That frame is the same as a hongfu fm258. There is plenty written on it here and on mtbr.  I have a similar frame (fm058) which is very very similar, just a different top tube seat tube junction and non-boost, but otherwise identical geometry.  It was also sold through pro-mance, and sissypants wrote up a fair bit of details out his - check out his thread on here.  I am still riding mine, and am still super happy with it, have had great success XC racing on it.

Those other frames you mention are not the same frame.

test rode bike today (towing kids in a trailer, a bit over an hour, lots of climbing, road stuff with a little bit of offroad).  shifting was excellent (light enough action, and perfect shifts every time) and there were zero rattles.  wasn't a big deal to put some silicon in there to fill the gaps around the cables due to the overly enlarged entry/exit holes.  very very happy with the outcome.  am still very happy with the 057 bike and hope to get another six years out of it.

i have some experience with this.  not the actual implementation of the internal routing with full length housing, but I have experienced issues with this frame's internal routing, so i have done a bit of research on this topic over the years, but not yet implemented.  my FM-057 (pretty sure it is the same frame still) has just turned 6.  it lasted a couple of years with internal cable routing for the rear shifting, but it deteriorated over time, such that i ended up externally routing it.  i did consider the idea you are thinking (trying to get the housing through the frame), but, at the time, i couldn't see how it could be done, and i did read at least one or two stories of people who did it (buried somewhere in the monster thread on mtbr), and i got scared off - they didnt really detail how they did it, what their issues were, but they advised against it.  so i have been running external routing for at least 3 or 4 years now. 

only a couple of months ago, i have become interested in this topic again, as a pretty bad rattle has suddenly developed, and i have traced it to the empty internal routing for the rear shifting, seems to be around the area near where it attaches internally around the head tube area  (i.e. the front cable stop).  i'd love to remove that internal routing tube to get rid of the rattle.  problem with this frame is the access - with the BSA BB shell, there is no access around the BB area, the only access is in through the head tube, and while i have considered drilling out the cable stops at each end (near the head tube, and the one on the chainstay), i cannot get a good enough view (in through the headtube with the fork off) to know for sure if the internal routing tube is attached/glue/fastened somehow around the BB area, so it would be a risk to drill out the cable stops, as, if the internal routing tube IS attached around the BB area, and i drilled out the cable stops, i would end up not being able to pull out the internal routing tube, so it would end up loose in the downtube, probably rattling even more.  so i gave up on the idea again.

but the rattling over the last month is starting to get to me.

your thread has prompted me to have another look at this.

there doesnt seem to be any thorough explanation anywhere online on how to perform this task on this frame.

but, this time around, i found this old thread (surprised i didn't see it before):
https://forums.mtbr.com/29er-bikes/chinese-fm056-frame-internal-cable-routing-flexes-stretches-792079.html

the fm-056 is the same frame as mine (and probably yours), except it has different rear dropout (i think it might be 135mm only).

it sounds the OP on that thread got some good vision of the going ons inside the frame, using an endoscope, but sadly his vids and pics dont seem to be on youtube anymore.  however, i did get a few key takeouts:
- the internal routing tube is NOT attached to the frame in the BB area, so the only attachment points are at the two cable stops (i.e. at the entry/exit points, one at the front, and one on the chainstay),
- so drilling out the cable stops at each end will be enough to detach the internal routing tube from the frame.
After drilling out each end, the internal routing tube would have to be pulled out of the frame, and the only route to do this is out through the headtube.  I am not sure what tool to use to get in through the headtube and grab hold of the internal routing tube, to pull it out.  gonna have to think this through before drilling out.  if i cant find some kind of super long nosed (and curved) pliers, i have an idea that might work: partially thread a gear cable through the tube (from the rear), do some fairly precise drilling/cutting (either with a very small drill, or some kind of dremel attachment) around the inside sides of the rear cable stop (to detach the internal tube from the frame), then drill out the front cable stop (detaching it internally), then push the gear cable the rest of the way, the objective being to get the end of gear cable to poke out through the top of the head tube.  then pulling the gear cable out through the headtube would take all of the internal routing tube out with it (the head of the cable will pull on the detached-from-frame rear cable stop). 

