KC8QVO

All,

I am piecing together a 20" wheel set for my bike trailer. At the moment I am working on a method to convert a cone/race hub to a stub axle so they will work with the current configuration. However, if that won't work for what ever reason I do have it in my mind I might need to make a new "axle" section that incorporates an outer rail for the wheel axles to be supported on both ends as in conventional forks/dropouts. That would be best - and is the idea I have for my new trailer design (when I get around to that).

Since the new trailer is going to have to wait - what I need to get up and over right now is the high rolling resistance from the low PSI rated tires (35psi). I am bumping up from the 16" current wheels to 20" to open up tire selection.

The two tires I am looking at right now are the Schwalbe Pick Ups in a 20x2.35 and We The People Activate in a 20x2.7. See links below.

https://www.schwalbetires.com/Schwalbe-Pick-Up-11159259
https://www.benscycle.com/wtp-activa...j1931-tr0776/p

The WTP tire has a much higher pressure rating - 100psi vs the 65psi of the Schwalbe.

I sense the Schwalbe would be a more durable touring tire. Though, the WTP is meant for park type use with freestyle BMX = slamming in to obstacles and landing from jumps is par for the course = probably a pretty tough tire if it is designed for that use. The question I would have is if the rubber compound would handle miles also, or if they are subject to wearing quick.

What thoughts do you have?

Tourist in MSN

100 psi on a 2.4 inch wide tire would put a lot of stress on a rim, I would never put that much pressure in that wide a tire regardless of tire rating.

Photo below is from my Mavic A719 rim that is 19 years old. A719 rims had a good reputation for being a strong rim for touring when there was a lot less selection available. They are saying to not use that much pressure in a tire that is only 1.5 inches wide on that particular rim.



Years ago Jan Heine published a piece suggesting a 15 percent tire drop. That was not intended for trailers, but I think that you could consider that a good pressure for the minimum on your trailer tires, maybe go up to a third (33 %) more pressure than that if you wanted a harder tire as long as you stayed below the tire rating pressure.
https://www.adventurecycling.org/def...SIRX_Heine.pdf

My point here is that for a lightly loaded trailer, why have so much pressure?

Unfortunately, his graph only goes up to 37mm wide tires. But for your trailer, I see no reason to go over 40mm wide.

That would mean you need to put a scale under each wheel the first time you loaded it up. Or, use a luggage scale to lift the tire off the ground to see how much weight on each tire.

The folding bike board on this forum has a lot of people using 16 or 20 inch wide tires on their bikes. Maybe look there for tire suggestions?

abdon 

How much weight are you putting on that trailer? You may be overestimating the rolling resistance.

Meaning: a 180 pound person on a 30 pound bike carrying 40 pounds of gear is bearing down 250 pounds on the tires. That weight is a huge factor on the rolling resistance. I'm not an engineer but i'm sure somebody must have calculated the whole weight/friction/pressure/yada-yada-yada. Long story short carrying 50 pounds on a trailer will contribute a lot less to rolling resistance on those two tires than the 250 pounds on the bike tires.

But out of practicality you should probably go with as skinny a tire as you can use.

Why even considering the Schwalbe that is fatter, more expensive, has a thread that you don't need and adds to rolling resistance/noise/bumpiness, and lower PSI?

By the way the correct PSI is whatever is needed so the tire keeps its proper shape under load. Fully loaded trailer you bump the pressure while giving up a suspension, lightly loaded trailer you can run a much lower pressure without affecting rolling resistance in any meaningful way.

Calsun

What counts the most is the diameter of the wheel. Trailer wheels have greased bearings for the most part and the faster the wheel spins at 60 mph the more grease is lost in the process. Ideal are the trailers with larger diameter wheels but this also means either a wider trailer or on the is higher off the ground. 12" diameter or larger willl work well. 175/80R is a tire size commonly used on POC trailers and what I would use if building a bike trailer to travel long distances.

Thulsadoom

I've had the best luck with Kenda Kwest 100 psi tires on my bike trailers. Best mileage (around 2000-2500 miles) and good durability for the price. I'd run the 1.5 inchers if it were me.

79pmooney

Stub axle hubs? Have you looked at wheelchair hubs? I don't know what is out there now (my research was 35 years ago) but nearly all are stub axles and many support a lot of weight.

KC8QVO

That was another question I have had - how much pressure a rim could hold. With rim brakes that would be a moving target. I have heard of people with 20" wheels touring/riding a lot of miles that have worn down the rims so much from the brakes that the side walls give out.

At the start I won't have brakes, however the hubs I have coming are disk brake hubs. I have an idea that utilizes that disc mount for a dynamo of sorts, but brakes are a thought also, not sure. Either way - the rims won't ever be subject to braking so there isn't that same concern of rim wear.

Rolling resistance. And sometimes I have the trailer heavily loaded. The higher I go on the weight the more squishy the tires get and the more rolling resistance there is. At the 35psi in the tires now I can push on the trailer and squat the tires, let alone loading much weight in it. The wheels are from an old Instep kid trailer so I can see the idea of having low pressure tires to act as shock absorbers for the kid passenger.

