Jukadi

Discussion in 'BUILD OFF 10 BIKES' started by us56456712, May 1, 2015.

  1. us56456712

    us56456712

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    Once the seat post is rewelded it should be OK. I ran it almost as hard as the worst places I can go. I will continue to watch the welds, but I think they are OK. The rear wheel might be a problem. I needed 268mm spokes but only had 265 so to compensate I used 16 mm brass nipples. One of the mountain bike forums had a discussion about using short spokes and long brass nipples and the consensus was that they had held up for all the people that tried it, except one guy that got a stick stuck in the spokes and it sheared off a bunch of the nipples. His lasted for a good while before they were sheared off. I always treat these posts as hearsay anyway and will be a little careful initially. I will have to wait and see if I can get the 2 speed working and if I like it I might get proper spokes in the future. I hope the Bendix manual 2 speed has a wide gear ratio, lo for steep hills and hi for the rest. I am also toying with the idea of changing the front coaster brake cable mounts. If I can't get the braking action I need then I will weld a lever on the fork to double the pulling distance, but then the mechanical advantage (force) will go down by half. It won't be hard to do the but dang, I want to ride it, not continue to fuss with it.
     
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  2. us56456712

    us56456712

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    I got the Rebuilt from junk Bendix manual 2 speed working. What a chore, very touchy. I don't think the ratio is as wide as I hoped. It's raining out so I just rode it in the shop, but its shifting. Whether or not it stays in adjustment is something I have to see about. This thing is funky, hard to adjust and poorly designed. The craftsmanship is nice. I could have never figured out how to adjust it without the instructions I found on the Bendix coaster brake web site. The poor design is a result of a hollow soft steel axle that bends and is prone the thread stripping. A hardened rear axle would have been nice. Mostly kids had these on their bikes with heavy duty high quality steel 4 cross rims. A few curb jumps or being towed behind a motor scooter over rough roads toasted many of these axles. It's hard to find a good one. I used the only straight one with good threads on my friends bike, so all I had left was junk from my parts box. It would be sooo cool if I can get it to work on the trails. The axle I used was stripped for a short distance at the brake activation arm mounting point. The original thin nut that held the arm in place just spun so I ground down another axle nut so it wasn't as thin as the original and that grabs good. The axle I used was also bent but it was better than my other one. I used bolts above and below where it was bent and clamped the bolt at the bottom of the bend in my vice. Then I gently tapped the bolt above the bend with a copper hammer. I moved the bolt around and kept tapping until it was straight. It didn't take very hard taps to straighten it as these axles are so soft. The chain line looks OK. I have to compress the rear stays a little as the rear triangle was originally for a 5 speed. The 2 speed hub is wider than a modern coaster. The thicker bolt at the brake arm also makes it a little wider, but not by more that a few mm. I stumbled on a downhill race last night when I went out for the test beat. Someone spotted me going up the old power line and ran out to stop me so they could see the bike. The constant ringing of the bell caught their attention. "Hey look, he even made his own wheels". The bike was a big hit with the local bike shop mechanics and a few others. One mechanic proclaimed it the coolest bike ever, of course he was assuming everything on it was working. Bad mistake there. The elite riders who can't turn a wrench and spend a lot of dough on their bikes were giving me looks of disgust. I feel sorry for these folks who can only appreciate something with a $2000 wheel set.
     
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  3. LukeTheJoker

    LukeTheJoker Moderator

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    :21: :113:

    Luke.
     
  4. us56456712

    us56456712

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    My welder friend told me something else wrong with my stick welding technique. You move the rod away in a circular motion like "stirring the pot" but you can't go back over what you welded as it remelts and drives the slag and impurities into the weld. I was moving all over the place. Lots to learn. This might be why there are gaps in my welds?, or just poor beginning technique, like welding over chrome. He said my seat post failure is typical when welding over chrome, the weld gets brittle and brakes in the middle of the weld, leaving the weld attached to both pieces. Thats exactly what happened. I got to get a MIG for my next frame.
     
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  5. us56456712

    us56456712

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    I have been riding the Jukadi and I am going to try it with a 30 tooth chain wheel or change the rear cog from 19 to 18 as I have both. The 24 tooth front chain wheel I have on it now is too low. I have to find the right compromise. I like the low gearing for hill climbing but you can't go very fast on the flats. I want to race this thing and I need to try some more ratios that better fit the road parts of the race. The steep hills I will give up on and cary the bike with a strap I have to make. It is now mostly down to fine tuning. The front brake may need a different cable set up and the gearing need the above mentioned work. The seat post is re welded. Both the front and rear coaster brakes have been assembled without lubrication: the front for welding the clutch shut and the rear because I don't know which cog to use. The cog has a gear attached and you have to disassemble the hub to replace the gear on it. Once I have that settled I can lube them up. No paint is planed. Getting close.
     
  6. LukeTheJoker

    LukeTheJoker Moderator

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    The problem is called "Hydrogen Enbrittlement" the chrome plating puts and traps excess hydrogen in the steel, hydrogen is the enemy of a strong weld, in fact structural steel welding only uses what are called "Low Hydrogen" electrodes, normally a number 16, but they are harder to use...

