Rear suspension on delta trike

Joined
Aug 11, 2020
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Having purchased several of Brad's plans, I am looking at combining the rear suspension of the delta wolf with the Lode Runner, possibly the tandem (2 shocks in this case) to be equipped with a 500W motor and solar panels for outback travel as discussed on a previous thread.

The load to be carried is equivalent to a third person - about 80-90kg (motor, batteries, water, camping equipment) in about 200 litres of storage space in addition to 2 riders of about 65kg and 73kg respectively. I am also looking at being able to dismantle the trike for travel. The trike will have 20 X 2.4inch tyres as we will travel mostly unsealed surfaces, sometimes ungraded but not MTB tracks.

My question: how much would front and rear suspension contribute to the comfort of the ride (20inch suspension forks are available if I can't find any at our recycling centre). Is it worth the extra complexity and weight?

I would be grateful for any advice/experience with rear suspension such as on the delta wolk trike.

Alex
 
Joined
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I'd suggest full suspension would be close to essential. It's not just the comfort factor but full suspension will take some of the shock loads off the chassis. Given the chassis will be well loaded it'll be important to get some of the impact loads into springs rather than welds and beams. Having rear suspension will give you a ready and easy dismantling point too.
 
Joined
Aug 11, 2020
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I'd suggest full suspension would be close to essential. It's not just the comfort factor but full suspension will take some of the shock loads off the chassis. Given the chassis will be well loaded it'll be important to get some of the impact loads into springs rather than welds and beams. Having rear suspension will give you a ready and easy dismantling point too.
Thank you - that's great advice. The wide tyres deliver quite a bit but I am sure you are right about the suspension with the extra load. I am going to join our local Men's Shed for the welding equipment and expertise. I will run a thread on the build once I have the design drawn.
 
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What a neat concept! I love it. A lot. I admire your ambition! I think it's definitely doable. I don't intend to contradict what anyone else has said, but this is my take on it- and it might :p

The way I look at it, you're talking about hauling about 550lbs of people and things. That's a significant amount. I read your other thread, and you'll be doing it in some pretty unforgiving terrain. My main concern with your project is durability. To be durable, you need to be either simple or have done many iterations of design/build/break/redesign. I prefer the simple approach. If I were doing what you're doing, here's how I'd go about it.

Kevlar lined tires will be really important. And for your use, I would go with 26" tires. They have better traction (longer contact patch) and will give a better ride on rough surfaces partly due to the larger diameter but also due to longer spokes. As long as you build the hubs with plenty of triangulation in the spokes (nice and wide hub) just as the plans say, you should be okay. Look at Fat Tire wheels- the spokes are actually spaced out in both axis on the wheels, and the hubs are quite wide. If you use high quality double walled rims made for fat tire mountain bikes, I'd think you'd be fine. You can to go 2.5" or even bigger, if you like.

The other consideration is braking. High quality disk brakes on your rear wheels will be enough.

As for improving the ride, a good seat will make a huge difference, but so will distance between your seat and the wheels. Steel frames are quite flexible. Sitting further from the wheels puts more steel between you and the wheel, which gives a better ride. This also aids in weight distribution. You want that front tire to have traction in turns and not get light on you.

And if you're on especially rougher roads, airing down the tires just a few pounds can be great, although they'll take more effort to pedal.

If you do go for a suspension I'd keep it as simple as possible and make sure that the rear wheels can't move up and down independently of each other so that you don't compromise handling unnecessarily. Remember- the suspension on cars isn't there to make a better ride only, but also to help the tire maintain contact with the road on uneven surfaces. To do that, they have spring and shocks. While maintaining contact is no issue on a trike (meaning you won't need much suspension travel) You'll need shocks in the suspension in order to stay safe. With 550lbs on a rough road, you don't want it to get bouncy on ya!

I guess what I'm really trying to say is that if I were in your shoes (which I'm definitely not) I'd ditch suspension in favor of a sturdy frame that can take the punishment, and I'd use 26" wheels, fat tires, and build it to flex a little bit. Mind you, this is what I've done on my own build which is clearly different from yours with a much different use case. But I put a lot of thought into the design of my trike, including distance from wheels, to get a good ride and also improve weight distribution for my 350lb self. Check my username if you want to see my build thread, etc.

