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


Go Back   > >

Recreational Cyclocross and Gravelbiking 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 :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-15-08, 03:25 PM   #1
seely 
The Rabbi
Thread Starter
 
seely's Avatar
 
Join Date: Apr 2004
Bikes:
Posts: 5,087
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Unemployment births Frankencrossbike.

Working 10hrs a week lately, I have had a lot of time to sit at home and stare at my bikes. I continually pose the question... how can I make them weirder?

I started on the old Schwinn Criss Cross today. It was set up as a 1x9, but the gears annoyed me. Still, I couldn't stand the thought of spinning a 2:1 around town, or mashing a slightly bigger gear in a cross race.

This spawned an idea, loosely based on the Surly Dingle Cog concept. What if I took a 15t and a 17t cog, spaced them about 2.5mm apart, ran an 8spd chain and a 34t ring...?

Now keep in mind the bike has vertical drops, so this means I need a tensioner. I think in this case its actually beneficial. I used an old Suntour ARX rear derailleur, mid cage, and wrapped the chain around the rear cog, and then down and through the *lower* pulley, effectively bypassing the upper pulley all together. This gives me a ton of downward tension on the chain, and allows me to leave enough extra chain so I can switch between the 15t and 17t without having to monkey with chain tension. To visualize it--the bottom pulley is actually pulled up so it is nearly touching the rear cog with the 17t cog, and has about 8-9mm of clearance with the 15t. Great tension in either cog.

Now, I adjusted the derailleur so it would rest below the 15t (outer) cog. I then set the derailleur limits just as I would on a full cassette, adjust the travel so the low limit was right below the 17t (inner) cog. This allows me to change gears by simply pulling the chain off one gear and plopping it on the other. The play I left in the derailleur allows it to make up for the "bad" chainline a bit. Rather than jumping off the cog, the derailleur moves with the chain.

The chainring sits almost in the middle of the two, so the chainline is only off about 1mm in either gear. So far, works great. Seems like a really good option for anyone with a vertical dropout conversion. The derailleur holds tension much better than a Singulator, and is much easier to adjust. The springs and pivots give a little room for error as well, vs. the static Singulator. Can you tell I've never liked Singulators?

Anyways, hope to have pictures up soon. Meanwhile, I'm going riding in the snow!
__________________
commuter turned bike mechanic turned commuter (also a Velocity USA employee, but this is my personal account)
seely is offline   Reply With Quote
Old 01-15-08, 05:18 PM   #2
DDYTDY
Senior Member
 
DDYTDY's Avatar
 
Join Date: Nov 2006
Location: Methuen, Massachusetts
Bikes:
Posts: 519
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by seely View Post
This spawned an idea, loosely based on the Surly Dingle Cog concept. What if I took a 15t and a 17t cog, spaced them about 2.5mm apart, ran an 8spd chain and a 34t ring...?
How about a friction bar end or down tube shifter for a two speed?
DDYTDY is offline   Reply With Quote
Old 01-16-08, 12:22 AM   #3
DinoShepherd
cycle-dog spot
 
DinoShepherd's Avatar
 
Join Date: Mar 2005
Location: Portland, OR
Bikes: Look, Niner, Ellsworth, Norco, Litespeed
Posts: 1,538
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Rabbi -

Oy vay!

This reminds me of that goofy SunTour BMX freehub that was a two speed with a lever. The idea was a lower gear for the start, then when you release the lever it shifts into the higher gear. Neat idea for a question nobody asked.

However, if your idea makes you happy, I say GO FOR IT! That's what building bikes is all about. Post pics too.

-Z
DinoShepherd is offline   Reply With Quote
Old 01-16-08, 11:35 PM   #4
wompwomp
you can go backwards?!
 
Join Date: Jun 2005
Bikes:
Posts: 390
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
WEIRD
I had the EXACT SAME SET UP
on the EXACT SAME BIKE
earlier this winter, for the
EXACT SAME HATRED OF SINGLEATOR
(we have a bunch of broken ones around my shop)

Now I'm back to 1x9 just because we had the parts and I needed a bike with gears to haul some stuff around on the trailer, but the two-speed manual was definitely a blast.
wompwomp is offline   Reply With Quote
Old 01-17-08, 10:07 AM   #5
seely 
The Rabbi
Thread Starter
 
seely's Avatar
 
Join Date: Apr 2004
Bikes:
Posts: 5,087
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thats really funny--the Criss Cross seems to be a commonly *******ized bike. I imagine its because the geometry is really weird, and there are a million of them for free/cheap all the time. Not to mention the decent tire clearance. Mine was given to our shop, and an employee took it for his girlfriend, but since the geometry was so odd it didn't fit her. Thankfully, my geometry is odd! Right now its set up to be my winter/monster cross bike, so I'm trying to avoid shifters... had too much trouble with the 9spd setup so this seems to be a good compromise and uber reliable.
__________________
commuter turned bike mechanic turned commuter (also a Velocity USA employee, but this is my personal account)
seely is offline   Reply With Quote
Old 01-18-08, 01:05 AM   #6
wompwomp
you can go backwards?!
 
Join Date: Jun 2005
Bikes:
Posts: 390
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
About the geometry and availability: I know, right? Mine fit the crazy 700x47 panaracer smokes we had at the shop on this mtb with kids function we helped out with when I rode with them. It feels just as comfortable to me with slicks going fast as it does with knobby's going moderately to extremely slow. and braze-on's galore!
wompwomp 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 01:29 PM.