Pusher-Trailer: A Bicycle-Frame Solution

General Discussion about electric bicycles.

Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Mon Apr 04, 2011 4:38 pm

Greetings –
This is a bit of an odd request but I have been thinking of a new approach to using a bike trailer in the form of a bike-frame as a pusher. The idea involves using a late model MtB or Jumper frame that can accommodate a 26” diameter wheel up to 2.5” wide Hookworm.

  • If I can source inexpensive frames, then it is possible to mount it as an extension to the existing bike via the double-crown headpiece. As a former tree-farmer, I am familiar with the 3-point hitch on a tractor; the two lower arms swing out for easy on/off – and using a double-crown could simulate similar action to both provide a solid secure fixture and afford relatively easy disconnection. The whole frame and hitch thus would be heavy-duty and superior in weight-carrying capacity over any common bike trailer.
  • The framework would allow for panniers, saddlebags, and totes, whilst providing a solid mounting structure for the third wheel as a pusher.
  • The argument for such as frame is that most of the bike trailers are limited to 55 to 66 pounds, with only a couple rated above 70. My issue is that I plan on putting my entire battery load with camping gear on the rear attachment; with batteries alone I’d nearly exceed the weight carrying capacity.
  • In studying the bike-frame approach I noticed that most of the late models weigh between 3.5 to 7 pounds and are very affordable; less than $350. You can hardly find a fork for less than that! My BOB Ibex weighs 35 pounds empty <yuk!> :x
  • The design for the interface though would be similar to a BOB where the two arms come forward and attach at the rear axle. The rest of the framework should handle up to 200 pounds (not that I need that much).
Therefore – to begin the process, I am keenly interested in Jumpers that can accept a 26” x 2.5” wheel because these have a small triangle and lower profile. Second to that would be Hardtail MtBs, and finally FS rear pieces as a last resort though only because of expense. If you own a jumper that can take a 2.5” wheel, please comment on make, model, and year.

Thanks kindly, KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
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The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby spinningmagnets » Mon Apr 04, 2011 5:00 pm

Seriously consider a BMX frame using a 20" wheel as the pusher, perhaps an option?...

Several push-trailer builders have commented on hinky handling over 20-MPH, so...if you limit yourself to a power sytem that tops out at 20-MPH, the 20" wheel using a fast-winding can be pretty efficient at 36V, yielding good range from an affordable battery pack. Either way, best of luck with whatever you choose...
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Mon Apr 04, 2011 5:26 pm

Thanks for the reply!

So you mean they get flakey over 20 mph? To tell you the truth - I was planning on 35 :twisted:

The idea is that I'd keep my ebike as a FWD, and instead of fussing about with making it a 2WD by adding a rear hub motor and dealing with the goofy freewheel that instead I'd just do the pusher trailer add-on: A push-me/pull-you XC configuration for my 2011 version of the Going to California trek :)

My FWD can already take me to 35 mph at 63V, it's just for those big long hillclimbs where I needs extra power; "spread the load".

BWEVG ~ KF 8)
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Rassy » Mon Apr 04, 2011 5:42 pm

I have seen where there is an adapter, I guess like a BOB hitch skewer or nuts, that allows a second bike ,usually for a kid so there may be a weight limit, to just have the front wheel removed and the rest of the bike becomes a trailer. I don't know how a front fork could fit over a rear axle without spreading a lot. I'm going to go search and see if I can find one of these setups.

Edit: guess I was dreaming this up. There are Trailer Cycles and Tag Along bikes that are made to turn a standard bike into a three wheel tandem. They attach to the seat post with a long tongue.

http://www.dickssportinggoods.com/produ ... Id=3614140
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=69419
One Delta Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=88536&p=1291260#p1291260
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Mon Apr 04, 2011 6:21 pm

Rassy wrote:I have seen where there is an adapter, I guess like a BOB hitch skewer or nuts, that allows a second bike ,usually for a kid so there may be a weight limit, to just have the front wheel removed and the rest of the bike becomes a trailer. I don't know how a front fork could fit over a rear axle without spreading a lot. I'm going to go search and see if I can find one of these setups.


They're called Trailer Bikes; Wikipedia has the best consolidated mfr list. Max capacity is 85 lbs. Worth noting...

