The International CBX Owners Association

The gearing on my 79 cbx is currently 18 front and 42 rear, as im changing the wheels for dymags i need to get a get a new rear sprocket to suit the dymag.....i can obviously count how many teeth are on the old sprocket but how do i tell whether the chain ive got is a 520 etc as it doesnt say on it ? Cheers

It may say on the rear sprocket what size it is. Clean it up and check. If it is the original sprocket that was new on the bike, it is a 630. If it was replaced with a smaller one, it is most likely a 530. I would replace everything, front sprocket, chain and rear sprocket. That will make it easy to have matching parts.

You can measure the chain:

Chain size is in inches, the three digit number is used to discribe the chain size .The first digit is for chain pitch. This is the distance between the pins. The second and third digits are the roller width, with a decimal point inserted between the second and third digits.

For example: a 520 chain has a pitch of 5/8" = (15.88mm) and a roller width of 2.0/8" = 1/4" (6.35mm).
A 530 chain has a pitch of 5/8" (15.88mm) and a roller width of 3.0/8" (9.52mm).
A 630 chain has a pitch of 6/8" = 3/4" (19mm) and a roller width of 3.0/8" (9.52mm)

EMS wrote:It may say on the rear sprocket what size it is. Clean it up and check. If it is the original sprocket that was new on the bike, it is a 630. If it was replaced with a smaller one, it is most likely a 530. I would replace everything, front sprocket, chain and rear sprocket. That will make it easy to have matching parts.

You can measure the chain:

Chain size is in inches, the three digit number is used to discribe the chain size .The first digit is for chain pitch. This is the distance between the pins. The second and third digits are the roller width, with a decimal point inserted between the second and third digits.

For example: a 520 chain has a pitch of 5/8" = (15.88mm) and a roller width of 2.0/8" = 1/4" (6.35mm).
A 530 chain has a pitch of 5/8" (15.88mm) and a roller width of 3.0/8" (9.52mm).
A 630 chain has a pitch of 6/8" = 3/4" (19mm) and a roller width of 3.0/8" (9.52mm)

This is a tremendous post and got me head-scratching about my '80, so I just poked around and found that the '80, '81, and '82 bikes all use the 530 setup, just for reference. You cannot mix and match 5xx and 6xx components I am told.

N.

You are correct, Nils, you can not. Many have replaced the 630 chain set-up on their 79s which is large and heavy with the lighter and (equally strong) 530 chain set-up from the 80-82. I know of some who have even gone to a 520. Chain technology and design has significanlty improved since 1978 and the smaller chains today do the same job as the big ones did back then.

Talon Engineering supplied the sprockets for Dymag. Here's the info if needed...

TALON ENGINEERING LTD
44 LYNX TRADING ESTATE
YEOVIL
SOMERSET
BA20 2NZ
United Kingdom


Tel No: 0044 (0) 1935 471508 (delete the bracketed zero if calling internationally..)

Fax No: 0044 (0) 1935 431825

E-Mail: info@talon-eng.co.uk

What are the new rim sizes? don't forget if you are changing the rear rim diameter it will affect the over all gearing.

Jeff Bennetts wrote:What are the new rim sizes? don't forget if you are changing the rear rim diameter it will affect the over all gearing.

18 front 18 rear Jeff...

alimey4u2 wrote:

Jeff Bennetts wrote:What are the new rim sizes? don't forget if you are changing the rear rim diameter it will affect the over all gearing.

18 front 18 rear Jeff...

No problem then.

Thanks for the information and the help folks....much appreciated !

Paxo