the next step would be to route the housing through the frame.  this would obviously go through from the rear (as i have doubts that just pushing the cable from the front would just magically go out through the rear exit), and there would be a risk that simply pushing it through might not work, as it has to get around the bend in the BB area, and i cannot see if there are any angles in the carbon on the interior of the frame around the BB area, that a cable being pushed through would get stopped by.  internal snags when pushing through housing are often gotten around by putting bends/kinks into the end of the housing before pushing it through, and failing that, pushing through a more easily bent cable (inner) might work, using gravity to help (i.e. have the frame upside down when trying to push the cable through the bend in BB area), then using the inner as a guide to thread an outer over it.  there would still be a risk it wouldn't work.  having said all this, perhaps this routing-of-housing step could be better done if it was combined with the previous step : attach the housing to the end of inner cable that is used to pull the internal routing tube out of the frame - not sure how to get it firmly attached though (i have tried this before using insulation tape, and it almost always does not hold).

the last step would be to get the housing out through the front exit.  this would be quite hard to get it to line up perfectly and go out through that exit (as that hole is the same size as the housing), but i got some idea from one of those threads : have the end of the cable housing behind the front exit (down towards the bottle cage slightly), then push a cable inner through the housing from the rear and then get the inner to go out the end of the housing (inside the frame), the out through the exit (would be much easier to inner cable to do this than housing, as it bends easier so can be directed easier (either with gravity and/or by sticking a wire down through the headtube to try directing/manipulating it), and is thinner so will go out the exit easier), then thread another piece of (short) housing onto the cable inner that is poking out through front exit, then push that housing in through the front exit (so some of the housing is in the frame, some is still outside) then push the "main" piece of housing from the rear until it butts up against the short bit of housing (so the short bit of housing becomes a guide for the main housing), then push it some more (again, from the rear of the bike), and it will come out through the front entry/exit hole.

before the last step (i.e. before the housing is pushed out through the front entry/exit hole), it would probably be a good idea to feed some capgo noise protection onto the length of housing that will reside in the downtube.  this optional step would be pretty easy (push the housing out through the headtube, then thread the noise protection tubing over it), and would virtually eliminate any risk of cable rattle.

as the rattle in my frame is bad as it is, i now feel that i have nothing to lose, so i am gonna try doing the above.  as i have had some pretty tricky internal cable routing jobs over the years now, i am quite aware how difficult, time consuming and, above all, frustrating, some of the above steps are.  am i also aware that there is a risk that i might not successfully complete the above described steps.  eg1. i fail to pull the internal routing tubing out of the frame (but i doubt the rattle caused by loose internal routing tube would be much worse than i have now). eg2. i fail to get the housing past the BB area (in which case, i'll just continue to externally route).

anyway, hopefully you get a few ideas of how you might go about doing this task.  i'll let you know how i go, but it'll probably be a month or so until i attempt it.

the reason this process is so difficult is because there is no access around the BB area.  Just in case they have changed things over the years, and your frame is different to mine, the first thing you should do is remove the BB and see if there is any access (holes) inside the BB shell.  If so, this process might be much easier (the less risky) on your frame than it is on mine.

you probably need to narrow down the geometry that you are after, mainly head angle and seat angle.  there's a fair range of geo across the options you have there.  also is your main priority xc/endurance racing speed, above all else?  from the description of your terrain (i dont know the area though), it sounds like 100mm travel would be enough.  you also need to work out your preferences and must-haves.  e.g. is bb92 ok?  need boost spacing? dropper post compatibility required?

i'm not sure if 67/77 angles on a short(ish) travel bike like that Carbonda FM936 would work that great for xc racing.  who knows though, it might be way of the future.  in the meantime, i find myself putting a setback seatpost on my 69/74 angle FS XC race bike, as the seat tube seems a bit steep compared to what i am used to (having said that, my recently acquired trailbike has a steeper seat-tube, but it is longer travel, and at sag everything gets a bit slacker).  maybe this upcoming race season, i'll look into moving the saddle forward a bit (maybe even save a bit of weight and use my zero offset seatpost).

you should also have a look at the scott spark rc copies.  e.g. hongfu fm258, pro-mance (not sure of the model, if it is the 9007 or 7007?), and some other resellers i cant recall the name of.  i have one of these (the earlier non-boost fm058 from hongfu) and i find it close to perfect for the racing i do on it - since i have been racing on it (since mid-2018), my results have improved significantly (some of that had to do with diet and fitness though).  i am not sure if a 120mm fork is what the frame is aimed at (it is designed for 100mm fork), but i don't think the geo would be screwed up by an extra 20mm at the front - in fact, it would put it in the same ballpark as the frame you mentioned that you quite liked - probably around 68.5/73.5.

