Fat tire Bob style trailer- Mtbr.com
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  1. #1
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    Fat tire Bob style trailer

    I just wanted to share my recent project. I do a lot of trail work at the local park, and there are many areas which are hard to access by foot carrying tools. I wanted a Bob trailer, but I'm cheap, and I knew I could make my own. I ordered a Bob fork and the rest I'm building from scratch. I have a spare 150mm spaced carbon wheel so might as well use it. I made the rear yoke to fit a 150mm hub, I'll have 2 axle options so I can use a 27.512x150 dh wheel or a 26 15x150mm fat wheel.

    I still need to make my dropouts, but I'm waiting until I get the Bob fork until I decide the axle mounting points. So far everything is just tacked together, no sense going nuts until my plan is finalized.

    This is the base of the trailer. I'll have a railing above the base and I'll probably use some expanded aluminum sheet on the floor and walls.

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    Attached Thumbnails Attached Thumbnails Fat tire Bob style trailer-uploadfromtaptalk1455591344525.jpg  

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  2. #2
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  3. #3
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    Nice! We have a customer that uses Yakima ski racks to carry his tools on his BOB. Are you planning any custom tool racks?
    Keep us posted on your progress for sure. Looking forward to seeing photos of the first field test of the only single wheel trailer with a carbon wheel! Looks great so far.


    Fat tire Bob style trailer-11263787_10206520575792500_1682296402_n.jpgFat tire Bob style trailer-11267518_10206520575832501_622795196_n.jpg

  4. #4
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    This is my version: http://forums.mtbr.com/fat-bikes/cus...er-914234.html

    I used 24" wheel with 100mm spacing.

  5. #5
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    Quote Originally Posted by RobertAxle142 View Post
    Nice! We have a customer that uses Yakima ski racks to carry his tools on his BOB. Are you planning any custom tool racks?
    Keep us posted on your progress for sure. Looking forward to seeing photos of the first field test of the only single wheel trailer with a carbon wheel! Looks great so far.


    Click image for larger version. 

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    I still need to order one of your axles. I'll be doing that this weekend.
    It's going on a foes mutz 177mm x 1.75, my only concern is that the dropouts don't allow much access to the axle for tightening.

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  6. #6
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    It doesn't look like much, but I finish welded to lower frame and assembled and welded the upper frame. At this point I need the Bob fork to go any further, so onto other projects until next week I suppose.

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  7. #7
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    Making some progress... I've been away all weekend playing on wooden ramps, back to reality today. I managed to squeeze in a little Shop time after work and a quick ride.



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  8. #8
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    It's coming along nicely Roller. Can't wait to see it all behind your Mutz in the wild.

  9. #9
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    Love these custom trailers.

    I had access to a BOB years ago that I used pretty extensively for trail work. At one point, I think I had about 100lb of rocks in it. On another, I used it to haul a cooler full of ice and cold drinks through the desert for a work day. Unfortunately, it wasn't actually mine and I had to return it to the university.

    This is the kind of project that makes me REALLY want to learn to weld. I might be able to convince my dad to give me some lessons. He has a small welder in the garage, and has built a trailer for his motorcycle. He has the capacity to machine and mill custom parts at work, too.

  10. #10
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    ^ Dude, your dad has the tools and you haven't already asked? I wish my dad had some machining tools. Go get some quality time man.

    Awesome trailers fellas.
    I don't know why,... it's just MUSS easier to pedal than the other ones.

  11. #11
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    I wish I made more progress today, but apparently the welding shop gave me empty tanks last week. Imagine my surprise when I switched from my backup tank to the one I just paid for and the gauge read zero......



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  12. #12
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    Subscribe....

    That thing is AWESOME, let me know if you want to go into small batch construction?!?!?!

  13. #13
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    This will most certainly be a one-off. With the costs of materials and parts I could have bought a Bob, but it wouldn't have been exactly what I wanted.

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  14. #14
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    I have done a few projects also that if looked at from a financial point didnít work out, but it nice to build it the way you want it and when itís done it feels good to have built it yourself. Good Job!

  15. #15
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    Small bit of progress tonight, kinda mocked up the ride height. It's been a rough week, I basically just finished a few welds and mocked it up.
    At this point it looks like I'll be extending the top rail to parallel the legs that will attach to the dropouts. I will then make a dropout that spans vertically between the upper and lower legs.

    I wish I could spend more time, but I have to rebuild my 36 tonight. And I have a to-do maintenance list on the mutz a mile long.




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  16. #16
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    Quote Originally Posted by dbhammercycle View Post
    ^ Dude, your dad has the tools and you haven't already asked? I wish my dad had some machining tools. Go get some quality time man.
    Yes, I'm a terrible son. This post motivated me to ask him to teach me to weld. So he's going to teach me. Not gonna do a trailer for my fatbike for now. After I learn the basics of welding steel, I'll probably build a two-wheeled cargo trailer for city use to pull behind my Vaya with 135 dropouts. Probably use the Surly style hitch.

