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Aiming for sub 20lbs Fatbike build.... Lightest 31.6mm mtb seatposts?

32K views 144 replies 39 participants last post by  WickedLite 
#1 ·
Wondering if I can go lighter? Anyone know the lightest 5 31.6mm seatposts for this year that can take xc mtbing?

I am debating a new seatpost or run what I have for my new ww fatbike for snow riding. I am 140lbs. Aiming for sub 20 lbs with front suspension.

I have a Woodman Carbo EL seatpost, 30.9 x 400mm at 125g. Add a 40g aluminum shim puts me at 165g.

I can drill out my shim and knock off 10g easily and safely I believe. Might be able to trim post down too but still waiting for my frame to come in the mail.

WW Wisdom is appreciated...
 
#54 ·
I know, I know John. I like to see pics too but I guess I'm pretty lazy at the moment. I have a shatter/waterproof case for my phone but I gotta rip the thing apart every time to upload pics.

I will be vigilante on getting more pics when I get my frame and wheels back for the paint.

The goal is chrome and black keeping true to Borealis except I am breaking up that red side stripe into a broken black stripe, kinda like the 1970 AAR Cuda side stripe.

I will add that those inserted tubes that come in the inner routing of the Borealis frame.... I learned, you should use the tube to guide your rear brake through. Derailleur internal routing are no problem to route through, so I am told and I will learn the truth of the matter when I start puttin it together.

Here is a pic being dropped at my paint shop yesterday. Room Bicycle frame Electrical supply Picture frame Wire
 
#101 ·
Great suggestions xc71. Nice for that UNO. I have most parts already including a couple Extralite stems. I know a bit about bolt tuning but have never gone to the extreme of doing it. Most parts I usually buy already have light bolts.

I have all parts to build and ride. I just need to lighten up with Schmolke post, absoluteBlack ISO Ti rotors (not available yet) and new bolts. I have everything really. Seat is being made. Just these hubs and ring holding me up waiting. Everything else is in hand.

I have been debating on those carbon bolts and trying to find all the places I can find for them so thanks for steering me in the right direction. Those ProTi bolts look great and strong but I can't compare weights to other ti bolts. There are no figures between companies. Maybe there is lighter ti bolts just not as strong and that's fine for this build.

I have al rotor bolts at 0.796g per bolt ($12.95 shipped for 6) and was planning running 3. I do 4 on my xc bike. Never had a problem. I have Silicone Tidds (0.25g each but I can shave them) for any holes I wanna fill while not using. Going to my bolt store in the next couple days to see what they can do.

Again, I appreciate the weighin pics and bolt suggestions. Something many of us can use.
 
#109 ·
It's been a while I know and I have been tinkering here and there. So here's a little update till I finish weighing everything in.

Hubs finally came. Northpaws are built up with CX-Rays.

Not so good news (but not bad):
1. My paint guy couldn't get the test shots right. When he gets it right, I'll tear down and get'er done the way she is suppose to be.
2. Schmolke hasn't answered my order request on bolts and post yet. Holidays I guess.
3. 2 month wait time on Pillar Ti Xtra Lite spokes. I ain't waitin.

More good news:
Dash saddle should be here by the 18th.
New black replacement decals get picked up Monday.
Proti Ti bolts on their way.
Other Ti bolts on their way.
Sapim Super Spokes show Wednesday for my Darryls.

Couple pics of what's been up. A few more holes here and there lol including chainring. Derailleur now has Fibrelite carbon rear mech cage plate and KCNC pulleys. I countersunk all faceplate bolt holes. Panheads just to show diff. I'm really debating drillium on my spindle and rear derailleur parts. See what she weighs in at first.

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#131 · (Edited)
Woaah DeeEight, haven't seen you in a while. Life good?
According to fatbike.com link from DITCHMAN (thank you sir), the Snowshoe mounted on the Rolling Darryl measured 4.2187 inches.

I did not choose tires by weight which would really help on this build. Almost got Huskers. Knards look great for summer but this bike ain't for that. Tires must function in the great white open and I really wanted to see what the buzz was on floatin with the width of these BLs which came in at pretty decent 1235g and 1264g on those (that's what I remember but will weigh again. friggin memory edit: That weight was on my Dillingers). Glad I got Dillingers with all this freezing rain.

(Rear wheel with no skewers, tape or rim strips)
Darryl, Borealis hub, SuperSpokes, qr end caps and nipples came in at 1056g.

tape, skewers, Lou and tube on that rear wheel: 1million gazillion grams (man that just feels heavy). Due to my holes on the edges, I must add twice as much tape. Son of a didn't even think of that.

