It actually was considerably cheaper to put this together than buy something off the shelf. The donor bike was a secondhand 2021 Procaliber 9.5 (lowest spec!), that I got for £995.
I sold a high end TT bike so put all the funds into this and built it for under £4000, including the forks, wheels and powermeter. The only thing I may still do is upgrade to SRAM AXS.
For me, it’s a more desirable spec than the Procaliber 9.8, which I would still want to upgrade!
I think that’d be a good idea. Having owned 2 Cube mountain bikes and 1 Cube road bike, in my experience the geometry is pretty safe. Think VW Golf: it works well for a large number of people, it is not too sporty, but not to wallow-y, dependable. I put on a 120 mm fork on a previous Cube hardtail after the fork broke (I just never did any maintenance 
), and it significantly changed the way it rode. If you like a sportier riding position, I recommend you stick to 100 mm.
On the other hand, a more upgright seating position should help you on gnarlier terrain — in addition to 20 mm of additional travel.
That is an excellent idea. If you decide to go that route, why don’t you post in this forum? Spending other people’s money is one of our favorite pass times here 
PS Learning bike handling on a hardtail is probably a good idea. Going from a fully to a hardtail meant I have had to re-learn that hardtails really reward good line choice. You can really tell when you pick the right line and get the timing right.
Very smart. Plus, you can buy the parts you get with the bike — or keep them as spares. I reckon you can even start with a pretty vanilla aluminum frame and make an amazing bike out of it.
Will do! I’d document the transformation for sure!
I also see the benefit on learning on the hardtail. I think I will stick to this route for the time being until I have space for 2 bikes atleast.
Another questions but slightly unrelated - would you know what cranks would fit as a replacement. On the website it says Boost - so does that mean I have to buy a boost crank? Is that outlined on the chainline and q factor?
I would go with SLX cranks if you can live with the blueish color, same weight, cheaper.
Your fork has to go, my TwoStroke came with one of those and told my wife after the first race that it was being replaced, it is awful compare to the SID Select SL I put on it.
I keep 2 MTBs in the stable. I race the hard tail when there is a chance for wet weather because I don’t need to service pivots all the time.
I’d just upgrade my BB to a ceramicspeed BB for the lifetime warranty, and I swear you can feel how little drag it has. It was $$$ but a lifetime warranty and serviceable bearings are big for me.
Thanks! Good advice on the cranks - I can’t figure out if I need boost or not.
You need boost but, not the super boost, I believe the 52mm chain line, the 55mm chain line will work, just pushes the drive or ND side over 3mm.
The lightest budget set up would SLX crank with M9100 chain ring.
It’s going to be hard to upgrade form there. For that bike (and I just bought a Chisel with similar specs),
Crank and cassette are the easiest way to save weight
Crank - I found a used SLX crank for $70 and then get a lightweight ring for $35 on Amazon - that’s 200gr for $100. That MT611 has a funky q-factor / long spindle so the OEM can use it on a lot of bikes.
Cassette - That’s an SLX cassette? A Rotor 11-51 is about 200gr lighter for $250 (maybe you can sell the current one for $100), which would make the rear end easier to finesse at slow speeds.
Those wheels are pretty light at 1599gr (i’d weigh these by the way, that number is not right) - probably overly light! The rims are probably about 440gr ea based on the dimensions, spokes & nipples are about 280gr per the website/pillar, so the hubs are 399gr for the pair roughly (which is too light). That leaves you with about 20gr from the lightest hub you can find. A narrow carbon rim 360gr would take that down 160gr(pair) or an expensive one lightweight front could that down another 60gr (220gr total) - so if you spent about [$1200] (XC925 Carbon MTB Wheelset - Light Bicycle) you could go from a 1599gr wheelset to about 1375gr realistically. There’s no reason to do this. You said you buckled the rims, I’d either get a set of DT350 / no-name carbon rims or just get another set of AL rims about the same dimensions, reuse the spokes.
If you keep the dropper up most of the time and you’re light, you can get a lot better ride quality (and save 250gr) out of something like Canyon’s split carbon seatpost than a suspension dropper (A normal dropper is going to ride like crap because it can’t bend and work).
