Bicycle Mechanics - Shimano 3 speed hub

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CrosseyedCrickt
10-26-06, 09:23 PM
I think I have finally made up my mind, I'm going to get a Shimano Nexus 3 speed hub for my winter commuter and now I have a few questions.
My bike (ATB frame) has 135mm spacing in the rear and non-horizontal dropouts. It seems that the 3 speed hub is only 110mm? Is that right? I'm having trouble finding detailed information on the hub and what I do find kind of confuses me. Will I be able to use spacers to fill the gap?
I am hoping for a coaster brake, but have heard that you can not use a chain tensioner with a coaster brake equipped hub. Since I have vertical dropouts I pretty much need the chain tensioner don't I? Or can the chain be shortened well enough by chosing a differant sized rear cog?
And last but not least, where can I get one of these hubs? Every online retailer I have searched, about half a dozen so far, seems to be out of stock.
??? Pretty technical questions unless one knows a helluva lot about the Shimano Nexus 3.
Why don't you just get an old three speed hub from an old three speed bike and be done with it?
Good luck finding a coaster brake 3-speed hub used, however. They are sought after by collectors.
Yes, you are correct, you cannot use a coaster brake with a chain tensioner. Look, if this is for a winter commuter, why not just get and old three-speed and use the frame? You can change the handlebars if you like.
I used a three-speed for a commuter for many years and it worked very well. I think you will like it too. In my opinion, the riding geometry on the old English 3-speeds was better for winter riding than today's mountain bikes or road bikes. They are more stable and easier to balance on ice and snow.
CrosseyedCrickt
10-26-06, 10:59 PM
Well, I already have the bike and everything else, plus I have too many bikes than storage allows so I was hoping to just use what I have.
So from what you are saying it probably wouldn't even be possible for me to use a shimano 3 speed hub for the bike I'm building? Yes it would be for a winter commuter, but I'd likely use it in the summer when it was raining as well.
Well, the tricky part is going to be the vertical drops. I suppose you can take a few links out of the chain and see if you are lucky enough to get it to fit.
Can you use an old wheel "as is"? If yes, that would sure be easier than trying to build a wheel with a new hub. Of course, you would have to make sure that the spoke numbers match and I THINK the typical mountain bike wheel has more spokes than a three-speed hub, but I am guessing at that one.
CrosseyedCrickt
10-27-06, 12:11 AM
Not sure what you mean by using an old wheel "as is". I was going to order the hub and rim and have the bike sop lace it up. And the shimano 3 speed hub comes in a 36H, so I shouldn't have any problems finding a rim to match.
Not sure what you mean by using an old wheel "as is". I was going to order the hub and rim and have the bike sop lace it up. And the shimano 3 speed hub comes in a 36H, so I shouldn't have any problems finding a rim to match.
Sounds like a good plan as long as you can use the wheel when you get it. Let us know how it goes.
DieselDan
10-27-06, 04:50 AM
Shimano 3 speed coaster brake hubs hard to find? Hardly at all. Go to any shop that sells Electra Townies and see have rare they really aren't. You can buy a new one at a pretty fair price too.
Little Darwin
10-27-06, 05:34 AM
I am starting a plan to convert an old 10 speed to a three speed. The bike I have has horizontal dropouts, so I don't have that specific challenge, but there are others.
Just to give you food for thought, here are some of my thoughts.
1) I might cold set the rear triangle to reduce the spacing. This will be pretty much the opposite that most people do to accept wider hubs... Since I am not looking to swap back and forth this is probably a better solution than spacers. This is not an option if your frame is aluminum.
2) I plan to use an old Sturmey-Archer hub. Three speed hubs are pretty bullet proof (part of what you are looking for I am sure) and an old S-A hub can be found on eBay pretty affordably.
3) I either need to grab the special washer for wider dropout slots (one can be seen at Harris Cyclery, but it is out of stock) or fabricate something... This is needed because 3 speeds need the axle to not turn in the frame to work properly. I don't know the axle size of Shimano to know if this is an issue with their hubs.
As a note, SA hubs for 28, 36 or 40 hole rims can be found on eBay at any given time.
Also, Sheldon Brown has an article about coaster brakes some of which apply to all hubs, even the Shimano... Such as you should have hand brakes anyway, since you don't want to be brakeless if you lose a chain. You also lose the ability to position your pedals by back pedaling. In addition he states that additional friction is an issue, whether this specific issue applies to the Shimano hub is unknown to me.
In my mind, the additional complexity of the hub just adds something to potentially go wrong. Although I did consider this option myself, I have decided to avoid the coaster brake issue.
Recenty bought a new shimano 3CC hub off nashbar with trim kit for $30.
Converted a 7 sp DR to the 3 speed, first DR bike and didn't like it, just a 3 sp guy I guess.
I-Like-To-Bike
10-27-06, 11:35 AM
Such as you should have hand brakes anyway, since you don't want to be brakeless if you lose a chain.
Lose or break a chain? So unlikely a possibility in normal use that it can be ignored. Having an additional front brake is a good idea but not for this reason.
Little Darwin
10-27-06, 12:40 PM
Lose or break a chain? So unlikely a possibility in normal use that it can be ignored.
It only takes once... And when it does happen, it matters little to the victim that the probability was small. :D
I would agree that a front brake is essential for solid stopping power in any case...
It only takes once...
Have fun while you are riding around with a roll cage fitted to the bike, safety first! There is more chance of blowing a front tyre on a downhill or getting collected by a car, provided you look at your chain more than once a decade. :rolleyes:
thomson
10-27-06, 03:52 PM
I have very little experience bicycling in ice but wouldn't it be better to spread the braking load over two (hand) brakes than one (coaster) brake?
I-Like-To-Bike
10-27-06, 04:51 PM
I have very little experience bicycling in ice but wouldn't it be better to spread the braking load over two (hand) brakes than one (coaster) brake?
If you had experience cycling in below freezing conditions you would know that one working coaster brake is worth a dozen inoperative frozen cable operated rim friction brakes made useless with packed snow or ice.
thomson
10-27-06, 07:15 PM
If you had experience cycling in below freezing conditions you would know that one working coaster brake is worth a dozen inoperative frozen cable operated rim friction brakes made useless with packed snow or ice.
Ahhh, good point. I am glad I asked.
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