|   Double Speed | Willy in Pacifica
Jul 25, 2003 9:42 AM | | I am considering building up a SS road or cross bike. Mainly to commute on. However, I live in a town called Pacifica which is just south of San Francisco. I have a couple nasty hills to get up both ways during my commute. I would have a hell of a time getting up these particular hills unless I gear the bike with a ratio that would then be too small for the rest of my commute.
Here is my idea.
Use a 9 speed type rear hub with one cog on it and spacers to fill in the rest.
Run a double ring up front with front der
Use a chain tensioner/singulator off the rear der hander
space the rear cog so it lines up between the two rings up front
I could run say a 20 in the rear and perhaps a cross crank set up front with say a 36-48
Run a bar-end front shifter or a Kelly take-off for the front der
Can you think of anything I am missing or any reason it would not work. I like the idea of a nice smooth looking single speed but really need the second gear. I may try it as a single speed but if it is a pisser getting up the hills I would like to have a back-up plan.
Thanks for your help, Willy in Pacifica |
| re: Double Speed | shinewheel
Jul 25, 2003 10:14 AM | | I ran a very similar set-up when I had some hills in my route except I didn't use a front deraileur and did most of my shifts by stop and move the chain by finger, not bad once you get used to it and use a dry chain lube. I could also downshift on the move with my heal. I used a 32/44T front and 18T rear on a mtn bike. It worked fine.
Do you cross at Sharp Park? |
| Pacifica | Willy in Pacifica
Jul 25, 2003 10:52 AM | | If 12 teeth is too much of a jump to use a singulator what can I use? Someone mentioned that a singulator wont work because it has teeth and it would need to be lined up perfectly. He suggested something with a pully wheel. Makes sense now what should I use. I guess it also needs to take up enough slack for the 2 front ring differences. I am not familiar with te varous chain tensioners, but don't they just push the chain down to take up the slack. Does the singulator just not have enough downward range?
Pacifica gets a bad rap for its Fog. Actually it is Daly City's fog that sneeks over the border into Northern Pacifica. But since most folks enter Pacifica from the north, down Hwy 1, they think all of Pacifica is covered in fog. Actually, we live toward the southern end, maybe 3 miles south, in the Vallemar/Rockaway Beach neighborhood and we get mostly sunny days. It is amazing the difference a couple miles makes. When we were looking to buy a house in Pacifica we told our RE agent to not even look north.
When I commute into The City the first thing I have to do is ride up Sharp Park Rd which is just over a mile and it goes up about 400-500 feet. Quite the wake up. This is the pisser of a hill on my 20 mile commute, but loads of fun on the way home.
On the way home I get hit with tremendous headwinds as I head west toward the Golden Gate Bridge. Around 4-5 PM the winds can just about knock you off your bike especially when it gets funneled between highrises. This 5 mile flat section along Crissey Field and Fishermans Wharf can actually be harder then the morning climb.
Once out of the wind it is up thru the Presidio then I hit Golden Gate Park where I can hit some dirt trails before I hit the Great Hwy along the Pacific. Then it is up Hwy 35 (Skyline) for a 5-6 mile gradual climb before dropping back into Pacifica.
Right now I am riding a Ritchey SwissCross as my commuter and it is a blast to hit some nice trails hidden in the park.
Thanks, Willy |
| Yeah,... | shinewheel
Jul 25, 2003 12:13 PM | | ... I guess I should have clarified I used an old rear deraileur for tensioning, not a Singulator. good luck, the SA hub sounds trick, too. |
| Yes | mmmatt
Jul 25, 2003 10:15 AM | | I have a friend who lived in Paficia for a while. That fog is something else, at least for an east coaster like me.
Sounds like your plan will work, except the singleator part. A singleator won't take up enough slack for a 12 tooth difference in the front. Better to use an old derailleur, or a Paul Melvin should work. You can also leave off the front der and shift with your hand (or foot). |
| Oops.. I meant Pacifica, not Paficia | mmmatt
Jul 25, 2003 10:16 AM | | |
| sounds like you need | SSO
Jul 25, 2003 10:35 AM | | a 3 speed Sturmey-Archer hub. IMO the set up you propose has too much hardware for just running 2 speeds. At that point why not just run a bunch more?
Personally, I'd try it single speed, gear it so that you can just barely make it up those climbs when standing and mashing. Do that and the gearing should be pretty decent for the rest of the ride. |
| I'll try that | Willy in Pacifica
Jul 25, 2003 11:05 AM | | Next week i will see what i am using on my Ritchey. I have a 53-39 in the front and a XT 11-32 in the rear using a XTR rear der. When I head up Sharp Park I am in the middle cog or the next one bigger. I guess that puts me in the low 20's. I guess I can then leave it there and see how I do on the downhills, flats and against the headwinds.
