BXT-MTB-117 150mm AM bike

[scourge]

I am considering the frame to replace my AM831. My 831 creaks terribly and I can't figure out where it is coming from. It's super annoying. I messed with the headset and replaced the bottom bracket and that didn't fix it. I thought the bottom bracket fixed it at first, but it came back as annoying as ever. I bought the bearing upgrade created on here and there is a little less flex, but there is still some and the loud creaking. I can't pinpoint where it is coming from and I don't want to keep throwing money at it replacing things.

This frame looks great but I am nervous about getting burned again. Don't know if I should give this one a try or stick to alloy frames. Keep us updated on how you like it, please. Did they offer any other colors besides the one on AliExpress?

[grinchy]

Thanks for all the info and build documentation! I'm in the market for something in the 130-150mm travel range and might go with this frame.
Grinchy, your BXT experience wasn't bad? I think that's my biggest concern right now.

I bought from the official BXT store on Aliexpress. Make sure you have the correct model, they are still advertising the v2 that doesn't have thru pivots.

My experience was completely fine. BXT verified the color, logo/no logo, and size. I asked some Q on the weight and verified it was thru bolt version, which they answered. They suggested I tack on $45 for Fedex shipping. This I did, but it was optional. The Q/A phase took a couple days, they were responsive, but there is a time zone difference and I have a job, so often I could only respond once a day, then they'd respond. Nothing unusual about that.

The order was sent to paint, and about 10 days later shipped out. Then about five days get to my location. In total it was about four weeks from order to receipt.

I have one question open with them regarding the upper link upper washer orientation, they haven't ghosted me, but it seems to be going in circles re: getting the info back, but I've already decided which way the washers should go, so it is only for verification at this point.

I've had the bike out once so far, with another, bigger ride this weekend. It's dead silent and absolutely a pleasure to ride. You should get one.

[grinchy]

I am considering the frame to replace my AM831. My 831 creaks terribly and I can't figure out where it is coming from. It's super annoying. I messed with the headset and replaced the bottom bracket and that didn't fix it. I thought the bottom bracket fixed it at first, but it came back as annoying as ever. I bought the bearing upgrade created on here and there is a little less flex, but there is still some and the loud creaking. I can't pinpoint where it is coming from and I don't want to keep throwing money at it replacing things.

This frame looks great but I am nervous about getting burned again. Don't know if I should give this one a try or stick to alloy frames. Keep us updated on how you like it, please. Did they offer any other colors besides the one on AliExpress?

All good so far. Biggest issue is people on MTBR giving me grief for using SC decals. As far as my frame goes, it's beautiful. I highly recommend the white.

[grinchy]

On frame flex, this version appears to have none. It is rock solld. And silky smooth. I have been afraid to torque to the 20Nm. I chickened out before my wrench clicked. I may try again after my next ride, at least to 15nm.

There are only a couple of minor quibbles.
The upper link is solid aluminum. Drillium could fix this.
The bearing races ride against washers. This is normal, but it's a little bit of a pain to sandwich the washers in between the link and frame and then put the bolt thru. Grease is your friend for this.

[scourge]

Thanks for posting your experience with this frame here and on the mtbr thread. I am really considering this frame or a Status frame. Your impressions of the bike really help.

[scourge]

How tall are you on that large, Grinchy?

[grinchy]

5'11". The way I have it set up with 15mm rise bars and a 35mm stem it's 32" to the handlebar grip center from BB center. I use RAD to do the initial fit on my bikes, though for this one I sought a longer reach and a shorter stack to get to my fit. I have a Hardtail that is a shorter reach and higher stack for the same 32", as it's future is headed for a DJ, party bike kind of ride.

SC posts a chart on their site for the HT2, identical geometry so I suggest starting there, FWIW 5'11" is smack dab in the range on the L size (473 reach).

[grinchy]

I mounted a coil in this frame. As it's a Hightower v2 clone that was always going to be a challenge, but I thought I'd try.

My shock tunnel pass thru was around 50.5mm wide. Most 'modern' 1 3/8" springs run 52mm+ in outside diameter. So the first thing is that you won't be putting a Fox SLS, Cane creek VALT, or any other modern spring thru it. Just accept that. I looked high and low for springs that would fit, and even ordered a cane creek DB IL Coil (with 500 lb linear Valt spring). The spring is 53mm wide . . .

Luckily I'm old. Usually that's a disadvantage, but i happened to own a Specialized full suspension bike in 1997. And I swapped the spring to a lighter tension. That bike was stolen in 2002, but I somehow still had the old spring in a bag. Back in the day, springs were built on 1 1/4" inner diameter. This 400x2.0 spring measures around 48mm OD. I would've had a dance party but it'd hurt my back. It isn't the 'target' spring constant (calculators put my weight and the HT2 leverage curve for that weight at 30% sag between 500 and 525 lb/in, depending on the assumptions).

So I was excited to try it out, but not to hopeful I'd get sag on this spring. 400 to 500 is a big difference!

I tossed that spring on the shock (adapters will need to be made eventually for the shock collars, but it works ok to test), and after pull the upper link lower bolt, finagled it in there.

I"m still not sure on sag this frame is devil hard to measure coil sag on as one person, but I think it's around 15mm (33%). Which isn't ideal (I'd like 25%), but it's workable. And this is no preload, so I could dial it back a bit. I'm not sure why calculated spring vs actual spring is so different, but this isn't really a Hightower 2, so maybe the leverage ratios are different.