Best of luck to ya!
 
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Joined
Oct 19, 2012
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Location
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4.0 fat tyre rims are indeed very solid and not likely to buckle easily and if using 26" wheels will be much less likely to buckle than regular size rims. They will also add a degree of suspension in the give in the tyre sidewalls. They will also give extra ground clearance over 20". They will add extra weight though. 4.0x26 wheels and tyres are very heavy when compared to more regular ones. At an estimate I believe they'd add 10-12kg over BMX sized wheels between the three of them and will doubtless cost a lot more. I'd suggest that thin 26" rims will have little to no chance of staying round given the weight and terrain. Well triangulated full fat 26" will probably take the strain as will 20" bmx type wheels. Given the weight on the driven wheel I doubt traction will be an issue regardless of choice even with two pedalling and a motor.
Front suspension is not moving from any definition of simple as it's simply substituting suspension forks for non-suspension forks in such a design. Rear suspension does add complexity but there's detailed plans for it in Brad's relevant designs. Any choice of wheels will be more likely to survive any given impact if allowed to transfer some of that impact into a spring, as will welds and beams.
As ever my ramblings are largely opinion with the odd fact occasionally making an appearance and no offence can be taken if anyone has differing opinions.
 
Joined
Aug 11, 2020
Messages
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What a neat concept! I love it. A lot. I admire your ambition! I think it's definitely doable. I don't intend to contradict what anyone else has said, but this is my take on it- and it might :p

Thank you so much for your detailed post.

The way I look at it, you're talking about hauling about 550lbs of people and things. That's a significant amount. I read your other thread, and you'll be doing it in some pretty unforgiving terrain. My main concern with your project is durability. To be durable, you need to be either simple or have done many iterations of design/build/break/redesign. I prefer the simple approach. If I were doing what you're doing, here's how I'd go about it.

One of the reasons I have been going over Brad's plans incessantly and why I have been impressed with his builds, is the ruggedness of the frames, and the clear-headed approach to solving the engineering problems. The frames simply look strong although those who have actually built machines would better be able to comment on durability in the field. I am under no illusions as to the strength required of this build and I will be grateful for comments once I have put up my preliminary design.

Kevlar lined tires will be really important. And for your use, I would go with 26" tires. They have better traction (longer contact patch) and will give a better ride on rough surfaces partly due to the larger diameter but also due to longer spokes. As long as you build the hubs with plenty of triangulation in the spokes (nice and wide hub) just as the plans say, you should be okay. Look at Fat Tire wheels- the spokes are actually spaced out in both axis on the wheels, and the hubs are quite wide. If you use high quality double walled rims made for fat tire mountain bikes, I'd think you'd be fine. You can to go 2.5" or even bigger, if you like.

There is a trade-off between durability and rollability. I had thought of going with 26inch wheels since they certainly do roll better. We ride 29er touring bikes rather than 26 inch when touring in Europe for the better rollability using Ryde Andra 30 rims - about as strong as you can get - with 50mm Schwalbe Allmotion tyres - great strong wheels with excellent puncture resistance for the low lateral forces on a leaning bike with all the traction we need on the surfaces we ride. Trikes are a different matter with substantial lateral forces in cornering. I think a 20 inch wheel will be inherently stronger, more durable, especially if I can source the 48h rims that Brad uses with the Loderunner (so far the best I have been able to source locally are 36h). The other advantage is a lower centre of gravity. We ride conservatively when loaded but I will be wanting to minimise the possibility of flipping a delta trike in a turn.

The other consideration is braking. High quality disk brakes on your rear wheels will be enough.

I am sold on the TRP Spyke cable disc brakes we have on our touring bikes. With 180mm rotors, they provided absolutely reliable braking under all conditions and are easy to adjust. My plan is to have dual braking at the rear from a single lever on the left and braking at the front with the right lever. I think independent front and back braking is relevant with a big load on loose surfaces but I am open to other opinions.

As for improving the ride, a good seat will make a huge difference, but so will distance between your seat and the wheels. Steel frames are quite flexible. Sitting further from the wheels puts more steel between you and the wheel, which gives a better ride. This also aids in weight distribution. You want that front tire to have traction in turns and not get light on you.

