Swamp Donkey 2.0 The BW200/XR400 Makes the Rockin World Go Round'

Tim

Administrator
Staff member
I don't think that rim is going to deflect much if at all. The big phat soft tire on that thing is going to do all the flexing. Run it! Looks like fine German engineering.
 

irk miller

You've been mostly-dead all day.
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I don't think that rim is going to deflect much if at all. The big phat soft tire on that thing is going to do all the flexing. Run it! Looks like fine German engineering.
You'd be surprised. I've experienced it first hand. Not to the point of being a huge deal, but I lost a nice groove of powder coat in a 12" rim running bias-ply street drag tires, which have no side load resistance. My lower shock mount clears the inside of the rim about 5mm, but still wore the groove in the rim and made a flat spot on the screw head.

 

Hurco550

Keep er' Between the ditches
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I think there is just as much of a chance of fork and axle Flex /twist that might possibly cause some issues. Either way I think I have plenty of option to grind some clearance on the caliper, so it shouldn't be much of an issue.
 
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Hurco550

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Still plugging away. Right now i'm mostly designing parts for the fork conversion and swing arm. Through the facebook tw200 group, I was able to borrow a tw200 swingarm to steal some dimensions from. Also got the 250mm rotor in, so I can make the adapter and finish up the front wheel spacers and bushings.

 
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Popeye SXM

Also used for MX
I love this thing
Sorry for the late reply. I was determined not to use a jack shaft. I narrowed the Honda hub (not difficult as made of steel) and used a 3/4'' offset drive sprocket to line up the chain. I used the front part of the DZR swing arm with the arms from a KX100 Now fitted with custom made triple clamps from Cognito moto, lovely
 

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Hurco550

Keep er' Between the ditches
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I love this thing
Sorry for the late reply. I was determined not to use a jack shaft. I narrowed the Honda hub (not difficult as made of steel) and used a 3/4'' offset drive sprocket to line up the chain. I used the front part of the DZR swing arm with the arms from a KX100 Now fitted with custom made triple clamps from Cognito moto, lovely
Awesome man, I love it! Thanks for the info. I think i will be running a wider rear tire and therefor will probably still have to use a jack shaft, but it wont be as wide as the bw200 swinger. I hadn't realized how wide they actually were until I saw the one in front of me on this bw200.

I am making my own triple clamps, and am planning on using a similar design to the XFR kit for the yz450. They will be out of 1" thick (25mm) 6061. I am assuming that they will be adequate, but I am a bit concerned about fork twist, as the stock RMZ clamps are much taller for a wider clamping area, and have two bolts per clamp. I may also be over thinking it, as these forks will be way stiffer in any setup than the stock bw200 noodles woulda been. Just kinda curious what yours are designed like from cognito?


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SONICJK

Reminds me of...me No, I'm sure of it. I hate him
Any particular reason for using 1" 6061?
Most triples are at least 1.25-1.5".

No expert opinion here, but if I were making them from scratch I would step up a bit to thicker material and use 2 m8 clamping bolts.
Unless you just have the 1" material sitting around for free in which case I'd go that direction lol
 

Tim

Administrator
Staff member
The bottom is where you need the strength, if my mind is working properly Monday morning. That's where all the real force is applied.

My BMW R75/6 has a plate metal top tree, for example. No clamping at all at the top - it is secured to the top of the fork tubes by the caps.

I think that may be why on so many bikes (my XS650, my tiny Honda ST90) the lower tree is cast steel and the top is aluminum, full of holes for gauge mounts etc.

I'd go thicker on the bottom tree and leave the top.
 

Hurco550

Keep er' Between the ditches
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Any particular reason for using 1" 6061?
Most triples are at least 1.25-1.5".

No expert opinion here, but if I were making them from scratch I would step up a bit to thicker material and use 2 m8 clamping bolts.
Unless you just have the 1" material sitting around for free in which case I'd go that direction lol
Bingo lol thats actually one of several reasons. The others are the fact that I don't have the access to the CNC equipment that I used to. If i used 1.5 thick material, it would be uber heavy as these clamps will be almost 14.5" wide outside to outside. I have access to a waterjet and a bridgeport with a boring head, the 1" offers the best path to complete. Water jet the profile, bore the holes to the finish size and call it licked. The other reason is that the kit that they are selling is 1" with single pinch bolts. My quandry comes from the fact that just because someone sells it, doesn't mean its right lol
 

Popeye SXM

Also used for MX
I am building mine to a boulevard cruiser so no mx! I am running a 23 x 8.0 (195/80) x 11 tyres. The chain my rub under extreme right hand corners, I am not sure how much the side wall will move. 3/4 inch was all i could get away with on the drive sprocket.
My triples are standard Cognito design (very nice) with 1'' top and 1 3/8'' bottom. I built plywood mock ups then when I was happy I sent Cognito the dims
 

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Hurco550

Keep er' Between the ditches
DTT BOTM WINNER
I am building mine to a boulevard cruiser so no mx! I am running a 23 x 8.0 (195/80) x 11 tyres. The chain my rub under extreme right hand corners, I am not sure how much the side wall will move. 3/4 inch was all i could get away with on the drive sprocket.
My triples are standard Cognito design (very nice) with 1'' top and 1 3/8'' bottom. I built plywood mock ups then when I was happy I sent Cognito the dims
Good info as always. I'm not planning on doing any real MX, but it will be subjected to some pretty rough single track and trail riding, so i cant have them coming loose. I'm looking at running a 26 or 27 x 9.0 r12 up front and a 24 x 10 or 11 r11 out back.
 

Tim

Administrator
Staff member
Make it fancy and double up the bottom tree. Space them apart by an inch or so. A true 'Triple' tree (why on earth are they called triple trees anyhow - the 2 forks and the stem?)
 

Hurco550

Keep er' Between the ditches
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Make it fancy and double up the bottom tree. Space them apart by an inch or so. A true 'Triple' tree (why on earth are they called triple trees anyhow - the 2 forks and the stem?)
Funny, a thought similar to that crossed my mind, and in a manner, may come into effect.

Also, always wondered the same on the name. I assumed it had something to do with the stem and 2 forks, but all google can tell me is further speculation lol
 

Tim

Administrator
Staff member
Apparently it might be from the Tyburn Tree / Gallows. Triple Tree comes from the triangular shape realized from the forks leading in front of the steering stem. So it might all be related to geometry, which would make a lot of sense.

I guess this is what people did for fun before motorcycles.

Tyburn_Tree_mural_large.jpg
 
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