Also reviewing BMX bikes - though admittedly I know little about them since they came out long after I got into XC/MtBs. The diminuative size is appealing, though not entire sure how the mounting would go.

~KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Eric » Mon Apr 04, 2011 10:28 pm

Hello Kingfish,
I have an Adams Trail-a-bike and used it with my youngest (probably 60Lbs at the time) for longer bike rides. The trailer's seat post mount stays clamped to the tube and allows easy removal of the trailer.
HitchSideView.JPG
HitchSideView.JPG (187.7 KiB) Viewed 9122 times
There is a U joint on the trailer side of the mount to allow horizontal and vertical rotation (but not around the axis that the bike is moving). I picked this up at the Play it Again Sports in Woodinville for about $70. During about 200 miles of use, we never experienced any handling issues, but only exceeded 20MPH a few times while riding down steep hills.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby amberwolf » Tue Apr 05, 2011 12:31 am

Regarding the kid's seatpost-tongue-mount bike/trailer, I have one that will eventually become a pusher experiment. But it could be problematic on a "normal" weight bike, as it will tend to push down on the front wheel but lift up on the rear wheel, due to where it pushes on the frame. See the last post here:
viewtopic.php?f=2&t=21060&start=0

As for adding a full regular bike as a trailer, I have seen pics of someone doing that to tow a bike before, I thought it was here on ES but it might've been on FreakBikeNation instead. I myself have done it to haul bikes home, but it depends on the bike in question whether I can secure it to my rear frame or not, and it had to be mounted upwards on the chainstays near where the brake studs are, due to width of front dropouts. I didn't always make it home without trouble, though.

If you don't mine spreading the dropouts of the trailer bike's front fork (easy to do on certain U-forks and old 10speeds), then it's very easy to mount it on there, if you have sufficient rear axle length to just stick it on outside the dropouts and tighten the nuts down. Much better is if you can stick it on outside the nuts and use second pair of nuts to secure it, though hardly any rear axle I've ever had was long enough for that.

It's also possible to bolt the rack eyelets together on them if they line up right and you have a long enough screw, but I would only use that to haul the bike with, not to use it as a pusher trailer. ;)


I've yet to actually test out any motorized push trailers, just the pedal one in that thread, but I keep gathering parts for doing it. I swear one of them is going to be a dog-treadmill-powered one just to prove it would work. :lol:


KF, I think that if you are using your main motor for the 35MPH flats and such, and you're willing to slow for the hills to use the pusher, it'd probably handle fine. But the lower the trailer is, and the more directly it pushes on the rear axle in a direct line with the front axle, the better it should work.

I think that the idea is to not push down on the rear wheel too much, or it may lift the front wheel, losing traction on that motor. But if you push on the front wheel, it may lift the rear wheel and lose traction there, which could jackknife you in a sharp turn at speed. :(
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Lemlux » Tue Apr 05, 2011 12:44 am

I had considered using a bmx frame for a pusher but read that standard bmx rear dropouts were 110 mm. Was this source mistaken?

http://www.vintagebmx.com/community/ind ... c=27027568
Last edited by Lemlux on Tue Apr 05, 2011 12:48 am, edited 1 time in total.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby amberwolf » Tue Apr 05, 2011 12:46 am

That sounds about right. SInce all of the BMX frames I've found so far are steel of one kind or another, it should be no problem to widen them, though. :)
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Tue Apr 05, 2011 2:46 am

If I went with the BMX, the 110mm rear mount would not be an issue because I was planning on using a spare 2806 FH anyway. I read a thread earlier today where a member did that with his BMX. :)

AW, you are absolutely correct about where to place the mounting: The load has to go to the rear axle and be as low as possible to avoid pitching/cantilever effects. The seat post is great for towing, but not the other way around. I have no fear of creating my own axle.

I just still need to let this bake in my head; my plan was to use a 26” tire, but a 20” or 24” are appealing too. Since we’re talking assist on the hills I don’t think there would be much of a problem, I mean – I will be pedaling too! Imagine that the batteries for the trek alone will weigh close to 100 pounds: 1/3 will be loaded as they are now up front and the remainder on the trailer.