    Luke.
     
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  7. us56456712

    us56456712

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    The TV weather guy said a cold front was coming through on last night's news. He didn't say it would get so cold my hands would get chill blanes working on my hubs. Wah! the high so far today is 46F with intermittent drizzle. My garage is even colder because of last nights frost. There is a strong N wind right off Lake Superior which isn't helping. Cripes, almost the fort yuly and it could snow. Anyway, back to the Jukadi. I am packing the hubs inside to avoid frozen fingers. I am going to leave the 19 tooth on the hub and try a 30 tooth chain wheel. I don't know how the Bendix manual 2 speed is geared so I will have to see how fast I can go on the road and gravel in high and how well it climbs in low. I might go with a 32 tooth if the Bendix low is low enough. I can't find any information on the gear ratios of the old manual 2 speed Bendix hubs. If I don't like that I will have to dismantle the hub and replace the 19 tooth with my 18 tooth with the 32. A 36 tooth would make many of the single track hills too hard to climb and there is nowhere to get off on some of the hills, it is all bush or steep drop offs in these places. Some wide hills like the sand dunes and Kurby's hill are too steep for me anyway so I will have to carry up. I will post results of the gearing experiments.
     
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  8. us56456712

    us56456712

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    I tried 30 x 19 gearing, still too low. I have a feeling that 32 x 18 is going to be the best one. Unfortunately that would require dismantling the 2 speed again. I will try 32 x 19 next, just to make sure. 30 x 19 or 18 would be good for my rides with the above 60 crowd on single tracks, so after the race I will change it back to what it is now. I am assuming that the bike will be ready for the race, but I don't know, it's going very slow. The Bendix 2 speed manual seems to have a wide gear ratio with a nice low so I am hoping to gear it a little high for advantage on the road. This could be a good 2 speed, ratio wise, for me. People now-a-days generally don't care for wide ratios as they are use to the narrow ratios on mountain bikes but I like them for two and 3 speeds for trail use. I'll keep posting any progress on the gears.
     
  9. OddJob

    OddJob

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    Ahhhh, summertime in the U.P.....where the ice cream never melts over your cone...
     
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  10. alistair clark

    alistair clark

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    Snow in July?! When I was in Montana in the mountains I would expect that but not in Michigan. I guess you be have a week of summer this year. But when I worked near Cedarville I go swimming in October and be told that this the warmest day they had all summer.
    But it hasn't been all that warm under the bridge either we had a lot of rain. Since I do most of my bike work outside it has been a problem.
     
  11. noodlenoggin

    noodlenoggin

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    I once bought a $2500 wheelset.



    It came attached to a '95 Thunderbird that I drove to work for a year. :21:
     
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  12. us56456712

    us56456712

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    I can understand that. A $2000 bicycle wheel set won't help my riding, I am too far over the hill, but a car is something else.
     
  13. us56456712

    us56456712

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    Nicer today, still cool in the 50s but no rain and it is sunny. Same tomorrow, then it is going to get to the 70s.
     
  14. us56456712

    us56456712

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    I can't believe how well the Jukadi fits me, but that is the idea behind building your own frame. It runs straight and is a joy on the single tracks. It is either going to be 30 x 19 or 32 x 19, probably 32 x 19 for my selected gear ratio. I am having a big problem with the Bendix 2 speed. I adjust it and it works perfectly, for awhile. The cable between the rear tensioner on the chain stay and the gear toglge works loose and pretty soon you only have high gear. I get off and turn the cable adjuster and it is OK for awhile and then comes loose again. Pretty soon the cable is all the way tightened as far as it will go and when it gets loose after that all you have is high gear. I have put the bike on the stand and disconnected the cable and toggle and put a tiny screwdriver into the shift pin and it shifts up and down when I move the screwdriver in and out. I figure it can only be one of 3 things. The anchor on the chain stay is slipping (thats not it, it is really solid) or the cable has some kind of bunched up or slipping problem inside the thumb shifter or the spring is shot inside the hub. The spring seems real stiff and solid when I use the screwdriver. ??? Anyone got any suggestions. I could swap the spring as I have another but that is used to. I know springs can be a problem with these but it looked good when I rebuilt it? Dah! This bike is tons of fun, but I may make it into a single speed if I can't get the 2 speed sorted soon. Any suggestions would be appreciated.
     
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  15. us56456712

    us56456712

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    I rode the Jukadi up Mt. Mesnard which is pretty much all rock scree and roots. Shake rattle and roll and the frame and seat post held. Six miles. The Bendix 2 speed coaster got so hot coming down that I could only touch it for a little over a second. No smoke, just hot. The descent was slow as that part is all rock and roots to. This is not a good trail for a coaster. I screwed in the shift pin a little this AM and I only had to adjust the cable once, which is a big improvement. I probably need to screw it in a little further, perhaps take it out and oil the spring. The shift cable came unscrewed once with all the bouncing so after it is sorted better a little blue lock tight might be helpful. The chain line is a little off so I am going to remove one spacer when I put on the 32 tooth chain wheel. 30 x 19 works good for the trail but stinks for the road. A few more weeks of tinkering and I should have it finished. The front brake is marginal. I am going to try and put a cam on the brake cable to double the pulling distance and if that doesn't give me the braking power I need then I will put my DBS Gigant front drum on it.
     
