Author Topic: 21 inch cafe?  (Read 61904 times)

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Offline XN

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Re: 21 inch rear wheel cafe?
« Reply #150 on: January 08, 2009, 07:30:14 AM »
to be clear, nobody here is saying the 21" rim isn't strong enough, were he to use a 80-90mm tire that would not support the weight of a 500lb cb. He found a 3.00 inch rim and a tire that would support it so there is no issue there. Once again people are opening thier mouths without reading.



I said it before I'll say it again. A 90 series 21" wheel / tire combo is plenty strong to support a 500lb CB. Look at half of the custom choppers out there most are riding on a 90 series tire. I'll even kick it up a notch my bud rides a 1300 VTX with a 90 series 21" wheel... It weighs a lot more than 500 pounds...



Another 90 series 21" wheel on a VTX and a spoke one no less



Check out big bear choppers (yes they are DOT legal) most run a 90 series 21" wheel and are around 700lbs

http://www.bigbearchoppers.com




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eldar

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Re: 21 inch rear wheel cafe?
« Reply #151 on: January 08, 2009, 07:33:10 AM »
I certainly agree about the spokes. After all, spoked do flex so proper ones are called for. It appears the wheel issue may be taken care of now though. Also, I usually do not try to offer up unsafe advice. I may have unsafe ideas but if I do, it is because it was an idea that I have not seen or tried. I assume that most people here would test out an idea to see if it is safe or see if there is a way to make it safe.

Also, much of what I tell people is things that I have learned from mike, Sean, and others. If I do not know something for sure, I generally state that and usually offer up a way to find the info. Obviously I cant expect you to read every post I make though. I certainly have not worked on every little detail there is but I do my best to make sure it is done right and I pass it on for people to try if they want to.

As for opinion or anecdotal, he was asking for ideas for something not many have done. Of course most everything will be an opinion. Aren't all ideas opinions?

I didn't come here to be a jerk, it happened but I was not the instigator even if I did participate. We have had our spits before but worked them out we could get over it. I have followed your example and removed my garbage that does not pertain to this thread topic.
« Last Edit: January 08, 2009, 07:40:23 AM by eldar, Master of the K8 Thunder! »

Offline XN

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Re: 21 inch rear wheel cafe?
« Reply #152 on: January 08, 2009, 07:39:26 AM »
Dang I almost forgot a stock Honda Shadow Spirit runs a 21" 90series spoke wheel and it weighs over 500 pounds...
78 Honda CB750K
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Offline Geeto67

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Re: 21 inch rear wheel cafe?
« Reply #153 on: January 08, 2009, 07:42:07 AM »
to be clear, nobody here is saying the 21" rim isn't strong enough, were he to use a 80-90mm tire that would not support the weight of a 500lb cb. He found a 3.00 inch rim and a tire that would support it so there is no issue there. Once again people are opening thier mouths without reading.



I said it before I'll say it again. A 90 series 21" wheel / tire combo is plenty strong to support a 500lb CB. Look at half of the custom choppers out there most are riding on a 90 series tire. I'll even kick it up a notch my bud rides a 1300 VTX with a 90 series 21" wheel... It weighs a lot more than 500 pounds...



Another 90 series 21" wheel on a VTX and a spoke one no less



Check out big bear choppers (yes they are DOT legal) most run a 90 series 21" wheel and are around 700lbs

http://www.bigbearchoppers.com


yeah I fail to see where a 90mm wide tire is being used as a REAR tire in any of those pics. Front and rear tires behave differently during motorcycle cornering, Remember the rear tire is propelling the bike as well as doing the cornering, that is an added force the front does not have to deal with. My statements were concerning a small tire as a rear since I was unaware at the time that there was such an animal as a 3" 21" rear wheel. 

Also the bikes you have posted pics are choppers with front 90 mm tires, the weight distribution is completely different from a cb750. I have a 2 inch front tire on my cb550 chop and at the limit of that bike's cornering you can feel the tire push, but that probably has as much to do with frame and fork setup as it does with wheel.

This is moot anyway since he found a 3" rim. But I tell you what XN if you are so sure go mount a 90mm REAR tire to a cb and go take some laps around an exit ramp to see if it can take it.
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fuzzybutt

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Re: 21 inch rear wheel cafe?
« Reply #154 on: January 08, 2009, 07:46:09 AM »
IC, where did you get that seat? i like it

Offline Geeto67

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Re: 21 inch rear wheel cafe?
« Reply #155 on: January 08, 2009, 07:57:48 AM »


I didn't come here to be a jerk, it happened but I was not the instigator even if I did participate. We have had our spits before but worked them out we could get over it. I have followed your example and removed my garbage that does not pertain to this thread topic.


