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

Wide gearing on a Cross bike using road bike componients

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.

Wide gearing on a Cross bike using road bike componients

Old 09-30-11, 06:54 PM
  #1  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Wide gearing on a Cross bike using road bike components

The Shimano Ultegra "GS" (long arm-road) rear derailleur has huge chain wrap and cog size capacity that is much greater than stated on the Specifications.

I've combined a 50, 39 & 26 Crankset with the 10 speed Tiagra 12-30 cassette. This provides the range of a Compact with a 12-26 cassette using just the large and middle chainring. The 39t middle chainring is good to 25 mph at a 100 rpm cadence. The 26t small chainring and 30t rear cog combination can crawl up a 20% slope at 4 mph with a 60 rpm cadence.

The chain-wrap limit of the Tiagra/105/Ultegra GS, according to Shimano, is 37. I'm operating safely, with every gear combination, using a chain-wrap value of 42. It is also possible to exceed the 27t Cog size capacity and use a 32t.

The practical chain-wrap capacity, with a correct length chain, of the road "GS" RD allows the big-big combination of 50t front Chainring & 30t rear cog with a little safety margin and also allows the small-small combination of 26t & 12t without any slack in the chain.

I also used a Sram 11-32 cassette with a compact last year and had no issues with a 32 size cog. This may not work on all bikes, YMMV.


Last edited by Barrettscv; 10-01-11 at 11:08 AM.
Barrettscv is offline  
Old 09-30-11, 08:48 PM
  #2  
Senior Member
 
canflyboy's Avatar
 
Join Date: Aug 2008
Posts: 204
Likes: 0
Liked 0 Times in 0 Posts
Nice Set up - What FD and Shifters are you using? There's a race in Ontario, every spring- Paris to Ancaster - that mixes rail trail, gravel road, single track and a brutal climb at the end that most will walk. This looks like the perfect setup for speed and final climb.

Thanks for posting

Canflyboy
canflyboy is offline  
Old 09-30-11, 10:07 PM
  #3  
Senior Member
 
Andy_K's Avatar
 
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,886

Bikes: Yes

Liked 4,117 Times in 1,528 Posts
Good to hear. I just got one of those 12-30 cassettes and I was hoping I wouldn't have to get a new derailleur. I had some problems with an 11-32 with my old Tiagra 9-speed rear derailleur. It nearly worked, but bounced a bit in the big cog. The rear derailleur I'm intending to use now is the Ultegra SS model (capacity = 29), but I'll be using it with a 46-34 crankset, so I think I'll be alright.
__________________
My Bikes
Andy_K is offline  
Old 10-01-11, 05:44 AM
  #4  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Originally Posted by canflyboy
Nice Set up - What FD and Shifters are you using?
Canflyboy
I'm using a 105 series FD-5703 front Derailleur and older 5603 brifters. I also installed a system like this on my road bike and used a chain-catcher from K-Edge;

I've assembled the K-Edge Chain deflector for triple, Shimano FD-5703 front derailleur and the Shimano SM-AD15 clamp band for front derailleur (34.9mm size). The three part assembly is pictured below;





I was concerned that the K-Edge Chain deflector needed a braze-on plate to install, but it fits properly on the Shimano SM-AD15 clamp band. On the road bike I'm using the same 50, 39 & 26 crankset, but use a 12-27 cassette and a new 6703 Ultegra "GS" RD;


Last edited by Barrettscv; 10-01-11 at 11:09 AM.
Barrettscv is offline  
Old 10-01-11, 05:59 AM
  #5  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Originally Posted by Andy_K
Good to hear. I just got one of those 12-30 cassettes and I was hoping I wouldn't have to get a new derailleur. I had some problems with an 11-32 with my old Tiagra 9-speed rear derailleur. It nearly worked, but bounced a bit in the big cog. The rear derailleur I'm intending to use now is the Ultegra SS model (capacity = 29), but I'll be using it with a 46-34 crankset, so I think I'll be alright.
Yes the front triple with a 50, 39 & 26t adds 12 units to the chain wrap value compared to your 46 & 34t double. You should have the same outcome and be within the practical chain wrap capacity of the "SS" RD.
Barrettscv is offline  
Old 10-01-11, 06:57 AM
  #6  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Originally Posted by canflyboy
There's a race in Ontario, every spring- Paris to Ancaster - that mixes rail trail, gravel road, single track and a brutal climb at the end that most will walk. This looks like the perfect setup for speed and final climb.

Thanks for posting

Canflyboy
Here is a side by side contrast of 50, 39 & 26t triple with the 12-30 cassette a 50 & 34 compact double with a 11-28 cassette.



The middle ring on the triple is a ideal range and covers 80% of my time on the bike. Almost any cycling in the 10 to 25 mph speed range can be done on the middle gear. The big ring only is needed with descents and faster pace-line riding, but provides 35 mph powered cycling. The little ring is only needed for very steep climbs at speeds less than 10 mph and improves climbing cadence by 40%.

It's a great range for just about any type of riding, including gravel road, light touring and hilly century rides.

Last edited by Barrettscv; 10-01-11 at 11:13 AM.
Barrettscv is offline  
Old 10-03-11, 04:16 PM
  #7  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Liked 1,360 Times in 866 Posts
nice touring bike drivetrain..
fietsbob is offline  
Old 10-04-11, 06:52 AM
  #8  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Originally Posted by fietsbob
nice touring bike drivetrain..
No.