The fork is listed at 1814gr by Trek, so you can take 450gr off that by spending $600
Just to confirm your thoughts further and agree with others, that’s a nice bike.
I’d focus on getting inserts, and any upgrades I’d be making sure I could take to the next bike.
I would consider carbon wheels, you’ll she’d weight, they’re more robust, and they should be an upgrade on whatever you get next.
I’m always wary of recommending suspension upgrades as it’s very easy to over capitalize. You could try pick something up second hand.
120mm would give you the benefit of a slightly slacker HTA and the higher BB so that’s definitely worthwhile.
I’ll be keen to hear what you think of the Mt Zoom stuff!
Component list indicates Deore cassette and chain and shifter. @C_Nay these are easy gains when the cassett wears out replace with XT. The sweet spot for cost vs weight/performance.
yeah😁
The cassette has one black cog - thats an m7100. 2 rings =XT; 3 = XTR; 0 = Deore
I don’t think the shifter or chain weighs anything different. https://r2-bike.com/MTB-Shifter_2::en/shimano__12-speed https://r2-bike.com/Chains::en/shimano__Chain__12-speed
Interesting point on second hand forks… I thought this would be something you would buy new for longevity? There is a fork being sold locally second hand for 500 euro. Its a sid brain fork from a 2020 specialized hardtail evo.
What do you think of this fork for an upgrade? What should I be wary of? I’m worried I won’t be able to find spare parts in the future.
I personally wouldn’t go near a brain fork, especially second hand. Theory being they are more specific maintenance wise.
It’s hard to say what the best option is. From the posts above mine it seems like you could pick up a SID ultimate or whatever in 120mm for not heinous money. To buy here would be a third the cost of a pretty flash Lux TR or Trek Top Fuel.
If you upgrade your wheels, you can buy a decent spec bike and still use them on the new rig. definitely get inserts Tubolight are light, not that expensive, and effective.
Yes, if you have a Boost frame, you’ll need a boost crank. Shimano cranks are not too expensive, when I checked last night they were about 90 € for a pair of XT cranks. You could go for a fancier upgrade and e. g. get a Rotor Kapic crank (in carbon or aluminum), which is lighter. But then you’d have to replace the chainring and the BB, too.
Others are suggesting upgrading cassettes and other parts. Those are good ideas, and you could do upgrades piecemeal once the old parts wear out. This way you are not left with a bunch of parts that are well-used and hard to sell — unless you want to start having a parts bin. Starting a parts bin might also be a sensible idea.
One thing I caution is to go “too light weight” if that makes any sense. A mountain bike should be robust and dependable.
That’s tricky. It is certainly a risk: brain forks need to be serviced by qualified personnel. And you don’t know what state the fork is in. IMHO when buying used there are two great scenarios: (1) You get a garage queen, i. e. a bike or parts that have seen little to no use. (“I tried mountain biking and it wasn’t for me.”) Option (2) is someone who heavily used his bike, but took meticulous care of it. My used bike fell into the second category.
Lastly, what you want is the analog of a sports car, a Ferrari or a Porsche. Getting a Porsche serviced is not cheap, but that’s part of the ownership experience. I’m sorry if I can’t give you a clear yes/no answer. It is a risk, and the risk could well be worth it.
My worry with an slx7120 (I’m guessing i get the one with a 55mm chainline?) is that the chainrings are specific to slx aren’t they? Online it doesn’t say that XT / XTR chainrings are compatible with SLX - is this correct? So my inclination is to go XT just as it would be easier to get aftermarket chainrings in the future.
Thanks everyone! I think I found my answer - and from all of your advice I feel less bad for having the need/want to upgrade my MTB. It’s a lot more different than my road biking days and component choice make such a big difference to the riding experience.
What I am going to do -
First step - at the end of my season in Novemeber I will need an overhaul - So I will buy all the maintenance kits, seals, oils to do a full services on my dropper and shock. At this time I will get tyre inserts, XT casette, new cranks (165mm slx w/ lightweight chainring) - Get a set of nobblys for my winter wheels and train between the two wheelsets. I am going to replace my buckled back rim with a carbon rim of the same dimensions/height and re-use all the spokes.
