Daan

Yes, that's why I wonder why they didn't go for 9 mm. Hayes have done so with the Dominions, which have the same slave piston area as the V4. The T4 lever on the V4 caliper has a tight enough free stroke to be able to handle that. Hardly notice a difference in this regard to the the T3 lever.

All calipers flex quite a bit of you look at them closely, even big ones like the Hayes Dominion, Magura MT5-7, Hope V4. Or maybe especially big ones, since they usually see forces that are quite a bit higher than weaker brakes. As you say, always a trade off between weight and flex. Don't know really why Hope didn't go with 9 mm MCs like Hayes, Trickstuff and TRP, for just that bit more oompf. Having used the V4 T4 quite a bit, I feel they could have. But in the end it's all a trade off between leverage and stroke, and feel at the bite point. Go too small on your MC, and you would need a lot more lever stroke to move the slave pistons the same amount. You could make pad clearance smaller to make up for this. But there's only so much you can play with, as you still want to be able to set up the brake without it rubbing the disc. A solution to this are variable cams like Shimano Servo Wave or SRAM Swing Link. They modify the lever stroke, so leverage at the beginning of the stroke is low and pad movement high, and at the end of the stroke, leverage is high and pad movement little. Then again, it makes for a non linear feel, and when executed poorly, uneven and a lot of wear on the MC piston/bore (looking at you Shimano).

Don't have the Trial Zone lever anymore unfortunately, but it was basically a Hope Race lever with a slightly longer lever blade. Now I don't know if the Race lever has the 10 mm MC diameter of the T3, or the 11.5 mm diameter of the Tech Evo, or something in between? If it's 11.5, then the mechanical advantage gained by the slightly longer lever blade probably won't make up the difference lost by the lower hydraulic leverage. If it's 10 mm, then it's probably slightly more powerful than the T3 due to the higher mechanical leverage. If you have an original Race/TZ lever, do measure it up for the sake of science What we'd need is the MC diameter, and for a rough indication of mechanical leverage, the distance between middle of the pressing finger to the pivot point, and the distance between pivot point and cam. As for function: they both will work fine on any Hope caliper. The differences other than leverage with the T3, is that the TZ lever rotates on a crappy bushing that sees a lot of forces, and wears out pretty fast (I actually wore out not only the bushing, but the lever blade as well that way). The T3 is a lot more durable. However, the TZ/Race lever is lighter, so I reckon that's why some guys might run it. If you don't have the TZ lever already, I would personally only get it if it's very cheap. TZ/V2 calipers have always had 25 mm pistons, so powerwise on the caliper end, old and new is all the same.

Yeah, quite similar. Trialzone caliper is based on the old V2. Just no top loading pads on the TZ, so theoretically marginally stiffer. TZ has alu and magnetic pistons too instead of the V2's phenolic with a spring between the pads. Theoretically again slightly smoother performance. I doubt you'll feel any difference between the two when mated to the same lever. However, the Moto V2 and Tech V2 levers have a larger MC piston diameter than the both the Tech3 and Tech4 levers, so in stock form, any V2 brake is weaker than the current and previous TZ brakes. If you're interested, I made this tool that compares theoretical power of a few brakes, based on solely hydraulic and mechanical leverage. Not super accurate, bit gives a good idea. The Tech Evo V2 in there too (you can enable it in the sidebar): https://brakes.ddzyne.nl/

Pistons are the same size, just the bore cap is massive.

Aye a fellow single speeder Don't get me started on bearings haha, but that sounds like a proper hack setup you've got there with some nice and large bearings! I guess single speeders a a particular (peculiar?) kind of breed

That keen eye can be a bit annoying sometimes You also have me curious though Adam, with busting weird stuff on mtb. Any good stories?

Hahaha oh shit busted! My style with everything seems to be a bit 'more power than technique', but I felt my trials riding was definitely getting a bit smoother lately. Don't know man, maybe it's my weight (93 kg or so with clothes) that's a bit much for these little parts? Or maybe I'm too much of a perfectionist expecting and noticing too much? I do have some fairly recent practice clips of me torturing my bike: https://photos.app.goo.gl/croG2YU9idAu2bKKA

Besides that huge tear, it was tearing off knobs left and right, not really worn out, so probably just absolutely not suited to trials abuse. Haven't had that with other tyres, so must be something Schwalbe, or at least this tyre. Trying the race king protection now.

Hm, I might try something else than Racing Ralphs again, damn, two big ass tears. And on closer inspection, many side and middle knobbies coming loose/half torn off. Meh.

Well, complete system failure today. Not only a faulty lever seal, DOT fluid is now also leaking past one of the caliper pistons (connected my old T3 lever to be able to continue riding). Couple of rides old. Unbelievable.