And that is somehow suppose to be better? I fail to see how you can claim any kind of decency when you threw a whole heap of gas on an already burning fire. Like I said you have no more high ground than anyone you castigate, you owe as much to this mess as anyone, be a man and stop crying "well he started it" - that crap went old in second grade.

754, hit the nail on the head in the chopper world it is not a new idea, but in the chopper world the frame layout is completely different. If you are willing to remake the frame of course it is possible with a cb, if you use a stock frame, sure you might be able to pull it off after surgery but your weight distribution is going to be all off and make the bike an unsafe ride at best. think of it like this - on a cb the plane where your rear comes to rest is several inches above the top of the wheel, on a chopper frame it is below the top of the tire.
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eldar

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Re: 21 inch rear wheel cafe?
« Reply #156 on: January 08, 2009, 08:00:49 AM »
Geeto, I DID admit fault. Did you miss that? I see you are not taking any credit for it. Thats all I will say. I did take part, I have removed my garbage, lets see you do the same.

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #157 on: January 08, 2009, 08:04:59 AM »
yeah yeah, jerks bla bla bla,

I didn't get on the single cam forums to watch a dick stretching contest played out in text form.
 I'm here to put a thousand heads on one concept.
and I think that's actually going well.

now back to the show.

the list hanging on a post-it note goes like this.

(rear)
4 inch extended swing      -$160
120 link chain                  -$70
21" hoop                        -$85
40 magical spokes            -$80
rear cost                        =$395
it's just an estimate, but I won't pay more than the stated prices, I got patience...
I already have bronze bushings in the swingarm.
I'll need to make a new brake stay arm, and a new brake actuator, but those don't cost anything
did anyone see the ones i made?

aircraft aluminum.

(front)
40 glorious spokes   -$80
21" hoop               -$85
fender to fit 21" rim -$50
                           =$215
again... It's just an estimate
I'll have to fab up a taller fender mount/fork brace a 21" wheel will likely have a greater centrifugal pull on the fork tubes while turning, so i figure brace it up for good measure.
anything I'm not thinking of?
oh and Eldar, Geeto, stop stretchin' em at each other and play nice!!  ;D
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #158 on: January 08, 2009, 08:07:50 AM »
oh.... Eldar seems to have stopped. :-X
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline crazypj

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Re: 21 inch rear wheel cafe?
« Reply #159 on: January 08, 2009, 08:40:48 AM »
I think you liked the controversy  ;)
Still think 750 is too wide for what your thinking though
PJ
« Last Edit: January 08, 2009, 08:53:04 AM by crazypj »
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Offline Geeto67

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Re: 21 inch rear wheel cafe?
« Reply #160 on: January 08, 2009, 08:41:19 AM »
are you going to strech the stock swingarm or are you going to build a new 4" over swingarm. The cb750 stock pressed halves swingarm is ok in stock length but crappy to extend (and you run the risk of splitting the welds with the extra leverage). To do this job proper why not make a new swingarm out of box tubing - at the very least it will be stronger than the crappy swingarm. If you get the correct box tube dimensions you can even rob the axle adjusters off a cbr 600 f2/f3 (uses the same axle diameter as a cb750). If you have ability to strech the stocker then you have the ability to make a new one.

and why 4"? did you measure or just guessing.

Looks like you are using cb900F shocks. Really? as if you weren't killing the bike enough you are going to run 20+ year old shocks on it? Look around you can find cheap new ones or at least newer used ones.

you may want to think twice about drilling as many holes as you did in your new brake arms and actuator arms. there is actually a science to drilling "speed holes" that has a lot to do with the size of the hole, the pattern, the size of the part, its mateiral, and the way it will be stressed. The actuator arm I don't really see being a problem but that brake stay may strech over time which is not something you want.

I still think it is a dumb idea.
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Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #161 on: January 08, 2009, 09:27:39 AM »
I figured for the inch and a half on the rim + an extra inch for the tire + and an extra inch and a half for clearance. still just estimation.
 I'll take measurements when I actually put a rim together. Then i'll make the swingarm. (or have the guy across the street do it.)

