2

We love to travel by bike. Last summer we did a trip of about 650km on mostly asphalted roads (with quite some medium long climbs and descends) with our son in a bike trailer (type Croozer, see picture below).

Croozer Kid for 2

During this trip we had to change the outer tires of the cart two times. The first change could be related to previous use (intensively used for commuting), but after another 400km we had to change them again due to wear (all rubber deteriorated on the outer tires).

As you can see on the picture above the cart has wheels that are a bit tilted, making it more stable. We noticed that the wear appeared not in the middle of the tires but more towards the inside (due to this tilting).

The cart is coupled to our bikes with a kind of spring mechanism, which allows free rotation in all directions and some vertical and horizontal movement. The spring has some negative effects. You notice the effect of that when braking (the cart itself has no brakes). Going downhill the cart tries to break out. Would changing this to a ball hitch contribute in solving my problem?

The wheels each have their own axle that makes it easier to remove the wheels. This is handy when taking it on a train or parking it somewhere (you can lock the cart to a post and remove one wheel so nobody can ride away with it). However, due to this system there is a little bit of play on the axles. The tires are size 20 x 1.75.

Details on the link to the bike, tires and weels

The wear on the outer tires makes it difficult to take longer trips because you need to take spare outer tires for every 400km you plan to do. I was wondering if I could make adjustments to this trailer in order to improve the lifetime of the outer tires.

The wear was a lot slower when using it for commuting (no steep descends on the road) compared to our holiday trip (climbs and descends of 5%, load at 80% of the max load allowed by the manufacturer).


What I found on sheldonbrown.com already helps a bit in determining the tire pressure. I think I will inflate them a little bit less. I always used maximum pressure (4 bar, 60 Psi) so I would need less force to pull the cart. However this can contribute to faster wear apparently:

Trikes and two-wheel trailers are very different from bikes, because they don't lean in corners. Most tire wear comes from cornering forces. On a bike, these forces act on different parts of the tread, according to how far one leans into various corners at various speeds.

With a trailer or trike, all of the wear is concentrated on the middle of the tread. If you overinflate the tires, you'll be riding on only the very center of the tread, and it will wear rapidly.

In addition, wheel alignment is never going to be perfect. As a result, the paired tires will always "scrub" a bit. If the tires are rock-hard, this will cause rapid wear. If the tires are softer, they can flex slightly sideways to accommodate the scrub, without wearing the tread off.

However I want to improve lifetime further. Which steps can I take next?

  • What tire pressure are you running? Pressure too low or too high could contribute to tire wear. For those tires I would guess you should be running at least 40psi, maybe 60. And, of course, use good quality tires. – Daniel R Hicks Nov 27 '14 at 14:10
  • Tire pressure is the recommended maximum pressure (4 bar ~ 60 Psi). – tvandenbrande Nov 27 '14 at 16:40
  • 1
    Sheldon Brown's website (sheldonbrown.com/tires.html) has some additional info that might be helpful here. There is a section on trailers and trikes. No solutions, but helps with understanding the forces involved. I'm sure that the one sided axle mount doesn't help either (compared to regular dropouts). What size of tires does it have? Picture looks like 20's, smaller the tire, more rotations it needs to go the same distance. – BPugh Nov 28 '14 at 2:30
  • Added details about the axle and wear. There is indeed some play on the axle. Any ideas how I can make some adjustments to make the forces on the tires smaller so that they wear slower? – tvandenbrande Nov 28 '14 at 9:11
  • 1
    It's also possible that the extra load (implied by longer trips) means more scrubbing. It would seem to be worth trying to get to the bottom of the play in the mechanism - perhaps some close-ups of that would help. – Chris H Nov 28 '14 at 15:08
3

That is not scrub a bit - that is scrub a lot. I don't agree a softer tire will not scrub. Yes a softer tire will give bit but then it has no option but to scrub. With no load I suspect the wheels are not aligned perfectly and then those short short axles play. A little play on that short radius is a lot of alignment.

I get you like the portability of the short axles but for long trips go with a trailer with a solid single axle.

This diagram is the trailer being pull toward this line of text. When you brake it is like pushing the trailer and the play would go opposite.

