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Aligning rear wheel on trike
#1
I have an ICE trike. I am installing an electric rear wheel (necessary for medical/physical reasons). Having done so, the center-line of the wheel is one-quarter inch to the right of the center-line of the fork. Does it matter? If so, why? I have spoken with bike shop people and they all say it should be centered, but the reasons do not seem founded in physics or engineering.

It seems to me that — with the two front wheels aligned — the location of the rear wheel is not a critical issue. If I were to take a sharp turn at a high speed, I can imagine potential imbalance possibilities, but the likelihood of that occurring is very remote.

Brake considerations are not a factor. The trike has disc brakes that are mounted on the front wheels. If I added washers to the right, freewheel side, the result would be correspondingly greater distance between the derailleur and the freewheel and also increased tension to the forks.

Thanks.
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#2
Ideally everything should be even, but without brakes to worry about and provided the wheel isn't rubbing on the frame I wouldn't have thought 1/4" would make a huge difference on a trike. Try it amd see how it rides, as long as it's not pulling to one side and there are no odd handling issues I would think it's OK.

Having said that, it shouldn't be too much trouble for a wheel builder to re-dish the wheel, so that it's 1/4" over; although it might need new spokes.
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#3
Thanks, xerxes. This is what seemed likely to me, but my experience with bike mechanics is a bit limited. I came here believing that folks posting here would be more knowledgeable.

I don't know whether the wheel could have been built to center, however. The distance between the dropouts is 140 mm. ICE said it was 135 but actual measuring showed it to be 140. If the wheel was centered, the freewheel would necessarily be farther away from the derailleur. Perhaps the freewheel doesn't have to be so close to the motor hub, which seems to me to be the only way to center the wheel and keep the derailleur appropriately close to the freewheel. But then I would worry about the potential for the chain to slip in behind the freewheel, in between it and the motor hub.
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#4
Hi UGW;

Most bikes are designed to flex a little when you tighten up a wheel, so the dropout are typically spaced a bit further apart than the OLD of the hub - but 5mm is a bit much.

I do not think that you understood what Xerxes wrote. The freewheel (or cassette) needs to be lined up with the derailleur - it is not an option to move it relative to the hub. The spokes can be adjusted a certain amount to move the rim to the right or left with respect to the hub - one or two millimeter is usually do-able - more than that will will require different spokes. That is called "re-dishing".

Your derailleur may have enough travel for you to move the whole wheel a millimeter or few. In the USA McMaster Carr offer 1mm thick M10 stainless steel washers that are good for this - they should be placed between the locknut and the bearing cone or the locknut and the existing spacers. I did this for an older wheel designed for a 5 speed freewheel that I have a 7 speed freewheel on.
Nigel
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#5
Ah, yes. You're right, nfmisso — I did not fully understand what xrexes had said. Thanks. I had wondered what he meant about the spokes. As I had indicated, I'm not terribly knowledgeable about bicycle mechanics and knew I needed to reached out to folks who are.

By the way, the new freewheel and the old one are both nine gears.
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#6
(05-21-2012, 07:21 PM)UGW Wrote:  .....

By the way, the new freewheel and the old one are both nine gears.

The you have a cassette not a freewheel.

http://sheldonbrown.com/free-k7.html
Nigel
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#7
Durn! I'll get this lingo down yet. Thanks!
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