So I'm doing the 545 mile AIDS lifecycle bike ride next year on a fixed gear bike and I have a 46 tooth front chainring and currently run a 16 tooth cog in the back. I have a flip-flop hub and was wondering what gear I should put on the other side of the flip-flop for going up hills and if I should change the front as well. I've been running this ratio for years and love it for commuting but am wondering what anyone might suggest for a chainring and 2 cog sizes for the flip flop to get the job done and accommodate the diversity of the terrain.

replace with a 17t or 18t, and get a 15t for the otherside (for going down hills and long flattttttt sections)

Why don't you show us the terrain profile or something? Are we supposed to guess what you mean by so called diversity?

It's California. It has everything.... 50 miles where you don't gain a foot. Rolling hills. 12% Mountains.



I'd personally go with a 15t cog on one side, and a 19t freewheel on the other side (assuming you have brakes).

They wouldn't let me enter my bike without at least one brake. It is not a freewheel, I'm dead set on doing fixed without SS to challenge myself.

Then i'd go with a 15t and a 19t.

There are some pretty mean climbs here.

I agree--15 /19 freewheel. 545 miles on the PCH, I'd say brakes are mandatory.

Next year huh? Seems like you have some time to try out a few things. What am I missing?

If you plan to switch between 15 and 19, I think you might need a chain breaker tool.

+1 on 15/19. Chain breaker might not be necessary if you have long dropouts and play your cards right.

You won't need a chainbreaker. Thats 4 extra teeth, 2 extra inches, an inch of movement in the dropouts.

Slam the 19t forward, or slam the 15t back.

i have a very big birthday coming up & plan to celebrate/thumb my nose at father time by riding fixed for a certain high mileage number up our coast highway on the east coast.

op, if you think you may need a bit wider variety of gearing, here's my own plan:

i have pretty long trackends & use a big chainring - going to throw a 17/21t dinglecog on one side & split the difference with a 19t cog on the other.

am figuring this set-up ought to enable me to handle just about any terrain. my calculations tell me it will fit my bike & chain, hope they are right...i'm not so good with this higher math stuff

whadaya think?

We decided while you were gone that one tooth difference was 1/8" and not 1/4". So it'd be a half-inch.

https://www.bikeforums.net/showthread...1#post14463733
https://www.bikeforums.net/showthread...=1#post5018993

Just bring a bucket full of cogs and swap them each time the road gets too hard.

Riding a fixed gear with a handful of gear options pretty much defeats the HTFU purpose.

https://www.mapmytri.com/routes/view/37235078
https://www.mapmytri.com/routes/view/38692482
https://www.mapmytri.com/routes/view/37235594

Does not look particularly challenging for a regular road gearing. If I was planning to do this ride I would just run 71" and call it a day.

But I bet 75"/67" would be more fun, even if it required flipping the wheel a couple times.

I've done ALC once and volunteered twice as a roadie in Bike Parking. Of 2200 riders, all but a couple of the dozen or so riders doing it on fixed gear bikes wind up getting sagged almost every day. I'll be riding again next year (on a geared bike).

Here are the profiles for days three and four of ALC11 (this year's ride). These two days had the toughest climbs.

You may want to use 2 chainrings as well. That will minimize the distance your wheel will move in the dropout (or track end to be more precise). Google the White Ind dingle setup.

Sounds like a fun ride.

Consider a Sturmey-Archer S3X hub if you can't make one gear (or two on a slip-flop hub) work for everything.

Surly Dingle cog

17/21
You give up top end obviously but, man, you have a lot of wind to deal with as well as hills. You are not going to be challenging for top speed on that ride.
Going thru the central coast, you are going to be hurting.

Sounds like a fun challenge, best of luck!

yeah, I have a 2 sided fixed/fixed hub and I have a 15t on one side and an 18t on the other combined with a 48t chainring and it all works with the same chain.

Thanks. I'm pretty well aware I may get sagged, I could care less I just want to try on a fixed without anything more intricate than my chainring and a flip flop and do my best. I've considered doing it on my own time but I figured it'd be more fun with the group and why not raise money for a great cause while I'm at it.

that thing is interesting

What does getting "sagged" mean? Is there a time limit?