Gearing Question....

[oldschool rider]

Ok guys I have just bought a new rear wheel with a Khe Astern freecoaster and although the normal gearing would be 25/9 I have a feeling it's gonna be real close to my brake which is mounted on the chainstays.

I know the 25/9 can be done on bikes with chainstay lugs but I want to know if anybody has tried 27 or 28/9 just to give my chain a little bit more clearance.

cheers,
Steve.

[oldschool rider]

Cheers Glen 



Steve.

[teamsano]

stevie, i find the easiest way to calculate gearing is based on the old 44/16.

if you divide 44 into 16 you get a figure of 2.75, now using more modern gearings pick the one closest to a ratio of '2.75' i.e 28/10= 2.8

so imagine 28/9=3.111

now multiply the old freewheel of 16x3.111=49.8

so that would give you a gearing almost equal to the equivalent of the old school 50/16. quite stiff i'd imagine.

[oldschool rider]

 
I know about the math behind gearing but never thought 2 teeth would make that much of a change. I remember going from 42/16 to 40/16 and there not being a great amount of change, but I suppose i never really thought about the rear end now losing almost half the teeth my old feewheel used to have.

well I'll work something out.


Steve.

[welsh denny]

here's something for you to get your 'teeth' into...


doing up my 26" dmr trailstar as single speed. got a peregrine 43 t chainring up to go up front.
what would be the best size rear cog for the cassette... or am i gonna have to go with a 16t as the single gear pack comes and get a different sprocket up front?
would like it similar to bmx gearing...

part of my build so far...


gonna have white halo wheels soon (when i get some cheap enough)

[oldschool rider]

Idealy it would be a 15 or 16 to get a bmx feel.



Steve.

[Voodoocars]

My cruiser has a profile 46 front and a 16 rear and its real tough to pedal compaired with my 20" which has 28/10. I think th 24" wheels has something to with that - can someone confirm..  Good for top speed tho' 

[moley]

My cruiser has a profile 46 front and a 16 rear and its real tough to pedal compaired with my 20" which has 28/10. I think th 24" wheels has something to with that - can someone confirm..  Good for top speed tho' 

Gearing is based on 3 sizes.

Front Sprocket, Rear Sprocket and Wheel size!!

If you have 44t (front) and 16t (Rear) and 20" size wheels compared to 44t (front) and 16t (Rear) and 24" size wheels then its going to be a lot harder to turn the 24" wheels. 

With a 44t (front) and 16t (rear) a 20" wheel will rotate once and so will the 24" and because the 24" has to travel further it is far harder.

To get the same rate of travel either decrease the size of the Front Sprocket or increase the size of your rear sprocket to get your ratio the same as a 20"!!

[lodge]

Ok guys I have just bought a new rear wheel with a Khe Astern freecoaster and although the normal gearing would be 25/9 I have a feeling it's gonna be real close to my brake which is mounted on the chainstays.

I know the 25/9 can be done on bikes with chainstay lugs but I want to know if anybody has tried 27 or 28/9 just to give my chain a little bit more clearance.

cheers,
Steve.

27 or 28/9 will be hard work mate.