Disc sizes – matched or not?

I’m currently builing up an old Patriot and this will be my first bike with disc brakes.

Due to the selection of used parts I have aquired to build this bike from I’m basically looking at two options.

180F/180R
or
180F/160R

I have a 180 disc and will need to buy just one disc (and approprite caliper mounts), so do I go for 180 or 160?

It won’t be used for full on DH, more AM/FR. I expect either will give me more then enough braking for my needs it’s more the F/R balance of braking I’m interested in.

Appreciate thoughts, pros/cons

Thanks

180 front 160 rear works good and looks good/balanced.

Always bigger on the front. I wanted 183/160 for my v2 but they don’t make a floating 160. Therefore, o had to get 203/183.

i always run a size down on the back, find it much more progressive, i regularly find running the same front/rear being a light rider its very easy to just lock the back end up

Go 160 on the rear, you really don’t need a big rear disc … due to weight transfer under braking a bigger rear disc is actually more likely to cause you to skid / make brake control more difficult.

I’ve got 180F/160R and I think it’s a good balance… but I’m an XC mincer. If it’s going on a Patriot I’d have thought you’d want something bigger say 203F/180R. Either way I wouldn’t get too hung up. Adapters are cheap, disks need replacing and both are readily available in the classifieds if you change your mind.

I had Hope mono minis 183/160 on my Orange 5 from new. Round the local trails it seemed fine, although I never felt that the rear brake worked very well. I then had some time on a Trek EX9 with 180/180 and it felt so much better balanced, but did have different brakes- Avid Elixir R. I decided to try a 183 on the back of the Orange and it transformed the braking feel of the bike for me- now much better balanced and I am more confident with it. Had this set up for the last PDS and had no fade or excessive wear issues over four days of riding in the Alps.

I have 183 on both wheels, spot on around here.

90% of your braking is done by your front wheel so bigger on the front. However if you decend alot then bigger on the back is useful as using the front brake on a decent can be a bit awkward.

So it depends. I run 180/160mm on my disc bike but ride in East Anglia. No big hill to come down here.

I would have gone with 200/180 but my forks (2001 Bomber MCR 130’s this is a budget build) are only rated to 180, and while they are obviously well out of warranty I don’t want to run the risk of damaging them, hence thinking 180 front. I’m leaning towards 160 rear as I’m not a heavy or extreme rider and think it will give better breaking balance. Use will be mostly trail centers, but not hard core DH. To be honest I’ll be under utilising the Patriot frame.

i run 203 front, 160 back and I still pull the front lever harder than the back one.

bigger on front, i run 203/183 – never had a problem

I’m 183’s all round and don’t suffer any ill effects from it. It’s probably down to being used to what you ride.

Pick whatever you like and run with it, as this’ll be your first disc brake setup you’re learning from scratch anyway.

The smallest disc i could put on my Bomber 66 rc3 was a 203!!! i also had a 180 on the rear, perfect combo, also depends how heavy you are, but on a patriot id go for bigger is best.

180/180 balanced

It doesn’t really matter. FWIW I run 160/140

I guess as opinion is divided neither option is going to be to disastrous.

But what finally has swung my decision is getting a 160 mount and rotor FOC, my kinda price 🙂

So will fit that and see how I find it.

Thanks for the input

For me 203/203 on the DH bike, 180/160 on everything else.

160/140 here, can’t see I’d ever go bigger than 180/160 myself.

Slight thread hijack but why if most of your braking is done on the front do your rear pads wear out faster ?

That’s more a reflection of technique than physics.

I run a 185f/145r on my ht xc bike an 203f+r on my gravity bike
weigh 15 st and both brakes serve their purpose well.

“most of your braking is done on the front do your rear pads wear out faster ?”
Think that sentence wants rewording

Most people don’t brake to the full potential of the front brake IME. Many people will use the rear brake as the brake to go to first/to ‘comfort brake drag’ with, especially on steeper stuff

Wrong yes, but I’d reckon this kind of thing is partly why people tend to go through rear pads faster than front ones
That and the rear pads have more chance of getting coated in whatever the front and rear wheels throw up (mud/water/etc)

I have:
185/185mm on FS bike.
185mm rear, as a brake dragger (especially) when out of my comfort zone) I found 160mm heated up and becomes harder to brake more quickly. max rotor size on previous frame was 185mm
185mm front because 203 seemed to need more braking to get it to bite properly than I give it (in the UK) tbh 185mm is a bit like that

185/160mm on XC HT. Used to be 160/140mm on old hopes. Wanted more modulation/power when using as stand-in for FS bike, so swapped brakes around. Dont have any smaller rotor/adapter combos, so 185/160mm

203/160mm on 4Xish play-bike HT. Was 160/140mm. Wanted more power on the rear for messing about on local DH spots. 160mm rotor to the rear. 203mm rotor only other rotor going. I had a +20 and a +40mm adapter kicking about which fitted my IS mount (hope) calipers
203mm rotor up front isnt good (though an ’04 XT?), I dont use it very much while riding. Guessing it never gets enough heat into it? Plus wants a bleed ..