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  16. us56456712

    us56456712

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    I put the cam/block and tackle on the brake cable to double the pulling distance and I only have the strength to close the brake lever half way now. Every time you double the cable pull you get half the force. It works just the same as it did before when I could pull it all the way before I doubled the distance. A coaster brake on the front wheel activated with a cable just doesn't work. If you want something that looks cool then go for it, if you want something that works forget it or go with a chain and long lever. The welding of the clutch makes it always work in the same spot but doesn't help it to stop any better. I have a very strong grip as measured at my Dr. before and after my carpel tunnel surgery so a wimpy grip is not the issue. I proved this doesn't work so don't do this! On the other hand battery welding is a viable method of frame construction. Also using short spokes and long brass nipples has so far also worked for wheel building, but I would have preferred to use spokes that were 3mm longer if I had them. I have read that a stick in the spokes will shear off the spoke nipples when the spoke is not reinforced by the rim. I am going to put my DBS Gigant front drum brake on this bike and change the gearing to 32 x 18. I will replace the 19 tooth cog with the 18 when I repack the 2 speed Bendix, which got cooked coming down Mt. Mesnard on one of my test beats.

    Problem Solvers Travel Agent brand block and tackle to double the pulling distance. Phooey!!
    [​IMG]
     
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  17. us56456712

    us56456712

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    I took the Jukadi single track riding this evening. I rode with 13 others and we had a guest from Austin Tx who is a mountain bike instructor and was teaching others to be mountain bike instructors. He gave us pointers on the technical sections, lots of good information but the Jukadi doesn't have a collapsable seatpost or strong brakes. I broke the ice and was the first to go through the rock steps after his demo. Everyone else couldn't be shown up by a bike that you couldn't give away for junk and even some of the more timid riders went down it. I broke my chain after about 10 miles. The axle retainers or whatever they are called on the side shown in this photo were mangled from the twisting brake torque and the wheel got canted and broke the chain. Others riders were a little miffed that I ride such a piece of poo and they were worried about me finding my way out of the woods, which is no big deal. One of my young friends is an avid racer and he said that the bike is good for racing but I should ride it hard to get the bugs out before the race. It needs new stronger axle retainer gizmos.
    [​IMG]
     
    Last edited: Jul 15, 2015
  18. us56456712

    us56456712

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    I built a heavy duty chain retainer from an old road bike toe clip. I beat it up today and it didn't go anywhere, the wheel stayed straight so that problem is solved.

    [​IMG]
    I put a alloy rim I laced up to a 1960 Gigant front drum form a Norwegian Kombi bike. It works a lot better than the coaster front brake but the plastic brake lever has too much flex so that has to be replaced with a metal one from my junk.
    [​IMG]
    With better brakes I really beat it up and went real fast through tough rocks and jumps for 10 miles, until two of the frame welds broke. It felt like a cheap Mongoose Wally World full suspension bike crossed with a swing bike. I only had to walk it two mile to home as I live on the trail. My wife made some comments that sounded like "your a scary guy that likes to beat himself and your equipment up and it doesn't surprise me that it broke". I also herd her mumble something about "user error with the welding technique". I'm deaf so I can't believe she said those things, I think she was really praising my amazing talents.
    [​IMG]
    I am going to go over to my friends house again and redo all the welds on the seat post tube. Then I am going to drill holes in the BMX track type drop outs and screw in sheet metal screws, flush grind both the head and point of the sheet metal screws, peen the screw with a drift punch and then tack weld the screw ends. The drop outs have not cracked, but I am getting tired of this. The bike is working mechanically perfect and rides amazing. I have the gearing figured out 32 x 19 is perfect for the 2 speed and the race course I want to run it on (hope, hope). I have a ways to go before it will be race ready.
    [​IMG]
    I think battery welding would work for a street bike unless you are a Clydesdale type person.
     
    Last edited: Jul 17, 2015
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  19. LukeTheJoker

    LukeTheJoker Moderator

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    Shame about the cracks, but I am loving that front drum!

    Luke.
     
  20. us56456712

    us56456712

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    I made another Klunker from the Jukadi components. I took the new klunker for an 8 mile single track in 90F. Mechanically it's good but I got a lot of pedal strikes and it is not as forgiving or as fun to ride as the Jukadi. The Jukadi fit me perfectly and was much more responsive than the 1950 Columbia frame I put all the parts on. I think I will race the Columbia klunker but it will be a poor second to the Jukadi when it worked. I am going to have to re weld it this winter and transfer moist of the parts back. I was saving the Gigant drum for this winter's Klunker build off. I would like to put old cantilever brakes on the Jukadi and use the Gigant this winter. I have to look for some old cantilever brakes.
     
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