Hey everyone. I got a little question to ask "the experts"

Im riding my track bike with a 42 tooth up front and a 16 tooth in the back. Me starting out from a stop light is fine, but me speeding down the road, I find myself, as what Ive heard other people refer to, as "spinning." Im pedaling real fast and not really get any more speed. I WAS running a 42/18, but went down to now a 16.

Do I just need to go to a 14 or 15 tooth? or maybe put on the 52 tooth that came with the crank? Im not that knowledgeable when it comes to gears.

I live in an urban city with a few hills.

Any help would be great. Thanks.

Practice on the 12 speed. Find a gear you like.

Or, pedal slower.

Well your pulling almost 71 gear inches and that's about average
for a road bike. You must be doing short twenty mile or less rides
on flat roads or your a brute. You can easily figure out the ratios
or gear inches: 42/16=2.625x27=70.875 (for road tires) about 71
inches. Or here is a gear calc for ya.

https://www.bikeschool.com/

-VÈÑÍ VÍÐÌ VÌÇÍ.

42/16 is what I use for fixed gear. Interestingly, the most used gear on my freewheel is the 42/17. I like hills.

I pushed a 42/16 for a long time and moved up to 47/16 because I was spinning out way too much. 47/16 is a pretty comfortable gear though my starts aren't always as quick as I'd like. I can climb for quite a while before I get totally burned.

Well, what about me going down to a 15 or 14 tooth in the back?

Yeah Veni, Im in the city and going short distances. For some reason, I just cant go slow on my bike. Im just used to hauling a$$ wherever I go. My road bike is out of commision right now, and its been some time since I rode it to even remember it.

Like I said, Im not so knowledgeable about the whole gear math stuff. Veni, what exactly am I looking for with that gear calc?

i use 42:15 with 172.5 cranks. works with me in the flats and slight rolling hills. works less with me on 40+ rides or steepass hills but i like pain.

i think i might try a 47 chainring though...

I run 39/15 on my Schwinn (the 39 was the stock inner chainring on the 1pc crank) and I spin out around 25-26mph, which I'm getting a little tired of doing on the flats where I want to go faster. With my 27" wheels this is about 70.2 gear inches or something. At 70 gear inches, I can keep 19-20 mph without too much of a problem, 21-22mph is spinning a little fast but I'm getting comfy with that. I was going to swap in a new chainring, probably a 42 for now, but I'm going to fixify my old Fuji soon, and will probably run a ratio that gives me gear inches in the high 70's or around 80 so I have a sporty bike with higher gear inches and a workhorse with lower gear inches (probably throw a rear rack on my Schwinn, etc).

Rear cogs are generally not very expensive. I would try the smaller cogs if you want a bigger gear.

Added later - Also, cogs are an easy change since the only other thing you may have to do is possibly remove a link or two of chain.

Say you have a 44 and an 11. For every spin of the big gear, the smaller gear spins 4 times.

Torque is your ability to accelerate, and horsepower is your top speed. You make sacrifices on one aspect to improve the other.

To go faster, you lose ability to make progress from a standing start.

It seems you are asking for more horsepower. 63 x 11 will give you a great top speed, if you can make a standing start. You will start slower, but finish much faster.

The question is how fast must you go, and how long do you need to get there. No need to cruise at 28 MPH if you are constantly braking.

Cadance, a constant yield, a rate of speed, is what some seek.

I use a 40x17 on my single speed road bike(freewheel). It has the perfect combintaion of climbing ability and flat speed. I can sprint up to pretty fast(no computer or anything). On my beater fixed commuter, its a 39x14, and climbing is rough on it, but I get more speed on the flats of Bowling Green. You mostly tailor the bike to your needs. A 53t ring will make climbing almost impossible, in my opinion

It's actually more complex than that. Top speed isn't just limited by your cadence because wind resistance increases with the square of relative wind speed, so doubling your gear inches doesn't double your real-world top speed since wind resistance is now 4 times as great. Also, as you would expect, climbing becomes more difficult with a higher gear. You may have a mostly flat city, but if your gear is too high, you'll find out right quick exactly how many hills there are.

I comfortably cruise around 20mph on my 77" gear and can break 30 on the flat under my own power. But I don't expect to go any higher since I spend enough time starting and stopping that acceleration is important to me and maintaining higher speeds in a higher gear would be much harder due to the wind.

Sheldon has a nice online gear calculator. https://www.sheldonbrown.com/gears/ 67" - 80" is generally the FG for the street range. Most people are pretty comfortable starting out around 67 - 72.

edit: oops, @ 47t, my gear inches are much closer to 77. 78 was w/ my old 48t ring.