Loading touring bikes are better off with a 48, 36 & 24t chain-rings using a 110 & 64 BCD crank. A 12-36 cassette with a MTB RD would be needed for hilly routes using a touring bike with enough camping gear for self-sufficient camping in damp weather.

Last edited by Barrettscv; 10-04-11 at 06:55 AM.
Barrettscv is offline  
Old 10-04-11, 02:05 PM
  #9  
Senior Member
 
Andy_K's Avatar
 
Join Date: Jan 2008
Location: Beaverton, OR
Posts: 14,886

Bikes: Yes

Liked 4,117 Times in 1,528 Posts
Originally Posted by Barrettscv
Yes the front triple with a 50, 39 & 26t adds 12 units to the chain wrap value compared to your 46 & 34t double. You should have the same outcome and be within the practical chain wrap capacity of the "SS" RD.
Confirmed!

I put the new cassette on this weekend. I didn't change the chain length or adjust the derailleur cable tension -- just put the new cassette on the wheel and tried it out. The chain length is pushing the limit, but seems to be acceptable (the chain was cut to accept a 12-27). The shifting is outstanding. If anything, it shifts better than it did with the old 105/Ultegra cassette. That may be because of accumulated grime in the hyperglide bits of the old cassette, or it may be that the old cassette was just worn.

I just posted a full review on the Commuting forum.
__________________
My Bikes
Andy_K is offline  
Old 10-15-11, 01:44 PM
  #10  
djb
Senior Member
 
Join Date: Jul 2010
Location: Montreal Canada
Posts: 13,287
Liked 994 Times in 815 Posts
barretts, you've mentioned your setups before, and I agree 100% on how versatile the 39 tooth is. While I am intrigued by compact doubles, I really think I will always be a triple fan, especially as I can often have a pannier with stuff on a bike, and then also because I like you, find the middle chain ring to be so versatile for so much of my riding and not having cross chaining.

tks for the charts. Us gearing nerds find those neat.
djb is offline  
Old 10-21-11, 09:47 PM
  #11  
Senior Member
 
canflyboy's Avatar
 
Join Date: Aug 2008
Posts: 204
Likes: 0
Liked 0 Times in 0 Posts
Your triple gave me an idea. I'm building up a triple and will us it for one race this coming spring. It's a 60 kms point to point done on a cross bike. Country roads, single track, rail trails and steep climb at the end that I (and 80% of others) have to walk. Last year I used a standard compact with an Ultegra 11-28 which was perfect for everything except that final climb.

I want to use a 50/34 chainring, so that means I need a 110 bcd. Sugino makes such a crank. It's 110/74 bcd with a tapered square drive. My set up will be 50/34/26 and an 11/28 in back.

I'll let you know how this works out in the spring

Canflyboy
canflyboy is offline  
Old 10-22-11, 05:16 AM
  #12  
Senior Member
 
Join Date: Apr 2010
Location: Fredericton, NB, Canada
Posts: 1,430

Bikes: 2010 S1, 2011 F75X

Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Barrettscv
No.

Loading touring bikes are better off with a 48, 36 & 24t chain-rings using a 110 & 64 BCD crank. A 12-36 cassette with a MTB RD would be needed for hilly routes using a touring bike with enough camping gear for self-sufficient camping in damp weather.
I think what fietsbob is getting at is.........

Its great that your bike can climb a 20% grade at 4mph at 60 rpm - great math - but in a CROSS race, you're better off jumping off and running

Whats the gear spacing on that cassette? Given the range, I'd imagine theres some considerable gaps in the gearing - many prefer the tighter gearing gaps of a 12-25 and a cross compact (46/36).

Last edited by simonaway427; 10-22-11 at 05:20 AM.
simonaway427 is offline  
Old 10-22-11, 02:39 PM
  #13  
Have bike, will travel
Thread Starter
 
Barrettscv's Avatar
 
Join Date: Feb 2006
Location: Lake Geneva, WI
Posts: 12,284

Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

Liked 288 Times in 158 Posts
Originally Posted by simonaway427
I think what fietsbob is getting at is.........

Its great that your bike can climb a 20% grade at 4mph at 60 rpm - great math - but in a CROSS race, you're better off jumping off and running

Whats the gear spacing on that cassette? Given the range, I'd imagine theres some considerable gaps in the gearing - many prefer the tighter gearing gaps of a 12-25 and a cross compact (46/36).
Your statements could be correct, if I was cross racing. I am not. I've used, and would use again, a 44t single chainring if I was racing cross. I would not use a triple. Did U read the prior posts?
__________________
When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.

Last edited by Barrettscv; 10-22-11 at 03:17 PM.
Barrettscv is offline  
Old 10-22-11, 06:09 PM
  #14  
Senior Member
 
Join Date: Apr 2010
Location: Fredericton, NB, Canada
Posts: 1,430

Bikes: 2010 S1, 2011 F75X

Likes: 0
Liked 1 Time in 1 Post
Sure did...just seemed like you scoffed at the term "touring", despite describing your bike as such in your signature.

But I digress - I have a race tomorrow......
simonaway427 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
UnfilteredDregs
Bicycle Mechanics
12
03-02-22 08:41 PM
PDKL45
Bicycle Mechanics
25
05-28-17 07:18 AM
Sparky52
Bicycle Mechanics
10
05-14-17 05:39 PM
Lightchop
Bicycle Mechanics
12
02-13-17 10:00 PM
Vexxer
Bicycle Mechanics
7
06-08-16 09:03 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Your Privacy Choices -

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