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Old 04-01-08, 12:27 AM   #1
harrier
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Alfine hub on Bianchi bad on hills. Help!

I bought my wife a Bianchi Milano for Christmas. It is beautiful, and rides really comfortably, and she is really happy. Unfortunately, we started going for longer (20 miles) rides together and found a fatal flaw for us. It really has no gear for climbing more than a really moderate slope. I live in Marin (SF Bay Area) and there are hills everywhere.

I don't want to get rid of the bike, and I am considering either replacing the rear wheel with a cluster that has a climbing gear and hanging a traditional rear derailler, or replacing the crank with a double and installing a front derailler.

Both of these may be terrible ideas, and I count on you very smart people to let me know.

It currently has a Nexus Alfine 8 sp rear hub and a 44T front sprocket.
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Old 04-01-08, 12:43 AM   #2
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You could gear the whole system lower by replacing the front chainring with a lower tooth. Does she use the top end on the current setup very much?
My Alfine setup is a 38x19, pretty low geared (I also have knee issues though)
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Old 04-01-08, 12:46 AM   #3
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How often does she use the seventh and eighth gear on the Alfine? If not often, I would suggest knocking the front chainring/sprocket back to a 38 or 39 for a start. It's a much cheaper option. The next best option would be a the double crankset, but again you would need to choose your gears carefully, and probably look at a 32/44 combination (ie, an MTB crankset but without the smallest chainring screwed on).
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Old 04-01-08, 03:07 AM   #4
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Can you change out the rear cog? I am not at all familiar with the 8spd hub, but I do know that going from a 17t to a 22t on a Sturmey Archer is a quick fix for excessively high gearing.

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Old 04-01-08, 09:31 AM   #5
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The stock setup on a Milano is a 20T rear cog, and a 44T chainring. With the 26" wheels, this gives the following "gear inches".

8th Gear: 88.4
5th Gear: 54.7 (direct drive)
1st Gear: 28.8

That is, generally speaking, fairly low gearing. But that top gear is pretty high, I doubt I'd ever be pushing 88 gear inches on an upright bike around town. Check with her, does she use 7th and 8th gear much?

If not, you should try upsizing the rear cog, or downsizing the front chainring. You may not be able to go down much on the chainring, probably down to a 38T on that crank. That would get you to these gears:

8th Gear: 76.3
5th Gear: 47.3 (direct drive)
1st Gear: 24.9

That is quite a bit lower, you give up the 8th gear, and add a new lowest gear, basically.

To take it down even further, you can go up to a 22T rear cog.

On your stock 44T (this is a fairly small drop) - it is the same as giving up half of your 8th gear, and adding a new slightly lower 1st.

8th Gear: 80.3
5th Gear: 49.7 (direct drive)
1st Gear: 26.2

In combination with a 38T chainring - This is the same as giving up 7th and 8th gear, and adding a new 1st and 2nd.

8th Gear: 69.4
5th Gear: 43.0 (direct drive)
1st Gear: 22.6

For more numerical fun, try: http://sheldonbrown.com/gears/internal.html RIP

-Sam

P.S. There are a lot of ways to calculate "gear ratio". I like the Gear Inches method, just because I'm comfortable with it (I ride a highwheeler, sometimes), and can very quickly make comparisons. It takes into account gear ratio, wheel size, and tire size. Gain Ratio is more accurate because it adds crank length into the equation, and Gear Ratio is less accurate, because it doesn't take into account wheel or tire size.
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Old 04-01-08, 11:21 AM   #6
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Another way of extending the gear ratios to a hub gear without adding chain tensioning issues is to replace your crankset and bottom bracket with a Schlumf drive. It is a planetary gear system that can add a down-gear (mountain-drive) or up-gear (speed-drive) to your ratios. I have seen and tried them in action on Brompton folding bikes and they work quite well. The gear shifter is a button you kick with your heel.
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Old 04-01-08, 01:58 PM   #7
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The Schlumf drive is VERY cool. Unfortunately, it costs as much as the bike did! But I am glad to be introduced to it.

I am going to try a smaller front chainring first, then move up to the more complicated choices. As always, the advice is very much appreciated.
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