KC8QVO

I want to have capacity for up to 400lbs comfortably. As to what I will run it with over a lot of miles? Maybe 200-ish. My new trailer design will be, and the current one is somewhat also, sectional where I can change length/configuration for a variety of applications. There is no telling what it could be used for down the road.

The wheel set I am working on putting together is so I can use it with what I have now and my new design, if at least to get started. Though, I think after having the current one I have a pretty good idea of how to do things better on the new one. That is, in part, the basis of the wheels also.

I may ride on some soft ground from time to time. Some of the crushed gravel trails I have been on over the years have been mushy and my tires have sunk in. Having a wider tire will offer better flotation over that ground.

KC8QVO

Very interesting idea. I would have never thought about that.

Had I not already ordered hubs I would give this some consideration.

However, to a point I made in the past couple posts - I am building the wheel set with the anticipation of using them with another trailer in the future that will have the 2 sided support. A conventional cone/race hub is also a lot more serviceable. So there are some benefits.

As to how to convert to a stub axle - I have access to a machine shop and am working on some ideas to turn some custom axles. The long and short of it is the axles would have a fixed bearing race on the inside and 1 "cone" on the outside. There is no need to "center" the hubs as there is no center line to worry about. For aesthetic purposes I'd want to keep the dimensions pretty close on both sides, but eve 1/8" or so variation isn't going to be very noticeable. Between your bicycle dropouts that would be a big problem, though.

I can still make an "axle section" for the current trailer that does the 2 sided wheel support. However, I don't want to go down that road unless I have to as it would require a lot more fabrication that I don't want to do on a design that I don't want to keep around forever. It is possible I may need to, though.

What I want to be clear on is I am not simply going to attach a conventional axle on just one side and expect it to hold up to any significant weight. Under load testing with the current wheels the set up with the stub axles has handled a couple hundred lbs OK and to date I have not bent an axle, but that doesn't mean it can't happen, or that an axle can't just snap off.

abdon 

At that weight class, no amount of tire width will stop it from sinking. You will gain 0 float from having a slightly wider tire on the trailer.

I would bump your design to 26" tires. On mushy ground having a larger radius will help the wheel roll over mush and rocks better than a smaller tire. A mush hole that would make a small tire get stuck would let the larger tire roll out with less effort. You'll have better options for building a tire that can actually carry 400 pounds, a tall order even for regular bike tires.

Tourist in MSN

You plan to put 400 pounds on a bike trailer, for touring? Are you serious?

KC8QVO

What you quoted:
You missed the boat. When quoting it would help to have more full context. See full quote to fill in the rest of the conversation that you missed:

The main part that you missed in your quote is highlighted below in bold:

Keep in mind, I use the trailer around town. It isn't strictly touring duty. So there is a lot more to its' use than what you may have in your mind. The other thing to keep in mind is with respect to any use (touring included in that) - not everyone has the same perspective. Hence this exact post. If people take your question on the surface and what you quoted they miss a whole lot of perspective.

To the point of rims and tires - I need the perspective of the high end to get to the best choice. If I put down that I am going to run with a 50lb touring load the input would be steered by that, and not a 400lb utility load. With 400 in your head - now you have a very different perspective on what the wheels could be subjected to. That was precisely my goal - not to throw off the discussion to "You're crazy to tour with 400lbs".

So back to rims and tires...

KC8QVO

Just a quick point on weight and perspective with tires -

The Schwalbe Pick Up tires I linked to earlier in 20x2.35 have a 125kg load rating. That comes out to about 275.5lbs doing the conversion. So with a pair of those that is about 550lbs in load capacity for the tires - more than my target 400.

I haven't found a rating on the WTP tires, not that it doesn't exist - I just haven't come across it. When I get a chance I may look.

Though, no matter the tire I'd like to have a spare on hand anyway. Same for the rim. I'm much less concerned with hubs. However, spare axles are another "have just in case" item I'd say.

fishboat

...of course, you realize this is a touring forum..so it wouldn't be too unusual to assume we're talking about bicycle..touring.

200 lbs...oh..that's much more reasonable..perhaps the Utility Cycling forum might be a better fit.
https://www.bikeforums.net/utility-cycling/

Tourist in MSN

You are absolutely right.

When I am on this board (touring), I assume touring. When I am on the randonneuring board, I assume long distance endurance riding. When I am on the electronics board, I assume everything from commuting to touring to racing. And I respond with those perspectives in mind.

Thus, I assumed less than 50 pounds per tire maximum load. And based on that, was assuming probably less than 40 psi was appropriate in a tire between 35 and 50mm.

It would have been nice if the opening post described also using the trailer for cargo purposes with that much weight capacity too.

