Gear inch/ratio question

lucky for some

Thats true but
everywheres about three times the distance
my college is 13 miles of big lolling hills from my house
Nice

I'm quite new to fixed and am riding 48x15 which is starting to have an adverse impact on my knees. I'm undecided whether to move to 48x17 or 44x15 to ease the pressure. Can anyone advise which would be better and also where would be good to pick up either a 17tooth sprocket (plus lockring - I'll use the unoccupied flop side of my flip flop)or a 44tooth chainring this weekend. I don't want to spend too much on either but would like something half decent.

Cheers,
Ben

I have a 17t Miche sprocket you can have for £8

Its probably easier (and cheaper) to just change the back rather than the front

I'm quite new to fixed and am riding 48x15 which is starting to have an adverse impact on my knees. I'm undecided whether to move to 48x17 or 44x15 to ease the pressure. Can anyone advise which would be better and also where would be good to pick up either a 17tooth sprocket (plus lockring - I'll use the unoccupied flop side of my flip flop)or a 44tooth chainring this weekend. I don't want to spend too much on either but would like something half decent.

Cheers,
Ben

When I transfer my chain and back wheel from my beater (which is 42-16) to my lo-pro (which has a 54 ring) the chain needs 2 less links. But when I drop it in to the vert drop outs the chain just isn't tight enough by about 1 links length.

So to get my 'magic gear' I need to either put in a half link or go up to a 17t cog, is that right?

Sorry, I'm a total 'tard when it comes to ratios, maths was never my strong point. I was quite surprised my chain fit too, but the chainstays are obviously much shorter on the pro than the beater. How does chainstay length effect the gearing, if at all?

J

Magic ratios are a mystical science - on mine i ran 48/18 with a half link chain - i would try going up a cog on the back - help if you posted pics

http://eehouse.org/fixin/formfmu.php

Thanks eyebrows, very enlightening, yet baffling! I think I know what I need now.

I have a 17t Miche sprocket you can have for £8

Its probably easier (and cheaper) to just change the back rather than the front

sounds good ummar. where are you based? and do you have a lock ring tool that I could borrow?

Thanks,
Ben

a extending the chain = 1"
half link = 1/2"
1 tooth on either cog or chainring = 1/8"

that info shud see you through ;)

Sorted now...I got hold of a 17tooth Miche yesterday from Cyclopolis in Balham. The guy in there fitted it for me (and sheared my lockring a bit which pissed me off) but it's a much snappier ride now.

i hope the threads are ok on the lockring????

What crank length are you using on that 47:18?

Is anyone riding a 44 15 ?

Yes and it's my first time fixed. I find the peddling fine but I think at 78GI it's a bit too hard to stop quickly without brakes. If I change to 70GI is it going to make slowing and stopping easier?

Also is there any real difference between 48/18 and 42/16 aside from 0.4GI?

• Yes
  
  • No
    
    

Do you have a brake?

Also, my calculator makes that a difference of 1.1 GI.

I have brakes and am no hurry to take them off, but would like to learn to brake just using the pedals.

With 172.5 crank arm length and 700x28c tyres, the Rabbit calculator gave me 70.2GI for 42/16 and 71.4 for 48/18, so right you are a difference of 1.1GI or so.

Sounds like 42/16 is the better bet given I already have a 42T chain ring and it's slightly easier on the pedaling.

hi

Trying to decide what ratio to go for Ive got a 46 chainset on the front and was thinking 16t (single speed not fixed)

I live in wimbledon so fairly hilly so looking for something fairly good for that – any ideas?

Cheers

sam

Yes, sounds perfect, you should be able to get up almost anything with that, spin up to 25mph on the flat for short distances, and go down hill at any speed.

I think I've found that 48.18 is Much to spinny for cornwall But should i drop another tooth or two? i cant decide
If i go down to 17 that means il have 17 skid patches by my calculator which is better than 3 :)

go down to 17 then

I've just got a new Gary Fisher and to my horror realized the gear ratio is all wrong for me at a 130BCD 44T x18T - it's way to easy for me especially compared to the pile of junk I was riding round with broken gears for several years. Anyway I want to change the ratio to improve the ride as I just can't go fast enough.

I was told increasing the chain ring to a 48T would do the trick but then I was also told that to do this I would need a bigger chain as the tension would be too high on an increase like this... I was then told to change the back from an 18T to a 16T and this might help... the only thing is that it might not be so simple this way either, and may not make much difference... not having a bottomless budget I'm wondering what the best way to go is? Will a change from an 18T to a 16T be noticeable? if so what's the cheapest way to go about it? If I do the work myself am I going to need 100 tools like a chain cassette lock ring and a chain link tool?

Ta

Dom

yes, change the cog to a 16 tooth. it'll be plenty noticeable and it's the cheapest way.

you'll need a lockring spanner and chain whip. make sure you buy the correct type of cog (1/8 or 3/32 depending on the rest of your set-up).

A two-tooth change at the back has more effect than a two-tooth change at the front; have a look at the gear calculator thing on Sheldon Brown. And remember you can run a 1/8th chain on 3/32nd rings and cogs but not the other way round.

Cheers guys will get on it ASAP

44 with a 17 is nice. You almost get an infinite number of skip patches.