munklefish

I have an Kona Dr Fine with an Alfine 8-Speed Internal hub. As I've gotten more active and got more commited to cycling I now use this bike for 20km+ rides in addition to my 2 mile commute.

As a rresult I'm finding these 8 gears to be a bit limiting in that I only really use gears 5-8 and only really drop down to four and below on hills with gears 1-2 being reserved for hills that most people wouldn't even attempt to ride up.

So I'm wondering if changing the chainrings in any way would give me a bit more range. What I'm hoping is that by changing the chainrings I might be able to have the effect of moving my gears up a bit so that they are effectively gears 2-9 rather than 1-8. (Hopefully that makes sense).

Is this possible / likely? Assuming it is what would be the best combination?

At present I have an 18 teeth chainring on the back wheel and 42 teeth on the front. Research suggests that Shimano offered a 16 teeth version for the back but unofficially it'll take a 14 teeth chainring.

P.s The chainring teeth are a fair bit worn down so I'm needing to replace at least the front chainring in the next few days anyway.

Any advice would be really appreciated.

sweeks

And you *still* need a higher gear?

I'd try the 16-tooth cog first. Then you can fit as big a chainring as you like, provided the teeth don't hit the chainstay.
Steve

munklefish

newb level question.....

Why try the 16-tooth cog first? Wouldn't that effectively lower my gears?

Or do you mean; fit a 16 tooth rear chainring, and then put whatever I want on the front?

Presumably, by lowering the back teeth it makes the steps between the gears smaller to partially counter the extra teeth on the front chainring? My, thought was to leave the back ring as 18teeth and get a 44 toothed front ring so just increasing it by 2 teeth.....

sweeks

Yes, if you currently have an 8-tooth rear sprocket.

Cogs are the gears on the rear hub; chainrings are the gears on the cranks.

You can increase your gear-inches by increasing the number of teeth on the chainring, reducing the number of teeth on the cog(s), or both. You can play around with a gear ratio calculator to get some ideas.
Steve

munklefish

Ah, that was a typo.

I have 18teeth on the rear chainring.

Also, it's an internal hub, so the 'cogs' can't be changed. Hence why I referred to the back as a chainring (I thought that was the proper term with an internal hub, so as to differentiate between the hub and the external 'cog'/rear chainring).

GamblerGORD53

Get a 46T and let'r rip. ha
My SA 5 w went 46 mph with 116 GI.

JohnDThompson 

While you can't realistically change the internal gearing, there's no reason why you can't change the cog mounted on the outside of the hub. If you want higher gears, mount a smaller cog on the hub, or a larger ring on the crank, or both.

sweeks

Heh... I was about 200% sure of that. How small would an 8-tooth cog be?

It's true that "cog" is a sort of generic term for "gear", but in the context of bicycles the gears that are driven by the chain are "cogs" in back and "chainrings" in front.

The (single) cog on an internally-geared hub is held on by a snap ring that can be removed (carefully!) with a small flat-bladed screwdriver. You should be able to try a 16-tooth cog, which should bump your ratios up about 11% if I have done the math correctly. For a single rotation of the chainring, the smaller (16-tooth) cog will turn slightly more times than the 18-tooth cog.

Steve

hermanchauw

Do you want more range or higher overall ratios?