Rotorhelp: 6-bolt Rotor Standards

Are there different 6-bolt standards? If so, can one get an adaptor?

My choice of alias was based on music rather than a knowledge of brakes. In fact I’ve never owned a disc bike until this 1999 Marin Nail Trail which came with, on the front, a Dia Compe 6-bolt rotor hub and a Dia Compe mechanical caliper -which was pants. The back is a v brake, oddly.

I upgraded to a modern Avid BB7 caliper but left on the original disc for period looks. All was okay but as I’m now rebuilding, I thought I’d put on the modern Avid rotor that came with the new brake for better performance.

Here’s the thing, laying the modern rotor on the old one which is fitted, the bolt circle circumference on the new one is materially larger than the old. I.e a modern one won’t fit the hub.

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Any disc brake experts out there?

With avid you have to put the avid adapter, avid rotor and avid spacers, you will not have problems. I have mixed a avid rotor with shimano adapter and caliper and doesn´t fit, the rotor is larger.

Those original Dia Compe cable discs that came on Marins had their own BDC.
I remember at the time everyone had to change the brakes because they were so bad they were dangerous. This probably explains why the rear on this one was changed to a V. People who wanted to upgrade to a Hope or a cheap (£100ish) at the time Avid cable disc found they had to change hubs/wheels.
This often caused some tension if you had just sold someone a new Marin with crap brakes, then you told them the price of a brake upgrade that wouldn't work without new wheels.

OllieJones":xaba7h95 said:

Those original Dia Compe cable discs that came on Marins had their own BDC.
I remember at the time everyone had to change the brakes because they were so bad they were dangerous. This probably explains why the rear on this one was changed to a V. People who wanted to upgrade to a Hope or a cheap (£100ish) at the time Avid cable disc found they had to change hubs/wheels.
This often caused some tension if you had just sold someone a new Marin with crap brakes, then you told them the price of a brake upgrade that wouldn't work without new wheels.

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Balls!
Guess I'm stuck with the retro rotor unless anyone has a late 90s/early 2000s black Ritchey rim/conventional six bolt hub.

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You could just run v brakes front and rear, or get a newer front disc hub and have your rim built on to it. The rotor you already have will fit, and you retain the period look you have now.