Agattu help needed - Pedelec Forums

Wallie · #1 (**permalink**) 25th April 2008, 19:16

Hi all,

I'm feeling a bit bereft. I ordered a pair of Marathon Plus tyres for my Agattu from Halfords. They managed to take the front wheel off and changed the tyre. However, they could not remove the rear wheel due to the gearing and claims that the rear wheel is set up in a way that they had not seen before. I got them to talk to 50 Cycles and Tom (I think) gave them advice on how to get the wheel off over the phone. However, they still have the bike as they want to wait until another mechanic comes in to have a look on Monday.

Any clues as to what the problem is and whether there is an easy way to get the wheel off? I haven't heard that this has been a problem but any help you could give me so that I can pass this on to Halfords would be really appreciated. I am so missing my bike!

flecc · #2 (**permalink**) 25th April 2008, 20:08

It's a perfectly normal wheel mounting, common to hub gears. I can only assume they are only used to the derailleurs on the cheap bikes they sell.

The gear cable can be fiddly to detach, but at a pinch the tyre could be changed even without detaching it, if that's what is confusing them.

Otherwise it's just a matter of releasing the brake cable as on any other bike, loosening the wheel nuts and dropping out the wheel. If the tyre is butting up against the inner front of the mudguard before the spindle reaches the end of the dropout slots, just letting down the tyre a bit gives the extra clearance.

Are you confident that someone there doesn't just want to try out the bike at the weekend? It's an old motor trade trick, "Can't repair it until Monday Sir".

If you think that's possible, remove the battery on the excuse that you want to charge it.
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Wallie · #3 (**permalink**) 25th April 2008, 20:26

Thanks Flecc.

When I was there, they were flumoxed by the gears and were concerned that if they did anything then they would breach the warranty that I have on the bike. Having undone the brakes and the wheel nuts, there was the additional task that they had to do to release the wheels and just didn't know what to do. What would they have to do? I only wish there was a film they could look at on You Tube!

flecc · #4 (**permalink**) 25th April 2008, 20:35

It's best to release the gear cable before undoing the wheel.

However, as they really don't seem to know what they are doing its best to do one of two things to avoid damage.

1) Wait for the mechanic on Monday, or,

2) With the bike on it's side, drop the wheel out with gear cable still attached and fit the tyre like that. It doesn't leave much room to do it, but I've done that for speed on the odd occasion with hub motors rather than unsoldering cables, and it's quite easy to do. That will avoid them having any need to interfere with the gear cable or adjustment if they refit the wheel in the same position.

Whether they'll do that on a Saturday is another matter though, as it's their busy day of course.
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HarryB · #5 (**permalink**) 25th April 2008, 21:07

I am also about to take the wheel off my agattu but to change the rear sprocket. I have settled on an 18T as it seems a good compromise (and a local shop has one in stock). How does the gear change cable attach to the hub itself. Does it unhook or do you have to release a clamp - it is difficult to tell as visibility is limited.

I know this info is somewhere but how many links in the chain do I remove for the move from 22T to 18T - is it 2? Finally how much slack is there supposed to be on the chain. I know the idler should take up the slack but even so it seems excessive at about an inch on the bottom run - is this normal? The wheel still has a bit of travel left to take up some slack by the look of it. You can tell I am new to hub gears.

flecc · #6 (**permalink**) 25th April 2008, 22:04

On the basis that a picture is worth a thousand words, I've edited out two enlarged bits from Shimano's technical documents on this hub. If you look at the first illustration below, the outer cable sits in the "socket" at the back of number 41. Then the inner cable goes forward and runs around under the "pulley" number 40 and is clamped in the inner cable fixing bolt number 43.

That has a line drawn up to the slot in number 40 where the inner cable fixing bolt sits. Rolling off the gear change to give the maximum slack will make it easier to release that. There's a slot under the outer cable socket in number 41, and pulling back the outer cable will allow you to pass the inner through the slot to release plenty of slack. Then you'll be able to angle up and unhook the inner cable fixing bolt from the slot where it sits without undoing the inner from the bolt. Below the illustration is the parts list giving the names and numbers, and more info below that:

Exploded view.jpg

Part list.jpg

The number of links to remove Hal is 2 as you said.

The chain slack isn't critical. It's usually about half an inch up/down movement at the centre, but make sure it's not pulling too hard on the motor's chain idler, so a bit more slack does no harm.
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HarryB · #7 (**permalink**) 25th April 2008, 22:18

Thanks a million Flecc, much appreciated and I feel well prepared. I will give it a go over the weekend.

Hal

simonbarnett · #8 (**permalink**) 25th April 2008, 23:56

Flecc- I've not done the sprocket change as i'm waiting to get some more miles before deciding to go ahead. But I had a look and didn't see the different chain link I was expecting. Maybe I'm old but there used to be one link in the chain with something that looked like a small hair grip. You'd undo that and shorten from there. Has all that changed?

Aldby · #9 (**permalink**) 26th April 2008, 01:02

To remove the rear wheel on the Agattu.

Select 1st gear, this releases tension on the gear cable.
You should now be able to pull the outer cable forwards by a few millimetres where it locates into a holder on the rear fork stay.
The inner gear cable will now be free of tension and can be easily detached from the gear hub.
Slacken off the rear V brakes completely so that the wheel and tyre are freely removable.
Slacken off the hub nuts enough to be able to remove the wheel from the dropouts.
You should now be able to lift the the wheel out and remove the chain from the rear sprocket at the same time.
Replacement is a reversal of the above, but align the wheel nuts to the original marks left on the dropouts. This should put the wheel back into perfect alignment.

Hope that is helpful and I am not teaching my Granny to do that digusting thing with an egg

John

flecc · #10 (**permalink**) 26th April 2008, 01:35

Quote:

Originally Posted by simonbarnett

Flecc- I've not done the sprocket change as i'm waiting to get some more miles before deciding to go ahead. But I had a look and didn't see the different chain link I was expecting. Maybe I'm old but there used to be one link in the chain with something that looked like a small hair grip. You'd undo that and shorten from there. Has all that changed?

Yes, those detachable links are no longer fitted as standard, you'll need to use a special tool now. Here's an illustration of a typical one, various makes obtainable from all good bike shops:

Chain link extractor

and this web page describes how to use it:

Chain tool use
.