Fat Trike Build

[blown240]

Time to start my fat trike build! I need a break from my fork build.

Im starting with my aluminum cruiser. I will use a steel freewheel hub for the jackshaft. It will have a 7 speed freewheel and a cog bolted to the opposite flange. There will be a gear reduction from the jackshaft to the rear axle, probably about 50%. There will be a single gear and a disc brake on the rear axle.

I need to make some decisions:

1. Rigid or full suspension. If I go full suspension it will be independant in the rear. I know how I will do it, but it will add some weight to the trike for sure, and some expense. Rigid is easier, but my bikes I really like are full suspension.


2. Fork. I have my rigid beast fork, it already has a disc tab on it. OR, I could make some crowns for some shock legs I have, or wait till my second linkage fork is done, and put my original one on this bike.


3. Should the seat and bars be cruiser style or MTB style.


4. Front Wheel: I am trying to decide if I should buy another fat tire for $35 or build a double wheel from parts on hand. I have some white wall cruiser tires and some MTB tires. I could do 2 rims on 1 hub fairly easily.


What do you guys think? Give me some opinions, input, scolding, etc.

 

[blown240]

I started to get some parts together that i am going to use.
So far I have the fork off of my Beast, it has a disc mount. I have a pair of 26x4 tires from my beast, but I may get 3 Devist8rs for this build. I have an ok set of pedals i forgot i had too.

I also made the jackshaft. I want to use as many parts I have already, so I started with a rear freewheel hub that I have. I turned the end of it down a bit, and rounded out the inside of a cruiser cog to weld to it. Ill let the pics do the talking.

As a side note:
Its best to do welding on a hub with it totally disassembled. That way you sone boil the grease, and have to rebuild it, like i did...

 

[LukeTheJoker]

Nice work!

You may find you need to weld the flanges to the centre to stop them spinning loose under load though.

Luke.

 

[blown240]

Good call! I'll have to watch for that.
Thanks!

 

[blown240]

I did the gearing calculations:

Crankset is 24/34/42
Cassette is 13/28
Jackshaft to axle dear reduction is 50%

So hi gear will be 1.61-1 and low gear .42-1. That should be a relatively useful range based on what I want this bike to do and the weight of it.

In comparison to my other bikes:

Fat Trike: .42 low gear; 1.61 high gear
Fat Bike: .52 low gear; 2.0 high gear
Yeti 575: .61 low gear; 3.72 high gear

 

[LukeTheJoker]

That should be very useful!

Luke.

 

[Joosh]

watching this! I vote for a full suspension mtb fat trike!!!

 

[blown240]

I got a couple more parts for this build.

I found a set of Hayes Hydraulic disc brake with 203mm rotors for $40 on craigslist. I also got a pair of lights from a buddies motorcycle. I think they are off if a newer Triumph. Not exactly sure how Ill use them, but they are pretty sweet and were free. Im thinking of making a 12v battery pack and swapping some LED bulbs in.

Now I need to see what I am going to do for a front wheel. I can get a 26x4 wheel with a disc mount for $140 from a local shop.

 

[LukeTheJoker]

Some nice parts there!

Luke.

 

[blown240]

I finally got some garage time yesterday, and was able to get some work done on the Fat Trike.

I used the fork, stem, and bars that came stock on my Beast. Also the stock front hub, and a spare rim that I had laying around. I had a random set of spokes too, that just happened to work nicely as a 2 cross.

Here is the bike with the fat front:

Then I got to work on the back. I really wanted to avoid having to make supports that ran up to the seat post, and I think I found a good solution. I used a couple of stamped steel channels that are for a garage door opener. I bolted them in with the rear jackshaft/hub. Then I bent them so that they sit on the kickstand mount. Later ill make a brace to reinforce this area a bit. Im pretty sure this will be strong enough to not have to use kickers up to the seat post, and it gives me something to build the rear trike portion off of.

Here are some pics:

Thats it for now. Hopefully I'll get more time with it later in the week.

 

[nito900rr]

Lookin good bro!

Nito

 

[LukeTheJoker]

That looks great!

Luke.

 

[blown240]

Now that I have bandwidth again on photo bucket, I can do a much needed update to this build.

I was able to go for my first test ride tonight. It went OK, but not great. Its strange to ride a bike that doesn't lean, and I overlooked 1 BIG thing....

First some pics to show where I'm at with it:

So I think it looks really cool. And I know that when I get the bench on the back for the kids, they will LOVE it.

But heres where I screwed up. My idea for the rear hubs was terrible. Basically I just took standard cheapie front hubs, knocked the races out of them, slid them onto the axle, and drilled a hole for a grade 8 bolt to bolt them on. The problem is that I underestimated the force that is on the hubs when turning. Both wheels drive, so there is a lot of drag as one wheel is forced to slide sideways when cornering. This force caused the grade 8 bolt to rip thru the hub body. I should have known the hub bodies were not strong enough, but I never thought about it.

This pic is after about 100 feet of riding on the street in front of my house:

So my next step is to make some new hub shells out of DOM tubing, then ill weld them to the hub flanges I have, or maybe make some hub flanges.

 

[LukeTheJoker]

Ouch! I guess that is why most trikes are one wheel drive or have a twin freewheel system...

Luke.

 

[dracothered]

The twin free wheel is the way to go if you want to drive both wheels.

 

[dracothered]

Here is one that I found on the web that someone made.

 

[blown240]

thats a cool idea! Thanks!

 

[LukeTheJoker]

Works kind of like a Detroit Locker, drive will always go to the slowest wheel, and the faster (outside) wheel will freewheel. Great method of getting both wheels driven without scrub issues!

Luke.

 

[dracothered]

Luke I'm impressed that you know what a Detroit Locker is.

 

[LukeTheJoker]

Luke I'm impressed that you know what a Detroit Locker is.

I may be only 32, but I have a wealth of car knowledge and experience from my Father and much older Brother...

Luke.