Losing my mind trying to confirm if frame can fit BSSHD and the 42T offset chainring.

bp-santo

1 mW
Joined
Jun 17, 2024
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12
Location
Europe
Heyo!

I've found a shop offering a new-old 2022 NS Bikes "Eccentric Cromo 29" (nsbikes.com/eccentric-cromo,98,pl.html) at a discount and was hoping to fit a Box Three P9 x-wide kit in place of what it comes with and then a BSSHD.

However after searching for dozens of hours at this point I just don't know if the BSSHD itself can fit on many MTB frames including this one without hitting the chainstay, ie. before I even try to put the chainring on!.
This particular bike/frame comes with a 32T chainring and all they mention is `32T recommended`... with no indication as to what is the actual max possible.

Can someone please help me figure out if the BSSHD itself can properly fit on this frame or will the chainstay get in the way of the motor body?
If it does fit, is it at all feasible to try the 42T large offset chainring that is popular out there or is it a waste of time and the amount of spacers necessary to get it to clear the chainstay would result in a bad chainline anyway and should get the non-offset 32T instead?
If I did get the 32T without offset, how many of the largest cogs would I lose in practice to maintain proper chainline?

Are there any similar frames (alltrail/enduro hardtail, ideally chrome-molydnenum steel) or complete bikes to recommend that could fit the BSSHD including that 42T chainring?
I searched a lot but information is often US specific and/or mentions bikes that where picked due to a bargain that can't be replicated here.
I am mostly limited to new bikes or finding a frameset in a shop that I can build on cause slim pickings on our used market for a tall guy.

Only other good offer I found was for an NS Bikes "Snabb 150 plus 2"", but again have no idea if it would be any better re chainring/motor fitment.

Hoping someone with more experience could help me figure out if either of those two bikes/frames would be an acceptable pick!
 
To determine chainstay clearance you’ll need access to the frame. Measure 88mm (42t chainring radius) back from the centre of the bottom bracket, and out from the centreline by whatever the BBSHD chainline is (e.g 55mm). If this point clears the chainstay by at least 3mm the 42t will just be ok.
 
Cheers for the specific measurements and the template link.

I've found a bunch of templates already and was staring at the technical drawings for bafangs and a few other alternatives but unfortunately bike manufacturers seem to not give out drawings of the frames themselves - if only they did would be so much easier. 😓

I've tried contacting the manufacturer of those particular frames to get some info but not having high hopes that they won't just give me an undersized "max" rather than actual practical max (ie. as mentioned 3mm seems livable).
Would go to bike shops and measure but the stock here tends to be meager and usually either tiny cheap bikes and then horribly overpriced ones are the only ones on the floor.


Are there any known great hardtail mtb boost frames that would be good for this, to easily buy in europe? I have no idea about optimal geometry except would usually need a ~21" frame for 29" wheels or the "L/XL" variant for a frame to not feel too small.
Would not mind taking a gamble on the frame geometry and putting everything myself as long as I could get the perfect chainline with it just don't know where to look and for what specifically.
 
As you are in Europe, have you considered a Decathlon Rockrider.? They usually have them on display so you can take some measurements for the motor and see if the bike fits you.
 
As you are in Europe, have you considered a Decathlon Rockrider.? They usually have them on display so you can take some measurements for the motor and see if the bike fits you.
Ye we for sure have Decathlon here - got some good value bits and bobs from there!
Would you reckon there is a chance the rockrider will fit the 42T or maybe it's unlikely for 148 boost reared bikes overall?

edit: I just noticed you have a Rockrider - is yours with the luna/lekkie 42T or that 40T expensive kit from lekkie perchance?
 
I had the same concerns before installing my mid drives. In the end I decided to take leap of faith. I told myself - it will work or not. Worst case scenario I would convert another bike.
...it worked.
 
I have a 1990 Rockrider Fire and I have the standard Bafang chainring.

The new Rockriders are completely different from my old bike.

IMG_0019.jpeg
 
I had the same concerns before installing my mid drives. In the end I decided to take leap of faith. I told myself - it will work or not. Worst case scenario I would convert another bike.
...it worked.
May I ask what frame did it work out with? I don't mind putting in that expensive lekkie 40T kit but since the 42T can be had as a cheap thing from aliexpress my idea was to test it physically first to see if 42T fits and how bad the chainline is and on the basis of that figure out if I should get the Luna 42T or that whole lekkie 40T kit.
 
May I ask what frame did it work out with? I don't mind putting in that expensive lekkie 40T kit but since the 42T can be had as a cheap thing from aliexpress my idea was to test it physically first to see if 42T fits and how bad the chainline is and on the basis of that figure out if I should get the Luna 42T or that whole lekkie 40T kit.

Oh... I was installing TSDZ2B and TSDZ8, don't think frame names will help you... I was like you trying templates etc. In the end I had to improvise - dremel frames and one motor, but I am very happy with end result.
May I ask why BBSHD? It is illegal in Europe, isn't it? My TSDZ8 is set to 16A with 48V and I find it overpowered for my needs.
 
My BBSHD came with a BBS01 250 watt sticker in the box.

IMG_0206.jpeg
 
Oh... I was installing TSDZ2B and TSDZ8, don't think frame names will help you... I was like you trying templates etc. In the end I had to improvise - dremel frames and one motor, but I am very happy with end result.
May I ask why BBSHD? It is illegal in Europe, isn't it? My TSDZ8 is set to 16A with 48V and I find it overpowered for my needs.
On public roads sure but the actual spec is too restrictive for me to bother with DIY and genuinely respect it - it's not just 250W continuous power limit but also 25km/h, PAS only and the torque curve for it should fall off the closer you get to the speed limit.

For the purpose of this exercise I therefore own a very long stretch of hilly private land and want a robust, easy to service motor.

In terms of just peak power I could get the cyc photon but it's way too expensive to buy and service where I am.
I can get the bbshd kit, 52V 20Ah battery, luna style chainring and bottom bracket adapter (with various spare parts available fast and cheap) just for the catalog price of the photon with 34T - before all the import fees and issues with getting spare parts in good time and price.
The TSDZ8 is cheaper and has a torque sensor which seems very cool but the chainline issues seem even harder to fix with it given lack of aftermarket chainrings with good offsets - perhaps something I could get for my next bike once it's more established.
 
Couldn’t u just further pinch the chainstay?

Here’s a lot of frames with the chainstays out of the way:
I am not sure what `pinch the chainstay` means - modifying the frame?
 
I found this on the bikesdirect site and it seems absolutely perfect yet they don't ship internationally.
Any idea if this style of frame is made/sold by anywhere that ships to Europe?

1718832841773.png
 
I am not sure what `pinch the chainstay` means - modifying the frame?
Yea modify the frame. As long as it’s steel it should be no problem. I’ve done it to aluminum frames as well with no problem but not as acceptable. It looks like it’s often done to aluminum frames. I think every metal frame they pinch them, you’d just be doing it further. With aluminum maybe they heat treat afterwards though, don’t know. A local bike shop could possibly do it or do it yourself.
 
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