Getting back to part of my original post: I am searching for a Jumper - or BMX frame that can take a 2.5” wide tire. Found one today that sold with a 24” x 2.4", and several with a 2.35" online; close! :wink:

Many thanks for support! KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Tue Apr 05, 2011 12:43 pm

Here's a little something to goad the conversation...

Image
Kent 20" Boys Hyper Mountain Bike
This is an inexpensive BMX bike configured with a DH fork. You can find it on Amazon for $136.

  • Strip the brakes, crank, wheels, seat, and fork.
  • Convert the double-crown to accept two parallel arms that fit the crown at one end, and tie-rod like bearings at the other; the tie-rod bearings are sized to fit the rear axle. The arms will need to be slightly bent to conform to the mounting.
  • Optional support bracket that mounts between the stem and seat post for draping saddle bags.
  • Unknowns: Weight capacity. Methinks 75 lbs is reasonable, though probably not more than 125; it's not going thrashing off-road.
  • Unknowns: Max tire width.

I didn't say I'm buying it; just musing in consideration of the possibilities :wink:
On safari, KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby jimw1960 » Tue Apr 05, 2011 1:20 pm

Not to be a stickler, but I'm not familiar with any part of a bike that is called a "double crown." I think what you are referring to is the headset.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Tue Apr 05, 2011 1:48 pm

jimw1960 wrote:Not to be a stickler, but I'm not familiar with any part of a bike that is called a "double crown." I think what you are referring to is the headset.


It's true - you're being a stickler :wink:

  • Headset = generic term for the whole mounting assembly that includes the steerer.
  • Dual or Double Crown = Triple Clamp; all parlance to describe the unique features of a common Downhill "headset".
Example: Triple Clamps

I don't make these terms up, though I do use them.
Onward through the fog, KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby izpirkt » Tue Apr 05, 2011 2:56 pm

I used the rear frame off of a cheap suspension bike as the connection for my pusher trailer, along with a 26" fork and a head tube. I have tried a 26 and 20 inch wheel with hub motor for the power. THere is definately some "wag" or oscillation at ~20mph. The side to side stiffness of the trailer and the wheelbase are the major factors in this. You can check out the build here: http://endless-sphere.com/forums/viewtopic.php?f=3&t=24953
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Tue Apr 05, 2011 4:40 pm

In many ways the short wheelbase is highly attractive; it’s just less so as a pusher. Having thought about the oscillation in detail, the way out of the trap is to have more power driving the front hub with the rear hub assisting up to 100%.

My thinking is that I never use my 3-way speed control; it’s always set to 120% (MAX) coz that’s wot I want 24/7 :twisted:

Therefore why not apply the 3-way to the rear hub. Set it at 40/70/100% for whatever the driving conditions allow. Cruising down a level highway = 40%, and climbing a hill maybe 70%. The front hub is doing the majority of the work and leading the way, therefore wag (oscillation) should not occur. The short story is we’re trying to replicate a contributing tandem or child rider. Also, I am quite familiar with steering dampening mechanisms, like on a go-cart. Large trailers have anti-sway bars. Not saying it’s required… though maybe all it takes is a little resistance at the steering column to reduce the effect.

Of course this is all theory. We needs a frame first! :wink:

Counting the number of brain cells it takes to change a typo, KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby rebelpilot » Tue Apr 05, 2011 5:06 pm

It's been ten years or more since I used the trail-a-bike, but if memory serves me correctly once the kids hit about 80 pounds the tail would wag the dog, and the rear tire slid sideways. Certain terrain could cause an oscillation at even moderate speeds. I currently take up to 100 pounds in my Wike trailer, and have only a minimum effect. I can feel it tug sideways, but it doesn't ever cause a loss of traction. I have gone very fast with this trailer. I believe the lower hitch point is partially responsible, but also the fact the Wike trailer has two wheels helps.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Sun Apr 17, 2011 3:01 pm

Update:
The Plan is moving forward. I’ve started a spreadsheet to track the deltas. Key to everything is finding a machinist willing to craft a few parts: If I had a garage I could do it on my own with a welder and hacksaw; gosh if I only had access to a lathe. Anyway that needs sorting.

