Fat brakes and rotor size?

[one piece crank]

My Otso came with Magura MT4 brakes. I just took them as they seemed like a decent brake and I didn't want to upgrade to a higher-end Magura for fear I would go back to SRAM anyway. The Maguras have a decent lever feel and significantly more pad/disc clearance, but coming from dialed G2 RSC's, I'm not really loving them. They have significantly less power and while this is not a DH bike, I do explore with it and need precise control or ability to modulate to a stop on super steep inclines. Are the MT4's going to bed in and improve, or should I jump ship now?

Next comes brake rotor size. My Fatboy has 200/180 G2 RSC's, which is a LOT of brake. That bike could lock the front wheel on pavement if I wanted. Should I be OK with 160mm rotors on the Otso (which I like the additional clearance and less deflection), or are the small rotors contributing the the MT4's underwhelming feel?

 

[Mr.Moto]

I have SRAM across the board myself and have not tried the Magura's so I can't comment on them. My thought is trying bigger rotors is a lower cost way to get a little more bite, but not sure if that will get you what you want. I did have 160's on my original fat bike and felt that they were a little underwhelming in tougher conditions.

 

[one piece crank]

That's a good point. 180/Front and spacers would be cheap and the Maguras appear to be good quality plus a 5-year warranty. But I'm all set-up for SRAM maintenance and CODE RSC and G2 RSC prices are dropping like a rock.

 

[one piece crank]

I guess the real question is, how much improvement will I gain going from 160mm to 180mm in front?

 

[Steve Vai]

About 20mm better braking.

 

[Karate Monkey]

I guess the real question is, how much improvement will I gain going from 160mm to 180mm in front?

About 20mm better braking.

Enough you should try it. A brake rotor is cheaper than a new brake 😉

 

[Patrick]

Enough you should try it. A brake rotor is cheaper than a new bike 😉

FTFY

 

[Steve Vai]

I'm gonna say for realz, I don't notice any difference in braking between rotor sizes. I just use whatever rotor size requires no adapter.

 

[one piece crank]

Enough you should try it. A brake rotor is cheaper than a new brake 😉

Yeah, I think I will.

 

[one piece crank]

180 front disc installed. Plan to bed the rotor today.

 

[Paul H]

Slightly off topic question... can you use the 160 to 180 adapter to go 180 to 203?

 

[one piece crank]

Slightly off topic question... can you use the 160 to 180 adapter to go 180 to 203?

I think you’ll need the 180 to 203 adapter

Seriously IDK. Look up your brake and see what adapters are available.

 

[Karate Monkey]

Slightly off topic question... can you use the 160 to 180 adapter to go 180 to 203?

I think you’ll need the 180 to 203 adapter

Seriously IDK. Look up your brake and see what adapters are available.

No, you need a +23 adaptor. Or two 1.5mm washers to put under the caliper, but I'm not your supervisor...I just hate bodging stuff when there is a correct solution.

BTW: the difference between the "regular" PM adaptors from Shimano and the more expensive ones is the bolt head/they are anodized instead of painted. They are only necessary when you have a magnesium caliper, as under perfect[ly wrong] conditions, you can get a situation where the caliper acts as an anode. No need to buy the expensive one unless you have super fancy calipers.

 

[one piece crank]

@Karate Monkey thanks for the translation, I don’t speak Shimano.

 

[one piece crank]

Cleaning, sanding, re-bedding the pads F&R helped a lot too (before the new rotor arrived), so there could have been some contamination on the new bike parts. But stepping the front rotor up to 180mm really did the trick.