Gear Ratios

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simongt

Guru
Location
Norwich
I'm considering a Brompton G Line, but am undecided about the gearing ratios ref. the Alfine 8 speed.
The standard chainwheel on the G Line is a 54t, the rear sprocket doesn't seem to be stated, but Brilliant Bikes have 44t, 52t & 54 t available. I've contacted Brompton to ask if they will fit a 44t if I order one from them, but it's the point of will it work for me - ? :whistle:
I know almost nothing about the logic & relevance of hub gear ratios , but I'm sure several of you do - ! ^_^
The only comparison I have is my Dawes Galaxy which I had retro fitted with an S/A Rx 8 a few years ago. The S/A has a ratio of 325% against the Alfine's 307%, so not that far apart.
However, my Galaxy setup is a 33t chainwheel & a 25t rear sprocket which suits me and my 72 year old knees just fine for anything but fairly steep hills. :okay:
Oh and just for the record, my wee Brommy M3 had a gear ratio of a modest 177% - ! :laugh:
 

TheDoctor

Noble and true, with a heart of steel
Moderator
Location
The TerrorVortex
IIRC the G line has a 54T chainring and 20T sprocket, for gear inches of 27" to 81" or so.
For comparision, to get your Galaxy bottom gear that low you'd need a chainring and sprocket of the same size.
 
OP
OP
simongt

simongt

Guru
Location
Norwich
IIRC the G line has a 54T chainring and 20T sprocket, for gear inches of 27" to 81" or so.
So proving my ignorance, if I had the 44t chainring fitted on the G line, I wouldn't be that far out in comparison to my Galaxy - ? :whistle:
Or would I need a bigger sprocket - ?
 
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