Renpho AI Smart Bike

Renpho's Ai Smart Bike is a functional, sub-£700 option that you can hook up to the training platform of your choice, and it'll do gradient changes and ERG training. It also comes with its own free-to-use environment that has some positives. The accuracy and the user experience can't match more expensive smart bikes, though, and if you're serious about training then a direct-drive smart trainer is probably the better option for you.

Getting it out of the box, the first thing you'll think about the Renpho bike is that it looks like a proper smart bike. It's solidly built, and the bits that need to be adjustable are adjustable. There aren't as many axes of adjustment as you'll get on more expensive bikes – you can't move the handlebar fore and aft, for example – but you should be able to get comfortable.

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If you're tall like me you'll probably have to set the seat above the maximum marker; I didn't have any problems with this, but it's worth noting. One of the big pluses over a bike-based trainer setup is that more than one person can easily use it, and that's certainly the case here: everyone in the house could make it fit them. (Renpho gives a user height range of 4ft 11in to 6ft 5in; I'm 6ft 2 1/2in.)

You get flat pedals and a big squidgy saddle, and up front there's a round LCD display (with a protective cover) and a shelf for your phone or iPad.

The dial around the display adjusts the resistance on the bike when it's not being controlled externally.

It's an easy bike to set up and use, and within 15 minutes I was able to hop on and give it a test ride. It was simple to link it to Zwift, RGT and Rouvy; I didn't try others but I can't imagine you'd have any issues.

Power measuring

One of the most important things a smart bike does is measure your power, so that you can muck about on your favourite training app and monitor your fitness. Obviously it's nice if it does that accurately. The Renpho has been a bit of a mixed bag there.

I've had two of these bikes. The first one consistently under-reported the power by around 10%. So, if I was putting out 300W to try to stay in a Zwift race, only 270W was actually making it to the app. I know this because I've got a pair of Garmin Rally double sided pedals that I benchmarked the Renpho against, and I know they're accurate because they agree with a bunch of other power meters I've used, including my Tacx Neo 2 and my Rotor 2InPower cranks.

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There's a certain amount of all these things being relative, but the Renpho bike is an outlier and the rest agree much more closely. And also, I was getting absolutely flattened by people I know I can keep up with in real life, which lends further credence to the argument that it was under-reporting. Anyway, as you can imagine, it didn't do my Zwift racing career any good to be suddenly 10% less fast.

After some discussion I got my hands on another bike, and it was also out by 10%, but the other way, so my 300W on the pedals translated to 330W in Zwift. Obviously, that isn't any better in numerical terms but is certainly a LOT better for staying at the pointy end of a race!

All of which is to say: I wouldn't say you can necessarily trust the bike to be objectively accurate. The reading *was* always under though (or always over the second time), so the numbers are repeatable, which means that you can track trends in your fitness using the bike. To be fair Renpho only claims 90% accuracy, which both my test bikes just about managed. Just about. There's no calibration available on the Renpho either manually or via a spindown test, so you're stuck with the reading you get out of the box.

The ride

So, you can adjust it to fit and it can measure your power and pair with things. What's it like to ride? The answer to that is a resounding 'okay'.

If you're used to a more expensive smart bike or a decent turbo then you'll be used to a nice heavy flywheel smoothing out the pedal stroke to make it easier to keep the power going. You don't really get that luxury here, which means the pedal action is very choppy, especially at higher power. You have to go hard at the pedals on the downstroke every time to make it through the dead part of the pedal cycle, which is a lot more tiring than hitting a high power on a good turbo with a heavy flywheel and keeping it turning.

One thing it does make you do is even out your pedal stroke to try to maximise the arc where you're laying power down. This is generally considered to be a good thing, so it's not all bad news.

Renpho uses a Smart Motor Damping Resistance unit in this bike which is the same fundamental type of technology as units like the Tacx Neo and Wahoo Kickr bikes use, so it may be that there are improvements to the experience possible through firmware updates.

I mostly used the bike with Zwift, and in Zwift you can use the virtual gears to make your life harder or easier by turning the control wheel around the display. The gradient changes also feed back to the bike like they do with other smart units. It all works reasonably well, and the gradient changes are handled quickly.

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If you're doing a workout then you can opt for ERG mode instead, where the trainer adjusts the resistance so that your chosen cadence matches the power you're aiming to hit. Again, this works well, probably better in fact than the free riding mode.

Position-wise things are okay. The cranks are a little far apart and the chunky pedals that come with the bike exacerbate that; it was much better with SPD-SL pedals on.

The saddle is big and squidgy and okay for shorter efforts, which is probably what the target market for a bike like this will be doing. If you're used to spending an hour in the saddle indoors, you'll probably want to swap it out for something a bit more road-bike-shaped.

App

If you're looking at a cheaper smart bike because your budget is limited then you'll be pleased to know that you don't necessarily need to drop £150 a year on Zwift on top of the spend on the bike, because the Renpho Ai comes with its own dedicated training app, Ai Gym. It's decent, especially given the fact that it's free: there are structured workouts, video spin classes and even a few real-life video routes baked into the app.

The first thing you'll need to do is a ramp test to set your FTP, even if you know it, because there doesn't seem to be an option to set it manually, but given that the bike's power isn't necessarily the same as your actual power, that's probably worth doing anyway.

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The structured sessions are pretty good. There are plenty of them, they're pretty well documented and they're easy to follow.

The Video classes are less well populated and there are only a handful of outdoor videos; on top of that, both of those workout types mean downloading a huge file to your phone/tablet in order to do the workout, so it's not a spur of the moment thing. The Spin class videos are pretty well shot and structured, though they're not my kind of thing. The outdoor videos don't really work that well: there's some work to be done with translating gradients in the video with speed, based on your power. I found myself having to keep up 300W to do about 15km/h on the flat, and even the downhills at times.

Conclusion

Overall, the Renpho Ai bike is decent enough. There isn't any one thing about it that's a deal-breaker, and if you're looking for an option for immersive exercise that doesn't break the bank then it's certainly got some good points, especially if there's more than one person in your household interested in a bit of indoor cycling.

If you're a fairly competent cyclist looking at a way to get onto Zwift/Rouvy/SYSTM/Bkool/etc then it's probably not your best option: even the cheapest smart trainers have a better ride experience than the Renpho does, and you'd likely be better off with one of them.

It doesn't compete in terms of experience with the Wattbikes and Neo Bikes and Kickr bikes of this world, but then at less than a third of the price of even the cheapest of those, you wouldn't really expect it to. I guess my overriding feeling is that it's not really aimed at 'cyclists' per se, more people that want to more generally do exercise indoors, and it's a pretty well-pitched option for that market. But as a cyclist, I can't get *that* excited about it.

Verdict

Proper smart trainer for a third of what others cost, but there are compromises along the way