[AdamITR]

After a bit of searching, I finally was able to track down a LNIB 2018 Specialized Fatboy ... SE model, size XL. Had it out for 3 rides so far, and loving every minute. The climbing, the traction, and stability are simply amazing.

Most of the trail system that I ride in Upstate, NY is lots of climbs, short bursty descents, some great single track too. Plenty of roots, rocks ... rough muddy terrain this time of year ... although, I could honestly see myself using this as primary trail bike all year. I do have a XC race bike also. Climbing is my forte ... I take it down a notch on the descents ... it's that 45 year old in me, lol.

Being the SE model and in stock config, the bike is equipped with an aluminum fork, and a pretty basic wheelset/tire combo ... with tubes.

RIMS
Stout XC 80, 26", 76mm internal width, 32h, tubeless ready
FRONT TIRE
Ground Control Fat, 60 TPI, wire bead, 26x4.6"
FRONT HUB
Stout 135, loose ball bearings, 10x135 QR, 32h
REAR HUB
Stout 190, sealed cartridge bearings, 10x190mm QR, 32h
SPOKES
Stainless, 14g
REAR TIRE
Ground Control Fat, 60 TPI, wire bead, 24x4.6"

So, here is my question:

I ran right around 4.5psi with tubes on a 11 mile ride the other day on the trails that I will be riding most of the year, through winter, etc. The bike was great, but without saying, a bit harsh on the descents, but still within my personal limits. I am making a decision to either purchase a 120mm RS Bluto, and appropriate wheel adapters, or a carbon fork, and a wheelset/tire upgrade. I will go tubeless either way.

Being new to Fat Bikes, just wanted to get some opinions from others who may ride similar terrain. Thanks so much for any insight.

Pic of course:

 

[mikesee]

I would start with a suspension fork.

Bluto is better than nothing, but if you can find one you'll be happier with a Mastodon.

 

[AdamITR]

Hmm, ok, which Mastodon fork? I did some brief googling, but there are a few versions it seems. Thx!!

edit: Also, since my current wheelset 10 x 135 qr, advice on adapters?

 

[RockyJo1]

Go with carbon fork, and a wheelset/tire upgrade even a carbon bar. 120 mm fork is going to mess the geo up.

 

[TeeCee]

If the front hub is trad cup and cones, loose bearings, I'd be surprised if you can get 150 through axle converters.

??????

 

[kosmo]

I take it down a notch on the descents ... it's that 45 year old in me, lol.

I am making a decision to either purchase a 120mm RS Bluto, and appropriate wheel adapters, or a carbon fork, and a wheelset/tire upgrade. I will go tubeless either way.

First, welcome, and congratulations on curbing your youthful 45 year old enthusiasm on the descents!

If you're truly aiming for year-round use, I'd go with a suspension fork.

This would also make it more enjoyable if you ever decide to slap on a pair of 29+ wheels/tires for summer use.

 

[prlundberg]

I use mine year round, but only occasionally in the summer. If I did ride it more in the summer, I'd have a Manitou and at a minimum another set of tires, if not another wheelset.

Since this is your first fat bike, I'd just ride it as is this winter and into the spring. At that point you should have a better idea of what you want. You may even find you'd prefer a different bike altogether.

 

[J_Westy]

Since this is your first fat bike, I'd just ride it as is this winter and into the spring.

^

@AdamITR: I'd spend my first upgrade money on studded tires while converting to tubeless.

P.S. Cool work stand! Having something permanently mounted outside is a stellar idea for washing etc.

.

 

[prj71]

Go with carbon fork, and a wheelset/tire upgrade even a carbon bar. 120 mm fork is going to mess the geo up.

No it won't mess anything up.. What is this statement based on?

 

[Cdal1770]

Welcome to the world of Chubby Chasing! I'd go with a suspension fork, but first look into how it'll change the geo. Given that you're riding rocky and rooty terrain, and that you might make this your all-year bike, a susp fork is a great investment. However, realize that there'll be a weight penalty of 3-5 lbs.

 

[singletrackmack]

Go with carbon fork, and a wheelset/tire upgrade even a carbon bar. 120 mm fork is going to mess the geo up.

No it won't mess anything up.. What is this statement based on?

I'd go with a suspension fork, but first look into how it'll change the geo.

Ya, a 120mm fork would be pushing it for this bike. The stock rigid fork is 467mm and at sag a 120mm fork is 505mm.