On weekends I will take my road bike over Devils Slide and I can get over fairly easily using my 30-15 on my triple. But there are so many hills of various grades it would be hard to be able to go with just one gear. That is why I was looking for the best way to get two gears. One ofr up and one for down. There realy isn't much else where I ride
Thanks again |
| sounds like you need | Willy in Pacifica
Jul 25, 2003 11:06 AM | | SSO,
What are the ratios of the SA hub?
Thanks |
| according to Mr. Sheldon Brown | SSO
Jul 25, 2003 11:30 AM | | "The Sturmey-Archer AW hub provides a direct drive middle gear, a high gear that is 4/3 of the middle gear, and a low gear that is 3/4 of the middle gear."
Lots more info right here:
http://www.sheldonbrown.com/english-3.html#sturmey |
| according to Mr. Sheldon Brown | Willy in Pacifica
Jul 25, 2003 11:56 AM | | If I were to go with the SA then I just need to figure out what front ring works best?
Willy |
| re: gearing | SSO
Jul 25, 2003 12:05 PM | | I believe so. Not sure what rear cog it comes with. Check here or email Sheldon direct, he should be able to set you up.
http://www.sheldonbrown.com/harris/sturmey.html |
| another solution... | natetheskate
Jul 25, 2003 12:59 PM | | run two chainrings, and two cogs. find two gear combos that work for you that have the same number of teeth (ie 38:18 and 42:14) this will allow you to get your chainline correct and keep the clean SS look. |
| another solution... | Willy in Pacifica
Jul 25, 2003 3:30 PM | | Does it really work that way? You just have to have the same number of teeth between the two gears? |
| re: Double Speed | 1x1 Speed Craig
Jul 25, 2003 1:27 PM | | Hi Willy,
If you go with your original idea, I would check out the Rohloff tensioner (3rd one down on the "How do I tension the chain?" section of the soon-to-be MTBR SS FAQ page). It's supposed to be able to handle a 20T gearing difference, I believe.
Craig |
| re: Double Speed | willfcc
Jul 25, 2003 9:24 PM | | It's not low tech, but if you want a really clean looking single speed look, try a Schlumpf Mountain Drive.
www.schlumpf.ch
In 1:1 mode, you can run, say, a 42/18 for about a 60 inch gear. Kick in the 2.5:1 reduction, and you've got a 24 inch gear. |
| I've done that ... as a 3 speed | GlowBoy
Jul 25, 2003 10:13 PM | | Hey if you've already got a triple crank, might as well run 3 gears. I played around with this a few months ago, and it worked well. You eliminate all the fussiness of rear shifting, but you don't end up ditching very much hardware relative to a fully geared bike.
By the way, as others have mentioned, you will need a two-pulley chain tensioner, such as an old derailleur or better yet the Rohloff or Paul Melvin tensioners. A 1 pulley tensioner like the Singleator can't take up more than a couple teeth worth of slack.
Natetheskate's idea about running two chainrings and two cogs, for two combinations with the same total teeth, may work but may have a couple problems. First, all the tensioners I know of are designed to work with a single cog, so you won't have a way of switching between the two rear cogs. You could do this same thing without a tensioner, but it's unlikely to work well with vertical dropouts, because the "same total number of teeth" rule is not quite exact - so if you find one combination that works with your chainstay length, other combinations with the same total teeth may not work. Works great if you have horizontal or semi-vertical dropouts though - in fact, I'm doing this on both my MTB and my 'cross bike. |
| my double speed SS | club
Jul 26, 2003 4:30 AM | | I lied, it's a 3-sp. SS. I'm running 24 and 36t rings with 15t and 20t cogs on a freehub. The 15/36 is strictly the road gear to get to and from the trailheads, I never run the 15 with the 24t ring. The 36/20 is the most used, trail gear. The 24t granny ring gets used only occasionally.
Not sure, but I think singulators won't handle your proposed 12t chainring difference, especially in pushup mode, the way you'd want to use it.
I use an old shortcage SunTour road derailleur, modified by replacing the pulleys with toothless ones off an ancient Huret derailleur, so they run silently. I also dremeled away some of the aluminum near the mounting bolt where the B tension screw would contact the lip on the hanger (I removed the whole B tension assembly). Now the derailleur wraps much farther forward so the chain wraps more teeth on the cogs. Not that it was skipping before, but more chain wrap is always a good thing, I figured...
I use the barrel adjuster to "shift" between the 15 and 20t rings, and I put a big honking rubber knob on the barrel adjuster, just because I had something that looked sano that fit.
Thing about using a front derailleur and shifter is, you're more likely to wimp out and downshift. If you have to shift with your finger, you're more likely to stick it out in the harder gear and only use the small ring when you must. |
| let's see some pics of your rig(s) club! /nm | Hollywood
Jul 27, 2003 7:57 PM | | |
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