70sSanO

Unfortunately the 13t 1st position cog has gone by the wayside. I found a 12-28 Miche 9 speed cassette (Shimano compatible) on eBay. Only 12-28 I could find.

I actually bought a 13t cog a couple weeks ago. If years ago someone would have said I would be doing that, I would have laughed at them.

John

David.P

Hello all,

I bought a fairly new fixie with a track frame with 120 mm OLD, which I want to convert to a 1x drive with rear derailleur.

I believe that I have read through all threads on this conversion issue available anywhere. Yesterday night however, I happened to come across this Bitex RAR8 cassette hub with OLD 120mm, which to my knowledge has not been mentioned anywhere before:

imgur.com/2Gfuj0P.png
imgur.com/RZvflUw.png

So this is a 120mm OLD hub that seems to be available with all current main drivers (except Microspline).

As I understand it, this means that with this hub you can run cassettes with up to eleven sprockets virtually in any OLD-120 frame.

Apart from the possibly problematic dishing, is that not sensational news?

Aardwolf

I've recently done something similar on an 82 Holdsworth Avanti (126 old, 6 speed freewheel) without resetting the spacing.

I bought some Mavic MA2 rims and they came with Shimano RX100 hubs, rear was FH-A551 which is the 8 speed version.
I managed to respace the rear hub and redish the wheel so OLD was 127mm with 5.5mm clearance between the small cog and the dropout.
I did have to get a SunTour Cyclone Mk2 GT to handle the 8 gears but it works fine with an SRAM PG-850 (11-32).

I believe if you can get an 8 speed freehub on there then you can fit 8/9/10 in the same space just by changing the cassette.

David.P

Here are two pictures.

First, a comparison of the Bitex RAR8 120mm cassette hub to a normal 10/11-speed cassette hub with 130mm OLD:
imgur.com/brPbxYR.png

Second, a photo montage with the Bitex RAR8 hub installed in a 120mm OLD track frame, including comparison with 130mm cassette hub:
imgur.com/8F1qnNP.jpg

The right hand side hub flange is basically in-line with the right hand side of the tire.

Do you gents think this is feasible -- or will the rear wheel collapse immediately on me because of the extreme asymmetry & dishing?

David.P

Thanks Aardwolf, however I believe that I can't do that since my bike has a 120mm rear OLD aluminum track frame that can't take anything else than 120mm rear hubs.

Here is the hub photo-montaged into the frame again, this time including rims and spokes:

imgur.com/8F1qnNP.jpg

hokiefyd 

I think that'll be the primary potential downside. What is the narrowest 8-speed hub traditionally available? I think 7-speed is as narrow as 126mm OLD and 8-speed is as narrow as 130mm OLD? I'm sure someone will check me on that. So this hub is taking another 10mm off compared to that, so you'd have to dish the rim towards the drive side by another 5mm compared with 130mm 8-speed, if I'm thinking about that geometry correctly.

I guess the main drawback to that is a wheel that's not as laterally stable or as strong as something with more symmetrical dish. Depending on how and where you ride, that may not be a concern.

David.P

Thanks! Actually the bike will be mostly used as a cafe racer in a flat area.

Maybe someone looking at this thread could be so kind as to upload the two images, so that they can be seen more easily by others. I am not allowed to upload pictures yet as a newbie in the forum.

Bitex RAR8 120mm cassette hub compared to normal 130mm OLD 10/11-speed cassette hub:
imgur.com/brPbxYR.png

Photo montage of the installation of the Bitex hub in a rear wheel:
imgur.com/Rpp1eCd.jpg

hokiefyd 

hokiefyd 

hokiefyd 

Pic assist. I'll defer to others who've built way more wheels than I have to offer their experience on something like this.

David.P

Thank you hokiefyd!

The second image in higher resolution can be accessed/viewed here:
imgur.com/8F1qnNP.jpg

Mackers

Best case scenario you'd end up with 39% NDS spoke tension.
That's less than 47kgf at 120kgf DS.

Personally I draw the line at 60kgf.

David.P

Thanks! I didn't know that you can actually calculate this from the dimensions of the hub and rim.

Someone writes here
bit.ly/3wOZ8nk
I shall do further research on this. Of course, I'd be grateful for any further opinions, especially experiences with rather high dishing.