A couple months ago while I was unlocking my bike at a Home Despot after buying some small item, a guy was loading up the lumber on his trailer that was attached to his e-bike. Not sure what his trailer was rated for but it probably is in the range of capacity you are looking for. But he had an e-bike designed to be a cargo carrier, so rolling resistance was not much of an issue for him.

If you have a 400 pound trailer attached to your bike, I really hope you have fantastic brakes.

tcs

I was impressed with this trailer: https://www.carlacargo.de/



Up to 440# rating, trailer brakes, unhitch and use as a hand cart, optional e-assist.

FWIW, they use the Schwalbe Big Ben Plus in 20". Schwalbe lists these rated at a maximum weight of 95kg ~ 210lbs per tire.

https://www.schwalbetires.com/Big-Ben-Plus-11101122


Flights of fancy: I'm imagining a fold-out, pop-up soft-wall camper version for bike tours.

Tourist in MSN

What? No dynohubs on trailer wheels for lighting?

KC8QVO

I will have to dig in to those a bit more. Thanks for the info.

The trailer/cart in the picture here shows stub axles - only supported on the frame side of the wheels. Looking over their website shows a lot more wheels with outer rails where the wheels are supported on both sides. I'll see if I can find some details on how they have the stub axle set ups configured. It appears they use conventional hubs, but there has to be more to it... I'll see what I can find there.

Thanks for the tire detail. Same there - something to look up and possibly add to the list.

Good stuff!

KC8QVO

The most I have had on the trailer where I went any distance of note was about 15-20 miles with around 300lbs I'm guessing. I had no trouble stopping. Surly Disk Trucker with disk brakes.

The 2 issues I had were the squishy tires (the issue I am working on with the new wheel set) and the hitch on the bike side - with the load it liked to sag down and push my rear brake cam and add a bit of resistance to the brake. That issue is going to be resolved with a modification to the hitch that will lock it to the chain stay and seat stay with metal brackets that match the diameters of the stays. Once I get those 2 issues nailed down I'll be in a lot better shape.

Last summer and fall I was running the trailer routinely commuting. I didn't have much weight, though. I had no issues with it to date. Just when I load it up heavier I run in to issues.

abdon 

Was the road at any point wet, slick, and downhill? You want your braking power to be strong enough for the worst case scenario, not just adequate for daily riding. If you find yourself having to do an emergency braking while coming down a slick hill with 300 pounds pushing on you even locking your brakes on the bike is not going to work.

tcs

Carla says their cargo trailer is approved by German StVO. Yes. There's a bicycle trailer approval regulation because Germany.

Here in Parts Unknown, bicycle trailers are out of sight, off the books and completely under the radar.

tcs

The world's countries and regions seem to have local flavor solutions to pedal-cargo.

In Mexico, I've seen these rigs, always painted chrome yellow.



Heck for stout. Front pair and trailer wheels look to be identical. Seems to just have a coaster brake. Probably doesn't meet German StVO.

I saw one in Texas. If somebody pedaled a rig like that up to my border crossing, I swear I'd wave 'em through!

Edit: Ah, from my notes, here we go - https://bikepacking.com/plog/mercurio-magnum/

Tourist in MSN

The German cargo bike looked like it was fitted with a Rohloff hub, disc rear brake, unknown brake on front, has two brake levers. The trailer on the German bike had the brake levers on the handle for maneuvering the trailer when it was not attached to a bike.

The Mexican trike has no brake levers, I assume a coaster brake on a single or two speed hub. I think it is safe to say that none of the cargo weight is over the only wheel that is used for braking, assuming a coaster brake. I hope it is not used on any hills. But with that gearing, or lack thereof, I doubt it goes very fast.

I think the German trailer has 32 spoke wheels on the rear, the Mexican one looks like 36.

saddlesores

i don't think you'll have much luck finding 16"/20" bicycle wheels capable of reliably handling 200-400 pounds of dead weight. and you'll need to consider the intended use of whatever wheels you find on the market. wheelchair wheels can safely move a 300-pound patient short distances across a flat floor or sidewalk. not sure how they'd hold up to dragging the same person behind a pickup at 30 mph for fifty miles on gravel.

to pull this off, you're going to need to over-engineer your trailer for local deliveries such that it's too heavy for cycle touring. it's one thing to pull a couple hundred pounds a few miles on flat city streets, quite another to lug half that up a hill on a rough surface.


why not build two trailers. trying to get one trailer to do everything involves achieving contradictory goals. you'll wind up with the F-35 of bike trailers - great for padding the pockets of the machine shop owner, but useless in real world situations.

tcs

...is a LarryvsHarry Bullitt.

https://www.larryvsharry.com/en/bullitt


Perhaps a bit outside our purview here, although Adventure Cyclist did a feature on a rider using a cargo bike on a cycletour.

https://www.adventurecycling.org/blo...-in-wisconsin/

But I thought the cool thing was the trailer brakes are rigged up to a mechanism on the tow bar, so if the trailer begins to overrun the bike, the trailer brakes are actuated.