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Post by Fast Eddie on Nov 4, 2004 18:03:43 GMT
hola g-freeks, fast eddie from usa here. this is for the g-bikers. i have been doing some homework and i am gonna start experimenting with a different wheel set up on my stock g-bike. i dont use sealed bearings in my stocker, i use loose ball bearings. here is what im gonna try - im gonna try using a rear wheel hub on both the front and rear of my bike. it took a while to find a hub that would fit the front fork but i have a mongoose rear hub that fits a mongoose front fork. rear hubs use bigger and fewer ball bearings than the fronthubs (front hubs use smaller and more ball bearings) after discussing with some bike shops and motorcyle mechanics at a local shop i have come to this conclusion - each ball in the hub has at least 2 points of contact with the hub during the wheels rotation, more depending on the location of the ball in the hub. more balls have more contact points therefore more friction, fewer balls have less of the these contact points thus less friction. also, the weight distribution on a g-bike is different than on a bmx set up, with more weight going to the front wheel than on a typical bmx set up (or at least thats the way g-bikes should be set up) so a rear hub on the front will theoretically handle the extra weight better than a front wheel hub and roll more freely equalling more speed!!! what do you guys think? am thinking too much? Fast Eddie outty
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Post by s8tannorm on Nov 9, 2004 20:53:26 GMT
Fast Eddie, having read what you wrote about rear hubs on the front of g bikes, coming from a motorcycle engineering background what you say makes sense but i reckon theres a couple of other things to think about. Loose bearings by their very nature are free to contact each other during use, this will cause friction, so grease gets put in there to help prevent it..problem solved or it would be if it wasn't for the grease causing drag and slowing the bearing down, instead of grease you could try a very high spec anti friction lubricant, the car shops are full of them, STP, Slick 50 etc, this will stop the drag that "normal" high melting point grease will produce however i have run into problems in the past where the ball bearings will start to slide rather than roll, wrecking the bearings and generating friction again. So perhaps not the solution! A better way of reducing friction would be to use a caged bearing, because the cage takes up quite a lot of the available space within the bearing, you're on a winner straight away, more cage = less balls means less friction. Some of the higher quality caged bearings run a light weight nylon cage which requires very little lubrication only a tiny amount of light oil (not WD40, that's a degreaser not a lubricant). So what you say about the number of balls is right Eddie but i do think you'll get the best results with a caged set up. cheers s8tan norm
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Post by Ian r on Nov 10, 2004 17:39:15 GMT
Hi ;D ,
Interesting idea! Not sure on the physics. I would guess that if you have twice the load on each bearing (cos you've halved their number) the overall friction will remain the same. Dunno. We've been running front hubs on both front & rear on the basis of reducing frontal area (small hub body & narrower spoke profile) , therefore aerodynamic drag. Still looking at ways of making a floating axle like on Randall Downhills, for standard wheels/hubs. I think this will give a significant reduction in rotational friction, especially combined with an appropraite lubricant. Perhaps a double ring of needle rollers?
Great to hear your ideas,
Regards,
Ian R
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Post by Fast Eddie on Nov 17, 2004 17:04:38 GMT
using caged bearings is a better idea than loose, i hadnt thought of that. ill see if i have em laying around when i assemble my new stocker. using floating axls is a great idea, ive looked into that and the best design i can come up with is just to cut metal tube that is the right diamater to fit a skateboard bearing into, and also cut it to the same width of the bearing, then welding them to the front forks and rear dropouts. a longer axl would be needed and a few speed washers, but i think it would make a bike very fast!!! i have sealed bearing in my Crupi hubs (skate board bearings) and they roll for days. what do you guys think? Fast Eddie outty
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