Thank you for clarifying this for me as your advice confirms my thoughts about how to configure the rear seat and luggage area. My plan is to push the rear wheels back with at least 50% or more of the luggage area, and more importantly at least 70% of the weight in front of the rear axle (actually entirely supported from in front of the rear axle with only 50% cantilevered back behind the axle). This will put quite a bit of metal between the rear axle and the stoker. Mesh is a necessity in Australia to dissipate sweat from the back. I have an AZUB trike with an excellent mesh seat which I can use as model for the seats for this trike. I prefer the semi-recumbent position to the full recumbent position so I have taken note of Brad's seat construction ideas for the semi-recumbent position.

And if you're on especially rougher roads, airing down the tires just a few pounds can be great, although they'll take more effort to pedal.

Yes. We run our 2 inch touring bike tyres at 3bar. With a 2.5 inch tyre, it may be possible to run at even a bit less. 2.5 inch is for me, the best compromise between rolling on pavement and good performance on gravel.

If you do go for a suspension I'd keep it as simple as possible and make sure that the rear wheels can't move up and down independently of each other so that you don't compromise handling unnecessarily. Remember- the suspension on cars isn't there to make a better ride only, but also to help the tire maintain contact with the road on uneven surfaces. To do that, they have spring and shocks. While maintaining contact is no issue on a trike (meaning you won't need much suspension travel) You'll need shocks in the suspension in order to stay safe. With 550lbs on a rough road, you don't want it to get bouncy on ya!

Yes - I just want to dampen the major bumps. I was not planning anything complex - just 2 shocks configured side by side fixed by rigid bars at each end of the shock - need 2 shocks in view of the extra weight.

I guess what I'm really trying to say is that if I were in your shoes (which I'm definitely not) I'd ditch suspension in favor of a sturdy frame that can take the punishment, and I'd use 26" wheels, fat tires, and build it to flex a little bit. Mind you, this is what I've done on my own build which is clearly different from yours with a much different use case. But I put a lot of thought into the design of my trike, including distance from wheels, to get a good ride and also improve weight distribution for my 350lb self. Check my username if you want to see my build thread, etc.

Thank you for the above. I would appreciate any further discussion/different opinions of the points above.

Cheers

Alex


Best of luck to ya!
 
Joined
Aug 11, 2020
Messages
12
4.0 fat tyre rims are indeed very solid and not likely to buckle easily and if using 26" wheels will be much less likely to buckle than regular size rims. They will also add a degree of suspension in the give in the tyre sidewalls. They will also give extra ground clearance over 20".

Ground clearance is less of an issue with my build. I am planning to transfer the Patterson bottom bracket gearboxes from our touring bikes to the build. This gearbox replaces the front derailleur, providing the equivalent of 28 tooth and 45 tooth crank chains. This means that I can use a compact cluster at the back with small cage given that the chain only has to traverse the cluster at the back and not differently sized crank chains.

They will add extra weight though. 4.0x26 wheels and tyres are very heavy when compared to more regular ones. At an estimate I believe they'd add 10-12kg over BMX sized wheels between the three of them and will doubtless cost a lot more. I'd suggest that thin 26" rims will have little to no chance of staying round given the weight and terrain. Well triangulated full fat 26" will probably take the strain as will 20" bmx type wheels. Given the weight on the driven wheel I doubt traction will be an issue regardless of choice even with two pedalling and a motor.

Samagaga (Taiwan) make a relatively light differential gear designed for heavyweight trikes so I am planning to drive both rear wheels. My plan is to drive the differential from a second axle to which the both the motor and the riders will be respectively engaged by separate freewheels - the design drawings will illustrate this.

Front suspension is not moving from any definition of simple as it's simply substituting suspension forks for non-suspension forks in such a design. Rear suspension does add complexity but there's detailed plans for it in Brad's relevant designs. Any choice of wheels will be more likely to survive any given impact if allowed to transfer some of that impact into a spring, as will welds and beams.
As ever my ramblings are largely opinion with the odd fact occasionally making an appearance and no offence can be taken if anyone has differing opinions.

Thanks

Cheers

Alex

 
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