Cruiser Gearing @ RAD

[shifter]

What's the popular opinion on gearing for cruisers @ RC??? I'm thinking my Felt came too short - not a deal breaker.

[JAlvey]

It seems like 37-16, 39-17, and 41-18 are the most common. A few people are running a bit smaller (36-16, 38-17) and a few 42-18.

All depends on your strength, spinning ability, crank length, and starts.

[shifter]

OEM on my bike is 39-17 and cranks are 180mm, so maybe I ought to shut my cake hole and just wait and try it.

[BLong]

I keep Stitch at the same ratio as his class bike (compensate for tire size of course).

-Brian

[awsm4]

I gear my 13x about 1 full ratio number higher ie: 53.7 class bike...54.7 cruiser...

[bnd]

I run a 40-17 w/ 175mm. cranks, 1.5 tires.

You'll want to gear down a tooth or 2 in the front for indoors as the holeshot is 90% of the race in there.

b.

[sspencer]

Everyone is different in their gearing needs (torquers and spinners) so it is best to try your gear before changing it out. Older cruiser riders tend to run bigger gears. Rad's starting hill deceives riders and parents into going up in gears also.

The best thing to do is to purchase a cycling computer and do a few test runs with different gears down the first straight. See which one gets you the highest speed.

Just some ideas but what do I know?
Steve

[JasonStout]

36-15 with 1.5 tires...

JS

[PAPAWHEELY]

I run 39-16 w/1.50 tires and 175 mm cranks. I'm sure that will change when my slicks get here for the paved corners...
Matt

[shifter]

Tell me about 1.5 tires? What does that mean? 1.5"? High? Wide?

[JAlvey]

1.5 refers to the width, but it also slightly impacts the height, and therefore the gear ratio. what most on here are saying is that a gear ratio around 54.5-55.5 is what most everyone is running.

[shifter]

1.5 refers to the width, but it also slightly impacts the height, and therefore the gear ratio. what most on here are saying is that a gear ratio around 54.5-55.5 is what most everyone is running.

Now you done opened a can of worms...

I'm used to figures (ratios) like x:y or the quotient of the two. Lay the math your using down for me if you please!!!

[J Gallo]

Here is a gearing chart I worked up awhile back, it may help:

http://www.utahbmx.com/pbp/tech/gearing.htm

[JasonStout]

no one really knows what that number means...We just use it to justify a gear change...



55.2

JS

[shifter]

no one really knows what that number means...We just use it to justify a gear change...



55.2

JS

I'm an engineer... I can't handle not knowing!!! So I've done some work:

chainring / rear cog x inflated diameter of the wheel/tire combo:

chainring: 34T
rear: 13T
inflated dia of a 20" rim w/ 1-1/8" tire: 20" thus...

34/13x20 = 52.31 (agrees w/ PBP chart)

larger tire, same gearing:

chainring: 34T
rear: 13T
inflated dia of a 20" rim w/ 1-3/8" tire: 21" thus...

34/13x21 = 54.92 (agrees w/ PBP chart)