Damn it, the T4 lever's MC piston seals are leaking. Solid lever, but squeeze it continuously for like 30 seconds (as in, keep the brake locked up) and it creeps closer and closer to the bar until it touches it. Obviously it's letting fluid get past the seals back into the reservoir. Great brakes otherwise, but man, get your quality control together Hope!

Just got my hands on some T4 V4 brakes. Got these instead of the TZ, so I can use regular discs, and have an optional backup set for my mountain bike. Before these used the T3 V4 for half a year or so on my trials bike. Before that also used the Hayes Dominion and the Magura MT5 on the same bike. And had the TZ on my old bike. So have ridden a few brakes Anyway, one ride in, using the stock green racing pads, and so far I'm impressed. They blow the T3 lever out of the water. Action is lighter, power is way way higher, hold is massive. Lever does feel a bit mushier; bitepoint is less hard/solid. Lever travel before the brakes engage is compareable. Compared to the Hayes Dominion, the Hope lever feels way more chunky and solid, and the action is a bit heavier. The Dominions have an unbelievably light movement in the lever. Power though is very compareable, maybe with a slight edge to the Hope, but this could also be the pads of course. Build quality is a lot better on the Hope. Since I only got a few rides out of the Dominion before the calipers started leaking, I've good hope the Hopes will fare better.

Yeah, always does it for me. Acetone and a toothbrush.

Check the bleed nipple and make sure it's done up really tight. I've had mine and those of a friend of mine leak from there. If you can do it up tighter, it's likely that's what it was leaking from. Though less susceptible, also check the banjo bolt while you're at it. If you want to check the slave piston seals, make sure the brake is clean, put a bleed block in there (no pads) and squeeze the lever hard as often as you can for a minute or so. Then check if there's any wetness around the pistons. Also in my experience, resurrecting pads works up to a degree, but never makes them as good again as fresh ones, especially so for organic pads like the Magura's.

I reckon with the pretty massive leverage they've got (T4 Trial Zone is close to the Trickstuff Maxima), you're better off with stainless steel braided hoses. Trickstuff supplies the Maxima exclusively with those hoses, to prevent the bite point becoming too squishy. I've got some T4 V4's on order, with the braided hoses. Long wait though, hope to give my impressions within a month or so.

Good luck. Again, I run the same 2019 Hex with the same wheels as Ali, you won't find much stiffer rims than those. There's a few mm clearance with the 2.35 Ikon, and it often rubs, you should see my frame. So sure, it's usable, but it isn't pretty. Hence I didn't get another 2.35 after it died.

Just know it will rub whichever rim you use.

Used it for a while, on stiff carbon rims, dead straight. It's too wide for the Hex, unless you don't mind a bit of rubbing under flex.

Those Shimano brakes are notorious for micro leaks past the caliper pistons. I've had it with Zee, XT, and Ultegra on the road bike of a friend of mine. If you use the blowtorch/acetone/alcohol method, and you find it works for one or few rides, and then it happens again, it's time to contact the warranty department. And don't buy Shimano brakes again.

I've been using the TRP R1 rotor on the rear for a good while now on my Hex. Was bending Magura HC rotors for breakfast, even when just locking the brakes and not hitting them, and have only smoked one TRP so far, when I landed right on top of the rotor. But nothing would have survived that. I like them. They're pretty cheap, they're noticeably more solid then thinner rotors, and brake power is the same as Magura rotors. No issues at all either setting them up with Magura, Hayes and Hope brakes.

Keeping this topic alive I've broken the bead/casing on my rear Ikon after two months, as usual with all my Maxxis tyres. After a while they just start to wobble like mad. A shame it happened so fast on this one, since the thread is still good. And I did really like the Ikon, great grip and a really damped/soft ride. But, it was also a bit too wide for the Hex in 2.35; tended to rub the chain stays. With the wobble, it really started to dig into the frame, making it quite unusable. So I just replaced it with a Racing Ralph 2.25 (super ground addix speed, who comes up with these names?). After mounting, it looks pretty skinny and low volume compared to the Ikon. However, first ride in, agree with you John, great grip! They also feel a bit smoother rolling and pivoting, maybe because of the rounded off tread. Pretty pleased with them so far! How are yours holding up?

Quick update on this: with a new seal and new piston installed, it all remains dry now. Won't be tempting fate by putting them on the trials bike again though. But the Hayes Germany service is great, even on a free set I probably shouldn't have received at all

Cheers Adam. Lever feel is my main gripe with the T3, the spring is pretty stiff. Did they actually change the seals in the calipers for ones with less piston retraction? Looking at the exploded drawings, I see they use a glide ring around the lever piston as well now, just like Trickstuff and Hayes. Should be great for durability and smoothness. They'll blow the Hayes out of the water as far as finishing quality is concerned, so I reckon they'll make a great poor man's Trickstuff. I may need to give them a shot

So, anyone got some time on the T4 TZ yet?