I need new Hope rotors – any reason not to go 220mm?

As above, my ten+ year old Hope Floating Rotors are both at or below min thickness, neither are straight anymore and I’ve been suffering brake fade a bit with older pads, calipers in need of a service too.

I’ve been tempted to go for M8120 XT 4 pots or M7120 SLX 4 pots with 203 front and back as I like the immediate power and feel of Shimano, and run Shimano on my XC bike. However I also do really love the Hope levers.

Before anyone says overkill or learn to ride, I’m not gram counting and I’d rather have the power there ‘in case its needed’. I have occasionally wished for more bite on my Hopes.

I’f im buying new rotors – other than a minor weight increase – any reason not go from (older style) 203/183 up to 220/220? Fork is not in Warranty, Frame is.

(I am aware the new ‘metric’ sizes will need new mounts).

Hightower, Fox 36, big wheels+tyres, 150mm travel big trail bike for reference.

Nope. Do it. Fitted 220s both ends of my Stumpy Evo a few weeks ago, huge performance improvement. It’s not so much the extra power, more the fact you have to pull less to get the same power, so delivery is lighter and you aren’t tensing up your arms,hence more fluid riding, less arm pump etc. Plus you have the comedy bonus as I found of completely screwing with braking points of your mates are chasing you downhill!

Check the frame will actually fit the rotor and caliper in there.
You may be voiding a fork warranty that no longer exists.

I toe the line between normal weight and overweight (so not a huge porker), and use 180 on a 27.5 bike, so I’d say 200 on a 29er is “normal”.

Go for it, just be aware in the wet they’ll take longer to warm up and be effective than smaller discs as you’ll be braking less.

One reason to run smaller discs and a powerful caliper during winter.

Cheers @andyrm thats sort of what I was hoping.

I use tiddly little 160mm Deores on my XC bike with no issues, so its about just not knowing how to ride, but this is my ‘big’ bike, this year I’ve been hitting stuff faster and harder, enjoying it but suffering a bit with arm pump, grip strength, braking, etc, all related, so I’m hoping its a worthwhile upgrade. If I get another ten years out of them I’d call that value for money too.

@snotrag also look at your lever angles too. I followed all the Frenchies’ lead a couple of years back and run them almost flat, found it makes a huge difference in terms of reducing arm pump 👍

Almost flat levers here too, rarely if ever get arm pump – leg pump, that’s another matter!

Slower to heat up, slower to bed in.

It saeems Hopes run with more adherent friction that other makes. This requires a layer of pad material to be depositied on the disc. this takes heat and pressure. If they never get hot enough you get cold polishing and inneffective brakes

IMO you should always run with the smallest discs you can to avoid then never getting up to temperature

Of course it may be that you will use them hard enough to avoid this but I find it hard to get the 200mm disc on the front of the tandem hot enough to work 100%. When heavily used on big downhills you can feel the power improve over repeated stops

I always bed my brakes in on my road outside my house before riding anyway, but I agree – my front v4 has metallic pads and when it’s cold it’s got very little power, when properly warmed though it’s like dropping an anchor. I run organic in the rear for the better cold bite.

Going to run the new purple e bike (semi metallic) pads in the V4’s on my next build, and probably 180mm front and rear.

Not an expert, but you are adding an extra 20mm or so of leverage onto the retaining bolts which hold the rotor to the hub, which are probably in an aluminium thread. Now I’m sure the engineers at Hope or whatever have accounted for this, but maybe the extra leverage will invalidate a warranty or two?

Now I’m sure the engineers at Hope or whatever have accounted for this, but maybe the extra leverage will invalidate a warranty or two?

Most new (MY2021) forks allow for a 230mm rotor. Before that and it was 203mm, so I guess it depends how long your fork warranty is from when you bought it if that’s an issue.

I followed all the Frenchies’ advice Jedi’s instructions a couple of years back and run them almost flat, found it makes a huge difference in terms of reducing arm pump 👍

Yes absolutely the forks will have to hold the extra leverage, I was thinking more of the extra leverage ripping the rotor bolts out of the hub. I dont think they would, but it might be something to think about, however unlikely. Like I said, not an expert!

Not an expert, but you are adding an extra 20mm or so of leverage onto the retaining bolts which hold the rotor to the hub,

Thats not how it works. all the bolts do is clamp the disc to the hub. the resistance to moving comes from the friction between the hub and the disc. Try running with them slightly slack and they will fret and break. You are not relying on the strength in sheer of the bolts

Slower to heat up, slower to bed in.