if i could do it again, i wouldve got the boost version of my frame, and would run a 34t chainring.  i had some chainring clearance issues with a non-boost chainline, exacerbated by running an oval chainring - had issues even fitting a 32t.  the anti squat on this frame is such that it pedals unbelievably well, and i run it with compression full open, no need for rear lockout, even stomping up hills - my climbing speed last year was such that i have been relegated to the top grade this year.  check out the climbing speed on kerschbaumer at last year's world cups when he was riding one of these frames (his is branded torpado, but it is the same frame as the 258).  having said all this, i think the frame is designed around a 34t chainring - i am finding the anti squat is a bit too much with a 32t, such that the suspension is too firm under power and not as active as i am used to (i have had a lot of horst link bikes over the years).  i am really splitting hairs here though - i have no intentions to change anything on my bike.

a couple more rides on the FM08, exact same trails (both times) as previous ride.

1st ride was with the same setup as previously (2 rear travel reduction spacers), but i increased the rear shock air pressure, to 140psi at the start of the ride.  without any major drops etc, it was getting about 49-50mm of stroke (of 53.5), so i increased it again to 150, and still seemed to get around 48-49mm.  despite a bit of techy climbing, lots of prime candidate rocks to hit pedals etc i simply was not getting any pedal strikes.  towards the end i was literally trying to hit pedals (pedaling around corners with rocks on the inside) and finally got a couple scrapes.  note that i use 170mm cranks on all my bikes, so this probably helps.  as the steering was still fine for the twisty stuff (i.e. not too slack), this was the final confirmation to make the decision to drop the rear end further, by adding another 1.25mm stroke reduction spacer (which also reduces the shock length).

after the 1st ride, i remeasured the BBH.  making sure the fork was fully extended (140mm), it was actually a bit higher than i previously measured, at around 341-342mm.  i then added the extra travel reduction spacer - now 3 spacers, which is 3x1.25=3.75mm, so the stroke is now 52.25 (56-3.75).  Based on the leverage curves (a bit over 3:1 near top out), i reckon the spacers reduce travel (and the rear end) by nearly 4mm for each spacer.  with 3 spacers, it would have around 138mm rear travel - if the leverage curves etc from the manufacturer are to be believed.  After putting in the extra spacer, BBH was again measured, now at 337-338mm.

further tweaks done to the bike at that time:
- went full tubeless.  i.e. converted the front tyre.  i dont think i've ever had a tyre seal so easily.  bike dropped a little weight, but less reduction than expected (i didn't realise i had a lightweight tube in it).  bike is now 13.16kg, which is pretty much right on 29 pounds.  that's the "final" weight, i reckon.
- found a lower stack height top headset cap and put that on.  maybe dropped the bars about 5mm.

the 2nd ride started with the rear shock at 150psi.  continuing with a similar less-disciplined approach to pedal timing as i have on previous rides, pedaling through the first few corners there was a noticeable increase in pedal scrapes.  so i tidied up my pedaling a bit, and it was far from a problem.  with bike slackened a bit further, i definitely felt more over the back wheel, and the bike was using a lot of travel (around 49mm of the 52mm).  halfway through the ride, i upped the rear shock to 160 (back to where i was months ago), and it was using only 44-45mm.  i reckon i will end up around 155psi.

confidence in front tyre has been increasing with each ride.  with it now tubeless, i have reduced to 20psi.  i seem to be much more comfortable putting it into some more extreme leans, such that i am starting to find the limits of the rear tyre's grip, with it letting go a few times, but not anything i couldnt catch.  maybe i'll have to move up from an XC tyre for the rear, or i could end up paying the price....

did a few pbs on some strava segments, including some fast downhill flowy/jumpy/bermy stuff, and some flatter twisty stuff.  i have ridden this trail quite a lot, so some of it was surprising, especially the flatter stuff, given i have done some fast runs on my XC bike through there.

i think i have settled on the final geometry, especially the rear travel / ride height.  for the first time, i did notice the steering a tiny bit "floppy" through some very slow speed series of corners through trees, so i think i've found the slackest i want to go with the steering (probably a touch over 66 degrees HA, with a 51mm offset fork).   i might need to drop the bars more (would need another stem,if i do), will see how it feels after the XC season starts and i start getting used to my XC bike again.  getting close to finalising spring rates on the the fork (75psi, uses about 120mm with no big drops) and rear shock (will try 155psi next time).  next step will be to confirm sag levels are good (and, if not, reduce air spring volume/s, and then re-do pressures again), and then do some experiments with different rebound settings. 

bike is turning out to be perfect for that trail.  i certainly appreciate how active the suspension is under power, as there a quite a few rock steppy stuff on the climbs on that trail.  a few more runs on it to confirm the bike is dialed there, then i think i need to try it out somewhere else.

