Sprocket size on a 3 speed
- Thread starter winjim
- Start date
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12boy
Guru
- Location
- Casper WY USA
I assume you have the 177% hub and not the wide range one designed for the two cog hub. I have a 14 which gives me 44.8 gear inches for a low, 59.7 for the middle and 79.6 for the top. For my needs I would really prefer a 13 ( the smallest available) which gives 48.2, 64.3 and 85.7. However, if you go to a 2 chain ring setup and add a 38 tooth chain ring you wind up with 37.2 , 43.6 and 58.1, at least with the 14 tooth cog. If you have a Brompton the chain tensioner will handle this easy peasy. You can shift with your greasy finger between the two chain rings which I do at a stop. I don't know the Sheffield hills but I can climb some fairly stout ones here with the 38 cog. When I get to the top I shift back to the big one for the ride home down hill. That trip takes about 3.5 miles to climb about a thousand feet.
OP
OP
winjim
Smash the cistern
It's an AW so yes, I think it's 177%. None of your fancy chain tensioners or double chainrings though. :-) I guess the thing to do is to sit down and work out the gear inches and compare it to my road bikes.
For reference, the steepest hill in the 2014 Tour de France, was in Sheffield.
12boy
Guru
- Location
- Casper WY USA
www.sheldonbrown.com/gear-calc.html is the place I go to calculate gear inches. Quick and easy and you can print out the results and tape to your handlebars if you wish.
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
www.gear-calculator.com has surpassed the Sheldon one for me.
I usually run AW hubs as roughly 45/60/80 but gradients rarely get above 10% for long here. I'd probably sacrifice the top end in Sheffield (yes, I've tried cycling there), run 34/45/60 and still accept I'm honking or walking up some of the steepest. On 16" with 52-tooth chainring, I think that would mean 20 tooth sprocket.
I usually run AW hubs as roughly 45/60/80 but gradients rarely get above 10% for long here. I'd probably sacrifice the top end in Sheffield (yes, I've tried cycling there), run 34/45/60 and still accept I'm honking or walking up some of the steepest. On 16" with 52-tooth chainring, I think that would mean 20 tooth sprocket.
OP
OP
winjim
Smash the cistern
That's a good site. I like the sliders and the ability to do comparisons.
I've just checked and the chainring is actually a monster 57 tooth. So for 34/45/60 you're looking at a 21 tooth sprocket. I'll probably go for a 22 which gives 32/43/58. That compares with my CdF which goes down to 32" on a triple chainset. Should be enough to get me up the hill to work.
"Sorry if I look a bit knackered, I've been honking the Bickerton."
I actually have two of these bikes, one is pretty knackered so I'm cannibalising it for parts. I think that one does have a 52 tooth chainring so I could always swap them over and go even lower. Once I've got this one roadworthy I might even build the other one up with some new parts. Could maybe go for the greasy fingered double as suggested by @12boy to give it a bit of top end.