Slightly OT:
The good news is that the Taxman cometh and he taketh much less than anticipated leaving me free to open the purse strings for this adventure. I am excited! Spent last week refining the route and calculating the distances on http://www.Bikely.com. My longest and most difficult days are coincidentally the very first and the very last. Using the parameters and achievements of last summer, I am betting that I can go 35% farther and 35% faster by using two driving wheels over the one.

AMENDMENT:
Just to be clear: I will be carrying more batteries so as to go the distance :wink:

Back to Trailering:
Rebel, I am with you that the lower attachment will make a difference; it is how the BOB IBEX trailer mates. One thing I did note is that the pivot point on the IBEX Frame is at a slight forward angle, thus I presume that has to do with handling through a curve, as well as dampen wag/oscillation on the straight and narrow. I may need to consider how to adjust this angle through the connection between the rear axle and the steerer.

Pictures:
There are two frames that I have centered upon. One is cheaper, though I do not much care for the color, and the one I like is quite a bit more. I suppose it doesn’t matter; the majority of the “trailer” frame shall be covered with bags. Oh wait, crap the ugly color frame has been discontinued; well that’s me done – I’ll need to shell out another $130 to get white. The image below is the 26” frame from DMR. And the one below that is the Battleship Gray colored one that has been discontinued.

Image
(Not keen on Red.)

Image
Looks like DMR quit making 24” frames after 2009; no mention of them.

I’ve decided upon the 24” frame with the 135mm dropouts because I will be able to stay with the 24” Hookworms and matching Kris Holm Unicycle rims that I had previously purchased. To the best of my knowledge there isn’t a true BMX frame capable of accepting a 2.5” wide tire on the planet. The DMR Transition Frame is… well the name says it all: A transition between BMX, Jumper, and MtB. The frame can accept both Vee- and Disc brakes.

Unfortunately I do not have a spare 9C 2806 RH, so I’ll need to fetch one of those. :roll:

Lining my ducks into a row, KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Lemlux » Mon Apr 18, 2011 10:17 am

KF:

Recently I bought this 17.5" 1993 cromoly Giant atx 770 frame for $20 off of Craigslist planning to use it as pusher.

giant_frame.jpg
giant atx 770 frame
giant_frame.jpg (9.32 KiB) Viewed 6538 times


I thought I'd buy a 28" BOB trailer yoke (I have a BOB Yak with stock 26" yoke) to connect the Giant frame, but haven't yet determined a mechanically appropriate way to connect backward leaning 770 headtube with forward leaning BOB yoke pivot.

I'm leaning toward using a 24" wheel on this 26" frame for torque reasons. I suspect that a 20" wheel might lead to ground clearance issues at the bottom bracket, but I'm open to that possibility. I'm still musing about where to mount the battery but think I may center it on the underside of the downtube if it fits. For stability reasons I don't think I'd put any additional weight (except controller) on this bike frame trailer.

Looking forward to go to school with your project!

If all else fails I've toyed with the idea of cutting off the front triangle and welding the rear triangle to the back of my Bob YAK.
Last edited by Lemlux on Mon Apr 18, 2011 11:20 am, edited 1 time in total.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby gogo » Mon Apr 18, 2011 10:49 am

Kingfish wrote:Back to Trailering:
Rebel, I am with you that the lower attachment will make a difference; it is how the BOB IBEX trailer mates. One thing I did note is that the pivot point on the IBEX Frame is at a slight forward angle, thus I presume that has to do with handling through a curve, as well as dampen wag/oscillation on the straight and narrow. I may need to consider how to adjust this angle through the connection between the rear axle and the steerer.


Yes, the angle of the pivot determines whether the trailer will lean with or away from you. To easily demonstrate the effect, simulate what will happen when the trailer is at 90 degrees to the bike. The pivot junction will rise and lean with you if slanted forward and if slanted backward will fall and lean away from you.

Check out the pics on my thread:
Subject: My project at mid-completion: It works!