    Quote Originally Posted by rollertoaster View Post
    Small bit of progress tonight, kinda mocked up the ride height. It's been a rough week, I basically just finished a few welds and mocked it up.
    At this point it looks like I'll be extending the top rail to parallel the legs that will attach to the dropouts. I will then make a dropout that spans vertically between the upper and lower legs.

    I wish I could spend more time, but I have to rebuild my 36 tonight. And I have a to-do maintenance list on the mutz a mile long.
    Looks pretty nice.

  17. #17
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    Thumbs up Harold! Don't get me wrong, I've lived with my dad since my mom passed away a few years ago and I still can have a hard time finding the time to just hang with him. I blame my wife and 3 yr old, mostly the 3 yr old. Post something when you get welding!
    I don't know why,... it's just MUSS easier to pedal than the other ones.

  18. #18
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    Making some more progress. I should have completed the top structure as a whole like I did with the bottom, but I didn't really think it through all the way ahead of time. I had some interesting clamp setups to get everything where I needed it. I still need to make the dropouts and get a little more tubing for a couple more braces. I have 32' of 1" tubing into it so far.



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  19. #19
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    This thing is starting to look super burly.

  20. #20
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    I made the dropouts today. The rear holes are for 150 x 15mm axles front holes are 150 x12 ride height is adjustable to allow different wheel tire combinations. I still have a lot of welding to do. Most of the rear welds are just tacked for now.

    I still need to build a floor and hook system for bungees, also need to build a fender and a provision for a rear light of some sort. I also need to bend the tabs on the Bob fork so they sit on the bobbins properly. Additionally I'd like to add one more pair of vertical braces to the rear, and one horizontal brace to the center of the floor.

    I haven't gotten my 15mm axle yet so for now the whoops bolted using a 12mm.



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  21. #21
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    Quote Originally Posted by rollertoaster View Post
    .... ride height is adjustable to allow different wheel tire combinations.

    Additionally I'd like to add one more pair of vertical braces to the rear, and one horizontal brace to the center of the floor.
    Good choice.
    Might I suggest a vertical section of tube adjacent to the drop out plate and maybe a diagonal along side of the wheel, top to bottom?

  22. #22
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    I had thought about a diagonal brace but the beauty of using square tubing is the rigidity of it. The trailer is very stiff without even being fully welded yet. I'm just going to add the vertical bracing and roll it like that. I can't wait to finish this thing up, our trails are in bad shape right now and need some help.

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  23. #23
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    Looking great! I was also going to have a pair of diagonal braces but the floor section alone was stiff enough to stand on it with minimal deflection.

    I like the adjustable wheel height, great idea.

  24. #24
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    So close.... I took a spin around the yard. I still need to add 3 braces and finish the floor. I can't give it a proper shakedown until I get my 15mm axle. I'll be glad when this little project is done.



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  25. #25
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    I did make a mistake by putting the front 2 vertical braces too close to the Bob fork. Oh well you can't win em all. Unfortunately I can't park the bike without leaning it on something, but that's what trees are for I suppose.

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  26. #26
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    That is so cool. Now I really can't wait to see it out for adventure. Looks like our axle is working well in your Foes.

  27. #27
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    The axle is perfect, but I definitely had spread the Bob fork and tweak the mounting tabs to make it all work together.

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  28. #28
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    That is amazing, I want one behind my Mutz... its so cool... I would love to see one with a rack over the rear tire to support a set of saddle bags.

  29. #29
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    Quote Originally Posted by JCHKeys View Post
    That is amazing, I want one behind my Mutz... its so cool... I would love to see one with a rack over the rear tire to support a set of saddle bags.
    You read mind. I need some more tubing, but I was thinking about a fender/rack over the rear wheel.

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  30. #30
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    Great job! Why isn't the trailer tire chosen for low rolling resistance? Maybe a lighter tire too?
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  31. #31
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    I would rather have improved rollover than lower rolling resistance. I think the vee8 tubeless on a carbon wheel will roll just fine

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  32. #32
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    definatley burly looking. nice trailer.

    what I want to know is, what are the 4 turbos for? I can see them in one of your pics.

  33. #33
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    Quote Originally Posted by tim208 View Post
    definatley burly looking. nice trailer.

    what I want to know is, what are the 4 turbos for? I can see them in one of your pics.
    Im gonna need 4 turbos to haul this thing fully loaded. Lol

    Everyone thinks those are turbos. They are actually old water pump housings which I'm using in a sculpture.

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  34. #34
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    Awesome job on the trailer!.....now lets see some sculpture!
    Quote Originally Posted by rollertoaster View Post
    Im gonna need 4 turbos to haul this thing fully loaded. Lol

    Everyone thinks those are turbos. They are actually old water pump housings which I'm using in a sculpture.

