Go Back  Bike Forums > Bike Forums > Cyclocross and Gravelbiking (Recreational)
Reload this Page >

Silly question about frame geometry of gravel bikes

Notices
Cyclocross and Gravelbiking (Recreational) This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like : "Unbound Gravel". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

Silly question about frame geometry of gravel bikes

Old 02-07-19, 05:42 AM
  #1  
Aznman
Senior Member
Thread Starter
 
Join Date: Jan 2013
Posts: 218
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 3 Times in 3 Posts
Silly question about frame geometry of gravel bikes

I've noticed that all of the gravel bikes that I have seen so far have top tubes that are shorter than their respective 'effective top tubes' (i.e. the top tubes are more parallel with the down tubes).


The above mentioned trend is so dominant that I have to ask: in the industry's terms, would a bike still be considered a 'gravel bike' if it has nearly all the same forks, wheels, tyres, and other parts but uses a 'Randonneur type' frame instead (where the top tubes are parallet to the theorectically flat ground; where the top tubes are the 'effective top tubes')?
Aznman is offline  
Old 02-07-19, 07:55 AM
  #2  
Hmmm
Full Member
 
Hmmm's Avatar
 
Join Date: Nov 2014
Location: Paris, France
Posts: 399

Bikes: TCX & CAAD3 SAECO

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 147 Post(s)
Liked 118 Times in 66 Posts
Sloping top tubes are an abomination. Long live the horizontal top tube.
Hmmm is offline  
Old 02-07-19, 07:56 AM
  #3  
Aznman
Senior Member
Thread Starter
 
Join Date: Jan 2013
Posts: 218
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by hmmm
sloping top tubes are an abomination. Long live the horizontal top tube.
Can't say whether I agree or disagree.
Aznman is offline  
Old 02-07-19, 08:02 AM
  #4  
Lemond1985
Sophomore Member
 
Lemond1985's Avatar
 
Join Date: Jan 2019
Posts: 2,690
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1628 Post(s)
Liked 1,057 Times in 631 Posts
Well, ask a silly question, get a silly answer. My silly answer is that if this "sloping top tube" trend continues unabated, then 20 years from now, us guys will all be riding girl's step-through frames (as well as wearing dresses and playing with dolls).
Lemond1985 is offline  
Old 02-07-19, 08:48 AM
  #5  
Aznman
Senior Member
Thread Starter
 
Join Date: Jan 2013
Posts: 218
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by Lemond1985
Well, ask a silly question, get a silly answer. My silly answer is that if this "sloping top tube" trend continues unabated, then 20 years from now, us guys will all be riding girl's step-through frames (as well as wearing dresses and playing with dolls).
Serious question and hopefully informative answer then.
Why are virtually all gravel specific bikes made and bought with sloping top tubes?
Aznman is offline  
Old 02-07-19, 10:45 AM
  #6  
Elvo
Senior Member
 
Join Date: Oct 2006
Location: Orange County, CA
Posts: 4,770
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 630 Post(s)
Likes: 0
Liked 369 Times in 206 Posts
The trend for shorter reach and maintaining relatively high stack heights
Elvo is offline  
Old 02-07-19, 10:54 AM
  #7  
tyrion
Senior Member
 
tyrion's Avatar
 
Join Date: Oct 2015
Location: San Diego, California
Posts: 4,077

Bikes: Velo Orange Piolet

Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 2228 Post(s)
Liked 2,011 Times in 972 Posts
Higher stack + crotch room. Without the crotch room it's just a rando bike.

Seriously, I think the whole slanted top tube thing is to allow a single frame size to accommodate a wider range of human sizes, so a manufacturer can get by with 5 frame sizes instead of 6. Yet another way to cut costs.

Last edited by tyrion; 02-07-19 at 10:58 AM.
tyrion is offline  
Old 02-07-19, 11:01 AM
  #8  
mstateglfr 
Sunshine
 
mstateglfr's Avatar
 
Join Date: Aug 2014
Location: Des Moines, IA
Posts: 16,535

Bikes: '18 class built steel roadbike, '19 Fairlight Secan, '88 Schwinn Premis , Black Mountain Cycles Monstercross V4, '89 Novara Trionfo

Mentioned: 123 Post(s)
Tagged: 0 Thread(s)
Quoted: 10901 Post(s)
Liked 7,390 Times in 4,148 Posts
Originally Posted by Aznman
: in the industry's terms, would a bike still be considered a 'gravel bike' if it has nearly all the same forks, wheels, tyres, and other parts but uses a 'Randonneur type' frame instead (where the top tubes are parallet to the theorectically flat ground; where the top tubes are the 'effective top tubes')?
If the important geometry is the same, then sure it's a gravel bike. Call it that if you want...it isn't a big deal either way.

if a level top tube frame and a sloping top tube frame have identical HTA, STA, trail, bottom bracket drop, tire clearance, chainstay length, stack height, and reach- then yeah they are capable of doing the same things and feel free to call them the same thing.

