so maybe Im a bit brain dead when it comes to chainrings. I also have never really messed with playing with ratio's on bikes, sticking with what came with them.
bike in question...hybrid used for commute. so Ive got a bike 8 gear cassette 3 in front,I rarely use the smallest front ring
the biggest in the front is a 48 tooth. the smallest in back is a 11 tooth. a friend has a chainring set that will fit my bike..so he says....that is a 54 tooth
will switching to this chainring make my bike faster. I would not mind picking up a little speed. and if I needed a little more "climbing" ease I could always shift to a different ring, maybe even use that silly little front one on occasion.
thanks

NO, it will not make your bike faster. You will have to press harder on the pedals at a slower rate to go the same speed with a bigger chainwheel or gear ratios. How fast you go is determined primarily by two factors - forces resisting moving forward and forces applied to make you move forward. Gear ratio does not change eihter thing. You should be able to go 30mph in your current top gear at a comfortable 100 rpm. If you put on a 54 tooth your top 2-3 gears will be downhill only. You will also have a big jump between the middle and large chainwheel, and you will likely wear the rear cogs faster.

Can you spin out the 11:48? you realize the greatest factor limiting speed at that point is air resistance, not the gear size?

Wheel sucking behind trucks and busses will lower the air resistance, since they push it aside, first. but is it Safe?

First, a few reasons why the 54 tooth chainring likely won't fit:

1. It's probably a time trial chainring which means a typical road bike BCD of 130mm and a 5 arm crank. I've never seen this type of crankset on a hybrid/MTB as stock so if you haven't changed to a road crankset yourself, chances are that makes it a no-go.
2. A lot of low end hybrid/MTBs come with cranksets that use riveted chainrings. For a number of reasons, it's not worth trying to modify the rings on these cranks though it can be done sometimes.

As others have said, until you are spinning out your 48-11 combo, a larger chainring won't do you any good. If you want to go faster (and you aren't gearing limited already) you either need to apply more force or reduce your wind resistance.

If you can only spin out the 48:11 on rare occasion going down hill, you'd get where you're going faster by saving your energy for the uphill.

What's your cadence?

Hi,

It won't make it any faster unless you are seriously fast.

My fastest on the flat (wind behind) was in hammering my
5th gear (of seven) (52/42 and 14 to 28). High gearing
doesn't make you go faster, except downhill / wind behind.

Also you may have issues with front shifting if you swap.
As well as lots of other issues, hard to say without specifics.

rgds, sreten.

A close ratio rear cassette with a realistic top gear and a
high lowest gear is a good way to involve the granny ring.
It will make you faster by giving more gear choices.

My touring bike has a 48 front, 13T rear top gear. I rarely, if ever, spin that one out. And when I do, I'm descending and simply tuck and coast. Enjoy the rest.

Please answer what your cadence is now...

Hi,

Calculations indicate I hit 28 mph with 52t/18t @ 120 rpm.

My normal cruising rpm is about 80 rpm, lower taking it easy.

rgds, sreten.

50+ so my best cadence is lower than the young.

thanks for the replies. After I put this in computer I went out and took a better look at my bike. the chain ring would not work anyway, since my chain ring is a 4 button and his is a 5 button.
but even if they were the same, sounds like it would not be worth the hassle or expense
thanks

To answer your desire (to go faster) rather than your question:

It pretty much goes without saying that if you ride more and ride hard (with off days) you will get faster. But there are things you can do immediately to improve speed, some of which will help you get in shape as well.

1. Proper fit - Saddle height has a significant effect on efficiency. When I was first in the biz we used to tell folks that an inch in saddle height was a 10% difference in efficiency. From what I just saw with a quick search that was an exageration, but height is still significant - about 2% for every 1/2 inch. Fore-aft position is also important, for efficiency, comfort and protecting your knees. Next comes the rest of the cockpit - reach forward to the bars and even bar width for the picky. Many, many opinions on the "best" position but from what I have seen and read 100% of leg length is a great starting point - in other words your leg should be straight with your heel on the pedal and hips level (let the other leg hang down). Fore-aft is more variable, depends more on pedaling style, leg geometry and rider preference.

2. Spin - meaning turn the cranks at higher rpm. There's no one speed best for everyone, though most racers tend to be around 100 rpm. I think below 80 is getting into undesirable range. Riders with heavier legs seem to not do well spinning as fast. Spinning is more aerobic, helping your heart and enabling easier blood flow and oxygen to your muscles, reducing strain on them and also helps build capillaries..

2. Maintain a consistent spin - Your body likes to maintain a certain rhythm and effort - takes less adjustment of all the parts that work together. So find a good rpm and keep to it most of the time. The reason for gears is to allow you to keep that rhythm - other than when prepping for a sprint you shift in response to changes in load, not to go faster.

3. Shoes and pedals - bike specific shoes matched to pedals can make a big difference over squishy athletic shoes. You don't have to walk around funny, though, as pedals that take shoes with recessed cleats are readily available.

4. Proper tire and inflation - skinnier tires and higher inflation is not necessarily better. I'm not going to look up all the sources of info, but this one's interesting: https://www.dorkypantsr.us/bike-tire-...alculator.html

5. To increase overall speed on longer rides - coast the downhills! Much of your effort downhill is just catching up the pedals to the bike speed, and the faster you go the more effort it takes to go just a little faster. The energy you save will be well applied on the uphill, where overcoming wind resistance is not a factor. Tuck down and you'l probably go as fast as you could pedal anyway.

Using the tern "button" instead of "bolt" infers it's a riveted chain ring which wouldn't work anyway.

sorry, it is a bolt system

I wasn't asking YOUR cadence, but niuoka's. 80 is too low. You can learn to spin up to 90-ish comfortably by practicing.