Soapbox Wheels
The traditional source for cartie wheels is the Silver Cross pram, but these are increasingly difficult to come by. Bicycle wheels are a good substitute, but there are a few issues that need to be considered.
Firstly, bicycle wheels are not designed to take side forces. When a bike is cornering the rider leans in to the corner so all the force still acts through the centre of the wheel. However, when a cartie goes around a corner the wheel experiences side forces which can easily cause it to buckle, with disasterous results.
Small wheels can take far higher cornering loads than large wheels, but they also have higher rolling resistance.This can be offset by the fact that smaller tires for smaller wheels can be inflated to much higher pressures than they can on larger wheels.
The conventional wisdom is that 20" wheels give the right compromise between diameter versus strength. Try to get hold of BMX wheels, which have more spokes than ordinary bike wheels and also tend to have thicker axles and so can be single side or "stub axle" mounted.
There is, however, some evidence that if you are prepared to pay the money for good quality wheels then you can use larger diameter wheels. The Wheel Nuts have had some success using 24" Halo Combat rims [see here], and Team Weasel were using 24" cast aluminium wheels acquired on eBay [see here].
Further Reading :
| Notes on wheel sources for recumbent trikes, which are solving basically the same problem as for a cartie - i.e. coping with high side loading during cornering. |
If I may I can add some more
Be my guest!
Aarr the great wheel debate.
Aarr the great wheel debate. Well I'm here to put a few of your myths to bed. As the (don't get bored now) reigning (undefeated) State Billycart Champion of Tassie for ten years now in multiple class's using three different machines I can help you racers get those carties going a bit quicker. Now I understand I may miss interpret some of what you guys are saying so please forgive me if I step on someones toes. Firstly I'd like to point out we the Southern Tasmania Billycart Group www.southerntasbillycart.com are allowed to machine our tyres and exceed the PSI ratings which we always do if the tyre will take it. Secondly what I tell you here is like folklore he on the otherside of the Earth. We as a Group have tested extensively and we know what works and whats not so good. So if you have ? by all means ask away.
Basics. The first basic thing always make your front wheels smaller than the rears. I see most of you run 20" 406 rims. We've found 16" fronts with 20" rears is way faster for mid range top end tracks. For courses less than 330m 12" fronts with 16" rears is the ultimate and gets a head start that is hard to catch.
Second Basic The strength of a wheel is not in the number of spokes but actually in the quality of the rim. Hence when you arrive for a race meeting in Australia 70% of the field will have Velocity rims. Velocity rim varieties are fantastic in side load. I preferr the Aeroheat but have used and still use the Fusion. Side load is very important on a carts. More so than bicycles as you guys have noticed. With the Velocity rims because they are so great in rim strength we have been able to reduce the number of spokes. Normal spoke counts for real heavy carts are 16" uses 28 and 20" uses 32". A couple of guys are using half the number (24) in a 48 spoke rim (Fusion I think it is) and this works no problem.
Third Basic Actually this not well known. It's one of my little tricky things I have up my sleeve. Bearings. Those of you running the sealed ball race you buy from a bearing service will find real good gains using a bearing classified as a C3. The C3 has greater side wall clearance than std bearing. My mate has C3' in his cart and is pretty well untouchable. I don't race in his class because he's at the top and I'm wise enough (I think) to not want to get my ass kicked by Tricky Patrick as we call him. I run C3' in my Gravity Bike and found a nice solid gain.
