Re Gimondi Chainset/Ring

[smep]

Hello,
Please would anyone be able to advise as to what ring would be compatible with the above chainset.
I am running a single speed but with a 48 tooth ring the gearing is to high.
I am trying to source an appropriate smaller tooth ring but not sure as to whether a 130 BCD/1/8" is correct and if so what brand would suit.
Any help would be appreciated.
Thank you,
Regards,
Steve.

[Gattonero]

Just measure center-center between two adjacent holes:

(holes) (distance) (BCD)
4 45.3 mm (1.78 inch) > 64 mm
4 56.6 mm (2.23 inch) > 80 mm
4 73.5 mm (2.90 inch) > 104 mm
4 84.9 mm (3.34 inch) > 120 mm
5 43.5 mm (1.71 inch) > 74 mm
5 64.7 mm (2.55 inch) > 110 mm
5 76.4 mm (3.01 inch) > 130 mm
5 79.4 mm (3.12 inch) > 135 mm

On a a 130BCD the smallest you can fit is 38t, but won't do well with a 1/8" size, a 39t will be a better choice. Specialites TA and Gebhardt do all sizes of chainrings, even 1/8"
https://specialites-ta.com/plateaux/track.html

[smep]

Thanks it is 130 and 3/32 " but don't know where to source such a ring.
I appreciate the advice.
Regards,
Steve.

[Brucey]

it is a very common chainring fitment. If you are running SS I recommend that you use a 1/8" chain, chainring and sprocket. You can use 1/8" chain on 3/32" rings and sprockets. In any event buy a chainring with full height teeth, that isn't meant for use with a derailleur system.

NB you can also change the gearing by altering the sprocket at the back; it is often cheaper to do this even though you might have to buy a new chain.

For example if you have a 16T sprocket at present, a 19T sprocket might be a good one

http://www.gear-calculator.com/?GR=DERS&KB=48&RZ=16,17,18,19,20&UF=2135&TF=90&SL=2.6&UN=MPH

cheers

[Des49]

Thanks it is 130 and 3/32 " but don't know where to source such a ring.
I appreciate the advice.
Regards,
Steve.

Spa Cycles are a good source. This morning I took delivery from them a couple of 1/8" fixed sprockets and a couple of KMC B1S 1/8 " chains.

I run a 1/8" fixed gear drive train on my mucky weather bike, with a TA 1/8" 47T chainring and a 19T sprocket. I find for what I use this bike the 1/8" gives a very good life, I reposition the chainring every now and then. Wish I could find a 1/8" stainless steel ring but the TA seems to last ok so far.

[andrew_s]

Thanks it is 130 and 3/32 " but don't know where to source such a ring.

https://www.sjscycles.co.uk/130-bcd-5-arm-single/
I'd get the Thorn Reversible 3/32" myself, so I could turn it round when it gets worn and wear out the other side of the teeth, without any change of chainline.

A quick glance at Spa didn't show any 1/8" in under 44T

In 3/32" chainrings, anything described as "outer" or "middle" will probably have cut down teeth for easy changing with a front derailleur.

[Brucey]

lots of chainrings here

http://www.velosolo.co.uk/shopcrank.html

cheers

[smep]

Thank you for the kind advice.
I have sourced a GIMONDI 32 tooth 3/32 chain ring from Germany so hopefully that will do the trick.
I am running a single speed but the current 48 T ring is to highly geared for my old legs.
Lets see.
Regards,
Steve