Really gonna keep an eye for what's comin out on carbon wheelsets this year for my 3rd superlite wheelset. Phat Moose is even lookin at possibly putting out a set for next season.

Due to my spacers being delayed, I have a few days to sand and paint. Gonna get that done. Paint dry, spindle spacer arrival and weigh in all parts.... assembly should be done by Thursday I'm guessin. A 3 month build..what the... but she is gonna be nice.

While I was stopped in my black pickup at the stop sign to the right, heading left, some little old lady behind me decided to floor it instead of braking. You can see she hit me so hard she pushed me to the right and still went through the intersection. A week should give my back some healing time. My head feels a little better. Good Times Mode of transport Automotive exterior Neighbourhood Car Fender
 
#3 ·
Perfect xc71! I shoulda known. I run a sub 100g 34.9mm TLO on my race machine. I also just searched my pile of bits and found a 31.6 aluminum post. Weighs in a 131g.

Hmmm so for about $18 a gram I can drop 33g..... To be decided upon frame arrival and weigh in.

Thanks xc71
 
#5 · (Edited)
Borealis Custom Build Sub 20lbs (Hope so)

I will weigh in when I have all parts but here is the guesstimate:

Borealis Yampa m 1270g
Next SL 175mm (30t ring/bb incl) 585g
Egg Beater 11 174g/pr
XX1
Chain 253g
Shifter w cable 105.5g (minus 10g switch to mini ilinks/swift)
Cable Housing 61g
Derailleur 242.1g (minus approx 40g for flite pulleys and cage mech)

Extralite 90mm stem 81g
Extralite grips cut 10g
Extralite headset (w topcap/bolt/taper adapt) 55g
Schmolke bars 80g (or 110g nn wider bars I have depending on how twitchy it feels in the snow),
Bar Plugs 1g/pr
Teknologika seat 126g
6KCycles Seatpost 131g (might have to go TLO 91g)
MT ZOOM clamp 5.5g
Total: 3130.1g

Wheelset #1: 5037g
Northpaws 550g (x2= 1100g)
Borealis hubs 189g + 359g= 548g
XD-11 Drive 82.3g
Cassette 263.9g
SiCCC SFL 160mm rotors 55g (x2= 110g)
Rotor Bolts 4.8g
Sapim Superspokes 64 spokes 240g
Husker Du's 1240g (x2= 2480g)
Skewers
Tape
Sealant 100g (x2= 200g)
American Classic Valve Stems 4g (x2= 8g)

Tubeless Wheelset #2: 5715.8g
Crazy drilled out Darryls 1170.8g
Borealis hubs 189g + 359g= 548g
XD-11 Drive 82.3g
Cassette 263.9g
SiCCC SFL 160mm rotors 55g (x2= 110g)
Rotor Bolts 4.8g
Sapim Superspokes 64 spokes 240g
Bud 1563g
Lou 1528g
Skewers
Tape
Sealant 100g (x2= 200g)
American Classics Valve Stems 4g (x2=8g)

And then of coarse my Look Fat Fournales 1578g (but drilling/shaving also say approx -150g) (EDIT Done: came out to 1519.8 but still swapping out bolts)

Will give true weights when come in but these are pretty close.

Using the lightest variance here I am 9720.5g/ 21.43 lbs not including skewers and rim tape.

I really want to hit 20 even or under just to do it.
 
#28 ·
Next SL 175mm (30t ring/bb incl) 500g
FYI QBP lists this at 545 grams w/o the ring. Add about 55g for the ring.
Let me give you the inside line on your FB build. We offer two FB spindle lengths both using the same 100mm BB (one for 170mm rears and one for 190mm rears). That said, our DM ring is reversible resulting in a 7mm outboard chainline shift.

Long story short, you will get a 75mm chainline (great for 1X setups with 190 rears) if you use a 170mm spindle and reverse mount the ring on your Yampa. Doing so with also reduce the Q-factor from 222 to 202 and drop some weight.

Weight of the setup described above is 585g including BB.

e-mail components@raceface.com if you have questions or need help sourcing that setup.

Thanks for riding Race Face.
 
#8 ·
I'm doing a very similar build with a Lefty and I'm projecting it out to be 28lbs. One of us is way off (hopefully me). My XL Yampa is 1398g, plus X01, Bud/Lou, drilled RD, R1's, etc.

Your housing will be much less than 61g (~20g) because of the internal routing. But I'd like to see a pic of your RD's at 550g or even 700g. I drilled mine to go from 870g to 800g each.
 