Now you guys that run the old style of bearing in a pressed metal cage are in luck because I have a beaut mod that I still race on to this day. Have you heard of Wynns Engine Products? You will need the cap off of the Engine Treatment. The top recess fits front cages perfectly and if you flip it the recess inside fits rear 7 ball cages perfectly. So heres what you do. Place bearing cage in the recess grab a nylon toothbrush and carefully push 3 balls out. Don't push the all out in a line, space them out. It will leave inconsistant spacing but thats as much as we can get away with before the hub becomes unstable. Place them in the hub with 3 drops of Tri-Flow wet oil lubricate (not the wax) and watch the speed come. Thats upto 4 kmh you just found. But theres are catch. The cones wear out a lot faster. So for every race meeting I always rebuild with new cones but stay with the old balls if they are ok. The best way to see if they are ok is to visually inspect them after cleaning in petrol then rinse in Acetone is to assemble the hub dry and give a spin. Tip the wheel over flat whilst spining and listen then tip it over to the other side and listen. You'll hear all sorts of things but after a while you'll learn what sound sright and what isn't. One othe thing small balls are faster tham big ones - fact. So always using the front 3/16" is quicker than 1/4" balls.
I've only touched in a few areas here but it's like this when someone actually beats me or one of my records I'll sit up and take notice. Oh and all my carts are Trikes and they all go like stink. I also race Street Luge and Stock Gravity Bike.
I helped a chap who bought a 2nd hand cart in NSW (about 1500 km away from me) and helped set up his cart thru emails and over the phone for the first ever Billycart race meeting at Bathurst Mt Panorama last May. In his first ever race meeting he recorded a class time 200th of a second slower than the winner. Not bad for a beginer. His name is Ross Osborn and his cart is Whispering Assassin. I'll dig up a pic and post it. Am I able to post pics on this site? Still on my L plates here...........trikes
Great contribution!
Wow! Thanks Trikes - that's a great contribution, and very interesting. Lots of foodfor thought there. You should be able to add pictures using the
button. You can't upload images directly to the site, but you can put add the address of an image from somwehere else on the interweb, such as imageshack, etc.
A question
I've just been reading the Fast Fact File on the STBG forum, and very interesting reading it makes too. I have a question about acceleration. You say that the smaller wheels give you better acceleration off the line, so I presume you are going from a dead start off the brakes. In the UK it's not uncommon to have push starts, so I presume wheel size would be less important in those circumstances.
I've had a quick look around for Velocity rims, and they seem to be a little hard to find over here. What hubs are you using and how do you mount the wheels?
Yes we are from a dead start
Trikes front 16"
This is a world first right here.
Nobody anywhere has set eyes on my wheels so meet my tough front wheel.
It's 16" Velcocity Aeroheat rim with a 32h Velocity high flange front track hub. Hub has 100mm drop out spacings. Hub utilises the bearings (steel) that were in the hub. I tried other bearing brands but put the factory bearings back in as nothing else was faster (in steel). Theres a lot of experience in this wheel. Look closely and you'll notice the spokes are tied and soldered but thats not the trickest bit. I was able to make the wheel stiffer by not letting the spokes touch at the cross over point. Meaning when the wheel is laced and when the spokes are interlaced they actually don't quite touch. This lets the spokes run straighter instead of kinking slightly at the cross over point. Then the spokes are lightly clamped together and held together with 15g fuse wire and the solder used is 99.8% pure. This means the solder is only 1/5 of the weight of normal solder and it's a lot stronger. By not intertwining the spokes you save 1.6 gm per spoke. Not much but it all adds up when you times it by 32.
As of yesterday this cart is ten years old and has now been decommisioned. We've certainly won more than our fair share. Hopefully somebody else will want it and will carry on in the manor in which it is accustomed.......................trikes
That other angled shot of my
Site Problems?
posting advice
hi there - grampianCarties here posting as anonymous just to test how it works.
Firstly - although you can post anonymously, it's really worth logging in first as you get a really funky editor with buttons for adding images,links, formatting, etc. Unfortunately, this site doesn't support BBCODE stuff like [url] and [img] and it will also strip out any html from anonymous posts.
Secondly - I'm afraid you will almost certainly lose your post if you preview it and then use the back button to edit it. However, you don't actually need to go back to edit because if you scroll down in the preview you'll find a live editing window which you can use to just correct all the spalling mistokes.