Wheel and Tire questions???

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

So I'm in the process of building a xs bobber. I want to use 21 inch wheels, front and rear. Here are my questions. Can you lace a front rim to a rear hub as long as they both have the same number of spokes? And can you use a front tire as a rear tire? Is there anything wrong with this?

I want to use an avon speedmaster front tire and would like the rear to match, but they dont offer a speed master rear, or at least i cant find one.
any help is much appreciated. thanks

yamaman · Posted: July 31, 2009, 7:17 am Post subject: Re: Wheel and Tire questions???

With the tyres, most tyres these days are directional, that is they must be put on one way only. Some tyres like Dunlop TT 100's and quite a few others, have directional arrows for front or rear fitting.

With bias ply tyres, the reason for this is at the point where the belts join (the weakest point of the tyre) you point it one way for rear fitment so as accelerative forces don't put undue pressure on this join. For front fitment, braking forces are the main force, so it runs the other way!

So if the Speedmasters have directional arrows going both ways, yep no problem. If they only have one arrow, then I wouldn't do it!

Fairly sure a rim is a rim, if it fits (number of spokes & pattern/angle) then it should be ok. I wouldn't take my word for that though, let someone else take on that one. Though I'm not sure you'll find one to suit a XS rear hub...... 21" is a bloody big rear wheel!
All the best with it, cheers.

Why stop at 21", go the whole hog! Laughing

xsleo · Posted: August 1, 2009, 12:47 am Post subject: Re: Wheel and Tire questions???

A rim has the spoke holes set to a certain angle to match the hub it mounts to. A rear rim is set to match the drum brake hub. A front rim is set to match a disc brake hub.
Putting a front rim on the rear or a rear on the front can have the spokes break at the hub or crack the rim. the wrong angles cause to much stress on the parts.
If I was going to do a rim swap I would consult a wheel builder for advice.

MountainCop · Posted: August 1, 2009, 3:22 pm Post subject: Re: Wheel and Tire questions???

Just a thought, but if you are going to have two tall, thin tires, it might not be a bad idea to optimize your braking abilities. Disc brakes on both ends could be a good thing. Seems to me that a double disc hub could be easily made to work as a disc / rotor hub. The spokes would like up that way as well.

Just a thought.

Can't wait to see the bike, sounds like it will be a fun look.

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

Thanks for the replies everyone. Im kind of going for a board track kind of look, i want the wheel/tire combo to look like a bicycle, tall and skinny. Discs are all fine and dandy, but i prefer the look of a drum brake. Its going to be a hard tail bike, and I dont plan on doing a whole lot of highspeed driving or intense cornering.

media.photobucket.com/...lue007.jpg

This is what the front hub kinda looks like. Very similar to the rear in the way the spokes connect to the hub. I would think the spokes would be good at any angle? Being as the spokes sort of swivel arround when they aren't connected to anything.....

xsleo · Posted: August 4, 2009, 1:08 am Post subject: Re: Wheel and Tire questions???

It has alot to do with the angles of the spokes. If you look at your outer spokes as they bend around the edge of the hub they have a certain amount of room to fit. If the spoke has to bend around farther to get to the rim it will hit the edge of the hub. This puts stress on the spoke.
At the rim end you will see that the spoke head is centered in the hole and the dimple points the hole directly at the hole in the hub the spoke comes from. If the spoke angle changes much it will put pressure on the edge of the hole and crack the hole.
I was just reading about this. Some where on here or xs650 garage.

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

thanks xsleo, appreciate the info!

pumps · Posted: August 6, 2009, 10:26 pm Post subject: Re: Wheel and Tire questions???

Do you have a picture of something that looks like what you are trying to go for. The board track look? I'd like to see that.

blackwidow · Posted: August 9, 2009, 9:20 pm Post subject: Re: Wheel and Tire questions???

Is this the look your after??I got this pic off of xs650chopper.com

bbjsw10 · Full Member Joined: Jul 15, 2009 Posts: 64

That is one cool bike, my .02. Good luck on your build and shoot some pics of it on here especially if it looks anything like bike above.

pumps · Posted: August 9, 2009, 10:02 pm Post subject: Re: Wheel and Tire questions???

Very interesting look.

