Hub Gear trouble

[JohnInStockie]

Hi everyone

Does anyone have any tips for tightening Hub gears, specifically the SRAM P5.

Over the last few months, I have changed the rear sprocket 4 times, first a 13 tooth, then a 14, then back to a 17, then a 16 2 weeks ago, and tonight a 15 tooth. Took it for a test drive and the gear were not changing correctly.

Got home and notice that there is considerable play in the rear wheel side to side. I would say that at the rim, the play is about a quarter of an inch.

could this this mean that the hub needs tightening, any clues how to do this?

John

 

[flecc]

Hi John, it sounds like the bearings have bedded in. Try adjustment just from the left (non-sprocket) side at first. Undo the wheel nut well out on the left, then tighten the inner nut into the wheel to the limit without force, and back it off of just a touch. Then tighten the wheel nut again, centralising the wheel of course, finally checking the slack at the rim. Trim the adjustment as necessary to remove virtually all the slack but leaving the wheel freely spinning.

This left hand inner nut holds the whole innards in place and is the master adjustment. It doesn't affect the gear change adjustment.
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[JohnInStockie]

This is ok even though the hub roller brake is on that side?

 

[JohnInStockie]

This is done with the wheel ON the bike I take it?

 

[flecc]

Yes to both John, the hub brake sits around and over the bearing cone and has no effect on it. The adjustment is quickly done with the wheel on and it takes only seconds.
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[JohnInStockie]

Think Ive done it. On mine it wouldnt turn whilst the brake was still connected to the frame, once I had removed that nut the it turned with the whole roller brake arm. I gave it a full revolution, which meant I had to use a moderate amount of force, but now it all seems ok, with the movement being about .5 mm and the rear wheel turning freely.

Hope Ive done this right!

Thanks very much Flecc

John

 

[flecc]

That's fine John, the brake obstruction just being the twist it applied while still secured.

It should be fine now. The ball bearing cage on the sprocket side is a much larger diameter and it's held into the hub by a pressed steel serrated washer which doesn't provide security. Then the whole inner assembly is pulled into position by the nut you adjusted, the cone and ball bearing cage pressing against the ball race in the shell on the left side. A very simple setup and you couldn't really go wrong in doing the adjustment.
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[JohnInStockie]

Thanks again Flecc. Plus I can now confirm that a standard 15T sprocket (not an offset one) fits and works perfectly fine on the Giant Twist with an SRAM P5, and thats the smallest one that will.

From the extremely quick test on the hill outside my house, it looks like Ive dropped a gear, so anything I climbed in 3rd, is now in 2nd, and so on. meaning that i should be ok up anything upto about 15-20 % minimum, possibly more.

However the plus side is that I seem to have gained the ability to go faster when on a slight downhill, which for me means that I will get to work faster, and coming home will be the same.

Looking forward to trying it out. Thanks to Fleccs advice.

John

 

[flecc]

And thanks in return for that very useful information John, I'd never tried a 15 tooth non-offset.

Careful you don't take off in strong gusts now!
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[JohnInStockie]

Just an update for anyone whos interested, I found on my 21 mile commute today that the gears seemed to keep slipping, but I couldnt tell if it was the hub or the chain slipping on the teeth.

In order to check, I ve swapped back to the 16T non offset and will advise tomorrow what it was.

 

[ITSPETEINIT]

Slipping gears.

Just an update for anyone whos interested, I found on my 21 mile commute today that the gears seemed to keep slipping, but I couldnt tell if it was the hub or the chain slipping on the teeth.

In order to check, I ve swapped back to the 16T non offset and will advise tomorrow what it was.

I expect that to fit the new sprocket you had to move the wheel and now it does not fit in exactly the same place in the 'rear end'. If that is the case it would be necessary to adjust the gear change cable - if it is a Sh. Nexus, so that the two red marks, visible on the outer right side of the hub, viewed from the top, coincide. This is done at the handlebar end by turning the barrel adjuster clockwise or counter clockwise until the marks correspond. Select the 4th gear (in the case of a 7 speed) before you do this.
P.

 

[flecc]

Also make sure that the chain isn't sitting on the shoulder curve of the P5 John with that 15 tooth, you'll find that out on your ride tomorrow probably.

I was a bit surprised that you found the straight 15 tooth was ok, since a 16 tooth only just keeps the chain off. Therefore your trouble could well be that, rather than gear adjustment, making the chain jump.
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[JohnInStockie]

Yes it was the 15T, its just too small. The only effect was when starting off from standing, thats when it would jump.

As I cannot find anyone anywhere selling a 15T offset, it looks like only the 16T normal or offset is the smallest it can go.

John

 

[flecc]

I thought that was probably it John. I've previously hunted for offset sprockets of 15 or less teeth, but drawn a blank. The last ones I ever saw were 14 tooth at Fishers about three years ago, but they discontinued them.

Trouble is there's no demand since the usual way is to change the chainwheel/chainring as well to get the desired ratio, but of course the Lafree chainwheel is very non standard and stuck at 37 tooth only.
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[JohnInStockie]

Hmmm, thinking about the Lafree chainwheel, IF someone was proficient with plastic moulding techniques, do you think a larger wheel could be fitted, and the cover re-moulded or is there more to it than that?

 

[flecc]

More to it John, since the Lafree chainwheel has a completely non standard centre. The metal is pressed into double width at that point and has internal spines which engage on the shaft, all much more like motor vehicle practice than bicycle.

You can see the splined shaft just behind the circlip pliers in the photo below:

If the cowling could accept a slightly larger chainring, the spokes of this chainwheel could be cut through and a slightly larger three spoke bike chainring bolted/welded to it. If bolted, the spokes would have to be offset fractionally to get the chain into line with the motor drive sprocket.

And with a larger cowling, a rather larger chainring would be possible, though limited by the chainring/motor sprocket gap.
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[JohnInStockie]

Ahh, I see, so its not impossible, just not as straightforward as it could be. I have to say that is the cleanest motor unit I have ever seen. And those are circlip pliers, first time Ive ever seen them despite searches on the web.

That gap though doesnt look that big really to make that much of a difference, its probably not worth it. Maybe the newer premium Panasonic motor it different?

 

[flecc]

The new Panasonic unit has a larger chainwheel, I think it's 41 tooth, but I don't know if the mounting is the same. It's got many substantial differences including much smaller motor sprockets and a very different shaped crankcase.

Those circlip pliers are a bargain from Machine Mart and have four interchangeable heads for different sizes etc, at £7.04.

The order code is 040211075 , online or branch at 71, Manchester Road, Altrincham.

And the motor unit is new, it's only duty is photographic modelling poses!
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[JohnInStockie]

....thats on my doorstep...cool

 

[flecc]

I thought that would be your closest of their branches John.

They have some posh pro circlip pliers as well, at higher prices, but these do the job ok.
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