Opinions and pointers wanted: Building a super capable fat bike.

[Ken Shopken]

Hey all-

I have been exploring the idea of building my own E-mountain bike for rough conditions.

I have mountain bike rode thousands of miles, but most of my experience is on motorized dirt bikes and older mountain bikes, back when I was really into it. (early 90s) So most of my newer tech knowledge is limited to what I am reading and being told by other mountain bike riders.

It will be going over generally frozen snow in the winter with power robbing top melt in the afternoons and lots of loose rock and loose duff in the summer. Lots of very long and steep climbs and at times motorcycle trails.

I am looking at bikes like this suspended fat bike: https://www.pinkbike.com/buysell/3783418/

Some downhill and enduro bikes are coming with pretty wide tires these days so I have not ruled these out. Great deals are available on downhill bikes but I have no idea how well they would climb with assist, slower steering angles and less than ideal seating and pedaling geometry for climbing.

Powered with the new CYC Pro gen 4 or maybe go with a lot less power but greater range and the torque sensor with the CYC Photon. https://www.cycmotor.com/ Better choices?

Perhaps use one of the new internal gear hubs to eliminate the fragile and vulnerable derailer and tortured chain angles?

With new proprietary geared mid drives being developed.. perhaps there is a universal, geared mid drive in the works?

I have no idea as to battery choices or capacity needed yet.

Thanks for any input.

 

[PDoz]

I'm looking forward to this - so many boring conventions to challenge.

1 Carbon fibre for a custom build? With your engineering skills, I'm sure you'll overcome it's limitations eg not liking crush forces

2 mid gearbox drive - cutting edge and imho the most exciting advance in emtb this design cycle. I'm almost hoping you concentrate on this and just fabricate your own frame.

3 a decent efat bike! I'm sure you've recognized most commercial efatbikes are designed for image rather than function . Except norco and haibikes offerings ? Its a market that is going to be hard to penetrate - riders tough enough to explore snow are often too stubborn to accept evolution. I'm looking forward to seeing what you produce.

Most of my snow riding has been on dirt and adv motorbikes , the only useful advice I have to offer is control beats power.

 

[PDoz]

Ps , enduro bikes can still climb, but we're getting to the point where even a trail bike is more capable than the mountainbikes you raced. There's some interesting trends in, eg, down hill capable hard tails that might translate into expedition bike design in the future, but everyone seems stuck on short chainstays which doesn't equate to good climbing ability

 

[Ken Shopken]

Time is such a limiting factor for me. Too many sports and interests to properly focus on a really worthy project such as a frame construction or a true innovative original setup.. I can see creations in my minds eye, like opposing cone variable ratio or fractional HP variable pulley transmissions.. If only there were not so many other investments! Money is going out on too many things right now to dedicate... I figured I would pick up pieces here and there and work towards a few amalgamated builds. Lots to learn via experience yet. I have friends that are also interested in riding such creations when fire season shuts down the dirt bikes or when the snow is too deep or dangerous to travel over!

I still do mountaineering, scrambling and backcountry skiing as best as I can with my age and yard-sale body parts! The fat tire with studs (I currently stud dirt bike tires) would allow me to reach objectives that I am no longer strong enough to endure the long approaches upon the frozen snow or long forest service roads with long melt out sections on south exposure sides.

Still collecting data and knowledge... inspiration will follow I am sure!

 

[Chargeride]

Fatbikes are great for climbing when motor powered, but you have the same issues, they track very poorly over rutted ground and don't perform as well as thinner tyres climbing in muddy ruts, tending the slide around over the top than digging in.
If you're climbing loose gravel, rocks etc, they far outperform thinner tyres.
Ultimately at lower pressure they can climb stupidly steep terrain.

Of course low pressures lead to pinchflats and I've lost count of the amount I have got, tubeless or inserts is essential if you are going to ride hard.

Another issue is wider cranks, pedal striked in ruts and the pedals mover further to the ground at the same lean angle.

Also if you are using a midrive, chain angle is an issue, rolling back after a failed climb and the chain might drop off the largest rear cog, resulting in dreadful noises as you take another go.
An internal hub or moving the cogs around on the cassette for a better chainline.

Also if you're running rear suspension, powerful mid drives and hi angle chainline can put serious strain on the rear frame bearings and structure.

You can hilariously see this on my bbshd build.

 

[Ken Shopken]

Fatbikes are great for climbing when motor powered, but you have the same issues, they track very poorly over rutted ground and don't perform as well as thinner tyres climbing in muddy ruts, tending the slide around over the top than digging in.
If you're climbing loose gravel, rocks etc, they far outperform thinner tyres.
Ultimately at lower pressure they can climb stupidly steep terrain.