a decent real world example-
I have a black mountain cycles gravel frame with canti brakes that uses a level top tube. The disc brake frame has almost identical geometey, but uses a sloping top tube to get a higher stack height as that's the one measurement thats different.
both are gravel frames.
mstateglfr is offline  
Old 02-07-19, 11:17 AM
  #9  
Aznman
Senior Member
Thread Starter
 
Join Date: Jan 2013
Posts: 218
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by mstateglfr
If the important geometry is the same, then sure it's a gravel bike. Call it that if you want...it isn't a big deal either way.

if a level top tube frame and a sloping top tube frame have identical HTA, STA, trail, bottom bracket drop, tire clearance, chainstay length, stack height, and reach- then yeah they are capable of doing the same things and feel free to call them the same thing.

a decent real world example-
I have a black mountain cycles gravel frame with canti brakes that uses a level top tube. The disc brake frame has almost identical geometey, but uses a sloping top tube to get a higher stack height as that's the one measurement thats different.
both are gravel frames.
Awesome. Many thanks.
Aznman is offline  
Old 02-07-19, 11:31 AM
  #10  
Phamilton
Virgo
 
Phamilton's Avatar
 
Join Date: Oct 2014
Location: KFWA
Posts: 1,273

Bikes: A touring bike and a hybrid

Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 454 Post(s)
Liked 97 Times in 69 Posts
You probably won't see many level top tube frames MARKETED/SOLD as gravel bikes, but I don't think there are that many level top tube frames on the market anyway. My commuter has a slightly sloping top tube, was sold as a hybrid when new, has cantis, clearance for 38mm tires, gravel/cross geometry, etc. I think I could call it a gravel bike if I wanted to, but I don't do "gravel rides" aside from an occasional 1 mile stretch of a gravel road on my commute, which my bike handles admirably. In other words, if a frame works for a certain purpose, isn't it whatever you make it to be?

Phamilton is offline  
Old 02-07-19, 12:48 PM
  #11  
BluesDawg
just keep riding
 
BluesDawg's Avatar
 
Join Date: Feb 2005
Location: Milledgeville, Georgia
Posts: 13,560

Bikes: 2018 Black Mountain Cycles MCD,2017 Advocate Cycles Seldom Seen Drop Bar, 2017 Niner Jet 9 Alloy, 2015 Zukas custom road, 2003 KHS Milano Tandem, 1986 Nishiki Cadence rigid MTB, 1980ish Fuji S-12S

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 173 Post(s)
Liked 33 Times in 22 Posts
Originally Posted by mstateglfr
If the important geometry is the same, then sure it's a gravel bike. Call it that if you want...it isn't a big deal either way.

if a level top tube frame and a sloping top tube frame have identical HTA, STA, trail, bottom bracket drop, tire clearance, chainstay length, stack height, and reach- then yeah they are capable of doing the same things and feel free to call them the same thing.

a decent real world example-
I have a black mountain cycles gravel frame with canti brakes that uses a level top tube. The disc brake frame has almost identical geometey, but uses a sloping top tube to get a higher stack height as that's the one measurement thats different.
both are gravel frames.
Great example. In fact, I used to own and ride one of the canti version Black Mtn Monster Cross frames and I now have the new disc version MCD. They both gobble up miles of gravel roads like nothing else I've ridden and they have a very similar fit and feel. The only times I notice the sloping tube on the new bike is having more crotch clearance when I stop and straddle the bike and when I have enough exposed seat post to easily clamp the bike in my work stand.

Sloping top tubes has been the industry norm for road bikes for many years. This is not something specific to gravel bikes. There are some exceptions, but not very many that I am aware of.
BluesDawg is offline  
Old 02-07-19, 12:48 PM
  #12  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 7,765
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,872 Times in 4,637 Posts
A sloping TT might be a small advantage with a gravel bike, as it will better allow a fast and sloppy dismount when the going gets rough. It also allows for more seatpost extended beyond the frame, which might dissipate some shocks and chatter that would otherwise be transmitted to the saddle. But that's not why the manufacturers are putting them on bikes.
Koyote is offline  
Old 02-07-19, 12:54 PM
  #13  
Marcus_Ti
FLIR Kitten to 0.05C
 
Marcus_Ti's Avatar
 
Join Date: Sep 2014
Location: Lincoln, Nebraska
Posts: 5,331

Bikes: Roadie: Seven Axiom Race Ti w/Chorus 11s. CX/Adventure: Carver Gravel Grinder w/ Di2

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 2349 Post(s)
Liked 406 Times in 254 Posts
Originally Posted by Aznman
Serious question and hopefully informative answer then.
Why are virtually all gravel specific bikes made and bought with sloping top tubes?
Virtually all bikes made recently utilize compact frames with sloping top tubes. This is not a uniquely "gravel bikes" phenomenon, this has been an industry-wide trend for years.
Marcus_Ti is offline  
Old 02-07-19, 02:21 PM
  #14  
redlude97
Senior Member
 
