Thorn 104mm BCD 4 Arm Reversible Single Chainring 3/32 Inch - Black

Customer Reviews (8)
4.9 / 5| Write your review
£44.99 Please note this product has selling restrictions to your country. was
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SJS Cycles part number : 
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Product Reviews (8)
Questions & Answers (15) Q & A
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Product Reviews (8)
Overall Product Rating 4.9 / 5
Real quality
By David Bean
06 Jun 2019
5 / 5
I recommend this product
ProsTop quality, durable
When I removed the existing sprocket ( same type) and cleaned it, decided to reverse it so won't be using the new one yet! Really high quality with a durable finish. Great that the sprocket is engraved on both sides.
High Quality Ring
By Paul
06 Sep 2017
5 / 5
I recommend this product
High Quality single speed ring. Double the mileage as it is reversible.
Single Speed Chainring
By mkackland
23 Dec 2012
5 / 5
I recommend this product
ConsNone yet
Prosquality, value
Impressed with the build quality, really like the choice of # of teeth, wish I'd tried one before, although will have to see if it stands the test of time.
Great Upgrade
By John Somers
12 Nov 2012
5 / 5
I recommend this product
ProsQuality, Weight, Price
I needed this to upgrade the new Kona Unit from a single speed off roader with a 32T chain ring in to a multipurpose beast of trail and rugged road bike with the 44T Thorn Chainring.

I was really impressed with both the build quality but the weight too this is the ideal upgrade frof this bike to ensure that it fullfills the trail and road requirements.
Pashley Hang Your Heads In Shame ...
By Richard H
17 Oct 2012
5 / 5
I recommend this product
ProsQuality, finish, efficiency
... my Pashley Paramount got dropped by someone moving it without my permission and the chainring got bent. The crank arm and spider were good as new so I was relcutant to replace the entire crankset (the only option from Pashley) even though this was cheaper than the Thorn chainring on its own. Great decision! I now realise how flimsy and poor quality the original was. This is the same weight, is much stiffer, holds the chain better, looks great and has improved the quality of drive on turning the pedals.
Solid Chain Ring For 104 Pcd Cranks
By Andrew
22 May 2012
4 / 5
I recommend this product
ProsAttractive, high quality.
Looking to increase my gear ratio I purchased the 48t chain ring to replace my 42t chain ring. My bicycle is a mountain bike single speed conversion. One difference is that this was about twice as thick where it is mounted than a normal ramped chain ring, so it shifted my chain line by a few millimetres.

Looks good, works well, recommended.
Single Speed Rings
By Anonymous
15 Apr 2012
5 / 5
I recommend this product
Very long lasting rings.
Used these on our tandem crossovers so buying the same again for our new tandem.
Top Quality Product
By mrhallorann
04 Oct 2010
5 / 5
I recommend this product
ProsQuality product, great value
Bought this to convert my commuter bike into a 1x9 speed. It's rampless, so there's no danger of the chain jumping off and causing an accident mid-shift. This is a lovely high-quality CNC'd lump of aluminium. Fits my Shimano crankset like a dream (after I milled some of the shoulders off so it'd fit the middle mount. It's even reversible, so when you wear one side of the teeth out, flip it and bingo - a (nearly) new chainring!
Questions & Answers (15)
Can I use this (11054S42) to replace the chain ring on my existing 37682T42, please?
11 Apr 2022
Thank you for your enquiry, yes this should be fine
Can I use this with a SHIMANO FC-543 triple?
26 Feb 2021
Can I use this with a SHIMANO FC-543 triple on the outer ring for use with a Rohloff hub?
Thank you for your enquiry, yes will fit fine

WD 26/02/21
Will use with a 1/8 inch chain instead of a 3/32 inch chain make much difference? Thanks
22 Sep 2020
Yes, a 1/8th is much wider and will be a baggier fit.

Difference between a narrow wide chainring
10 Jul 2020

Can I use these for a 1 x 10 speed or do I need to get a narrow wide chainring? Will there be any difference?
We would only recommend a narrow wide chainring as with the chain moving its likely this would drop the chain.

Thanks - 10/07/20
Compatible with Shimano XT cranks?
24 May 2020
Can this chainring be installed on the Shimano XT single-chainring crankset (FC-M8000-B1)?
No, those cranks use a slightly different BCD pattern and standard 104 rings will not fit.

Thanks - 25/05/20
14 Aug 2018
If I wanted to use this chainring (39 teeth) with "Thorn 104/64 PCD Triple Crankset MK2 - Black (SJS Cycles part number : 31813l150) " is there any suitable, quality bash guard available?

We have these suitable up to 38, or up to 44t.

SJS Cycles part number : 11082

Crankset compatibility?
13 Apr 2018
Hi, please confirm that this is compatible with SJS Cycles part number : 31813L155 used as a single chainring.

By the way, the link to the sizing chart appears to be broken.

Thanks, Ian
Hi there,

Yes those two items are compatible.

We can not see any issues with the sizing chart, please contact us if this issue persists for you.

All fit for outer position?
11 Feb 2018
Can I use any of those chain rings (32 to 50) on the outer position on the Shimano XT- M770 crankset to work with the Rohloff hub?
Hi there,

Yes you could fit these to the outer position to achieve the correct chain line.

Can I use this in the outer position on the Shimano FC-M622 crankset to work with the Rohloff hub.
11 Jan 2018
Hi there,

Yes you can fit this to the outer; I would be sure to create a chainline that is as straight as possible though.

Crankset Compatibility
12 Jun 2017
Hi there. Will this work as a replacement chainring for my Truative Firex single crankset? It's an Alfine 8 equipped bike.
Best wishes

This chainring should be fine for use with the crankset and an Alfine 8spd hub.

What Material Is This Made From? Steel? Al Alloy?
13 Feb 2017

This chainring is made from 7075-T6 alloy.

What Torque Should The Bolts Be Set At?
14 Jan 2017
Thorn Endoro MTB with Rohloff gear.

It depends on the bolts you're using and if they're either alloy or steel but the typical recommended range is 6-8Nm.

Chain Size
05 Oct 2016
Hi, I thought all 8, 9, 10, 10/11 speed chains were 3/32? I run a 10 speed chain, this should fit this chain ring right? I thought you only got 3/32 and 1/8 in chains/cogs etc, with the internal measurement of the 3/32 staying the same but the outer being different for the cassette speed? I hope I'm right as I run a single chainring (currently 46t) with a 10 speed chain/cassette and I want to up to a 50t chainring. Thanks

Unfortunately this is not the case; 5-8spd chains are 3/32, 1/8 chains are for single speed use only and then 9, 10 and 11spd chains get gradually narrower as they try and squeeze more sprockets into the same cassette space. The internal dimensions of a chain gets smaller as well as the chainrings themselves get narrower. It is possible that you're currently running a 3/32 front ring but it is more likely that you're running a narrower ring than this. We would recommend fitting a front chainring that matches the speed of chain that you are fitting.

Hi, Just Wanted To Check This Ring Is Okay To Use With An 11 Speed Chain? Thanks.
04 Oct 2016

This ring would not be suitable for 11spd chains I'm afraid, this ring has been designed for use with 3/32 or 8spd chains which are much wider than 11spd chains.

25 Apr 2016
i'm looking for a chainring with 40 teeth , 104 , 4 holes bcd , that will fit a Shimano LX ckrankset. it should work with a bushguard, as single (the bike is with rohloff).
will this item fit ?
do you have a cheeper item that will fit ??


Hi, this:
or any of these should do:
cheers, Robin