but louder and wears the rear tyre.
- Check the axle and the cassette of your bike first, before you choose a model.
- Look for FTMS. Then the trainer works with almost any app, including Zombike.
Direct drive or wheel-on?
Without the rear wheel
You take off the rear wheel and put the chain directly on a cassette on the trainer. Usually quieter, more accurate, no tyre wear, but more expensive and heavy (often over 15 kg).
With the rear wheel
The rear wheel stays on the bike and runs on a roller. Cheaper and quick to set up and take down, but louder, with tyre wear and a little less precision.
Complete device
An indoor bike with the trainer built in. No setup, lots of comfort, but the most expensive and space-hungry.
If you have the budget, direct drive is the better choice for most people. If you have little space, ride irregularly or want to try it out first, a wheel-on trainer does fine. In the long run wheel-on trainers are usually not the place for hard sprints, because the rear wheel can slip.
Does it fit your bike?
This is the mistake many only notice after buying. Check beforehand:
- Rear axle: quick release (usually 130 or 135 mm) or thru-axle (often 12 × 142 or 12 × 148). Many trainers come with adapters, not all.
- Cassette mount (freehub body): Shimano and SRAM usually use the same type, Campagnolo and SRAM XDR are different. A wrong freehub body is easy to swap, but only if the matching part exists.
- Gearing: do the number of gears and the chain fit? With direct drive you need your own cassette that you mount on the trainer.
- Brakes: disc brakes with thru-axle are no problem. Still check that the bike stands stably.
Technology that counts
- Compatibility (FTMS): the FTMS standard (Fitness Machine Service) over Bluetooth makes sure the trainer talks to many apps. Brands such as Tacx, Wahoo, Elite, Saris or the Zwift Hub count as FTMS-capable. Check the manufacturer’s page of the specific model before you buy. Whether ANT+ is also available is useful but not decisive.
- Accuracy: manufacturers often state a deviation of about one to two percent. That is perfectly fine for training. More important than the absolute value is that it stays constant, so you can see progress.
- Maximum power and gradient: for most people trainers that handle a few hundred to over a thousand watts and simulate gradients of ten to twenty percent are enough. Strong sprinters need more reserve.
- Noise: more important in an apartment than you think. Direct-drive devices are usually quieter than wheel-on. Read reports on exactly your model and test if you can.
- Weight and stability: a stable trainer does not wobble and also withstands sprints. A carpet or rubber mat underneath dampens noise and protects the floor.
New or used?
A used smart trainer can save a lot of money. Look out for:
- Does it work with the current firmware? Manufacturers usually update the software through an app.
- Is there play in the axle or unusual noises when turning?
- Are power supply, adapters and cassette included?
- How old is it? Some older models are not FTMS-capable and only work with the manufacturer’s app.
Prices vary a lot and differ by brand, model and time. Compare several retailers before you buy and watch for offers in autumn and winter.
Checklist before buying
- Which axle and which cassette does my bike have?
- How much space do I have, and how loud may it be?
- Is the model FTMS-capable (manufacturer’s page, not only the retailer’s)?
- Do I need adapters or a cassette, and are both in the price?
- What is the warranty, and can I return it?
And then? Which app?
If the trainer supports FTMS, it works with most apps. How to find the right one is in the comparison Zwift alternatives. Zombike runs in the browser (Chrome or Edge on a computer and Android), without installing anything, and you can try it free for 7 days.
Frequently asked questions
Do I really need a smart trainer?
No, but without one you measure no watts and cannot let apps control you. With a simple indoor trainer you train by feel. A smart trainer makes training measurable and controllable.
Does my old trainer work with Zombike?
If it supports Bluetooth FTMS, yes. That is in the manufacturer’s data sheet. If you are unsure, you can try it with our trial without buying anything.
How much space do I need?
Count on the bike plus about a metre at the sides and space behind the bike. A fan, a table for phone or tablet and a towel belong with it.
Note: All trademarks mentioned belong to their respective owners. Zombike has no connection to them. Details on technology and prices are general guide values. Check the data of the specific model with the manufacturer.
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