Given how small this bike is for an XL, probably best to go with an 80mm travel fork. That will keep the reach as long as with the stock rigid fork. Going to a 120mm fork would shrink reach down to less than 440mm which is super short for an XL. Even a 100mm fork would make the reach really short.


Geometry comparison with a 120mm fork at sag:

Geometry comparison with a 100mm fork at sag:

 

[Jayem]

Biggest difference with a carbon fork over steel is how easy it is to loft the front end. An aluminum is already pretty light and closer to carbon. I wouldn’t “upgrade” to a carbon fork.

 

[Pipeliner]

Assuming your tires and wheels cooperate, tubeless conversion is not difficult and very much worth the effort. YouTube is your friend.

Since your primary purpose is trail riding, a susp fork is a good upgrade. If sand or snow were the primary purpose, then tires, wheels, fork in that order of priority.… and stay with rigid fork.

 

[prj71]

Ya, a 120mm fork would be pushing it for this bike. The stock rigid fork is 467mm and at sag a 120mm fork is 505mm.

Given how small this bike is for an XL, probably best to go with an 80mm travel fork. That will keep the reach as long as with the stock rigid fork. Going to a 120mm fork would shrink reach down to less than 440mm which is super short for an XL. Even a 100mm fork would make the reach really short.

I don't think it would be that bad. Just a bit slacker HTA.

Old thread with some using 120mm.

FatBoy with Bluto?

Anyone done this yet?

www.mtbr.com

 

[prj71]

Biggest difference with a carbon fork over steel is how easy it is to loft the front end. An aluminum is already pretty light and closer to carbon. I wouldn’t “upgrade” to a carbon fork.

Carbon fork dampens the trail chatter.

 

[Jayem]

Carbon fork dampens the trail chatter.

With 4" tires at 5psi

 

[prj71]

With 4" tires at 5psi

I'm serious. Have tried fat bikes back to back with both aluminum fork and carbon fork. You can definitely tell the difference with a carbon fork even at the lower tire pressures. At least I could anyway.

Sent from my SM-G930V using Tapatalk

 

[Cdal1770]

Ya, a 120mm fork would be pushing it for this bike. The stock rigid fork is 467mm and at sag a 120mm fork is 505mm.

Given how small this bike is for an XL, probably best to go with an 80mm travel fork. That will keep the reach as long as with the stock rigid fork. Going to a 120mm fork would shrink reach down to less than 440mm which is super short for an XL. Even a 100mm fork would make the reach really short.


Geometry comparison with a 120mm fork at sag:
View attachment 1955549


Geometry comparison with a 100mm fork at sag:
View attachment 1955550

Wow, you're doing your HW! May I recommend a Lauf Carbonara fork?

 

[singletrackmack]

I don't think it would be that bad. Just a bit slacker HTA.

Old thread with some using 120mm.

FatBoy with Bluto?

Anyone done this yet?

www.mtbr.com

In that thread it is mentioned a few times that specialized doesn’t recommend anything more that 80mm travel fork.

You can put a 150mm fork on it if you want, do whatever. However, with a 120mm fork, the xl size bike becomes as short as the large frame. Not sure how tall OP is, but given he got an XL frame, that might be a big consideration. Needing to run a super long stem to compensate is not that great for trail or multi season riding which I assume that is what the sus fork is for.

 

[AdamITR]

Awesome responses guys! Reading through them now.

Just rode the same route as on Wed. (11 miles, 1,740 elevation gain), with a group of 4 similar aged riders, all on fat bikes. All in good physical condition. One rider on a '17 Med. Fat Boy, Carbon, with the 120mm Bluto, One rider on a '20 model (I think) 27.5 Beargrease, Carbon, Size Large with the older style 120mm Mastadon, One rider on a 2016 Cannondale Carbon CAAD, 27.5, Lefty, 100mm. They are running tubeless also ... no changes to my setup yet.

I'm not overly confident in the technical descents as the other 3 riders who often do bike parks, ski mountains, etc. They can pull a bit on those areas, and have a higher skill level than me too. On any level terrain, no issues, and on the climbs (again by forte ... road bike/xc background) is where no one can keep up. Not bragging, just is what it is.

Talked to my LBS today, and knowing my riding style, he seemed to think that staying rigid for now was a reasonable idea, perhaps a carbon fork, and lighter wheelset, and tubeless ... lighten the bike up some more. That's the route I am thinking ... or just tubeless for now, and re-evaluate when I have more hours on the bike.

Btw. 6'3, 204lbs, 34 inseam, Positive ape index, ride XL XC bikes, 61cm Road bikes, lot's of endurance training in the past 3 months.