marquis1366

calstar 

Absolutely not!

regards, Brian

HerrKaLeun

You will need a new shifter and derailleur and a chain. you may as well go to 10 or 11 speed, which is not much more expensive these days.

you can plot your existing and proposed gearing in the calculator. ultimately with more gears you can have a better chance to be in optimal cadence. however, with the same motor speed won't increase significantly.

Depending on what chainring size your 3x has, you have to take into account derailleur capacity. for example a 3x11 with an 11-42 cassette may be outside the RD capacity on a triple chainring. Obviously switching to 1x or 2x is an option, but now we are talking about even more $.

caloso

CliffordK

There are a lot of critical details.

Road Bike?
Mountain Bike?
Touring Bike?
Type of shifters?
Riding on road or dirt?
And, overall, what is your bicycle worth to you?

Do you really need that 11/34 or 11/36?

What is the condition of your parts?

In the basic sense, it is probably not worth it. However, if you already need to do some major upgrades, then it may not be so bad.

You probably won'g gain much for "tighter gearing" as you are going for a cassette with lower gears too.

Your 8s rear derailleur may be fine. But, you could have a pile of expensive upgrades. Crankset?

delbiker1 

What are you trying to accomplish by making that kind of change? Do you feel like you need lower gearing for climbing? Are you just looking for increase in speed. I do not think you are going to get any faster by making those changes. I have a bike, 9 speed compact double, that I have re-equipped with 37 mm tires, racks, bags, mirrors, etc., to be my commuter/errands bike. It is now considerably heavier. I changed the chainrings, 50/36 to 48/34, at a cost of about $52, on sale. The only thing I had to do extra was take a link off of the chain. The cassette is 12/26 that I have not changed. It gives me lower gearing to make managing the extra weight more efficient. That comes into play when I am climbing, mostly flat here, and really has made a difference when riding into a strong head wind. I live near the coast and windy conditions are almost always present. It has made it much easier on my 66 year old knees. For me, this was worth the minimal cost as I am not looking for more speed.

fietsbob

Your desire to go from 8 to 9 means you have to buy a new 9 click shifter.. they, in Brifters are expensive..

"Speeds " is not velocity it is a cog count, on a cassette, 9 cogs in a space, formerly with just 8..

gear ratios x cadence x wheel diameter gets you (a) distance per measure of time..







....

Bill Kapaun

An 11T top cog is an 11T top cog no matter how many additional speeds the cassette has.
Getting rid of a chain ring reduces the number of gear combinations available, thus increasing the odds of having a gear that ISN'T "just right".

I upgraded my bikes to 9 speed mainly because there are more cog combinations available.
Right Shifter, chain & cassette are needed. Absolutely no change up front needed.

IF an 11T cog doesn't give you enough speed, you probably need to work on the engine.

fietsbob

Air resistance still pushes back ... and it pushed back 4x as hard for 2x the increased speed, you know..\\



I'll copy this guy's reply he has more degrees & schooling than I could afford






....

nfmisso

Air drag force is 4x for 2x speed, which means air drag power requirements are 8x for 2x speed. Power is proportional to force times speed.

zacster

I upgraded a 3x7 to a 3x10, but not to get extra speeds. I wanted better brakes than the old cantis, and I put on XT v-brakes, which required new brake levers, which require new shift levers, which if I'm doing shift levers I may as well go for 10sp, which meant a new cassette, which meant a new derailleur, which meant a new wheel with 10sp spacing, which required a new chain, and on and on and on. I bought everything at bargain prices by scouring the internet for about 2 months. Now I have an old looking beater bike that is equipped with what at the time was the latest XT 10sp dynasys gear. It works beautifully, is super quiet, shifts with a light touch in either direction, brakes with one finger. This bike is my regular commuter bike now. At some point I put a new 48t large ring on because the old one was totally worn out. I also put on a dynamo front wheel, and the rear uses matching parts plus I built them myself.

Would I upgrade an 8sp to a 9sp, no way. You'll go through what I did but you still won't have an up-to-date bike. My big regret is that I did all of this but still have a 26" rim brake bike. I should have just gone with a 29er disc brake frame and tossed the old frame and built up from there.

bwilli88 

In DT shifter 9 speed is only found as a Dura-Ace and also expensive
changing from 3x8 to 2x9 will shorten the the Gear inch ratio span.

https://www.gear-calculator.com/?GR=D...28,34&UF2=2200

This was as close as I could get.

Phil_gretz

Don't do it.

Rarely, if ever, unless you a drivetrain so worn that you would be replacing anyway. And even then, no.

Yes and No. You want increased speed? (1) improved aerodynamics, (2) greater bio-kinematic efficiency through measurement and training, (2) more sustained raw power, through training or doping...

fietsbob

replace chain & cassette keep speeds count the same , buy a bigger chainring and work harder..

seattle29er

I've changed a lot out on different bikes, dropping and adding gearing, etc. In my experience, it really depends on what you hope to use the bike for, what sort of riding, and what you hope to gain from the swap. In your case, going 11-36 cassette will likely just keep your current 11-34 range +/- and add an extra, larger low gear. If you want tighter gears (I think you mean closer gear ratio), without getting too complicated, then get a closer spaced 8-speed cassette, such as an 11-28, and keep your triple crank. You can get a smaller small ring, if possible, to keep a super low gear, but how often do you use the super low granny gear? If not very often, a simple, tighter spaced cassette will do the trick nicely. So we need to know more information about your ride!