Of course low pressures lead to pinchflats and I've lost count of the amount I have got, tubeless or inserts is essential if you are going to ride hard.

Another issue is wider cranks, pedal striked in ruts and the pedals mover further to the ground at the same lean angle.

Also if you are using a midrive, chain angle is an issue, rolling back after a failed climb and the chain might drop off the largest rear cog, resulting in dreadful noises as you take another go.
An internal hub or moving the cogs around on the cassette for a better chainline.

Also if you're running rear suspension, powerful mid drives and hi angle chainline can put serious strain on the rear frame bearings and structure.

You can hilariously see this on my bbshd build.

Thanks. Good input- Neat build.

 

[PDoz]

Ken, private message sent - see top right " inbox" re cvt

 

[MinnBobber]

Thanks. Good input- Neat build.

@Ken Shopken
Just saw this.
I just got a great e fattie dual susp
Bike is from LaMere Cycles in St Louis Park, MN

Got it just in time for 2 back to back blizzards here in St Paul, MN

Custom carbon frame with 5” studded snow tires.
Friggen awesome in some snow conditions!
My city neighborhood was a snow bike Disneyland!
In 4 days of new snow, some epic conditions and some impossible conditions, I rode about 12 rides and loved it.

The beauty is —— bike just converted to summer
setup with 29 x. 3 wheelset.
Not much to report yet as only one ride on green trails near me.
I have lots of road bike experience but last mtn biking was circa 1993? and Bridgestone MB-1

Green trails were more difficult than expected, a lot of that being not used to a suspension.
Some big roots etc scared me until experiencing the suspension.
Got better with saddle time but not as initially comfortable and loved like the snow experience.
FYI, snow bike experience vastly exceeded my expectations of capability and fun factor.

I will try to post pics: night eide after midnight in snowstorm, 4th ride of that day.

 

[Ken Shopken]

@Ken Shopken
Just saw this.
I just got a great e fattie dual susp
Bike is from LaMere Cycles in St Louis Park, MN

Got it just in time for 2 back to back blizzards here in St Paul, MN

Custom carbon frame with 5” studded snow tires.
Friggen awesome in some snow conditions!
My city neighborhood was a snow bike Disneyland!
In 4 days of new snow, some epic conditions and some impossible conditions, I rode about 12 rides and loved it.

The beauty is —— bike just converted to summer
setup with 29 x. 3 wheelset.
Not much to report yet as only one ride on green trails near me.
I have lots of road bike experience but last mtn biking was circa 1993? and Bridgestone MB-1

Green trails were more difficult than expected, a lot of that being not used to a suspension.
Some big roots etc scared me until experiencing the suspension.
Got better with saddle time but not as initially comfortable and loved like the snow experience.
FYI, snow bike experience vastly exceeded my expectations of capability and fun factor.

I will try to post pics: night eide after midnight in snowstorm, 4th ride of that day.

View attachment 175559

Looks like a lot of fun! Nice- What model is your bike?

I am converting a bike with 3"- 27.5" tires now as sort of a cross over enduro sort of thing. I have lots of long and snowy BLM and FS roads that I ski or snowshoe on different climbs. A wide tire snow machine like your build would be ideal with maybe studs for the ice sections.

Where did you find your 5" stud tires?

1000w Bafang mid drive?

 

[MinnBobber]

Looks like a lot of fun! Nice- What model is your bike?

I am converting a bike with 3"- 27.5" tires now as sort of a cross over enduro sort of thing. I have lots of long and snowy BLM and FS roads that I ski or snowshoe on different climbs. A wide tire snow machine like your build would be ideal with maybe studs for the ice sections.

Where did you find your 5" stud tires?

1000w Bafang mid drive?

Johnny 5 with studs (oh so tiny studs) but did cross some glare ice very carefully.

LaMere is the shop and brand of their own frames and creation, the e-Summit.
Awesome snow bike , so much fun and not much concern about falling… so what if you fall in the snow
Shimano EP 801 with 630 WH battery

 

[Ken Shopken]

Thanks. Nice tire and bike!

I found these more aggressive bicycle studs that insert with a push tool, instead of using an insertion gun or screw in type. They only offer 4.6" wide on this webpage that I noticed anyway. https://bikestud.com/collections/studs

Not very deep knobs on the bicycle tires to hold bigger studs.

On the dirt bike tires, we have a Bruno Wessel pneumatic gun, but its still quite a forearm workout to stud tires.

Interestingly, I like to run a front studded tire even in the summer because it offers such superior traction upon dry hardpack with loose material on top. If on bedrock and large cobble, not so nice!

 

[Ken Shopken]

Johnny 5 tires and similar stud selections to the website I already shared above; https://www.terrenetires.com/collections/studs