Aardwolf

My 8 speed MA2 126 old has 90/39 kgf which is 43% NDS tension.
I measured the hub dimensions and did a spreadsheet to calculate the tensions, OLD, and small cog clearance with different spacers.

ofajen

I have a bias towards fewer gears, having spent most of the last two years riding only single speed. I recently put a Suntour narrow 6 FW back on my road frame but I don’t think I have used other than the 14,16 and 18 in back.

So, if I were thinking freehub rather than freewheel, I’d be more interested in this short freehub from SunXCD and maybe put 5 cogs on it.

Hubs ? SunXCD - Bicycle Components

That wouldn’t require much dishing of the wheel. I have my Schwinn spaced to 126 and running a narrow 6, I can just about run an undished wheel.

Otto

David.P

Yes, I've seen the SunXCD hubs, similar also these ones:
janheine.wordpress.com/2013/09/21/grand-bois-5-speed-cassette-hubs/?iframe=true&theme_preview=true

I think the problem is that there are hardly any 5/6spd cassettes anymore, and probably close to none with a higher gear ratio

Further, I have made an update to the photo montage by mounting the actual rims to be used, the H+Son SL42:
imgur.com/bAbvQtM.jpg

These rims should also relieve the situation somewhat, since they are very stiff, and the spokes are somewhat shorter.

hokiefyd 

How would a 5-speed cassette body work? Just install 5 of your favorite sprockets of whatever cog count you like and make your own cluster? I guess one might could even do 6 or 7 on it if one wanted to use 9- or 10-speed sprockets and spacing (and either friction or appropriate indexed shifters).

David.P

Yes, I believe it is possible to mount 5, 6 or 7 Shimano Hyperglide sprockets on both the SunXCD and Grand Bois 120mm hubs:
imgur.com/VgXln3o.jpg

Here is a very informative video about how to put a custom 7-spd cassette together for one of these hubs, using a standard 10-spd cassette:
youtube.com/watch?v=g59R7N-mvAk

Maybe I should better set up my track frame rear wheel this way?

David.P

Also, I'd love to hear any speculation as to which of the three 120mm cassette hubs SunXCD, Grand Bois or Bitex might have the least noisy freewheel:

i.imgur.com/REjKnFe.jpg

ofajen

Yeah, I’d likely just take four or five cogs out of a 7 speed cassette along with the spacers and then add extra spacers on either side as needed to line the chain line up pretty straight on the single speed combo, which would be something like 42/16.

Otto

David.P

O.k., have now decided to go for the Bitex hub with Shimano Hyperglide driver (for up to 11 sprockets).

Bitex hubs seem to be very high quality:
RyanBuildsWheels: Bitex Hubs, Our In House Hub Of Choice
JustRidingAlong: JRA hubs by Bitex



Also, this hub is still being manufactured, and upgrade/replacement parts are available, yummy ones btw:


Probably I will lace the hub radially on the right side (spoke heads facing inward) and triple crossed on the left side, which also eases the dishing situation a little more:


(full image)

t2p

not 9-speed - but 8-speed

back in the mid-90's spread the rear triangle on this lugged steel Schwinn Peloton and transplanted Ultegra 600 Dual Control / STI 8 speed components and wheel set from a Cannondale R800 ( w / 2.8 frame )

friend that was a frame builder spread the triangle / installed the fork (Kinesis alloy) and did most of the mechanical work

( note: the tires are flat - this is the first time this bike has been out of the basement in 20+ years )
.

ajh.me

I once laced up my 1st gen Dura Ace rear hub with a radial drive side/3x non drive pattern as a fixed gear (don't need no stinking lockring...) and a thousand miles later realized I'd broken the hub body by transmitting the torque across. Though the radial/3x is a cool pattern, it's just silly. My more modern Dura Ace 10sp freehub laced that way was the inspiration, but it was designed to take the stress.

These days, with weekend rides of 190 miles/16K feet in the backcountry, I don't deal with anything except 3x. The gains from shorter spokes are third or fourth order improvements, more for style (IMHO) than effectiveness. Take a careful read of Jobst Brandt's "The Bicycle Wheel".

David.P

Been there, done that. Doesn't work with these hubs because a) they have a slim waist, and b) their spindle is made from two parts that are simply pressed together. They basically don't handle any torque between the left and right spoke flanges.



Yeah, I'm doing it for style reasons, as well as to alleviate the extreme dish-situation with a 11spd cassette hub in a 120mm frame

Lempira

Have you really done it with the Bitex RAR8 Hub? Please share your experiences! 😀