It saeems Hopes run with more adherent friction that other makes. This requires a layer of pad material to be depositied on the disc. this takes heat and pressure. If they never get hot enough you get cold polishing and inneffective brakes

IMO you should always run with the smallest discs you can to avoid then never getting up to temperature

Of course it may be that you will use them hard enough to avoid this but I find it hard to get the 200mm disc on the front of the tandem hot enough to work 100%. When heavily used on big downhills you can feel the power improve over repeated stops

I always thought heat was the enemy of braking systems. My experience is the opposite of this advice – when I’ve been underbraked with smaller rotors I’ve always ended up with polished pads that when cooled the next day underperformed massively. When running the correct size rotors (or even bigger than needed) I’ve never had this problem.

Rockshox used to say 203mm max rotor, now they say 220mm, the yari/lyrik lowers hadn’t changed for a few years, not sure if 2021 beefed up the post mount, it’s probably the same I suspect.

prezet – there are two different things – glazing from heat and cold polishing from not getting hot enough. the working temp of a disc brake is measured in hundreds of degrees c

Why not just go 246mm and be done with it?

Thats not how it works. all the bolts do is clamp the disc to the hub. the resistance to moving comes from the friction between the hub and the disc

TJ please, stop making things up.

I’ve a 220mm. I’m running a Hope v4 front and while I love the lever feel, I’ve always felt they lacked a bit of power leading to much dragging and arm pump on longer steeper stuff.
To me it seems that the larger rotor brings this brake up to the power of other brakes available bit keeps the Hope feel.
As others have mentioned – they do take longer to heat up and bedding in my pads was a nightmare!

TJ please, stop making things up.

I remember learning about this in my engineering degree. It wasn’t specifically about rotor bolts, just bolts in general and how to calculate correct torque values.
Guess I should try to get in touch with the lecturer and tell him he was making it up.

Basic engineering no beer. go look it up.

Yes do it. I hated my e4 brakes and got loads of arm pump. 4 pot slx fitted and a 203 up front is plenty (29er, 85kg bloke and lots of steep fast)

On another note no beer. Think of this. Car. Heavy bloody thing and some brakes are mahoosive. However its 4 small bolts hold wheels on. Why dont they sheer every time you brake? …

Goodness. We use 203 on a tandem loaded with panniers and have no problems stopping. I had no idea bigger rotors were available

I remember learning about this in my engineering degree. It wasn’t specifically about rotor bolts, just bolts in general and how to calculate correct torque values.
Guess I should try to get in touch with the lecturer and tell him he was making it up.

Interesting, I must admit I’d always assumed in my mind that it was the bolts’ resistance to shear that was the critical factor but thinking about it, that is a different thing to the friction between the rotor and the face of the hub, hence correct torque which would result in the correct amount of friction between both surfaces. That how it works?

hence correct torque which would result in the correct amount of friction between both surfaces. That how it works?

Yep that’s pretty much it. In general, if correctly designed and torqued properly a bolt should only be in tension and not exposed to shear forces (as with anything there are always exceptions to this, generally in applications with small loads where simplicity/low cost is the main design concern)

i found i got savage brake jack with a 203 on the rear, so reduced it down to a 180.
it is on a single pivot though (29er five)
203 on the front still.

Fair enough, I did mention I was no expert though. Happy to be corrected, though I wasn’t talking about bolts shearing, I was thinking more along the lines of this:
Rotor made of stainless
Bolt made of stainless
Hub thread made of alu.
Unless of course rotor bolting surface, where it is joined to the hub is alu, which I believe floating rotors are, I’ve never had them.
I was thinking if the bolts slacken enough for the rotors to rotate slightly against the hub surface, as has happened to several people despite thread lock, then the rotor acts as a guillotine against the hub mating face, trying to shear the rotor bolts. Obviously they wont give, so the extra leverage would work against the weakest point, ie the alu thread, and pull them out that way. This is what I was imagini g. Not suggesting it would happen, just wondered if it would be a factor in stressing the hub threads.

I’ve got a big hope rotor in the spares box, but couldn’t fit it as Fulcrum/Campagnolo decided to make their center lock hubs the opposite way to everyone else so you can’t run them with adapters 😡

On another note no beer. Think of this. Car. Heavy bloody thing and some brakes are mahoosive. However its 4 small bolts hold wheels on. Why dont they sheer every time you brake? …

Or in my case, why did the forged steel half shaft turn itself into a 7/16 shaft and a load of chunks in the differential on a roundabout when the 3/8″ studs were fine. 🤬

I was thinking if the bolts slacken enough for the rotors to rotate slightly against the hub surface, as has happened to several people despite thread lock, then the rotor acts as a guillotine against the hub mating face, trying to shear the rotor bolts. Obviously they wont give, so the extra leverage would work against the weakest point, ie the alu thread, and pull them out that way. This is what I was imagini g. Not suggesting it would happen, just wondered if it would be a factor in stressing the hub threads.

I’ve had that happen with 160mm rotors. Cack handed maintenance (or lack thereof) is the root cause, not the rotor size.