Nice looking frame.  That supplier (winow sports) is not one i was aware of until now.  I googled their site.  Do you have a link to your frame - i couldnt find it on their site.  I am interested in the geo etc.

That frame sure is light for a 150/160mm build.

i am also intrigued by some of the components you put on there.  i've never noticed that crank before - i looked it up, and the one site i saw (a malaysian vendor) suggested the chainline is 48.5mm.  i'm had a look at those superstar chainrings.  am i correct to assume that you went with a BOOST version of their direct mount chainring?

Not sure if I'd jump to the conclusion that these BSA BB shells in Chinese frames are problematic enough to steer clear of them.  Not sure how liberally you guys grease the threads and faces of the BB shell, and what kind of resultant torque is required for you to install and remove the BB, but the BB setup on my '057 has been nothing but faultless, totally quiet, easy to maintain.  Coming up to 6 years soon, probably close to 2000 rides now - bought it off Peter when he was at xmiplay.  If I needed another hard tail frame (which I guess would only be required if this one got stolen), I'd get this exact one one, with BSA BB.  Heard too many issues with noisy BBs on the press fit version - then again, that's probably just due to bad maintenance, which will cause issues with any setup.

The new bike still hasn't yet quite reached its 'final' state, so the upgrade-testride cycle continues.

The latest test ride went close to expectations.  Not a great ride, as the trails were still wet from rain from the days before, and not familiar with the new tyre etc.

Firstly, the longer fork and taller front tyre definitely made the bike feel noticeably taller.  I was surprised at the difference.  I think it was barely 6mm higher at the bottom bracket - though I did re-measure it, and it was closer to 445 than the earlier measurement of 443.  I didn't hit my cranks once, riding the same trails as the previous ride, including a lot techy climbing.  And I was noticeably worse at cornering too.  Perhaps the wet roots and rocks contributed though.  Not sure.  But this has confirmed my approach with this bike, to lower it below the frame's standard specced geo, with a 10mm shorter-than-spec fork and lowered rear end via a shortened shock.  I still plan to start with 2.5mm off the shock's stroke/length, which translates to a ~8mm lowered rear end (to about 142mm travel), but I could end up droping it further again.  My only reservation about going further is that the angles might be getting a bit slack - I don't think my trails or riding style would benefit from a HA much lower than 66.5.  I'm glad I went for a 140mm air shaft for my fork too, as a 150mm fork would've made the bike too tall (or too slack, if I dropped the rear end to bring it back down).

For the first time, I noticed the feeling of being a little further back, which will get worse when I lower the rear end.  However this was only on a super steep climb (Probably 15%grade), so I don't think it will be a problem.

I thought I put 75psi in the fork, but I think I was mistaken.  I might've put the recommended 85psi in, just in case it bottomed with the no volume tokens in it.  Got over halfway through the ride and noticed the fork barely used 110mm of the 140mm.  I dropped  it to 75psi for the rest of the ride, but didn't hit anything big, so it barely used any more travel. I'll leave it as is, and see how it goes on some bigger stuff.

With the rear shock on full volume, I went for low sag initially, and pre-ride settled on 160psi to get just under 25% sag.  Mid way through the ride, it had used only 44mm stroke (of 56mm, so about 80%), so I dropped it to 155psi.  Was still around 44mm at the end of the ride.  I'll drop it to 150psi after I shorten the shock.  As expected, the McLeod shock was awesome at erasing bumps, while at the same time not ever feeling wallowy.  I thought the not-high main pivot on this frame could result in a bit of Bob, but it is near non-existent.

With the wet trails, i was a bit hesitant to really put the new DHF tyre into any big leans, but in hindsight it barely slipped at all.  Perhaps the next (hopefully drier) ride will be better, and I have more trust in it.

The latest round of upgrades added more weight (mainly the tyre).  Bike is now 13.44kg, which is probably as heavy as it will ever get. It will lose a little weight when I go tubeless, and a slightly lighter stem.