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- Finland
Some weird stuff has been going on with my bikes' brakes lately. Some combinations work, others don't, and there's no logic to it. Boring experiment results incoming.
When I built the fatbike I bought brand new Shimano RT66 rotors for it, I've had a pair (which we'll return to later) for more than a decade and they're known to be good. The actual brakes were old but freshly serviced M675 SLXs with their original resin pads, and it just didn't decelerate like it should. Even the first generation servo wave Shimanos feel like dropping the anchor when everything works but in this case something certainly didn't. Very low braking power and horrible squealing to add to the mix.
The next thing to try was a full set of used but barely worn sintered pads, just about nothing changed. Still very little power, sounding like someone is being tortured, and overall an abysmal performance. I figured that there must be something wrong with the brakes themselves and ordered a set of new M6100 Deores, my daily beater has those and they have an ergonomic advantage with the I-Spec shifter so they were a good choice.
Yet, with the new brakes and obviously new pads fitted... still the same situation. Logically thinking the rotors were the only thing that could make a difference anymore so I went looking for the old RT66s, noticing a small difference when at it. The old ones have sharp edges everywhere, looking like laser cut or something, but the new ones have all the edges rounded. Machined like that or nowadays made by stamping, no idea. It may be simply because at one point there was the huge panic of rotors just about decapitating people in crashes or at least that's how it was made to sound like.
The rotors indeed were the culprit as I put the old ones on and the problems immediately disappeared. Proper biting power and no squealing so it's pretty clear that the rotors just don't work, but this is where things get weird. I mounted the problem pair on my daily beater and set off with the intention of either crashing on the first corner with no brakes or getting some experience about what's wrong. Admittedly the first braking felt a bit soft but on the second one everything was fine, and has been since.
The only explanation I can come up with is that the rotors had to be broken in somehow, even though I've never heard of such a thing. Pads, yes, but not rotors. Until now they've always been ridden in pretty cold conditions and low speeds as the fatty just crawls forward so perhaps there's some truth to it, now it was a relatively warm day and I hit the brakes hard from 30+ km/h on tarmac which puts a whole different level of stress on them. Either that, no idea really, or they just didn't work with any of the previous pads but happened to be a good match with these ones. I don't know what the pads are actually, they may be stock M6100 equipment or they may not as the entire brakes originate from my Chisel and it wouldn't be unheard of to have non-standard OEM pads fitted on what is basically a club level racer. Got to check them some day.
When I built the fatbike I bought brand new Shimano RT66 rotors for it, I've had a pair (which we'll return to later) for more than a decade and they're known to be good. The actual brakes were old but freshly serviced M675 SLXs with their original resin pads, and it just didn't decelerate like it should. Even the first generation servo wave Shimanos feel like dropping the anchor when everything works but in this case something certainly didn't. Very low braking power and horrible squealing to add to the mix.
The next thing to try was a full set of used but barely worn sintered pads, just about nothing changed. Still very little power, sounding like someone is being tortured, and overall an abysmal performance. I figured that there must be something wrong with the brakes themselves and ordered a set of new M6100 Deores, my daily beater has those and they have an ergonomic advantage with the I-Spec shifter so they were a good choice.
Yet, with the new brakes and obviously new pads fitted... still the same situation. Logically thinking the rotors were the only thing that could make a difference anymore so I went looking for the old RT66s, noticing a small difference when at it. The old ones have sharp edges everywhere, looking like laser cut or something, but the new ones have all the edges rounded. Machined like that or nowadays made by stamping, no idea. It may be simply because at one point there was the huge panic of rotors just about decapitating people in crashes or at least that's how it was made to sound like.
The rotors indeed were the culprit as I put the old ones on and the problems immediately disappeared. Proper biting power and no squealing so it's pretty clear that the rotors just don't work, but this is where things get weird. I mounted the problem pair on my daily beater and set off with the intention of either crashing on the first corner with no brakes or getting some experience about what's wrong. Admittedly the first braking felt a bit soft but on the second one everything was fine, and has been since.
The only explanation I can come up with is that the rotors had to be broken in somehow, even though I've never heard of such a thing. Pads, yes, but not rotors. Until now they've always been ridden in pretty cold conditions and low speeds as the fatty just crawls forward so perhaps there's some truth to it, now it was a relatively warm day and I hit the brakes hard from 30+ km/h on tarmac which puts a whole different level of stress on them. Either that, no idea really, or they just didn't work with any of the previous pads but happened to be a good match with these ones. I don't know what the pads are actually, they may be stock M6100 equipment or they may not as the entire brakes originate from my Chisel and it wouldn't be unheard of to have non-standard OEM pads fitted on what is basically a club level racer. Got to check them some day.
