Plainsman

Wondering if there is a chart somewhere that shows overall groupset weights? I checked the Weight Weenie site but didn't see it for the newest groups. I did find a blog listing the difference in the mechancial groupsets, and it only came out to 164 grams. Any idea the difference in the hydro sets (Ultegra vs 105 Rxxxx series)?

If I can get a bonus question - I'm new to road discs - why do some bikes seem to come with 160mm rotors front and back, and others use 140/160? What is the advantage/difference of mixing rotor sizes?

Thanks!

Tom

friday1970

I'd love to see other mfr's groupsets added to the mix too, such as MicroShift's and Sensah's.

Ogsarg

Larger rotor = more stopping power given the same force applied to the pads. Since most braking is done in the front, having a larger rotor makes sense. Or looking at it another way, putting a smaller rotor on the rear makes it harder to lock up the rear wheel inadvertently.

Mojo31

Check out the disc brakes on your car. Front is almost always a larger disc on front.

surak

My disc brake bikes all came with 160/160, but I converted to 140 on the rear because I much prefer having less of a chance of locking it up. A slight squeeze can still cause a skid just rolling to a stop sign. Shaving some grams doesn't hurt. But I am a lightweight.

It's easier going down from 160 to 140. If a bike is specced with 140 on the rear, it may not come with the mount bracket that takes 160.

WhyFi

If it's a flat mount frame, which is most these days, you can pick up that little Shimano 140->160 wedge pretty easily. For whatever reason, when I bought my R8020 lever and caliper set, the front caliper had the 160 wedge but the rear didn't. I would have just went with 140mm for the rear, but I already had 160mm rotors and didn't want to buy another; I think the wedge was 10 or 15 bucks.

sfrider 

Having them both the same size pretty much only means there is one less potential mistake to be made when buying replacements or setting up a new wheelset.

PoorInRichfield

It's my understanding that the UCI requires a minimum of 160mm front and 140mm rear disc for this year's racing, hence all bikes are following that trend. Since disc brakes are relatively new to the racing scene, standards are still changing a little. You can find quite a few pictures of pro racers with 140/140mm disc brakes from years past, before the rule changed.

I recently went to 140/140 with XTR rotors on my Domane and I have a ton of stopping power. I can't really tell the difference between the previous 160/160mm rotors and my current 140/140mm rotors.

oleg232000

Umm what happened on the groupset weight comparison

IM curious myself

PoorInRichfield

https://ccache.cc/blogs/newsroom/201...ght-comparison

Plainsman

Perfect, thanks!!!

Robert A

Good resource, but one question:

Ultegra R8000 mech/rim = 2272 grams
Ultegra R8020 mech/disk = 2314 grams

If the difference between rim and disc groupsets is so small, what accounts for the extra weight of a disc-brake bike? The fluid?

Plainsman

I was thinking this had to do with the extra weight of through axles as well as the beefier frame and fork needed to handle the asymmetrical force of disc braking.

ridethecliche

Beefier frame, fork, fluid, but also many disc brake bikes come with wider tires. That adds some gramz as well (wider tires plus bigger tubes).

The difference these days should be relatively minimal to be honest.

Koyote

I think the comparison shows groupset weights. Beefier frame and fork, and thru-axles, would be on top of that.

Sy Reene

Would rotors be a part of those group weights also?

Koyote

For the disc groupset, I would assume so, yes.

Sy Reene

Hmm.. a lookup says a pair of Ultegra rotors is about 240g.. assuming the "brake" listing of 286g on the ccache might only be for the calipers? Unless they're lumping caliper weights in with the shifters.. not sure