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Recommend fixed-gear gear combo?(16 posts)

Recommend fixed-gear gear combo?SS_MB-7
Jan 23, 2002 8:15 AM
Hey Fixies,

I'm going to be riding a fixed-gear/SS road bike very soon and would like your recommendations for a gear combination(s) for city/country road riding with moderate to somewhat steep climbs and downhills?

Here's a gear inch chart I created based on a 700x23 wheel with 165mm cranks:



Ride Hard,
Mike B.
as 42 tooths are common/cheap - 42/16 fix, 42/18 free nmnaff geezer
Jan 23, 2002 8:21 AM
Why the difference in rear gear for fixed vs free? (nm)SS_MB-7
Jan 23, 2002 8:23 AM
Since you don't have to pedal down hill you can run easier gearsMB1
Jan 23, 2002 8:28 AM
Riding fixed it is the downhills that wear you out. If you have to struggle up it fixed it is going to be a killer trying to keep up with the pedals downhill. Riding free you can climb steeper stuff without worrying about the downhill. So you can run an easier gear and ride more places.

SS is big fun fixed or free.
Thanks! That is what I thought (nm)SS_MB-7
Jan 23, 2002 8:35 AM
Search the archives, lots of discussions of this.MB1
Jan 23, 2002 8:22 AM
For hilly riding around DC I use 42/17 free and 42/16 fixed. Miss M uses 39/16 free and 39/14 fixed. We have done centuries with this gearing.
41x16?Dog
Jan 23, 2002 8:24 AM
It depends a bit on what you have now. In other words, you might be able to change either the cog or the ring, but not both.

I started with 42x18, then 42x16, and now I have 41x16. The last one gives me 100 rpms at 20 mph, my typical cruising speed on flat ground. The idea for a fixie is to keep the rpms up, right? This allows me to climb 1-2 mile 4-6% grades standing, but longer climbs are too much. It also requires some pretty fast spinning down even moderate hills. 25 mph is 125 rpms, and 30 is 150 rpms.

You may have to experiment a bit to see what works for you. Likely, it will take a few weeks to develop the spin to be able to descend without braking. I think the goal is to be able to descend without brakes, keeping it "pure." But, no one says you can't.

Depends upon what you want, commuting, training, fun, etc.

Doug
46 x 16, or a little over 75 inches...Greg Taylor
Jan 23, 2002 8:26 AM
I tend to push a big gear, and this is a good compromise for climbing/running down hill. I commute on this all the time...your results may vary.

Have fun with it...fixies are a blast.
what does crank length have to do with it?nfm-
Jan 23, 2002 8:37 AM
didn't think so.
crank lengthDog
Jan 23, 2002 8:47 AM
It doesn't matter in the gear inch calculation, but short cranks generally permit higher spinning, and longer cranks give more leverage, especially up a hill. So, with longer cranks, you could run a harder gear.

Doug
5mm can mean just making a climb or walking itnaff geezer
Jan 23, 2002 9:01 AM
not that there is any shame in being wrongly geared for climbs on a fixed and having to walk it or flip it to your free.

just so you know even though your gear inches are fixed at say 75 inches crank length will make a difference in what you can actually turn over with a given amount of torque if needed. for most fixed roadbikes 170mm is generally just under the safe point in terms of corner clearance.

unless you have bloodlines from a rabbit and can hop safely whenever you want.

then again ive seen riders on 175mm who swear no problems.
It's a catch-22.Alex-in-Evanston
Jan 23, 2002 9:16 AM
I choose safety - 170's on mine.

Alex
I'm 5'6" - gear road=170; SS MTB=175...SS_MB-7
Jan 23, 2002 9:24 AM
I'm 5'6". On my geared road bike, I have 170's and on my singlespeed MTB, I have 175's. I'm new to fixed-gear riding so I was basing my 165mm choice on what I have read at Sheldon Brown's site based on spinning and ground clearance.

For the most part, I'm a gear masher, but I can also spin fairly easily at high RPM. What would you recommend for a crank length -- 165 or 170?

Ride Hard,
Mike B.
im not actually advocating 175mm..naff geezer
Jan 23, 2002 10:01 AM
the 5mm that i quoted was assuming your 165mm compared to my 170mm.

i suppose the reference of some riders with 175mm made it read that way.

personally my confidence isnt up to riding longer than 170mm fixed.

on a similar note i wish more frames would be made with quoted figures and the option of a higher bottom bracket. i can remember when frames were advertised as road or criterium with respect to their bottom bracket height. or am i just not reading the fine print properly?
It's not that big of a deal...Greg Taylor
Jan 23, 2002 11:16 AM
...in my humble opinion. Accepted wisdom would suggest using the shorter crank on the fixie. Whether it makes a difference on clearance issues when cornering, for example, depends in part on bottom bracket height, i.e. how low the bottom bracket is positioned relative to a line drawn between the front and rear axle. If the bottom bracket drop is set relatively low, a longer crank length might not be a wise choice. But ultimately a half-centimeter difference in crank length won't really make that big of a difference getting through a corner.

For me, it boils down to riding style. If you push a bigger gear and don't plan to really turn major rpms, then the longer crank is for you. If you want to gear it short and really work on spin, the shorter crank is what you need.
I ride a 42x17 with 175mm cranksSteve Davis
Jan 24, 2002 8:23 AM
This combo works okay for me in and around the hills in Southeastern Mass. Lately, I find that I'm mashing the pedals a bit too much due mainly to the winter winds. Downhills are fun though...

Regarding the cranks, I use 175mm cranks to match my main road bike(I'm 6'3"). I was concerned about cornering clearance, but I've never once hit a pedal. After all, the difference between 170 and 175mm is less than 1/4 of an inch. I would think that different types of pedals have at least this amount of variance in cornering clearance. BTW, I use SPD pedals on the fixie.