Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Touring Have a dream to ride a bike across your state, across the country, or around the world? Self-contained or fully supported? Trade ideas, adventures, and more in our bicycle touring forum.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-23-09, 02:21 PM   #1
gr23932
Si se Puede!!!....Ahuevo!
Thread Starter
 
gr23932's Avatar
 
Join Date: May 2007
Location: Sepa la chingad....
Bikes:
Posts: 1,114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Tiagra RD capacity...

I know that Shimano states that 27t is the largest cog it can handle but I'm curious if any one has used a 30T or 32T with success. It's on my LHT which I use to haul my two kids around on weekend trips and I must say that I've gotten my @ss kicked a few times on some big hills.
__________________
Ese dicho que me han dicho que tú has dicho que yo he dicho, ese dicho no lo he dicho, porque si lo hubiera dicho, ese dicho estaría bien dicho por haberlo dicho yo.
gr23932 is offline   Reply With Quote
Old 09-23-09, 02:27 PM   #2
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Bikes: Some silver ones, a black one, a red one, an orange one and a couple of titanium ones
Posts: 18,044
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 216 Post(s)
Quote:
Originally Posted by gr23932 View Post
I know that Shimano states that 27t is the largest cog it can handle but I'm curious if any one has used a 30T or 32T with success. It's on my LHT which I use to haul my two kids around on weekend trips and I must say that I've gotten my @ss kicked a few times on some big hills.
You can push it to 29 or 30 (good luck on finding a cassette with those as the low gear). Not much further, however. Your best bet would be to ditch the road derailer and go for a mountain bike one. Jenson has an LX for $49. It'll fix all your problems and you'll be able to run a 11-34 cassette.
__________________
Stuart Black
New! Pokin' around the Poconos A cold ride around Lake Erie
New! Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.
cyccommute is offline   Reply With Quote
Old 09-24-09, 07:55 AM   #3
gr23932
Si se Puede!!!....Ahuevo!
Thread Starter
 
gr23932's Avatar
 
Join Date: May 2007
Location: Sepa la chingad....
Bikes:
Posts: 1,114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by cyccommute View Post
You can push it to 29 or 30 (good luck on finding a cassette with those as the low gear). Not much further, however. Your best bet would be to ditch the road derailer and go for a mountain bike one. Jenson has an LX for $49. It'll fix all your problems and you'll be able to run a 11-34 cassette.
Thanks. I think I'm going to try changing just the small chainring first and see if that improves my climbing with the kids in tow.
__________________
Ese dicho que me han dicho que tú has dicho que yo he dicho, ese dicho no lo he dicho, porque si lo hubiera dicho, ese dicho estaría bien dicho por haberlo dicho yo.
gr23932 is offline   Reply With Quote
Old 09-24-09, 08:35 AM   #4
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Bikes: Some silver ones, a black one, a red one, an orange one and a couple of titanium ones
Posts: 18,044
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 216 Post(s)
Quote:
Originally Posted by gr23932 View Post
Thanks. I think I'm going to try changing just the small chainring first and see if that improves my climbing with the kids in tow.
The cost of a chainring may be about the same as a new derailer and cassette, depending on what kind of crank you have. And you may only gain a couple of teeth on the chainring. If you have a standard double road crank, the inner ring is probably a 40 or 39. You can't fit anything smaller than a 38 to that bolt ring circle.

If you have a triple (road), you can drop from a 30 tooth (pretty standard) to a 24 tooth. That makes a pretty good difference. But I don't know if the Tiagra will handle the chain wrap. The LX certainly would.
__________________
Stuart Black
New! Pokin' around the Poconos A cold ride around Lake Erie
New! Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.
cyccommute is offline   Reply With Quote
Old 09-25-09, 06:47 AM   #5
rodar y rodar
weirdo
 
Join Date: Jan 2008
Location: Reno, NV
Bikes:
Posts: 1,962
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Cool- I`m glad I ran into this thread because I was kind of wondering the same thing. It sounds like the OP is going with a smaller ring, but for what it`s worth, HG70 comes in 11-30, as do a few level SRAM casettes.
rodar y rodar is offline   Reply With Quote
Old 09-25-09, 08:30 AM   #6
barturtle
Senior Member
 
Join Date: Jun 2008
Location: Louisville, KY
Bikes: Jamis Coda
Posts: 798
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've been doing a bit of research into the same question, as part of my planning out my next bike. I'm looking at getting a cross bike to use as a "jack of all trades commuter/century/group ride bike". Looking at my current gearing (48/38/28 11-32 8sp) and what I use/don't use and planning it around a compact double with a 9sp.

