Want to replace 11T freewheel to 9T sprocket. Where to get?

Want to replace 11T freewheel to 9T sprocket. Where to get? [Almost solved]

Almost finished my first CHEAP build. Not to get me anywhere in a daily basis, but to waste my afternoons and to look at it in my lounge.
(No it's not a carbon fiber cruiser bike, it's cheap bike wrapped in carbon fiber looking vinyl.)

I did my research and found out my gear box (Hoot Chain Box) did not go well with 44T rear wheel sprocket it came with, so I installed 56.

But I reckon it can do lot better with 9T drive sprocket instead of 11T Freewheel sprocket. Bringing drive ratio 18.67:1, since I live in a mountain.

Problem is, I don't know where to find it.
Basically I want to bolt off current 11T and bolt on 9T without having to break the gear box apart and changing the shaft etc etc.

Any help would be appreciated.
Thanks!

Hi gravitty,

I live in Australia, where people export coal and import everything because they're lazy to make anything. So I had to buy all my parts from an importer named eBay.

I don't know what ratio your hoot has, but if it is same chain driven one like mine, that equals to 3:1. This coupled with 11t front and 56t rear equals 15.27:1 overall reduction.

Even with this setup, it's useless going up hill. Still great for flat speed though (theoretical = 38.5mph @ 7600rpm)

I hear people recommending at 16-20:1 overall ratio. So I am trying to chase 20:1 end of the scale with 9T driven sprocket. Bringing my ratio to 18.67:1 and theoretical speed of 31.5mph @ 7600rpm.

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So, I could not exactly find the sprocket that I wanted.
I thought I did, and ordered "Sears 67486"
Apparently for #43 chain, which was just thinner version of 415.
The sprocket thickness was same as my 11T so I don't think would matter greatly.

However, I was lazy and eyeballed the bore measurement... It ended up being bigger than the 11T i wanted to replace.

So I measured it up with equally inaccurate ruler, and found Sears 67486 has 1/2" bore, while the 11T has something like, around 7/16" bore?

I now need to make up a reducer sleeve to fit... and a bigger half moon key out of washers or something... Or should I flatten my shaft and use the 2 set screws on Sears? I dunno.

Fugi93 said:

They don't make it easy, do they? I think you're right because I was wanting to replace my 10t with the 11t and they said I would have to change the shaft. I scrapped that idea after I learned that the freewheel feature was garbage anyways.

It doesn't sound like you have a set of these? http://www.google.com/products/cata...X&ei=xaM1T_muKOqasgKSmMSDAg&ved=0CI4BEPMCMAA#

They will save you money down the road with your other bike parts too. I bought one at a local hardware store for 1 dollar. Good luck.....

Click to expand...

Hi Fugi,

Hahaha yeah I had a caliper somewhere, I can't find it now though. 1 dollar sure is cheap over there, I probably have to fork out 25 here.

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I decided to make up a sleeve and a bigger key for the shaft & sprocket.
Used a plasterboard wall plate bracket which had perfect thickness and was really easy to work with. Hammered it flat, cut it with tin snip, rolled it with pliers.
Also made a woodruff key by filing down a thick washer to fit the new cog.

But now that I look at it from the photos, the sleeve is too short. (Gap beside the key)
I'm gonna make a better fitting one, but you see the idea.

Too bad it's raining heavily this weekend... Can't test it.

I made much better fitting reducer sleeve and tested it. Runs great!
Now really pulls off from stand still and goes better on hills.

Have to admit it doesn't pull speeds that scare me like before, but that doesn't bother me as there aren't many flats to pull speeds where I live.
(Don't have speedo. maybe I'll use my phone gps software to track top speed sometime)

Interesting consequence after changing freewheel to solid sprocket is engine braking...

Will frequent engine braking put unnecessary loads on gearbox, engine itself?

I know some people swapped 11T freewheel to solid sprocket since 11T was known to fail prematurely, how are they going with engine braking?