Fat tires

GoldenMotor.com

mercadion

New Member
Dec 4, 2014
13
0
0
New Mexico
I live out in the middle of the desert, quite literally, and dust and sand on the roads are terrible. I cruise at speeds of 35 with my max being about 50, and Ive found a pretty decent setup on my tires to keep traction. But every so often I still slide, which is going to happen no matter what I realize. The problem is that it is kind of like sandbars in a lake, never in the same place twice because of wind, so I cant exactly avoid that corner over there or that hill up yonder.

I was wondering to those of you who use a "fat" rear tire, is the traction you gain worth the weight you add? And did you have to do frame stretching or anything of the like to make it work? Should be noted that a shift kit will be used so drive sprocket clearance wont be an issue.
 
Last edited:

Chainreaction

New Member
Dec 14, 2014
159
0
0
Tulsa OK
I think, generally speaking, that you will find that fat tires will make your traction worse. Reason being is that you will have less weight per square inch, more weight per square inch is what you need. A more aggressive tread pattern is what you need, one that has less rubber exposed to the road.
 

Davezilla

New Member
Mar 15, 2014
2,705
10
0
San Antonio Texas
I was going to say the same thing about the lack of contact pressure which could make the fat tires worse than better... especially on sand covered pavement where you got a slippery or instable surface on top of a solid surface, the thinner tires can sink to the stable surface but the fat tires will tend to float on top of this.

Now on the flip side, the fat tires will have an advantage over thin tires if you ride in sand or snow that's deeper because of the floatation qualities, you have less contact pressure to provide traction, but you gain floatation to keep the tires from sinking into the sand or snow which allows the bike to ride right on the surface.

Now on dry pavement, the added contact area will give an advantage for slick tires, but that advantage quickly goes away if the pavement is wet or covered in sand or mud due to the lack of contact pressure, but when dry, the extra surface is nice.
 

rogergendron1

New Member
Sep 18, 2013
882
2
0
42
woburn ma
I dont know guys. I switched out to fat 2 in wide rims and added inverted tread advantage pro arc 2.5 in tires on my bike and i will never go back !!
I feel the ride is a lot smoother and cushened. Also it slips less in the light snow, ice. Salt and sand heree in new england.

I think the wider rims make a big differance also cause the new 2 in rims make even standard tires streach out and flatten like a low profile tire would. But mountimg 2.5 or wider is the way to go.

I personally love it and it made me want to do a low geared fat tire bike like a single speed moonlander with direct drive no jack shaft and a 50 pluss tooth rear to keep it slow and powerfull. Would make an insane trail bike
 

Davezilla

New Member
Mar 15, 2014
2,705
10
0
San Antonio Texas
Sounds like a good build... big ports, long intake and small carb with a nice long header should make a strong torque engine that tops at around 6000 ram but makes a lot of power way down low like a trials engine... that could turn out to be a really fun machine for a small closed course or even as a trials style bicycle.... I don't think anyone has built anything like that before, but it would be interesting and fun....

Anyway, about the fat tire delima, experience trumps theory so now we know the answer... I've been wanting to build one of those fat tire bikes for a while too, just thinking about how to best work the sprocket alignment without offsetting the engine too far, but that idea is after I do a fee other builds I got on my mind first....
 

mercadion

New Member
Dec 4, 2014
13
0
0
New Mexico
In theory (we all know how that works right) use of a jackshift kit would eliminate the alignment for the sprocket. The only part Im concerned about is it pushing the shift chain into the drive chain from the extra width.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
..makes a lot of power way down low like a trials engine... that could turn out to be a really fun machine for a small closed course or even as a trials style bicycle....
I don't think anyone has built anything like that before, but it would be interesting and fun....
This Surly was built specifically to be a trials bike, ~15MPH top speed but a frigg'n goat that can climb cliff's ;-}

http://kcsbikes.com/topic.asp?TOPIC_ID=756



It's jackshafted to bypass the disc and clear the rear wheel but just a fixed sprocket on the rear, no gears, he didn't want them.



But back to fat tire bikes...

Your frame has to accommodate them.
Sure you could make your own front fork, but the back would be an issue modifying a bike built for 2" tires.

Best bet is to buy a decent fat tire bike to start with and jackshaft it.

The Sun Crusher is a pretty decent Fat Tire bike, it has a big center cavity a 4-stroke would fit in, 7-speed gears and dual V brakes that fit the 3" wide rims, tires run 3.5" wide in the middle.



It makes for nice 7-speed shifter with power and very comfortable to ride.





Great on the pavement and very good on soft surfaces, you should just float right over the sand bars on the road.
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
The Mongoose Dolomite is another decent Fat Tire with dual disc brakes and 7-speed but a small cavity.

You might be able to stick a 2-strike jackshaft in there but I went electric on this one.



3.5" rims and 4" wide tires in the middle.



The 54V 960W 35aH Lithoium Ion battery is in the triangle cavity.
It has a multi-voltage programmable Kelly controller and 24-48V 1680W BLDC motor driving the 7-speed rear wheel.

The Sun rides better, softer tires and better front fork I think, and much nicer handlebars but it hauls a$$ and scary quite.

The discs are pitifully small but that's easy enough to change with bigger rotors.

The Sun is long gone but I still have the Dolomite, putting a bigger controller in it as I burnt up two Kelly's.

Fun bikes no matter how you spin it.



Just make sure you have decent brakes!
 

Davezilla

New Member
Mar 15, 2014
2,705
10
0
San Antonio Texas
I was actually looking at the Dolomite as a cantidate for motorizing, but quickly scratched the idea after doing my small frame MTB and the Dolomite's frame is even smaller so squeezing a China Girl in there without cutting and welding would probably be impossible, but it does look great as an E-bike. Of course, if the frame is strong enough, cutting out a space for a Morini/ DeNardi, or KTM or it's clones type engine and making a mount loop would look awesome with those huge tires too.
That Surly build is exactly what I was thinking for a trials type torque monster...
Soooo... Has anyone figured out how to make a dependable 2 wheel drive system yet sorta like a Rokon copycat motorized bike? now that would be cool as a slow moving torque monster if it could be done reliably.