I reckon sram code rsc with 220mm rotors would be a decent real world/nnot breaking the bank choice.
I'm running Code RSC's with Uber E Matrix pads (my bike isnt an ebike) in each end, using Magura MDR-P discs in 220mm front and rear, using the Magura QM45 mounts.
Brakes feel great, I like a solid feeling brake that doesnt wonder from my BMX ubrake days and these do that and stop on a dime! I noticed Danny Macaskill used the MDR-P on the front of his bike for the slab video.
Another thing some of the tandem folk did in the early days of discs was to use a motorcycle trials calliper
I reckon you could mod a brembo motorbike calliper + 320mm disc onto a fork without too much issue 😀
Problem then might be getting it up to temperature!!
Personally I would use some temperature paint on the back of the pads, disc and caliper.
See what your issue is and decide a solution. It may be pads with a higher operating temp, it may be heat dissipation etc.
Pad friction falls rapidly outwith a temperature range
The fact they are working, then start to lack power would point to a temperature issue (assuming the lever feel is remaining constant). If that is the case you need to decide if you are going to attempt to keep the current pads cooler, or switch to a higher temp pad compound. Pads with a higher operating temp normally have reduced friction at lower temperatures.
Although I personally hate the multiple bike standards I do wonder if we are approaching the point bike disc brakes need a new standard for extreme DH and E bike use.
Personally I would use some temperature paint on the back of the pads, disc and caliper.
See what your issue is and decide a solution. It may be pads with a higher operating temp, it may be heat dissipation etc.
All very good, and fine for cars (and presumably motorbikes) where brake pad vendors specify temperature operating range for their pads and have a variety of pads available for a variety of temperature ranges, but as far as I know no mountain bike brake pad manufacturer publishes this kind of data for their brake pads, all you get with bike brake pads is some kind of wooly "works well at high speeds and high temperatures" statement.
The only time I have had total brake failure has been at Pila, and it has happened twice, and both in exactly the same spot; a couple of hundred yards from point where the trail ends and you pop out onto tarmac at the very bottom. Both times I went non-stop from the top of Chamole to the bottom. In both instances the mode of failure was the same. Lever to bar and no amount of pumping changed anything. 30 seconds of "stream cooling" sorted it and the brakes came back.
Bike: Scott Gambler
Brakes: XT 2pots
Rotors: 203mm front & rear
I have some Shimano 4 pots to fit to my 140mm trail bike. I don't think the issue will re-occur for me - I am older, and maybe wiser.
I have Guide REs on my Levo and they have been great on 2500m --> 800m descents. The bike and I must be nudging 120kg combined.
brake failure has been at Pila, and it has happened twice, and both in exactly the same spot; a couple of hundred yards from point where the trail ends
ISTR a very scary fast, loose runout with three successive braking zones from 50+kmh down to ~28.
30 seconds of “stream cooling” sorted it and the brakes came back.
Did you also "stream flush" the detritus from your undercrackers?
braking with only one finger, looking well ahead to anticipate the trail, dropping my heels, bending my elbows etc, etc. 🙂
😂😂 I was hoping for this.... blimey, short of 203 f/r Hopes or trickstuff (which are crazy expensive!!) where do you go!?!
DOT 5.1 fluid can cope with high temperatures better than mineral fluid. Obviously, you need to keep it in a sealed container, but the water absorption thing is massively exaggerated.
what counts as a sealed container? the screw up bottle it comes in? otherwise I've just wasted 2/3 of a bottle.
I also insists it lives in the house, not the bike shed with all the other fluids, for condensation reasons. (possible bollocks)
ayjaydoubleyou
Free Memberwhat counts as a sealed container? the screw up bottle it comes in? otherwise I’ve just wasted 2/3 of a bottle.
Yeah, it'll be fine. It's not best practice, but that's ok. Thing is even without a 100% perfect seal there's nothing driving air past the seals- no big pressure differences or anything- so it's OK. It'll soak up whatever moisture is in the air in the bottle, but that won't be much.