This play is exaggerated but the purpose is to show how much play affects alignment. enter image description here

  • So you would suggest to go for a single axis (running from one wheel to the other). Any ideas how I could make something like that? Can you also elaborate on your drawing which direction the trailer is going, which forces act on the wheels to get them in this stance? – tvandenbrande Nov 28 '14 at 14:59
  • You would not make as solid axle as in fabricate you would buy one. Depending on the frame and other design factors you may or may not be able to (easily) modify you existing trailer. I could not (easily) find a schematic of that trailer. I would first look for a second beefier trailer that is not designed to pack (break down). No I do not know of a kids trailer with that type of design. – paparazzo Nov 28 '14 at 15:10
  • 1
    On that picture if the hitch was on the top that is the trailer be pulled. When you brake that is like the trailer being pushed and the play would be on the other direction. – paparazzo Nov 28 '14 at 15:19
3

In addition to the alignment of the wheels, one needs to consider the alignment of the tongue. The pivot point where the tongue attaches to the bike should be exactly along the centerline of the trailer (even if the tongue is not attached to the center of the trailer), not off to one side. If the tongue (at the pivot point) is not centered then you are dragging the trailer sideways.

2

400 km on asphalt seems ridiculously low on any bicycle tire.

Try some tough and very durable touring/commuter tires, like the Schwalbe Marathon line. On a bicycle, you should be getting well over 10k miles on those, though due to the smaller wheels on a trailer, you will likely get something less (a friend of mine who uses a recumbent trike gets approximately 2.5k miles on a set).

Also, try to ride smoothly - if for example you're skidding the wheels, then you'll also wear the tires out unnecessarily. It would also be good if you posted how the tires were getting worn down.

  • I will add some pictures tomorrow (when there is light enough to take them) of the worn tires. – tvandenbrande Nov 27 '14 at 16:42
  • About riding smoothly. Will it help if I remove the suspension between chariot and bike? I noticed going downhill that the chariot tended to wobble a bit. – tvandenbrande Nov 27 '14 at 18:44
  • @tvandenbrande - What Suspension? If there's any suspension on a trailer it's going to be on the axel. I've seen some trailers with a coil sprint on the trailer arm, but that's so you can turn while pulling the trailer. What are you referring to? – ShemSeger Nov 27 '14 at 22:30
  • @ShemSeger Some of the kid trailers do have a suspension on them, it isn't common. Nothing really advance, perhaps a frame member designed to flex. – BPugh Nov 28 '14 at 2:25
  • 1
    @tvandenbrande right, the fiberglass portion is what I'm talking about. I have a few trailers that used the spring hitch system, they are horrible, constant tug and rebound. I replaced the hitches with the Burley flex connector system. It works really well, and takes all the falls, lay downs, and emergency stops with jackknifing I have thrown at it. – BPugh Nov 28 '14 at 15:28
2

My first suspicion would be the alignment on the wheels, if they are not properly aligned then they will wear, but I'm not certain what you can do to adjust the alignment on that trailer. Check the dish of the rims and also make sure that they are true, this may affect how the alignment and how the wheels roll and wear.

If the tires are only wearing on the insides, then rotating them is definitely an option. Swap the tire around on the rims so that the unworn side is on the inside, this may affect how the tires grip the road if they are directional, but you might lengthen their life a bit longer by evenly wearing out the tire.

  • As the trailer tyres are used for neither braking or accelerating its very unlikely the direction will make a difference. – mattnz Nov 27 '14 at 22:23
  • 1
    @mattnz - It won't make any difference to braking or accelerating, but there are still directional forces being applied to the trailer tires. – ShemSeger Nov 27 '14 at 22:33
  • I added pictures of the wear to the question. The wheels run true on their axle, however, there is a little bit of play on the axle when assembled in the cart (see picture in the question about that). The question is, how do I fix this? – tvandenbrande Nov 28 '14 at 10:09
  • 2
    @tvandenbrande - Yeah, swapping the tires (or at least flipping them around) will equalize the wear a bit -- would give you maybe 60% more tread life. Of course it means dismounting the tires, a definite PITA. – Daniel R Hicks Nov 28 '14 at 13:14
  • 2
    Rotating the wheels won't help, because the inside of the tire will still be on the inside, you will actually have to take the tires off the wheels and turn them around. – ShemSeger Nov 28 '14 at 15:03
2

Often the tires included with the trailers are low quality and will wear quite quickly especially with heavier loads (personal experience). If you simply bought the same tires as the manufacturer included with your trailer as the replacements your problem will persist.

As an alternative, you may want to consider determining the tire size (should be printed on the side of the tire) and purchasing some higher quality tires from a manufacture known for reasonably good quality tires. For example, Schwalbe sell a variety of tire sizes for their big apple tire which wears reasonably well.

  • Thank you for the reference to a good tire manufacturer. However I don't only want to trust on the quality of the tire but reduce the chance on wear too. – tvandenbrande Nov 28 '14 at 10:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.