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  35. #35
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    Quote Originally Posted by rollertoaster View Post
    Im gonna need 4 turbos to haul this thing fully loaded. Lol

    Everyone thinks those are turbos. They are actually old water pump housings which I'm using in a sculpture.

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    gotcha, glad I am not the only one.

  36. #36
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    Added the vertical braces and 2 horizontal braces to the floor.
    This thing is super stiff, it can handle more weight that the Bible fork could hold. I also extended the tounges that the Bob fork attached to. Now I can turn it a full 180 and it doesn't hit a stop prematurely. The expanded metal is noisey, I need to come up with a way to insulate that.

    Next project will be a rear fender.



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  37. #37
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    Quote Originally Posted by rollertoaster View Post
    The expanded metal is noisey, I need to come up with a way to insulate that.
    Noisy from cargo rubbing or from it rattling against sub-frame? Rattling, think you'd have to add more tack welds in problem areas or try to shim it up from the underside.

  38. #38
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    my bobs unloaded are just loud. loaded they are not.

  39. #39
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    Quote Originally Posted by bme107 View Post
    Noisy from cargo rubbing or from it rattling against sub-frame? Rattling, think you'd have to add more tack welds in problem areas or try to shim it up from the underside.
    I'm not going to attempt welding that thin expanded aluminum to the beefy tubing, I'd just melt the expanded sheet. I'm going to add a strip of rubber between all the contact points and sandwich it together.

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  40. #40
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    how wide is the rear axle on the bike you are using? Is there a 197mm TA option out there?

  41. #41
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    Quote Originally Posted by Jefflinde View Post
    how wide is the rear axle on the bike you are using? Is there a 197mm TA option out there?
    Robert Axle Project | 12mm Thru Axle Adapter for Bike Trailers | Robert Axle Project

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    Thank you for the link. i was not really clear on what i am looking for. the part of the trailer that hooks to the bike looks to be narrower than 197mm. So i was wondering if that portion will go around a 197 rear end. On BOB's website they say that you can get the 197 axle but there is no mention of if the trailer side of things is wide enough.

    edit: the part i am referring to is called the trailer forks.

  43. #43
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    The Bob fork will need to be spread to accommodate the wider bike axle

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  44. #44
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    Quote Originally Posted by rollertoaster View Post
    I'm not going to attempt welding that thin expanded aluminum to the beefy tubing, I'd just melt the expanded sheet.
    Do they make welding washers for AL?
    We specify them for steel sheets 0.028" or thinner.

  45. #45
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    Thank you


    Quote Originally Posted by rollertoaster View Post
    The Bob fork will need to be spread to accommodate the wider bike axle

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  46. #46
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    Quote Originally Posted by rollertoaster View Post
    The Bob fork will need to be spread to accommodate the wider bike axle...
    ...and after you spread it you'll need to bend the drop-outs of the trailer fork inward to make them parallel.

  47. #47
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    Worked for my farm bike. Fat tire Bob style trailer-imageuploadedbytapatalk1457107571.107901.jpg

  48. #48
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    Awesome photo!

  49. #49
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    Climbs like a goat!

  50. #50
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    I got the new Salsa Beargrease so I found some new uses for the Fatboy.
    Even without the hay, the goats will follow me around on a ride on our property!

  51. #51
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    Quote Originally Posted by dirt-nerd View Post
    Worked for my farm bike. Click image for larger version. 

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    Not baaaaaad.

    How does the Fatboy compare to the Beargrease?
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  52. #52
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    Test run tomorrow am. Wish me luck.

    Fat tire Bob style trailer-uploadfromtaptalk1457231150864.jpgFat tire Bob style trailer-uploadfromtaptalk1457231159789.jpg

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  53. #53
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    That trailer is beyond words, I hope its a great test ride... and you can start planning an awesome bikepacking trip...

  54. #54
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    The planning has already begun. Its less than 10 miles from my house to the nearest campground. Only 2 miles on road, then singletrack from there. I could always extend the route if needed

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  55. #55
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    Roller,

    How was the test ride? We want to see your creation all nice and dirty.

  56. #56
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    Roller- Awesome trailer!!

    No contest for single track the carbon Beargrease sus is the best.

  57. #57
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    I did 21miles 13 of which were hitched hauling a "lightish" test load. I stashed the trailer in my buddies sprinter in the middle of the ride to do a little loop with him. I climbed somewhere around 1500 ft of rugged singletrack with it. I was able to ride almost everything (except for really high logovers). Some of the trails are so eroded that they look like dried up rocky creek beds.

    The big wheel definitely has noticeable mass (still running a tube) and the sensation of trailer weight is substantial. However that big wheel mows everything down with very little hanging up. I think it is a fair trade off.

    Due to how rough the trails are I lost a zip lock baggie of cashew clusters.... I really wanted to eat them. Lol.

    Next step is load management, and tubeless. I'll also be replacing a bunch of self tapping screws with aluminum rivets



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