dushuodai

Hi, I recently bought a bianchi pista as my first track/fixed gear bike. I usually use it to commute so i can get to school/buy groceries...etc... I added a front brake and new handlebars but opted to keep everything else stock. Its been two weeks since I got it and lately I've been feeling slight popping in my knees as well as tightness in my thighs and knees. Ive come to the conclusion that the gear ratio is probably too high. Anyone have any recommendations as to what I could do to make it easier on my knees and thighs, seeing that this IS my first fixed gear. Should I change the front chain ring or change the cog in the back. What is a recommended ratio for my pista that will make my current setup a little bit easier on the knees?

captsven

What gear are you running now?

Aeroplane

Changing the chainring is a lot more straightforward for a new rider than the cog, though both are easy if you do it right.

Ratio is up to you and your geography. Try a moderate change and see how it feels. There are people who commute on a 52-14 and 42-18. If you drop too many teeth, you might have to remove a link or two from your chain, so be aware.

carleton

Popping in the knees is most likely due to improper seat height.

Tightness in thighs and knees is part of the game. You will be stronger in 10 days or so. If 48/16 is too much for you, it's cheaper to take it to a shop and have them put a 18t cog on the back than to buy a new chainwheel for the front.

C

carleton

Also, have the bike shop help you determine the proper seat height.

The difference between pain on the top of your knee, pain in the back of your knee, and comfort is literally measured in centimeters.

dushuodai

cool thanks. I believe the stock pista runs at a 48/16.

so the general consensus that i am getting is to just take it to the bike shop so they can install a 18t cog for me, and not change the chain ring.

you think it would be a lot of trouble for me to buy the parts myself and try to figure it out myself or am i better off letting professionals take care of it?

will changing from a 16t cog to an 18t cog be a very noticeable difference?

griffin_

what is the rule of thumb for seat height anyway?

Ken Cox

Go here:

https://sheldonbrown.com/gears/

With a 48t chainring, going from a 16t cog to an 18t cog will make an 8.7 gear inch difference.
A big difference.
From 78.8" to 70.1".
For small differences, change the chain ring instead of the cog.
For big differences, change the cog.
It cost about the same.

By the way, gear inches have almost nothing to do with sore knees, other than revealing inelegant body mechanics.
If a person does not want to put the work into changing how they pedal/spin, then, by all means go to lower gear inches.
I personally find 70"-72" very pleasant and versatile.

Buy a 43t chainring from Harris Cyclery and that will give you 70.6 gear inches.
I like a 47t chainring and a 17t EAI cog for 72.7 gear inches.

If one puts the Sugino/SR 130 BCD 47t chainring on the outside position of the crank star, and puts a 17t EAI cog in back with the flange towards the hub, it will give him or her a perfect chainline on a Pista.
I mean perfect.
Putting the chainring on the outer position will require spacers, so ask Harris Cyclery for some of those if you order the Sugino/SR chainring.
I think the chainring, cog and spacers comes to about $70, total.

At 59 years of age, I ride a 52t chainring and a 17t EAI cog for 80.4 gear inches, and I don't have sore knees.
However, I study body mechanics incessantly.
If a person doesn't want to do the body mechanics thing, go down to 70"-72".

When and if you use Sheldon Brown's Gear Calculator, remember to select your tire size and gear inches in the respective fields.

I have four chainrings and four cogs, and I experiment with them.
Fun.
I highly recommend EAI cogs.
The different cog manufacturers have slightly different threading (in my humble opinion) and switching back and forth between different manufacturers damages the hub threads.
Or so I think.

dushuodai

Ken thanks that was very useful information. I mean I think I could probably train my legs to withstand my current setup, but ever since I've been using my bike more often I've gotten a lot of comments about my calves getting bigger, which is something I would like to avoid seeing that I already have big enough calves as it is.

so i guess now my question is, what are the consequences if i change from my current 16t to an 18t cog. will i need a new chain? i like ken's idea about going 47/17 to make it "perfect."


and what is "the body mechanics thing" ??

dushuodai

also if you change the chain ring does that mean you need a new crank set?

captsven

I had a revelation this year as far as gearing myself. I was running a 42x16 with no problems. I wore out my CR and all I had was a 48, so I put that on. Within a few days I started getting knee pain in my right knee only. I checked my pedals, seat and seat position and everything seemed in line. I rode this for about 3 -4 weeks.

I finally broke down and got a 44 CR. This seemed a little better, but still had pain. I had a big ride coming up and needed to be pain free. I bought a 42 CR and within 3 days I was again pain free. Two weeks after putting the 42 on I finished a four day ride (DALMAC) were I covered about 80 miles a day for four days. I was totally pain free.

I am 40 and have been riding fixed for about 6 years. I really try to spin when I ride but I think that with the higher gearing I have a tendency to mash. Is this what you mean by body mechanics?

Sorry to hi-jack the post but this is fascinating to me!!

Ken, were can I learn more about this body mechanics stuff.

the homealien

Switching from 16 to 18 in the back will move the rear hub axle 1/2" toward the front of the bike. If you have that kind of room, no problem, and if not, a shop can install another link in your chain when they swap your cog. And yes, unless you have a lockring spanner, it's probably best to have a shop swap the cog.

Changing the chainring does not mean a new crankset. The ring is just that: a ring that is bolted onto the crank.

Jim Bonnet

I agree with the seat height comments.. Make sure your seat is right. I know if my seat is too low it messes up my knees.

good luck.

poopncow

Lower gearing will make you spin more which will add tone vice bulk to your muscles.