Join Date: Sep 2011
Posts: 4,764
Mentioned: 28 Post(s)
Tagged: 0 Thread(s)
Quoted: 1975 Post(s)
Liked 232 Times in 173 Posts
Just buy a cyclocross bike, they almost all have horizontal top tubes still for shouldering
redlude97 is offline  
Old 02-07-19, 03:17 PM
  #15  
Caliper
Senior Member
 
Join Date: May 2014
Location: Michigan
Posts: 990

Bikes: Many

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 385 Post(s)
Liked 58 Times in 43 Posts
Originally Posted by Aznman
I've noticed that all of the gravel bikes that I have seen so far have top tubes that are shorter than their respective 'effective top tubes' (i.e. the top tubes are more parallel with the down tubes).

The above mentioned trend is so dominant that I have to ask: in the industry's terms, would a bike still be considered a 'gravel bike' if it has nearly all the same forks, wheels, tyres, and other parts but uses a 'Randonneur type' frame instead (where the top tubes are parallet to the theorectically flat ground; where the top tubes are the 'effective top tubes')?
Considering that the paved road bikes also have a sloping top tube, I'd simply call it a feature of modern frame design and not think that it has any serious impact on what type of bike something is.
Caliper is offline  
Old 02-07-19, 07:26 PM
  #16  
koolerb
Senior Member
 
koolerb's Avatar
 
Join Date: Oct 2012
Location: Upstate NY
Posts: 1,082

Bikes: CAAD 12, ROS 9+, and some others

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked 13 Times in 11 Posts
I think gravel vs rando, the gravel bike will tend to have less BB drop, and a shorter chainstay. So, slightly higher BB and quicker rear end that a rando bike. That said if you compare geometries on multiple bikes there's overlap all over the place.
koolerb is offline  
Old 02-08-19, 07:05 PM
  #17  
NomarsGirl
Senior Member
 
NomarsGirl's Avatar
 
Join Date: Oct 2017
Location: Easton, MA
Posts: 632

Bikes: Specialized Ruby Sport

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 318 Post(s)
Liked 314 Times in 165 Posts
Originally Posted by Lemond1985
Well, ask a silly question, get a silly answer. My silly answer is that if this "sloping top tube" trend continues unabated, then 20 years from now, us guys will all be riding girl's step-through frames (as well as wearing dresses and playing with dolls).
I never understood why men's bikes had the horizontal top tube. Seems you guys need the clearance more than us ladies do. We don't have dangling bits to worry about smashing.
NomarsGirl is offline  
Old 02-08-19, 08:32 PM
  #18  
Cyclist0108
Occam's Rotor
 
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times in 1,164 Posts
Originally Posted by Aznman
I've noticed that all of the gravel bikes that I have seen so far have top tubes that are shorter than their respective 'effective top tubes' (i.e. the top tubes are more parallel with the down tubes).
TT = (ETT)*cos θ
Cyclist0108 is offline  
Old 02-08-19, 08:35 PM
  #19  
Cyclist0108
Occam's Rotor
 
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times in 1,164 Posts
Originally Posted by Hmmm
Sloping top tubes are an abomination. Long live the horizontal top tube.
If you have short legs and a long torso, it helps if you want the bars at saddle level.

Last edited by Cyclist0108; 09-26-19 at 02:32 PM.
Cyclist0108 is offline  
Old 02-08-19, 08:46 PM
  #20  
Cyclist0108
Occam's Rotor
 
Join Date: Jul 2013
Posts: 7,248
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 2366 Post(s)
Liked 2,331 Times in 1,164 Posts
Originally Posted by Aznman
Serious question and hopefully informative answer then.
Why are virtually all gravel specific bikes made and bought with sloping top tubes?
I think for gravel people tend to set it up so the tops of the bars are about the same level as the saddle, so it increases the stack relative to the stand-over height.

(Then there are people like me who have short legs, so all our bikes look like this.)
Cyclist0108 is offline  
Old 02-10-19, 10:04 AM
  #21  
BrocLuno
Senior Member
 
BrocLuno's Avatar
 
Join Date: Nov 2018
Location: Kalifornia Kollective
Posts: 350

Bikes: K2 (Marzocchi/Fox), Trek 6000 (red) MARS Elite up front, Specialized Hardrock Sport -> eBike (R7 Elite up front), lastly TREK 820 loaner. Recently sold Peugeot du Monde Record and 1956 Schwinn (owned since new).

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 75 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Me too. 5'11'' with 29" inseam. I'll take a sloping top tube any day
BrocLuno is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
TrailDogger
General Cycling Discussion
6
05-16-16 03:46 PM
inmemoryofpluto
Singlespeed & Fixed Gear
18
04-17-12 03:37 PM
TnBama
Framebuilders
5
03-16-11 11:49 PM
TejanoTrackie
Singlespeed & Fixed Gear
6
10-15-10 12:24 PM
waanfiride
Road Cycling
32
04-28-10 10:06 AM

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 -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.