The box tubing is a wonderful idea, I think it'll be alot tougher than the stock welded halves, like you said. come to think of it, there's some moly box at the shop in all kinda sizes... hmm

I also agree with you on the drilling of the holes, they're not really for speed, I just like holes, and it's kinda the theme on this bike.
like "rust" is the theme on my other bike.
those aluminum pieces for the arms are so hard to drill through I didn't think stretch on the actuator arm would be a problem. they're some t60-61 alloy I think, I can't remember.
also I've kicked the #$%* out of that pedal too... no problems yet..

you should hear the #$%* I get for drillin' my levers out...
"oh they're gonna crack"   
"oh, you're gonna die"
"oh this and oh that"
they're just your standard aluminum levers and I've dropped the bike a few times when i was pullin the motor, and didn't hurt 'em.

so if i have a problem with my drilled arms, i'll be surprised.

everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #162 on: January 08, 2009, 09:34:51 AM »
the shocks are in great shape for their age, but, like you say, I'll hafta replace 'em if they don't work out in this project.
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

upperlake04

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Re: 21 inch rear wheel cafe?
« Reply #163 on: January 08, 2009, 09:46:03 AM »
  Looks like you are getting lots of advice on the technical/engineering end IC  ;D    On the aesthetic part, to my eye, the rear cowl doesn't work with the tank and the dominant lines as well as it could.
  Beauty is a subjective thing, so take it for what it's worth.  :)



Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #164 on: January 08, 2009, 10:11:39 AM »
UpperLake-
you're right about the rear cowl, I don't like either. I did when I bought it, but now... it's too much.
 maybe the CR750, you know, that round one?

 I like em short and upswept a little.
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline Joksa

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Re: 21 inch rear wheel cafe?
« Reply #165 on: January 08, 2009, 11:38:38 AM »
The rear tire radius will change about an inch (~0.9" bigger) [110/90-18 compared to 120/70-21] and front tire radius will increase a bit over inch (~1.1" bigger) [90/90-19 compared to 120/70-21], so I wouldn't say it is so drastic. The rear wheel might even fit into original swing arm unless the 110/90-18 is really tight. At least it is something to try with chain adjusters all the way out.

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #166 on: January 08, 2009, 11:44:13 AM »

The people at the tire shop gave me a hard time for putting 195/40/17's on my civic.
"they'll be too big, suspension will wear out, they'll rub the wheel wells, too hard to turn, speedo will be off."
I rolled the fenders, dropped the car 3 inches, adjusted the caster and camber, aligned the toe front and rear, changed out the swaybars.... needless to say nothing rubs, tires don't wear unevenly, and it handles like its on rails.
the overall tire height was about an inch taller from the stock 135/90/13's.

not saying the bike will handle better, just an example of fitments, and tire shop worker opinions not affecting my decisions.
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline Geeto67

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Re: 21 inch rear wheel cafe?
« Reply #167 on: January 08, 2009, 11:51:23 AM »
racing levers are notched so that they break away if they are dropped, the ones on my ducati look really thin where the break point is. levers are not under a lot of stress so drill the crap out of them - who cares. Even the brake actuator arm is not under load the way that strut is. It is not common but I have seen them break on stock bikes (there was someone who posted to this forum with one that snapped on his 550 not too long ago - usually they snap after the crash), remember they have the entire weight of a spinning wheel on a them.

cars and bikes respond differently to changes in rim and tire size. All that a bike is - depends on their tires and rims.
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Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #168 on: January 08, 2009, 12:09:30 PM »
I know, that's what i say about the levers when someone talks bad about 'em.

Quote
cars and bikes respond differently to changes in rim and tire size. All that a bike is - depends on their tires and rims.
hmm. i'll keep that in mind
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #169 on: January 08, 2009, 02:50:20 PM »
I was thinkin along the lines of this seat.

before

everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

billybobobrain

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Re: 21 inch rear wheel cafe?
« Reply #170 on: January 08, 2009, 02:57:36 PM »
I was thinkin along the lines of this seat.



That what my old cb500 looks like. with the 18" rim more meet on the tyres though. And all electrics under the seat, no oil tank so you can see right thru. I'll see if I can find a Picture.

Offline Industrial Cafe

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Re: 21 inch rear wheel cafe?
« Reply #171 on: January 08, 2009, 03:36:18 PM »
I'm not real fond of the stock oil bag, myself. The oil bag off the 75 is cooler, it sits in the frame more.
If there wasn't a bag at all it would be all -full race "skeleton bike" which isn't really what I'm goin' for on this build.
Don't get me wrong, the empty space is very cool. 8)
everything I say is pure speculation and
I have no idea what I'm talking about  ._.


