I wave these brakes on a trek 3900 I Rebuild from leftover parts from my other bikes+ some new ones, So this is a bike I don’t ride often, But 2 years ago I rode these the bike with these brakes the whole winter, in various temperatures down to -11 Celsius ,And of course I used the brakes very often, but I noticed oil leaking trough the master cylinder on the left/rear brake, So I checked it it was the Torx screws that were the issue, but that was not the case, the threads I in the master cylinder were destroyed, they were polished to powder, so the screws did not hold the seal and the lid in place properly, so I ordered a new complete lever, but after only 2 trips about 10 Km each trip, the part which pushes the got scratched,and this was not caused by a crash, these brakes are just too weak.
The lever body is flexing when you press the lever blade all the way, Which I probably why the part that pushes the piston in gets scratched, and why the threads fail, and why the brake leak.
But there is significantly less flex in the 396 than m615, the m615 flex about halfway, and the m396 flex at near to all the way.
This is a way too flexible & weak brake, I strongly advise against buying these.
.I have used these brakes on 3 bikes, some more than others, until they failed.
No banjo fitting
The brake lever body/Master cylinder flex when braking harder than 50%,which is why the plastic lid & the separator & the Master piston unit to bend or get damaged, and cause leaks, so the lever will be soaked in oil, and oil will spit out through the middle where the plastic lid is.I compared the flexing in the levers on m396&m615 and there is significantly more flex in the m615, if you press the lever blade half way you wont see flex on the m396,but on the m615 you will.
Leaking caused by plastic cover bending upwards, and front and the back is also being pushed upwards but sideways too, causing a leak.
temperature changes, will cause changes to the materials, a minor hit can cause this. the design is clearly flawed.
I had to replace one master cylinder due to failed threads, and I had the leaking issues with the new one too.
Impossible so far to get placement seals/grommets/diaphragms, or just the master cylinder separately.
The cause of failure was certainly not over torquing the screws, It certainly was not a crash that caused it,because I never crashed with this particular brake.
Hinged clamp,no need to remove grips & shifter.
the levers are easy to bend back if you bent them,which I have done on 2 bikes so far.
good braking power,at least if you use Metal pads
it’s not too expensive
it’s not too heavy
no need to take off grips to take off the brake, because of the swing arm clamping mechanism.
The Brake Lever will bend if you crash into a tree(before I upgraded the handle bars i was used to ride on the fuel ex 7 with 720 bars),at low-speed,don’t just let the bike fall on the ground,it can bend the brake lever.
You can of course bend it back with proper tools and technique.
M615 Piston seals: the number written on pistons seals.
IUY 21.1 25 3.19 78 NOK
The Both brakes are too fragile.
Because the brake lever body/master cylinder is way too flexible and that there is a palstic lid,instead of metal lid,which causes the brake to leak.
I have seen a lot of reviews claiming these brakes are a good value at a low price point.
I agree with the braking power for the money is there, but not the reliability, these brakes are too fragile.
same goes for the other brakes with the similar design, for example, M396, M395, but at least it’s possible to get Reservoir Lid Unit for M396, M395.
The only reason I purchased it was because I had to have something fast.
This is a very flimsy assortment box, & am ran out of space in them.
Overpriced, low quality, easelywhichI can’t recommend this product at all.
the plastic hinges are all different, one falls off if I try to close the box open the case.
There is risk of the plastic hinges falling off, but there is even greater chance of the hinges falling off if you drop the box.the transparent cover, does not cover/close properly, which leaves a gap so tiny parts can fall out.
the design wastes space which could be used to store something in, strange shapes which are silly, this looks m ore like a kids toy that a proper assortment box for professionals.
One more thing I hate about this box is that you can’t stack them, if I put one on top of the another one it moves in all directions, and there is no way to secure them together.
Even trough the guide itself is made of plastic, it held up well.
I have been riding pretty fast in rough terrain, up and down steep trails, jumped, did some stunts, and drops, riding down steep stairs(40-50 degrees)in low gears, the chain never came off, there were not many signs of wear, but eventually you will have to change the guide,(the plastic part with Mrp logo), but I have been using it over a year and held up well, not much wear.
one of my first thought about the guard was it might get much mud stuck in it, but even though I have been riding in bad weather, there were not much dirt or mud stuck in there. But as long as you don’t ride in extreme condition, with a lot of mud, in something like Danny Hart’s 2011 world cup run, or even thicker mud, I am sure It won’t be an issue.
I there was some missing spacers, and I lost some of the thin spacers,but later I found them, so I switched to 2x thin spacers, which should, be better, but I still think bigger gravel can get stuck in between the chain ring and chain guide, but this is impossible to avoid.
But Now as I have a Sortimo boxes I don’t have a mess so it won’t loose any more small parts.
Make sure you Use the right spacers.
After riding a lot in the spring I noticed scrape on the 36T cinch narrow wide race face chainring, which I think is caused by a stone getting stuck between the chainring and the chain guide, causing a perfect circle scrape.
I had the bike in the repair stand, after riding on gravel paths, I noticed that there was a stone stuck in the chain guide and was scraping the chainring, and fell down again, I think that’s what happen the last time.
Very easy to install, & setup, No need to remove crankset or chainring to install the chain guide,
Minimalistic design, no bulky or unnecessary big parts.
after few hits, no damage done
all of the guides I got had missing thick spacers, and missing short screws.
Mrp claims it should fit 38 T chainring, But in my opinion, 36T is the max, with 38T the plastic will be too close to the edge of the chain. so if the guard was few millimetres bigger, it would fix 38T better, but I don’t need a 38T ring anyway.
Not properly Oval compatible:
Although MRP list this guide as Oval compatible it does not work as well with oval, due to the ovality of the chainring, the narrowest point of the oval causes more room and the chain could squeeze trough between the ring and guide.