160 mm or 140 mm rotors?

[AlanW]

Im just in the process of specing up a new bike, and was pondering over the rotor size. My Trek had 160 mm rotors front and rear and I never had any issues, but I do like the style/look of the smaller 140 mm rotors. I can understand the arguments for both sizes but I would be interested to hear from anyone that has experience on using both sizes.

Of course, 160 mm front and 140 mm rear would be an option, which I guess covers 50% of the style/looks

 

[monkers]

Im just in the process of specing up a new bike, and was pondering over the rotor size. My Trek had 160 mm rotors front and rear and I never had any issues, but I do like the style/look of the smaller 140 mm rotors. I can understand the arguments for both sizes but I would be interested to hear from anyone that has experience on using both sizes.

Of course, 160 mm front and 140 mm rear would be an option, which I guess covers 50% of the style/looks

Hi Alan

My other half has a Liv Langma with 160 front and 140 rear. The 140 provides perfectly adequate braking. There is one downside to the 140 rotor though - the closeness of the caliper to the fork end makes getting the bike on and off the turbo trainer much more awkward, resulting in some paint chips. Of course if you do not intend to use the bike on a turbo, this will never be an issue.

 

[AlanW]

Hi Alan

My other half has a Liv Langma with 160 front and 140 rear. The 140 provides perfectly adequate braking. There is one downside to the 140 rotor though - the closeness of the caliper to the fork end makes getting the bike on and off the turbo trainer much more awkward, resulting in some paint chips. Of course if you do not intend to use the bike on a turbo, this will never be an issue.

Thanks Monkers, interesting point and one that hadn't even crossed my mind to be honest. More so for transporting the bike in the car, as it wont be used on the trainer. But I'm having the frame wrapped like I did with the Trek before its built up, so pretty much zero chance of getting any paint chips...hopefully!

 

[Joffey]

I have SRAM 160mm on my gravel bike which are dire and Ultegra 140mm on my road bike which are excellent.

I am 100kg and using my 140mm Ultegra discs can stop so quickly my Garmin thinks I've crashed and wants to send a help message. You'll be fine with 140mm rotors

PS - I'm not sure how having 160mm rotors would stop paint chips when transporting in the car!

 

[Smokin Joe]

If I was having a frame built it would be with a front disc for stopping power and a rim brake on the back for ease of wheel removal and replacement. Rear disc brakes are overkill, you just don't need them.

 

[CXRAndy]

140mm should be fine for most types of braking you'll encounter. I would be a little concerned if you're a heavy rider and liked going up and down big mountains. Something that takes an hour to descend, then smaller rotors could easily overheat…says 100+kg rider coming down Mt Teide on 160mm rotors.

 

[Cycleops]

Unless you're concerned with your brakes catching fire with steep descents on the Pyrenees the 140s will be fine.

 

[Venod]

I wouldn't put 140 on the front, on the rear it will do do the job, but 160 will do it better.

 

[si_c]

For 99% of the time on a road bike a 140mm rotor will be more than sufficient, regardless of rider/luggage weight. That being said the weight saving between 140mm and 160mm rotors is insignificant, and if you already have a bike with larger rotors then going with the same size will allow you to swap wheels between bikes, which is useful.

On a good day I weigh 100kg and on a very good day 95kg, and I'm currently riding with a 160mm front and 140mm rear rotor setup. In performance terms a 160mm rotor will have more power, greater modulation and better resistance to heat build up, but I'm not sure whether this will be particularly noticeable in day to day riding for most.

 

[AlanW]

Im going to go with 140mm front and rear and see how I get on. Worse case, I can fit an adapter and increase the front to a 160mm if I encounter any issues.

The main concern right now is trying to source a groupset! I have been quoted for a Ultegra Di2 12 speed groupset an estimated delivery date of October 2023, yes, that's not a typo....2023

 

[JoeyB]

I've just switched from 160 Ultegra ice-tech to 140 Dura Ace ice-tech rotors because I've always wanted the black finish on the fins and I also like the look of the smaller rotor.

I've noticed no discernable difference in braking power.

 

[AlanW]

.....because I've always wanted the black finish on the fins and I also like the look of the smaller rotor.

The exact same reason why I have gone for Dura Ace to

 

[Jody]

I've noticed no discernable difference in braking power.

Isn't size more related to heat dissipation?

 

[Venod]

Isn't size more related to heat dissipation?

The more disc you have the easier the heat will be dissipated.

Also the larger the disc increases in diameter, the more torque available to slow the wheel.

 

[Kajjal]

My XC mountain bike has 160mm rotors and my newer FS mountain bike has a 200mm front rotor. The difference is very noticeable, it really depends if more controlled braking power is what you are looking for. I have had the 160mm rotors very hot smelling of burning on long steep off road descents but the braking was fine. The 200m rotors not so far.