                                    Marla              .:71CB750:.CAFE

Offline HavocTurbo

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Re: 21 inch rear wheel cafe?
« Reply #172 on: January 08, 2009, 07:22:29 PM »
are you going to strech the stock swingarm or are you going to build a new 4" over swingarm. The cb750 stock pressed halves swingarm is ok in stock length but crappy to extend (and you run the risk of splitting the welds with the extra leverage). To do this job proper why not make a new swingarm out of box tubing - at the very least it will be stronger than the crappy swingarm. If you get the correct box tube dimensions you can even rob the axle adjusters off a cbr 600 f2/f3 (uses the same axle diameter as a cb750). If you have ability to strech the stocker then you have the ability to make a new one.

It will be easier to add OE parts (and lighter) if you use aluminum for the swingarm. Although it will be more expensive and involve more physics to get the right amount of material where it is needed to avoid breakage. Another thought.... Maybe a longer MX swingarm modified? Just a thought.

Also avoid using square or rectangle steel tubing. Tends to be drastically stiffer and puts a lot more stress on the spokes.

and why 4"? did you measure or just guessing.

Who cares?

Looks like you are using cb900F shocks. Really? as if you weren't killing the bike enough you are going to run 20+ year old shocks on it? Look around you can find cheap new ones or at least newer used ones.

Honestly.... are you always an a$$hole or just to IC? Regardless of quality ever think about whether or not he likes the way they look? Show me a picture of your bike so I can pick it apart. Oh wait.... I'm not a thoughtless a$$.

you may want to think twice about drilling as many holes as you did in your new brake arms and actuator arms. there is actually a science to drilling "speed holes" that has a lot to do with the size of the hole, the pattern, the size of the part, its mateiral, and the way it will be stressed. The actuator arm I don't really see being a problem but that brake stay may strech over time which is not something you want.

While this is a valid and logical statement it is lost by your overall sense of attitude. You come off (at least in writing) as a jerk, putting things down and asking questions as if your ideas and opinions are the only ones that should be regarded.

I still think it is a dumb idea.

IIRC it has been stated already what you think and I still only see one other person who actually cares what you say. Eldar. So please.... Either contribute with facts, positive idaes, or easier ways to get things done, or I will be forced to treat every one of your posts this way. You are starting to irritate me.

racing levers are notched so that they break away if they are dropped, the ones on my ducati look really thin where the break point is. levers are not under a lot of stress so drill the crap out of them - who cares. Even the brake actuator arm is not under load the way that strut is. It is not common but I have seen them break on stock bikes (there was someone who posted to this forum with one that snapped on his 550 not too long ago - usually they snap after the crash), remember they have the entire weight of a spinning wheel on a them.

Just to let you know how dangerous they can be.... the levers on an early 90's 900SS are thin to break but they WILL almost always break up by the pivot point. Something the designers were told of but ignored. I've broken enough on my own 900 to seriously think about finding different MC's to replace them with. Broken a few just grabbing them to stop. Scared the crap out of me. Then I made some out of steel. Apparently I squeeze hard!!! >:(

For once I agree with you 100%.
 
cars and bikes respond differently to changes in rim and tire size. All that a bike is - depends on their tires and rims.
Another 100% agreement from me. I'd also like to add weight distribution both front and back and side to side.

Industrial -

Your final tire size will determine what size wheels you will need.

Final wheel size will determine swingarm dimensions.

Swingarm dimensions will determine where your sprockets will need to be placed and what size they need to be.

After that everything else is linear measurement. (i.e. brake arm, etc.)

Also.... might be easier to run a rear disc. Just thinking.
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Offline 754

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Re: 21 inch rear wheel cafe?
« Reply #173 on: January 08, 2009, 08:27:25 PM »
First about that brake arm that broke on the 550 or 750.
I never heard of one breaking, with a stock shoulder bolt. I asked that person what bolt they used and they never answered. I suspect it was not shouldered, and maybe lighter grade.. the threads could wear into the arm and weaken it or the bolt.

-------------------------------------------------------------------------------------

IC why not change the title to cafe style? It seems that some dont grasp the idea of just having a bike to ride vs a roadracer.

I am not saying this bike would handle superbly, but should be rideable.

I have a 6 inch over swingarm on mine, and struts, and lowered to where the top of my 18 inch tire is probable flush to the frame rails that hold the back fender on. Not a good handler but it goes straight no hands like nothing I rode before.

Cheap way to extend swingarm, is to add to the front of it..
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Offline HavocTurbo

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Re: 21 inch rear wheel cafe?
« Reply #174 on: January 08, 2009, 08:37:19 PM »

Cheap way to extend swingarm, is to add to the front of it..

I completely forgot about that!!!!!
'48 HD Panhead - Exxon Valdez
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