Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Ultegra R8020 VS 105 R7020 - A question for the weight weenies

Notices
Road Cycling It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle. -- Ernest Hemingway

Ultegra R8020 VS 105 R7020 - A question for the weight weenies

Old 10-02-20, 11:03 AM
  #1  
Plainsman
Senior Member
Thread Starter
 
Join Date: Jan 2005
Posts: 1,475
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 159 Post(s)
Liked 32 Times in 24 Posts
Ultegra R8020 VS 105 R7020 - A question for the weight weenies

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
Plainsman is offline  
Old 10-02-20, 11:44 AM
  #2  
friday1970
Senior Member
 
friday1970's Avatar
 
Join Date: Sep 2012
Location: Brighton, Michigan
Posts: 638

Bikes: Optima Baron LR, '14 Nishiki Maricopa,'87 Trek 330 Elance, '89 Miyata 1400, '85 Peugeot PGN10, '04 Fuji Ace, '06 Giant Rincon, '95 Giant Allegre, '83 Trek 620, '86 Schwinn High Sierra

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 218 Post(s)
Liked 150 Times in 98 Posts
I'd love to see other mfr's groupsets added to the mix too, such as MicroShift's and Sensah's.
friday1970 is offline  
Old 10-02-20, 11:54 AM
  #3  
Ogsarg
Senior Member
 
Join Date: Feb 2017
Location: Hollister, CA (not the surf town)
Posts: 1,606

Bikes: 2019 Specialized Roubaix Comp Di2, 2009 Roubaix, early 90's Giant Iguana

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 595 Post(s)
Liked 1,188 Times in 467 Posts
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.
Ogsarg is online now  
Likes For Ogsarg:
Old 10-02-20, 12:40 PM
  #4  
Mojo31
-------
 
Join Date: Jul 2020
Location: Tejas
Posts: 9,537
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 7262 Post(s)
Liked 4,575 Times in 2,499 Posts
Check out the disc brakes on your car. Front is almost always a larger disc on front.
Mojo31 is offline  
Likes For Mojo31:
Old 10-02-20, 12:56 PM
  #5  
surak
Senior Member
 
surak's Avatar
 
Join Date: Nov 2017
Location: Seattle
Posts: 1,826

Bikes: Specialized Roubaix, Canyon Inflite AL SLX, Ibis Ripley AF, Priority Continuum Onyx, Santana Vision, Kent Dual-Drive Tandem

Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 811 Post(s)
Liked 663 Times in 390 Posts
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.
surak is offline  
Likes For surak:
Old 10-02-20, 01:58 PM
  #6  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 39,330

Bikes: R3 Disc, Haanjo

Mentioned: 353 Post(s)
Tagged: 1 Thread(s)
Quoted: 20611 Post(s)
Liked 9,283 Times in 4,597 Posts
Originally Posted by surak View Post
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.
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.
WhyFi is offline  
Old 10-02-20, 02:10 PM
  #7  
sfrider 
Asleep at the bars
 
sfrider's Avatar
 
Join Date: May 2006
Location: San Francisco, CA and Treasure Island, FL
Posts: 1,735
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 230 Post(s)
Liked 203 Times in 135 Posts
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.
__________________
"This 7:48 cycling session burned 5933 calories. Speed up recovery by replacing them with a healthy snack." - Whoop

sfrider is offline  
Old 10-02-20, 02:54 PM
  #8  
PoorInRichfield
Senior Member
 
Join Date: Nov 2013
Location: Richfield, WI
Posts: 640

Bikes: Trek Domane SL7 Disc, Cannondale F29

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 351 Post(s)
Liked 264 Times in 161 Posts
Originally Posted by Plainsman View Post
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?
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.
PoorInRichfield is offline  
Old 10-02-20, 05:45 PM
  #9  
oleg232000
Senior Member
 
Join Date: Mar 2017
Location: Cali
Posts: 118

Bikes: Litepseed Catalyst Neutral Support Bike, La Pierre Spicy Team, Mercier Kilo TT, Cannondale Multisport2000, Goffa BMX, Haro Dave Mirra Freestyle

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 82 Post(s)
Liked 21 Times in 12 Posts
Umm what happened on the groupset weight comparison

IM curious myself
oleg232000 is offline  
Likes For oleg232000:
Old 10-02-20, 06:24 PM
  #10  
PoorInRichfield
Senior Member
 
Join Date: Nov 2013
Location: Richfield, WI
Posts: 640

Bikes: Trek Domane SL7 Disc, Cannondale F29

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 351 Post(s)
Liked 264 Times in 161 Posts
https://ccache.cc/blogs/newsroom/201...ght-comparison
PoorInRichfield is offline  
Likes For PoorInRichfield:
Old 10-02-20, 06:57 PM
  #11  
Plainsman
Senior Member
Thread Starter
 
Join Date: Jan 2005
Posts: 1,475
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 159 Post(s)
Liked 32 Times in 24 Posts
Originally Posted by PoorInRichfield View Post
Perfect, thanks!!!
Plainsman is offline  
Old 10-02-20, 07:50 PM
  #12  
Robert A
Senior Member
 
Join Date: Sep 2012
Location: Los Angeles
Posts: 750

Bikes: 2019 CAAD12, 2015 Specialized Sirrus Comp

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 559 Post(s)
Likes: 0
Liked 62 Times in 44 Posts
Originally Posted by PoorInRichfield View Post
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?
Robert A is offline  
Old 10-02-20, 09:11 PM
  #13  
Plainsman
Senior Member
Thread Starter
 
Join Date: Jan 2005
Posts: 1,475
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 159 Post(s)
Liked 32 Times in 24 Posts
Originally Posted by Robert A View Post
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?
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.
Plainsman is offline  
Old 10-02-20, 09:46 PM
  #14  
ridethecliche
Batw Creakcreak
 
Join Date: Jan 2007
Location: The illadelph
Posts: 20,756
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 215 Post(s)
Liked 273 Times in 150 Posts
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.
ridethecliche is offline  
Likes For ridethecliche:
Old 10-03-20, 06:41 AM
  #15  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 6,697
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 6074 Post(s)
Liked 9,196 Times in 3,976 Posts
Originally Posted by Plainsman View Post
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.
I think the comparison shows groupset weights. Beefier frame and fork, and thru-axles, would be on top of that.
Koyote is online now  
Old 10-03-20, 09:33 AM
  #16  
Sy Reene
Advocatus Diaboli
 
Sy Reene's Avatar
 
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,193

Bikes: Merlin Cyrene, Nashbar steel CX

Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4446 Post(s)
Liked 1,348 Times in 875 Posts
Originally Posted by Koyote View Post
I think the comparison shows groupset weights. Beefier frame and fork, and thru-axles, would be on top of that.
Would rotors be a part of those group weights also?
Sy Reene is offline  
Old 10-03-20, 10:18 AM
  #17  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 6,697
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 6074 Post(s)
Liked 9,196 Times in 3,976 Posts
Originally Posted by Sy Reene View Post
Would rotors be a part of those group weights also?
For the disc groupset, I would assume so, yes.
Koyote is online now  
Old 10-03-20, 11:17 AM
  #18  
Sy Reene
Advocatus Diaboli
 
Sy Reene's Avatar
 
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,193

Bikes: Merlin Cyrene, Nashbar steel CX

Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4446 Post(s)
Liked 1,348 Times in 875 Posts
Originally Posted by Koyote View Post
For the disc groupset, I would assume so, yes.
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
Sy Reene is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.