Second Step - As my first race starts again in Februrary - I will hopefully have decided by then between 100mm and 120mm sid ultimate. I’d hold off on getting the fork earlier as I train in winter so better I do that on my old forks.
Third Step - Sell up the fork and some other parts laying around and splurge on blinger bits like handlebars and stem.
Fourth and final step - AXS 
because why not with upgrade kits now as low as 350euro
This should get my bike to around 10kg with dropper! Probably from 12kg now.
And if things work out in the future I’ll have a decent parts bin that I can swap the good stuff to the new frame and either re-build the old frame and sell or keep for on-road training!
I’d get weak at that price …
I am contemplating that upgrade, and at that price I’d be all over it. My full sus has an XT shifter and deore derailleur, the shifting seems really stiff compared to my XT/XTR build on my hard tail.
Chainrings - No. The newest m9100 XTR is different, but otherwise the direct mounts are all the same. The m9100 has a single bolt arm, different splines all around. They all get -3mm offset chainrings (resulting in the quoted number) which is basically just the thickness of a ring - it’s not dished. 1x, just get aftermarket rings over Shimano. Same price and you’ll save 70grams. https://r2-bike.com/Chainrings-for-Direct-Mount__32-Teeth__Direct-Mount-Shimano_5_s2
(just writing an overview here incase someone runs into this like I did). The 1x cranks also have a different spline depth (amount of crankarm that covers the splines). The biggest difference is that the M7130, 20, & 10 have different spindle lengths which you need to adjust for with spacers. They all use the same crankarm ‘zig’, so you can make up for the wrong crankarm (for a powermeter) with spacers in many cases.
If you’ve got a common 148 rear, the 7100 is the way to go if you can fit it.
I’ve got a mounted cassette on a freehub here. The last cog on the cassette is 48mm out, the first is 10mm, so
Hub Center Cassette center End cap offset
148/2 = 74 (48-9mm/2) = 19+ 9MM
74-28mm = 46mm theoretical chainline
Shimano lists 12sp Boost as 52mm chainline, so they are favoring the little cogs pretty heavily. The 7100 would be the way to go in most cases. I’m thinking Shimano uses a bit of side load to retain chains and allow frame clearance.
7130 = 56.5mm chainline / 181 q-factor lots of BB Spacers https://dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/ev/EV-FC-M7130-4600.pdf
Note: Same left arm as the 7100 arm with a ; same zig and dimensions otherwise
7120 = Trail crank - 148 rear dropouts - 55m chainline 178 q-factor less BB spacers. Allows for more frame clearance. https://dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/ev/EV-FC-M7120-4559A.pdf
AASQ #142: Why are brands moving Boost frames from 52mm to 55mm chainlines? - Bikerumor
7100 = lighter XC crank 142/148 rear dropouts - 52m chainline 171 q-factor less BB spacers https://dassets.shimano.com/content/dam/global/cg1SHICCycling/final/ev/ev/EV-FC-M7100-4599A.pdf
The MT511 or MT611 (or similar cranks) seem to be OEM cranks based on the prior gen with traditional chainrings and long splines to allow the OEMs to use the same cranks in a narrow chainline or wide one.
Hi all!
So update - I got a little excited and bought most of the discussed upgrade above (will assemble and photograph soon)
Now the forks - I think I settled for 100mm travel!
Ideally I would get a Sid Ultimate SL with lockout but i do again have an opportunity to buy a 2020 Sid WC Brain fork in great condition. I called a local bike store and they did say that they are able to service these (although for a price).
What entices me is that he will sell me the fork plus a hope 2000 lumen light for 500 euro… as it will be a winter soon the light would be super handy and the light alone would be 250… What do you guys think? If I get this the full build will be done! Plus - no lockouts!
I personally wouldn’t recommend a used front brain fork. I have a 2021 SWorks Epic with the new brain and ultimately swapped it to a 120mm Ultimate and the difference is mind boggling, it’s just so much more versatile.