Ultegra Disc vs Mech how much weight

[arevir]

Hi, just wondering anyone know a reliable place to get a weight difference
I have seen 450g going disc is that about right?

Shimano ST-RS685, BR-RS785 and 160mm rotors
Vs
6800 set

Thank you.

[jeffy]

685 shifters are about 150g the pair heavier than 105 shifters.
140mm Rotors ~90g each

[ourmanflint]

Plus frames tend be beefier and therefore heavier as well. TRP Spyres are 350g a set plus as jeffy said around 90g each rotor. So I reckon it's more like 700g heavier than mechanical all told

[arevir]

wow I was expecting around 500g
I just found where I read around 450g
https://intheknowcycling.com/2015/01/15 ... oad-bikes/

[CBJ]

2017 Dura Ace will have new calibers which should bring the weight down even more. The 785s do have some amazing power and modulation but its not the weightweenie choice. I am still a little afraid of putting my GT Grade on the scale after it replaced my 6.5Kg no dics Roubaix.

[jeffy]

BR-RS685 caliper with pad is ~ 120g (240g pair)
6800 pair calipers with pads = 341g

rs 685 shifter = 640g
5800 shifters = 486g
6800 shifters = 425g
9000 shifters = 364g

so basically the weight difference is all in the shifters except for the weight of one rotor (other rotor offset by the lighter calipers)

so allowing for a full ultegra rim brake system thats ~315g lighter from the rim brake equivalent, with the caveat that brake cables are heavier than fluid - and that you will likely have hubs that are ~70 grams heavier for the pair. The hubs can certainly be mitigated - but it will be costly.

A full ultegra rim-brake system is probably $200 cheaper.

No doubt prices will fall relatively quickly. and choice needs to open up.

[maxxevv]

Rs685 shifters + Calipers + Discs + Hub weight penalty= 640+240+180 + 60 = 1120g

As Jeffy listed, that's the tabulated weight above.

Ultegra 6800 shifters + Rim Calipers + Rim weight penalty = 425 + 341 + 70 = 836

But if you look at disc specific rims, you can get a respectable 35g lighter per rim ( DT R440 vs a WTB CX Team i-19) for rims without a rim brake surface.

So if you ignore the cables and frame difference ( which I have no data on), the optimised weight penalty is about 1120-836 =~284g

Which isn't too shabby.

[ourmanflint]

Rs685 shifters + Calipers + Discs + Hub weight penalty= 640+240+180 + 60 = 1120g

As Jeffy listed, that's the tabulated weight above.

Ultegra 6800 shifters + Rim Calipers + Rim weight penalty = 425 + 341 + 70 = 836

But if you look at disc specific rims, you can get a respectable 35g lighter per rim ( DT R440 vs a WTB CX Team i-19) for rims without a rim brake surface.

So if you ignore the cables and frame difference ( which I have no data on), the optimised weight penalty is about 1120-836 =~284g

Which isn't too shabby.

Have you tried to find disc wheels that are actually lighter than rim wheels? I think you will find most of them about 200g heavier than rim counterparts. Also frames are considerably heavier as well.

I stand by the 700g heavier all told. It would take some insane spending power to lower it, though it can be done

[maxxevv]

Have you looked at how the figures and understood how they were derived before jumping on them ?

A DT 240S StraightPull hubset without disc weigh (FR/R) : 107/212

A DT 240S StraightPull hubset with centerloc mount weigh (FR/R): 126/228

Weight (total for the set) penalty : 35g. ( I listed 70g above)

A DT R440 rim for rim brakes : 450g. A WTB CX Team i-19 rim without braking surface : 417g

Weight penalty for pair of rims with rim braking surface: 66g.
Both rims above have almost identical ERD's, so they can use identical spokes and nipples.

So if you based on what I list here, you can actually build a disc specific, 20mm profile, 32s wheelset that's actually 31g lighter than a rim specific build!

Now... show me where did you derive your 700g difference from then ??

[jeffy]

apparently the rim and disc version of the Domane SLR are close enough in weight for the difference to be described as negligible.

[ourmanflint]

Have you looked at how the figures and understood how they were derived before jumping on them ?

A DT 240S StraightPull hubset without disc weigh (FR/R) : 107/212

A DT 240S StraightPull hubset with centerloc mount weigh (FR/R): 126/228

Weight (total for the set) penalty : 35g. ( I listed 70g above)

A DT R440 rim for rim brakes : 450g. A WTB CX Team i-19 rim without braking surface : 417g

Weight penalty for pair of rims with rim braking surface: 66g.
Both rims above have almost identical ERD's, so they can use identical spokes and nipples.

So if you based on what I list here, you can actually build a disc specific, 20mm profile, 32s wheelset that's actually 31g lighter than a rim specific build!

Now... show me where did you derive your 700g difference from then ??

I didn't mean to imply you were wrong on the specifics you gave, but in a more general sense if you look at stock wheels for discs an d rim brakes, there is usually a weight penalty of between 150-200g.

My synapse carbon disc frame in 56 is 400g heavier than normal synapse

[mpulsiv]

Hi, just wondering anyone know a reliable place to get a weight difference
I have seen 450g going disc is that about right?

Shimano ST-RS685, BR-RS785 and 160mm rotors
Vs
6800 set

Thank you.

BR-RS785 has been around for 2 years. Look for new flat mount BR-RS805. ~160 grams lighter and slimmer design. However your frame must support flat mount. Last I checked only Scott and Fuji introduced this in 2016 models. I hope see a handful of frames with flat mount by late fall.
Weights and specs https://www.bike24.com/1.php?content=8; ... ,4,320,322

[phlip]

An example:

[madcow]

We've done quite a few near identical builds using mechanical/mechanical, mechanical/hydraulic and electronic/hydraulic. You can move spec all over the place to produce a variety of results. If comparing two equal bikes setup for high end performance the weight difference is almost always 450-500 grams. Here's a comparison of two builds one in disc and one in rim brake, but using parts that represent the correct level. This is based on a straight Ultegra group vs a mechanical/hydraulic (685/Ultegra) setup. As mentioned it would be possible to do a lighter disc version, but then to be fair you could also do a lighter rim brake version and the differences would stay roughly the same.

Frame, Disc frame +30 grams
Fork, Disc fork, +40 grams
Skewers, Disc thru axles +70 grams
Hubs, Disc centerlock hubs +20 grams
Rims, Disc rims -70 grams
Rotors, 160mm centerlock with lockrings, +260 grams
Shifter/caliper setup +106 grams disc (The comparison here was Set 1, Ultegra shifter, Ultegra calipers with pads and moutning bolts as well as brake cables and housing compared to R685 shifter, 785 calipers with pads, hydraulic lines, fluid, mounting bolts but without any adapters which may or may not be required.)
Spokes +26 grams disc (based on the idea that disc front wheels need to be a min of 24 spoke but most rim brake fronts are 20, CxRay of course)

That puts the difference between these two builds at 480 grams, or roughly 1.1 pounds. That's the most realistic estimate we've been able to come up with and it's the one we use when talking with customers, "good rule of thumb, disc brakes will be about a pound heavier than rim brakes."

[Calnago]

Perfect @Madcow. That will be my "rule of thumb" going forward as well... about a pound. Thanks.