#9 ·
Looks like its going to be tough getting under 20 lbs. as you've done a great job so far.
At your weight and for snow riding you could look at Sapim Superspokes. I have a wheelset built with them and so far so good. (not a Fatbike )
Tune Speedneedle saddle is light at 87 grams, still has a leather cover which is nice for winter riding and the saddle does have alot of flex which I find makes it comfy.
I would go Powercordz prime housing with Powercordz cable or I-Links and Powercordz cable. I wouldn't run PC cable with Mini I-Links.
I'm really happy with Kettle's carbon brake pads for the SFL rotors - great stopping power and there only 8 grams for the set = XTR 985.
 
#10 ·
Good point on the housing. I still need some weight loss.

My total bike weight was with the lighter Northpaws with Dillingers which makes a huge diff in weight right there. Looks like I'm gonna be 21lbs or a hair under unless I drop my suspension.

I went with the Surly site stock weight on the Holy RD's 700g each. I weighed but lost paper and forget. RD's are at my machinist/engineer to get every gram I can outta there. A shop showed me a 30g drop drilling the odd spoke holes out that were not being used. In comparison, I should be a for sure 150g each off and hopefully a little more. I will get pics when I get them back, before and after anodizing. Huge cuts and many side profile holes.

It's all the little bits that add up and I think I am close to on track. I had a +38lb Necro TANK last year. I rode it so much last winter, I figured I earned this one.
 
#11 ·
Never heard of the Superspokes. Always ran CX-Ray. I see the they are about 40g lighter. Nice!

Hard to change the saddle. That Tune is crazy lite and scary..yikes. Teknologika just seems to fit and feel right. Every other saddle has always hurt. I prefer the flow but I have both on 2 bikes and 1 already for the fat.

I will have to weigh in the Formula organics. Google-ing I am seein 20.4g 2 pads.

All great info and I appreciate the help!
 
#13 ·
Those rims sure look sweet, tubeless ready and at 590g/ 85mm... very nice but at $1500 they are outta of my budget this year.

My Darryls should really come in between 630-650g if I am correct (so not too far off the carbondales) but then I have tape and more tape for a good seal. Hoping to get away without going ghetto which will pain me.

Northpaws are 120g each so huge weight savings in comparison but narrow with less float. Easy tubeless conversion.

Dropping my suspension puts under the mark forsure. Borealis fork at 575g uncut is crazy light but I gotta do my Fat Look Fournales at 1578g. It was magic when I put them on last year for longer funner rides. Gonna try and knock some weight off with the drill here too.

This is MAAAD science:)

So the dream now is weight drops for TLO post -40g, Superspokes -40g, rims -140g, housing -30g, fork unknown, brake pads unknown. That puts me at sub 20 lbs. These are still going to be a give and take when true weights come in and I still have to add skewers/tape/spacers and misc.

I will start getting picks when everything starts coming together. Frame should be any day. New 6 paw hubs are delayed till Dec 5th. So I'm itchin hard utilizing this time for cold hard calculating, hoping and customizing.
 
#14 ·
Lightest Holy Darryls Ever! I didn't say safest...

I stopped in to see how my Holy Rolling Darryls were comin. HOLY!!

So they weighed in at 853g and 871g before. Here is a pic of one after drilling. Still need to smooth the edges so it's not a rolling flat.

Now 600.5g for one and the other one is getting it's trim.

I don't know how safe this is but it's done now. I have seen bigger cutouts on clownshoes so not too worried but yes a little.

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#23 ·
Thanks for the reassurance guys! I usually push the limits of safety in everything without worry but was really curious on this one after looking at them.

Frame shows tomorrow or next and I will get a true weigh in before and after paint. I have always loved the Smokey & the Bandit and Smokey Yunick's gold/black theme but I think I am gonna love old school bmx, chrome (Alsa Killer Chrome) with black letters. Anno red wheels and hubs.
 
#27 ·
Yes, you are correct Silentfoe and thanks for pointing that out. I should include what I can for least surprise on outcome and that was overlooked. I will not cheat either with lighter parts to just weigh in. Just stuff as I will ride it.

I did pretty honest guesstimates overall I believe but some will weigh more, some under. I will do a full sheet on true weigh in when I have it all and cross my fingers for my goal.

A functioning tubeless setup is gonna make or break me I think. Not the end of the world but for my goal. If Borealis can make one at 21.09lbs, I should be able to beat it.

They win at saddle, tires, lack of pedals and def the fork for sure . I win with bars, stem, housings and rotors which are no significant but yes with the rims.
 
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