I don't think where you store it makes any difference personally for the same reason. The humidity of the air outside the bottle shouldn't ever matter.
Thing is even without a 100% perfect seal there’s nothing driving air past the seals- no big pressure differences or anything
Don't think this is true - if the vapour in the bottle goes into the fluid then there'll be a vapour pressure differential so vapour could work it's way in without air having to.
I put a bit of plastic film over the top then screw the lid on. I squeeze the bottle and nothing comes out so I think it's reasonably well sealed.
Hope V4's or Magura Gustav's
molgrips
Full MemberDon’t think this is true – if the vapour in the bottle goes into the fluid then there’ll be a vapour pressure differential so vapour could work it’s way in without air having to.
Only the water vapor in the air in the bottle will be taken up by the fluid and that's a microscopic amount- if I remember rightly even at 100% humidity there's under .1ml of water in a litre of air. So that's not going to suck in more vapour past even a halfassed seal in a flexible bottle. (the fluid will expand a little as well, I assume, but again by tiny amounts)
https://epicbleedsolutions.com/blogs/faq/what-is-meant-by-wet-and-dry-boiling-points-of-brake-fluid
The master cylinder reservoir in cars is typically vented to the atmosphere. "Wet" brake fluid is apparently defined as 3.7% water, which is typically 2 years exposure to the atmosphere (but will obviously vary according to humidity). From this figure, the higher performance DOT 4 fluids will still have a boiling point of over 200 degrees C after 2 years left in an open container.
Bike brake systems are sealed, so there is no transfer of moisture from the atmosphere to the fluid. If you flush and bleed them with fresh DOT 5.1 fluid, they should be good for years. The water absorption thing is hugely exaggerated.
According to manufacturer claims, Shimano fluid has a similar boiling point to fresh DOT fluid. Magura fluid has a strangely low boiling point, I suspect that is mistaken.
The (probably only theoretical) concern with mineral oil is that it does not absorb water like DOT fluid, so any water in the system will pool at the lowest point, which is the caliper, which is also the hottest part of the system. In DOT fluid, if moisture does get into the system (for example, if you pressure wash your bike and blow water past the caliper seals), the water will be absorbed by the fluid and distributed throughout the system. It will reduce the boiling point, but only by a small amount. With mineral oil, because the water isn't absorbed into the fluid, it will still boil at 100 degrees at atmospheric pressure, which is much lower than wet DOT fluid. So, if water actually does get into the system, mineral oil is probably worse than DOT.
I personally think this is extremely unlikely to happen unless you abuse your bike horribly, but the theory that DOT fluid goes bad after a few months and that mineral oil has a higher boiling point just doesn't hold up. They both work fine if you don't go doing anything really stupid. I have a mixture of Hayes, Avid, and Shimano brakes on my bikes. They all work fine (but I don't ride in the Alps, so not much chance of boiling the fluid, even if I filled them with tap water).
Formula Cura 4 must be up there with the best, they seem to be quite rare so don't get many mentions. Even the Cura 2 pots are meant to be incredible so the 4's can't be far off Trickstuff but considerably cheaper. Formula also seem to be very reliable.
There was a company a while back called Gatorbrake which made an 8 piston brake but I’ve only ever seen one pair for sale second hand.
I have a set on one of my cargo bikes, 230mm rotors front and rear. Horrible levers that you could fit all your fingers on but I just want to be able to stop when loaded up with me (90kg + 2 25kg kids)
Loic Bruni likes his brakes
https://www.magura.com/en/components/news/2018/development-story-loic-brunis-lever/
Give me Bruni's paycheck and I'll tell you how awesome Magura brakes are.
I won't mention the self tapper wood screw in the bar clamp or the plastic lever body with more flex than your Apollo V brake levers.
Are the V4s noticeably more powerful than the E4s or do they just deal with heat build up better. Toyed with the idea of swapping my E4 caliper for a V4.