Some issues:
It's pretty hard to source these old springs. There are some on ebay, they aren't particularly cheap because they come with an old shock, and they're all too stiff at the moment. There's a 550lb for $130. Which is a bit steep.
the 2.0 shock is probably a bit short. at 2.25 would be ideal, a 2.5 would be better than a 2.0. The shock may bind before reaching full travel. It hasn't yet, but I haven't been out really riding yet. I go tomorrow.
It's red. I'd much much prefer an old Fox shock, they're black.

[veeTee1Pah]

Edit: Added answers to my own questions after messaging BXT Official Store on aliexpress.

Hanger: Where can you order or find a replacement derailleur hanger for this frame? Should I assume it's not a UDH but a proprietary hanger?
Answer: BXT sent me this link to buy an extra hanger: https://www.aliexpress.us/item/2251832586891043.html  They do no list a boost 148mm option. Order the "axle thru 142 12mm" option even for boost 148 spacing. It's actually not just a derailleur hanger but a bolt on drop out that includes a hanger.

Shock hardware: I've never installed new shock hardware, and I could use a little guidance. If the bushings are 24mm, what size mounting hardware do I order? I see m8x23.88 or m8x24.89 listed here: https://thelostco.com/blogs/blog/mtb-rear-shock-mounting-hardware-explained?variant=32303772237905  (I'm assuming the bolt size is m8. Correct me if I'm wrong)
Edit: I found mounting hardware on aliexpress that is nominally m8x24mm. Seems like that's worth a try.

Headset: Does the frame ship with the headset? I assume it's integrated, so do the headset bearings come with the frame?
Answer: The headset doesn't seem to come with the frame.
Edit: I noticed that the headset BXT recommends comes with an expander nut rather than a star nut. I think expander nuts are more commonly used in carbon steerer tubes which suspension forks don't have. You may want to go with a different headset or buy a separate star nut and top cap / bolt.
BXT says you can order the headset here: https://www.aliexpress.us/item/2251832509492748.html
Order HS-001 for a tapered steerer tube fork. (HS-003 for straight fork, but I'm not sure who is using a non-tapered fork)

More information sent by BXT:
The order comes with: frame, rear thru axle, seat clamp, and derailleur hanger

Edit: The BXT rep was wrong on more than one occasion including the shock dims they quoted. Treat their advice as suspect.

[veeTee1Pah]

This frame is on CyberMonday sale through today. Aliexpress seems to be offering $80 off $450 (code: BFUS80) plus $4 of every $20 up to $16. I guess that means you could get $96 off the current sale price, and I think that would apply to any frame you order from Aliexpress.

[veeTee1Pah]

Edit: I tried a super deluxe select + on a medium frame, and it seems to fit fine. The BTX rep quoted me the wrong size shock, and tried to sell me a inferior shock. Treat their advice with some scepticism. The reps don't have much expertise and are selling lots of different models of bike frames.

[daifanshi]

Can anyone confirm that a piggyback air shock like the Super Deluxe will fit in this frame?

In my correspondence with BXT, the rep claims that piggyback air shock won't fit in this frame. It looks like the piggyback might fit similar to the hightower as long as the air can fits in the ~50mm width of the shock tunnel. I've attached the images the BXT rep sent me.

The rep said:
The dimensions of the shock seem wrong, and maybe the rep is just trying to sell me the deluxe inline shock they carry.

My son has this frame and I do not know if a piggyback shock will fit since he does not use a piggyback shock.  And Fox type air shock with a piggyback will probably fit, but a coil may not.  YMMV. The shock is definitely a 210x55 standard eyelet and the bushings are 24mm as I stated in reply #21 of this thread.  Do a little research on how shocks are mounted so you know what kind of hardware is needed for the shock.  There is nothing propietary about the mounting on this frame.

You will need to buy a headset with cups.  Nothing is "integrated".

For extra dropouts use the "142" 12mm  thru axle variety.   BXT has standardized this type of dropout on other frames including those with non-boost 12mm thru axle spacing, but they never bothered to update the listing.

[veeTee1Pah]

Thank you for the clarification, daifanshi. If I understand correctly, the frame has boost 148 spacing, but you order the dropout & hanger kit that's labeled as "142" from the link they sent. I also ordered the headset from another link they sent which is an "IS" type as expected. (My previous post has the links.)

The BXT rep did figure out the weird shock dims they quoted were wrong after I pointed it out, but they did try to sell me a 210x50 shock. I'll find and install my own 210x55mm shock.  The BXT reps are probably selling lots of frames, and they might get things wrong.

It's not clear if a piggyback air shock like the super deluxe will fit in this frame. I looked through the AM831 thread since the frame is similar. At least one person seemed to have success with a super deluxe on the AM831, but the frame clearance might be different. It may even be frame size dependent. It's clear that the shock tunnel is even narrower than a hightower and a modern coil won't work, but the limiting factor for a piggyback air shock is probably the clearance to the upper linkage as the suspension cycles.

[naeTech]

Do you use frame without bearing spacers or you modified links before hard using?

[naeTech]

Make a linkage model for S size frame. Indeed frame latched after 52mm of stroke (!) (with 210x55 shock)
I recommend using 210x50 shock.
Antisquat insesitive to cassette chainring. Sensitive to drive chainring - more tooth - less antisquat (at the same sag).