Currently, in addition to almost never using the 48/11 and 48/13 (and those only on downhills where I could otherwise rest), I find the spacing too wide, with 15%+ jumps between cogs. Also I know that I can climb hills over 9% in my 38/32 (mechanical issues prevented my from shifting to granny on a group ride with a documented climb).

This gave me an idea that I need gear-inches from ~95 at the high end to 31 at the low end, but with tighter spacing in between. A bit of playing with a gear calculator found a combo that would give me what I want 46/34 with 13-30 9sp. The 13-30 is a custom cassette that Harris Cyclery calls the "Century Special" and claims with work with even short cage derailleurs. This will give me a range of 94.7 to 30.3 (staying with my 700x28 tires) and spacing well under 13% on most shifts.

To finish off my statement, I'll quote Sheldon Brown on the ratings of capacity of rear derailleurs.

Rated maximum rear sprocket size, however, is also commonly much lower than what actually works. For instance, Shimano's models designated as "road" derailers are generally listed for a "maximum" sprocket of 27 teeth...because 27 teeth is the largest size that they make in a designated "road" cassette. However, in almost all cases, these derailers, even the short-cage models, will handle rear sprockets as large as 30 teeth in practice. (This somewhat depends on the design of the frame's derailer hanger, so once in a while you will find a particular installation where you can't use a 30, but I've never seen one where a 28 wouldn't work
barturtle is offline   Reply With Quote
Old 09-25-09, 10:26 AM   #7
HardyWeinberg
GATC
 
Join Date: Jul 2006
Location: south Puget Sound
Bikes:
Posts: 7,537
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Quote:
Originally Posted by gr23932 View Post
Thanks. I think I'm going to try changing just the small chainring first and see if that improves my climbing with the kids in tow.
I see where you're going, I've been there. Guess what, the kids will grow faster than your conditioning can improve. Try and get a 1:1 gear ratio.
HardyWeinberg is offline   Reply With Quote
Old 09-27-09, 11:04 AM   #8
gr23932
Si se Puede!!!....Ahuevo!
Thread Starter
 
gr23932's Avatar
 
Join Date: May 2007
Location: Sepa la chingad....
Bikes:
Posts: 1,114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks guys for you input and suggestions. I think I'm going to see if a 11-32 cassette I just got for nothing will work. If it doesn't, I will end up getting a new Rd and granny chain ring.
__________________
Ese dicho que me han dicho que tú has dicho que yo he dicho, ese dicho no lo he dicho, porque si lo hubiera dicho, ese dicho estaría bien dicho por haberlo dicho yo.
gr23932 is offline   Reply With Quote
Old 09-27-09, 11:06 AM   #9
gr23932
Si se Puede!!!....Ahuevo!
Thread Starter
 
gr23932's Avatar
 
Join Date: May 2007
Location: Sepa la chingad....
Bikes:
Posts: 1,114
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by HardyWeinberg View Post
I see where you're going, I've been there. Guess what, the kids will grow faster than your conditioning can improve. Try and get a 1:1 gear ratio.
I'm glad I'm not the only one that went through this. I have been able to make every hill I've faced with the kids and panniers but I just want to do it without feeling I got my a$$ handed to me after every big climb. Sounds reasonable??
__________________
Ese dicho que me han dicho que tú has dicho que yo he dicho, ese dicho no lo he dicho, porque si lo hubiera dicho, ese dicho estaría bien dicho por haberlo dicho yo.
gr23932 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 03:07 PM.