I have a 42:17 right now. I find it very comfortable for city riding and I also ride a local "mountain" (it's only 1 mile of climbing at a very steep gradiant) with it. So, I enjoy how snappy it is and I really enjoy climbing on my fixy, but on flats, I spin waaay to fast. All that said, I'm probably going to move down to a 15 toothed cog.

53 up front would be too big of a gear. I suggest getting something in between what you have now and 53. I ride 48 x 16 myself and it feels right for me.

i run 48x16 most of the time, through the sparse hills of columbus. Tough going up, but i still bounce going down (tops out at around 35).

The other side of my hub is a 15t, kills my legs. The jump from 78.8.to 84.1 gear inches hurts.

I'm also trying to figure out the right gearing before I make the conversion to Fixed. I've tried several on my bike (while still geared), and I can see many working fine. However, the only the smaller (42t) chainring can be removed from the cranks. So I'm left with the 52t. The calculations work out best for a 20 tooth cog (52/20 = 2.6 x 27.559 = 71.65, or 19 52/19 = 2.7368 x 27.559 = 75.42) Anything smaller is too long.

Can anyone think of problems this would cause? I'm going now to try to take the cranks and 42t off of my roommate's junk bike.

Thanks for your help.

so figure out how many inches the gears you say "work fine" total out to, then compare that to the numbers for running the 52- 20/19/18.

Yeah, I'm building with 44 up front and thinking of going 17 in the rear, but really have no clue. I do live at the bottom of a huge hill i have to get over to leave my house-- 4 blocks long and steep grade... Maybe I should start 44/16.

[QUOTE=nicelysmiling]I'm also trying to figure out the right gearing before I make the conversion to Fixed. I've tried several on my bike (while still geared), and I can see many working fine. However, the only the smaller (42t) chainring can be removed from the cranks. So I'm left with the 52t. The calculations work out best for a 20 tooth cog (52/20 = 2.6 x 27.559 = 71.65, or 19 52/19 = 2.7368 x 27.559 = 75.42) Anything smaller is too long.

For what it's worth, I remember reading somewhere (and it makes sense) that if you can achieve the same gear inches with a larger chainring and a larger cog, you will reduce the wear on each individual tooth. So running 53 x 19 is better than running 42x15, even though both yield almost the same gear inches (73.3 or 73.6).

Also, it's hard to tell the difference between a 15-tooth and a 20-tooth cog when you see them from a distance, but a 52-tooth chainring always looks huge, so people will think you are tough.

What Ya Tu Sabes says is technically true since the wear is spread over more teeth. For practical purposes I don't even take that into consideration. I try to work with whatever I have in the parts box or whatever requires the fewest other changes. Chains, chainrings, and cogs are expendables anyway. I don't waste too many brain cells trying to make something last a few hundred more miles. Heck, I'm usually playing with things and changing them out long before they wear out.

What is your actual cadence? I had no problem hitting close to 30 mph on a 42x18.
My Mirage runs a 52x16 and I can do flat sprints at nearly 35 mph and will top out
around 40 mph on a good down hill. That's with a controlled spin of about 155 rpms.
On a really good day I can manage 180 rpms and could go even faster.

No idea,

I'm going with the 52 20 set up. I want to get riding, and it seems like it'll work a-ok.

thanks again everyone.

-ty

Jesus man. I'm riding 42x17 and at about 120rpm's it feels like the centripital force/jostling is going to throw me off my bike and in to orbit. It's not the spinning that's so hard, but the jostling my body experiences. Maybe I need to lower my seat a bit.

Good spin. I usually start to spin out around 150 rpm, maybe a little higher. That's generally plenty fast for me with a 77" gear. Maybe if I was TT'ing I'd feel otherwise, but I'm not.

42/16=2.625x27=70.875 gear inches
42/15=2.8x27=75.6 gear inches
42/14=3x27=81 gear inches

If you go w/a 14 cog you better be ready to roll, I mean cruise speed will be about 27 to 30 mph
and if you can top that gear out you'll be doing well over 40 mph!

I run a 48/18=2.666x27=71.99 gear inches on one ride and 49/18=2.722x27=73.49 gear inches on
the other and I cruise between 20 and 24 mph. Flat out on level roads I do just over 36 mph (48/18). Here where I live there are lots of small rolling hills. I have run 48/21 and 49/20, w/this low gearing
you will learn to spin real nice circles which helps out when you try to go as fast as you can on
the flats or on downhills, you'll be spinning without your butt jumping on the saddle and btw I can
still cruise at 20 to 22 w/no problem. The low gearing is great for learning to spin but you really need
to push big gears to get stronger

52/18=2.888x27=77.99 gear inches
52/16=3.25x27=87.75 gear inches

You may want to try 42/15 or if your feeling strong go w/52/18 since you already have this combo.
If your legs are not pumped now they will be.

The gear calc gives you gear ratios in gear inches. You just plug in your chainrings and cogs you
want to try and it will give you the ratios