Author Topic: Thorn Nomad MK2 bottom backet  (Read 1937 times)

jul

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Thorn Nomad MK2 bottom backet
« on: August 21, 2023, 11:43:23 pm »
SjS told me that the bottom bracket from my Nomad Mk2, this one "Shimano UN55 73X110" seems to me, is no longer marketed.

It was replaced by this one : "Shimano UN300 73X113"

https://www.sjscycles.co.uk/bottom-brackets/113-shimano-bbun300-73mm-shell-square-taper-bottom-bracket-english-thread/?geoc=FR

Is there an incident according to you with this one, 3mm longer

mickeg

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Re: Thorn Nomad MK2 bottom backet
« Reply #1 on: August 22, 2023, 01:53:57 am »
SjS told me that the bottom bracket from my Nomad Mk2, this one "Shimano UN55 73X110" seems to me, is no longer marketed.

It was replaced by this one : "Shimano UN300 73X113"

https://www.sjscycles.co.uk/bottom-brackets/113-shimano-bbun300-73mm-shell-square-taper-bottom-bracket-english-thread/?geoc=FR

Is there an incident according to you with this one, 3mm longer

If your chainline was spot on, that would mean you have a chain line error of 1.5mm, which is very minimal.  I have about a 5mm chainline error on my Nomad Mk II.

If your bike originally had a thread on sprocket and now has a splined one, that could also change the chainline and it is possible that the longer bottom bracket spindle makes things better instead of worse.

In other words, it is complicated.  But the numbers are small, so don't worry about it, it will be ok.

UKTony

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Re: Thorn Nomad MK2 bottom backet
« Reply #2 on: August 22, 2023, 06:26:55 am »
This one would appear to be a closer match. Strange that SJSC didnt suggest it.

https://www.sjscycles.co.uk/bottom-brackets/tange-seiki-ln3922-73-mm-jis-english-square-taper-bottom-bracket-1105-mm/

JohnR

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Re: Thorn Nomad MK2 bottom backet
« Reply #3 on: August 22, 2023, 03:46:20 pm »
Going in the slightly narrow direction, I have two brand-new-in-box 107 x 73 UN55 bottom brackets which I bought for my Mercury when stocks were running out and there were concerns that the alternatives might not be so durable. The Mercury has since been rehomed so these parts also need rehoming.

jul

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Re: Thorn Nomad MK2 bottom backet
« Reply #4 on: August 22, 2023, 03:49:34 pm »
Yes i bought a Rohloff splined carrier "S", but before to install it, i have to use one or two more thread sprockets.

So if i understand, with my actuel thread sprocket i can order a 73x110.5 the one that offers UKtony

https://www.sjscycles.co.uk/bottom-brackets/tange-seiki-ln3922-73-mm-jis-english-square-taper-bottom-bracket-1105-mm/?geoc=FR

and if i change for a splined sprocket, 73x113 should be better than the original one (73x110)

https://www.sjscycles.co.uk/bottom-brackets/113-shimano-bbun300-73mm-shell-square-taper-bottom-bracket-english-thread/?geoc=FR

« Last Edit: August 22, 2023, 03:54:54 pm by jul »

mickeg

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Re: Thorn Nomad MK2 bottom backet
« Reply #5 on: August 22, 2023, 06:43:12 pm »
Yes i bought a Rohloff splined carrier "S", but before to install it, i have to use one or two more thread sprockets.

So if i understand, with my actuel thread sprocket i can order a 73x110.5 the one that offers UKtony

https://www.sjscycles.co.uk/bottom-brackets/tange-seiki-ln3922-73-mm-jis-english-square-taper-bottom-bracket-1105-mm/?geoc=FR

and if i change for a splined sprocket, 73x113 should be better than the original one (73x110)

https://www.sjscycles.co.uk/bottom-brackets/113-shimano-bbun300-73mm-shell-square-taper-bottom-bracket-english-thread/?geoc=FR

It is best to look at the numbers to figure out chainline when you change to the splined carrier.  I was just commenting on concepts.

JohnR

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Re: Thorn Nomad MK2 bottom backet
« Reply #6 on: August 22, 2023, 08:53:51 pm »
It is best to look at the numbers to figure out chainline when you change to the splined carrier.  I was just commenting on concepts.
Here are the numbers according to Rohloff https://www.rohloff.de/en/service/handbook/speedhub/assembly/crankset. Note that there are two versions of the splined carrier and the slim one is only suitable for sprockets 15T upwards.