What are the (dis)advantages of a tadpole vs. a delta trike?

Question

On a recumbent trike, what are the advantages (and disadvantages) of two wheels in the front and one wheel in the back (a "tadpole" in recumbent terminology), vs. two wheels in the back and one wheel in the front (a "delta")?

At Eurobike 2022, I had the opportunity to try:

• a Hase Kettwiesel (Rohloff) with one wheel front / two wheels rear
• an HP Velotechnik (Pinion) trike with two wheels front / one wheel rear
• an HP Velotechnik Streetmachine, which has two wheels in total, but failed to ride and succeeded to damage it.

Looking at other brands available from my local recumbent shop (Ice and Anthrotech), it appears two wheels front is more common. However, during the short test ride (around 2 km including a 40 metre ascent/descent), I found steering easier with the Kettwiesel. Why do most trikes have two wheels in the front and one wheel in the rear?

Answer 1

Having two wheels in the front is intrinsically more stable: there is a rollover risk when turning at speed when the two wheels are at the back. The cornering forces (that are in opposite direction of the turn, front oriented) are better counteracted when the two the two wheels are in the front.

On the other hand having the single wheel at the front is more maneuverable (at low speed only, at high speed there's a risk of rollover, added following Adam's response given the safety risk).

So the choice of a configuration is a matter of priorities. Possible reasons for the predominance of "tadpoles" (2 wheels at the front): there might be more speed enthusiasts, or manufacturers might prefer to offer the safest option.

A recumbent trike manufacturer has published an entry on this subject: https://www.rad-innovations.com/compare-trikes.html (archive link)

Answer 2

I generally agree with the article that Renaud links to, but I'll add a few comments.

• There's a rollover risk with either tadpole or delta trikes.
• The article mentions that deltas have a tighter turning radius, but you can only take advantage of this when riding slowly, otherwise you risk flipping the trike, so there may be little practical advantage.
• The drivetrain on a delta is necessarily more complex. Either one rear wheel is driven, which produces a different feel on left vs right turns, or there's a differential or twin freewheeling mechanisms (the same is true on upright trikes). Conversely, the steering mechanism on a tadpole is necessarily more complex.
• Braking power is better on a tadpole, since front brakes do most of the work on any vehicle.

My impression is that mostly because of the low center of gravity, tadpoles are better for riding fast, and are more popular for that reason.

Answer 3

As a delta rider I do not feel that those bikes are more likely to roll, it is the riding style rather than the trike confirmation which makes the difference.

I now ride a velomobile, which is a tadpole configuration. Where I never had my delta trike go on two wheels, I have had the VM on two wheels. I also own an open Delta trike.

But do not take my word for it, one of the most experienced riders of different bikes and trikes on the Dutch recumbent riders forum bought a Hase Ketwiesel, not expecting to like it as much as he did like his other trikes and came away loving the machine. He writes a comparison here (Dutch) in which he has a slight preference to his Delta trike.

An other site (also Dutch) compares Delta and tadpole trikes and the main line out of the comparison is that they are comparable for stability by the same seat height, with a slight advantage to the Delta trike. (But those are mostly a bit higher in seat height.)

So my conclusion is, buy the trike you are the most comfortable in. Both kinds will work for you. I personally think you can not go wrong with the Hase, but I have been in love with that trike but never been able to afford it.

Answer 4

It depends on your needs and riding conditions. I have many recumbents, including a well-known tadpole trike on which I've put thousands of miles. I like them all (have only test-driven Ketts). Deltas are notoriously hard to transport since they're a lot longer. They're also up higher, which is good or bad depending on your POV. Tadpoles also occasionally suffer from radical speed waggles that can be set off by something as normal as just hitting a bump on a big downhill. It has happened to me 2x, and it is scary as heck. Tadpoles can also lose traction with the rear tire on ice, water, or rumbles in such a way that the back end will immediately swing around toward the front, potentially pitching you into traffic. This also happens if you perform a "stoppie" by braking so quickly that the rear wheel leaves the ground. It will immediately pitch you into a turn. Watching your kid stoppie into the opposing lane of traffic at the bottom of a hill will leave you needing a new pair of Huggies. On a tadpole, you have a super-tight turning radius if you're moving slowly. The only times I've ever pulled a wheel off the ground (and nearly flipped) were yanking quick turns at low speed. At high speed, the danger is more obvious, and you just avoid it.

I have toured with moderate weight on the back of the tadpole as well, and it's a nice way to go, but depending on the build, it can introduce a ton of extra pedal steer, meaning the waggle you induce in pedaling (already a challenge when you first start triking) is even more pronounced.

There are other practical differences (in the rain, front and rear fenders are a must on a tadpole or you will be doused with filthy water in seconds) whereas you might get away with none on a delta.

Answer 5

The advantage of the tadpole configuration (two wheels in front) is you can brake hard while turning without rolling over. For use on the road, having functional brakes outweighs any other advantage the delta configuration may have.

This does not mean the tadpole configuration is perfect. I own a Trice Q. It's a pleasure to ride, but bulky and inconvenient to transport if you're not sitting in it. Rolling resistance is high, but the low position makes it almost immune to wind. With 50 km/h wind in your face, it will slow down, but an upright bicycle will not be rideable. On average, it is slower than a normal bike, but much more comfortable.

This trike is pretty low. Risk of rollover in turns is way overblown in my opinion. But... downhill in the winding mountain roads, due to the aerodynamics, it really wants to go at unsafe speeds. It will do 90 km/h downhill, which is completely nuts. It's up to you to not enter a turn at an unsafe speed. This applies to any vehicle.

It is heavy and slow on climbs, much slower than a normal bike, but it makes up for it on the way down. In fact one problem with the tadpole trike really is that it makes unsafe speeds so much more fun.

There are two front brakes, both capable of lifting the rear wheel unless the trike is loaded with stuff on the rear rack. Applying only one front brake while turning will lift the rear wheel and result in an instant spin. This is very convenient for making U-turns (you also have to fling your body in the proper direction to turn it around).

An unintentional spin could happen, which would cause an accident. However, braking hard will also send you flying over the bars with a normal bike, or roll over a delta trike. Basically, all these vehicles require proper control of the brakes, looking ahead, not braking at the last second, etc. The one thing extra you have to learn on a tadpole trike is to balance the braking between the two front wheels. This is absolutely required and you must learn it. It's not difficult.

The other problem with trikes is the low position makes it hard for drivers to notice you, especially in turns. For example, in this turn, the trike would be hidden by the wall on the right. That's why it has a flag on a pole...