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

That bike above is almost exactly what my bike will look like. He used the tc bros Hard tail (as am I), and those are both 21" wheels. My bike will have clubman bars, not shure if they will be mounted upside down or not, and also lowered forks. So it should have a leaned forward look if everything goes as planed.

this is my build thread
www.650rider.com/index...pic&t=8518

Just started cutting every thing up and what not.

pumps, here are some pictures of a few board trackers that I like.
y bike wont be exactly a board tracker, but i think its te closest category

Teebs · Full Member Joined: Aug 26, 2008 Posts: 255

This is probably a question better posed to guys who chop. You're asking questions about custom applications of guys who for the most part run stockers.

Bikers have been lacing mix-matched rims and hubs forever. Go to any chop site and you'll see that they're still doing it. That should be answer enough.

You're talking about cutting the frame in half and replacing it with a weld-on hardtail, something that carries plenty of it's own risk.

Common sense should apply here. Lace your rims, put on your tires, ride it, and BE VIGILANT. Maybe it won't work, but your wheel and/'or tire aren't going to just come apart all of a sudden. Put a front tire on the rear and it's going to completely change the handling. you're going to lose traction and it's going to turn a lot faster, as a front doesn't have nearly as much surface area making contact with the road.

Yamaman is right about tires being directional, and brought up completely valid points, but the worst that's going to happen is that your tire wears out faster than it normally would. Possibly a lot faster.

As far as spoke angle, again, I wouldn't be overly concerned. The larger wheel diameter actually helps in this situation. The fact that the rim is narrower is going to be offset by the larger radius.

The fact that so many people with no understanding of motorcycle physics, real welding skill, mechanical aptitude, or awareness of and experience with the dangers inherent in motorcycling are welding two halves of a bike together and riding around on it, or worse selling it to somebody else, is far more worrisome than tires and rims.

How many of these kids even know what the word "penetration" means in welding terms?

Ultimately, I say go for it, just be aware that you are always increasing the chances of physical harm and death whenever you do something like this as a hobbyist. And that's part of the reason why your average biker is considered to be a little crazy.

Laughing

Not necessarily the question you asked. I'll get off my soapbox now.

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

Teebs nice to hear from you so fast! I can't really agree with you more! Chopping s*** up seems to be pretty dangerous and all, especially with most people who do it are backyard warriors. I did go to school for welding and building cars (wyotech) and I'm pretty confident in my abilities. I think I'm going to go ahead with the 21" wheels. Everything seems to make sense to me in terms of spokes and what not, its just tracking down a god damn rear tire. I guess im going to repost in choppers. thanks
jim

Teebs · Full Member Joined: Aug 26, 2008 Posts: 255

Hey jim,
Sorry, didn't know your background, and in that case I think you should absolutely go for it. You would certainly know the risks involved and have an education/background that will help limit those risks.

I'm really looking forward to watching your build progress, so I hope you provide plenty of pictures. As to your question about a 21" rear tire, you're going to find that next to impossible because, as far as I know, 21" tires have typically only been used on the front and only in the past 40 years or so.

If you want some direct info on lacing a 21" rim and using a 21"tire both front and back, you might want to talk to Denis (Bobby Joe Fong) as the Fong Bros built a chop with 21s front and rear. Here is their Myspace:

www.myspace.com/fongbros

And here is a pic of the bike:

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

No problem dude, thanks for the lead though! Should be helpful. From what ive seen, those guys have some amazingly cool bikes and hopefully they will let me know what they did. They look like they are running the same as the front tire. Again thanks for the super fast reply and i will be shure to update w/pics as much as possible. actually working on the bike tomorrow( sunday), so hopefully the hard tail is on by the end of the day!
jim

yamaman · Posted: August 16, 2009, 12:10 am Post subject: Re: Wheel and Tire questions???

Pretty sure that purpose built rickshaw tyres will come in the sizes your chasing, if that helps...........I've heard of guys doing up pre war machines that needed 21" & thats what they went for.......Know anybody heading to asia?

yamaman · Posted: August 16, 2009, 8:27 am Post subject: Re: Wheel and Tire questions???

Could you squeeze one of these on?

store.coker.com/search...440/450-21

Looks like you'd have a better choice of rubber if you went to a 20" rear?????

jimxsrider · Full Member Joined: Oct 31, 2006 Posts: 67

rickshaw lol....Could be a possibility....google search rickshaw parts...
are those car tires? the first couple look like what im after..... very interesting? Have you ever seen anybody use car tires....
thanks yamaman.

jim

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