That was starting out with a mini-chopper frame that had a 45 degree angle to start with and so when I turned it upside down it was just right. I'd think you'd have to do some modification to get a regular frame to work.
"A conclusion is the place where you got tired of thinking." -Steven Wright
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Mon Apr 18, 2011 1:16 pm

Hi Gogo

It’s interesting that you thought of inverting the frame; that had crossed my mind as well. Here’s my brief study:

Image

  • On the left is the frame rotated 16°. The ground clearance is less, but acceptable. Unless I’m riding over boulders and curbs – what does it matter?
  • On the right is the inversion. My only concern in this orientation is the strength of the framework to take abuse. Realistically the frame is in tension, compression, and torsion when pedaling and landing. The ability of the frame to withstand shock is huge. I am convinced it can handle a 150 lb static load as a road trailer without issues. Off road, well – it’s going to see some horrible off-road this summer for a brief section, but then I won’t be taking that at 30 mph… no – more like 5 mph.
When inverted the angle will lean backward as oppose to forward. I do not think that will make a difference, so long as it leans. The angle at which it leans will determine how high the head/crown rises relative to the turning radius and angle of attack.

Reference:

Image
BOB YAK

Image
BOB IBEX

From these images the angle appears to be slight. I’ll try to do a bit of deterministic discovery later this afternoon on the BOB IBEX in my possession.

Inverted, however so slight - KF
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby gogo » Mon Apr 18, 2011 2:01 pm

Kingfish wrote:Hi Gogo
When inverted the angle will lean backward as oppose to forward. I do not think that will make a difference, so long as it leans.


Just to be clear, forwards/backwards changes whether it leans with you into the turn, or away from your direction of turn. If your angle is shallow enough it might not matter?

Another option is to get a rear suspension bike and put an extra long shock absorber on it. By choosing the correct length of shock you can get the head tube angle dialed in exactly where you want it while preserving ground clearance and proper orientation of the rear fork ends.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Mon Apr 18, 2011 10:48 pm

Hmmm. Well I measured the BOB IBEX and the angle is precisely 80° relative to the trailer bottom. However we can see in the pictures that the angle of the bottom to the ground is relative to the height of the rear axle; a tall tire could neutralize the effect, whereas a smaller tire would increase it.

With reference to the previous DMR pair of images overlaid in CAD, if I took the inverted frame (on the right) and lowered it till we had an identical angle with the BOB then the DMR head would be well into the dirt; completely unacceptable. The frame on the left when rotated to 90° relative as shown has a bottom-bracket clearance of roughly ½ of the radius. If it was rotated another 10° that would cut it to 1/3 the radius. These are 24” diameter wheels, so quick math says this will be 6” and 4” respectively. I am not terribly whelmed by the thought of having only 4” of clearance. BTW – the frame on the left has a backward 7° angle.

Gogo, I am not sure that I follow you on the front shock theory; wouldn’t that promote a rear-leaning angle?

In another direction, who do we know that builds bike frames? Maybe it is cheaper to fab what we want? :idea:
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby gogo » Mon Apr 18, 2011 11:44 pm

Kingfish wrote:Gogo, I am not sure that I follow you on the front shock theory; wouldn’t that promote a rear-leaning angle?


Its the rear shock that would need to be longer.
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Kingfish » Tue Apr 19, 2011 1:57 am

Ahh, gotcha. Need to model it to be sure - but I see the direction.

I couldn't resist admiring this article on Wikipedia: Trailer Bike. That's one happy kid with a contagious smile in the first pic :)

Although I wish to redirect your attention to the last one at full height that is in my mind worthy of a quick study:

Image

In this particular case, the mounting of the two frames appears to be perpendicular to the axis. That is however not the point I wish to consider: Imagine the front wheel and steerer tilting backward about 10° or so. You lean left, you turn left, the bike wants to go left... If the front section connected to the rear in the same manner, with the front frame acting like the front wheel relative to the frame, would not the rear frame follow accordingly?

Perhaps you are correct, that with small angles - it might not make any large difference. There's really only one way to know for certain :wink:
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Re: Pusher-Trailer: A Bicycle-Frame Solution

Postby Lemlux » Tue Apr 19, 2011 9:47 am

Another stability factor to consider:

Others have posted that pusher handling tends to be less squirrelly the greater the distance between the bike's rear axle and the trailer to trailer hitch pivot joint. This was one of my motivations in chosing a 28" wheel BOB yoke (BOB calls it a "fork") to attach to the pusher frame rather than using the 26" wheel yoke.
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