hi everyone,just got myself a 1989 nc30,quick question,on here ive seen various topics on sp1/cbr brakes and setup etc,would it be ok you think to run a single disc and caliper on my nc30 if it had the sp1/cbr caliper? if the braking is improved and it would save me some weight of the front end ( im trying to make the bike abit lighter) what do you all think? would it be worth it and ok? thanks, great forum by the way!!

not the best idea....

but welcome!

Nope. They came with two discs for a reason...unless you don't like stopping quickly.

It is common for drag bikes etc to run one disc/caliper but to be honest for a track or road bike, the amount of weight your saving you may as well have a big shit before you go out.

Also, would taking a disc off not put the wheel out of balance from side to side? Granted, on the road you don't use 100% of what the brakes can do, but what you would be doing is making one caliper do twice the work it was meant to, which could potentially dramatically increase pad and disc wear. Also, I'm not sure what your insurer would think if they find out you've halved the front braking potential!

thanks for the advice,think i will stick to twins disc etc.ta.

There is nothing to fear in terms of unbalance from running with a single disc. If there were then all bikes would be screwed as the chain only rotates up one side of your bike, doesn't it? That's a lot heavier than a disc.

You will have similar total braking strength as the SP1 caliper has bigger pads and is of a better design, although total power will be down a bit since you've only got one pair of pads acting on one disc. Thing is, it'd still be plenty in the end.

Where you'd get issues is if you put much heat into the brakes. Most single disc bikes use discs starting around 5.5mm or 6mm new thickness, whereas nc30 are 5mm thickness with 4.5mm minimum, IIRC? This extra metal gives you a bit more heatsink capacity, but it's not as much as a pair of discs, hence why sportsbikes above the weight of a 125 will tend to use twin discs.

If you wanted to do it, I'd say go get a CB-1 front disc, this is 310mm and 6mm (or 5.5, I forget) thick. The bolt holes will have to be opened out to M8 in the wheel, but there's plenty of meat for this. Then you just need to get a caliper adapter (you need one anyway) that's made for a 310mm disc upgrade. If it doesn't exist then I'm sure it's easy enough for someone to do. You'd want a 1/2" master cylinder to run a single one of those calipers, the one from an nc23/9 would be perfect.

I think in combination it'd look pretty cool with the SSSA on your '30.

As to whether there's any actual advantage? Well, weight would be down a smidge from the single (but bigger and thicker) disc, the SP1 caliper is very light with alloy pistons and you're only planning to use one, also only one hose, so a bit more weight off there. Simplification of the system from reduced parts count is a nice theoretical upgrade. You could grind about 5g off the spare fork leg by removing the unneeded lugs I suppose.

I don't think I would bother myself but if it floats your boat and particularly if you aren't going racing then there's nothing much to say you shouldn't do it.