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Old 08-08-08, 06:34 AM   #1
CmJc
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Acceptable Cassette Wobble

SRAM PG850 on a 2008 Jamis Ventura Sport

I've got a 4 month old bike with 3,000km ridden, everything is working perfectly.
I highly recommend the mount as a first time road bike. (The new Sora gears are terrific, Shimano fixed the trim problem, on compact chainrings at least.)

Whilst cleaning and lubricating the bicycle, I notice the cassette can be wobbled by placing your thumbs on opposite sides of the largest ring and pressing inwards alternately on each side, rocking the cassette.

There is visible play of about 2mm. Seems quite a lot to my eye.

I was able to compare this with a brand new unused identical model, and it too has play of about 1 or 2mm. You have to work at it to get the cassette to wobble when the bearings are packed with fresh grease, but wobble they do, even when new.

It is possible the assembler left them a bit slack on purpose, or was careless.

Is this an acceptable amount of wobble?

Looking at other bikes I find some cassettes are rock solid with no play at all.

If I wanted to remove this play, what precisely needs to be tightened up?

The cassette lock ring was tightened correctly to the specified 40Nm, but perhaps there could be a shim added to stop the rocking.

I understand there are large allen bolts deep inside the Formula hub that tighten the freewheel up, is it those that need tightening?

I'd like to know for sure before I let my dealer loose with the spanners. He's a bit green.

Ta!
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Old 08-08-08, 06:48 AM   #2
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Cassette should have zero wobble if the lock ring is properly tightened. Take the cassette off and now check if the hub wobbles. Could be the culprit. Could also be a spacer issue depending on the wheel manufacturer.
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Old 08-08-08, 07:36 AM   #3
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Thanks.

The wheels are Alex DC19 standard spec. for the Jamis Ventura Sport.

I recently did the wobble test on a brand new Trek Madone in a shop, and it had about 1mm of wobble too. Which was quite reassuring.

I watched the mechanic tighten the cassette lock nut using the correct tool, and I'm certain it is correctly tightened.

This play has been there from new, and, as I wrote, is also on an unused sister bike in the shop window.

Let's do a survey...

Try the cassette wobble test and post your bike model, its age, and the result please....
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Old 08-08-08, 08:21 AM   #4
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cassettes wobble. on everything. campy, shimano everything i have worked on.
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Old 08-08-08, 09:39 AM   #5
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Cassettes should not wobble whatsoever if installed properly. Now, they may "appear" to wobble due to the optical illusion created by the shape of the teeth cut to aid shifting. But if you can grasp a cassette and move it side to side that ain't good!
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Old 08-08-08, 11:36 AM   #6
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Wobbles happen, but I think yours is not acceptable.
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Old 08-09-08, 07:06 AM   #7
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Allow me to clarify:

The wobble we are discussing is not when the cassette is rotating, it is only the movement you can make by pressing with your thumbs alternately on the stationary biggest cog. Mine moves about 1-2mm. and has done from new, and so do two other similar new models in the shop.

The cassette rotates perfectly true, and doesn't wobble when rotating, and functions perfectly.

Added: I don't think the play is in the hub itself because pressing on the wheel rims alternately produces no discernible movement at all. The wheel is true and balanced. If the hub were the source of the cassette wobble then I would expect there to be wobble when you press on the wheel rim.


Most new unused bikes I have tried this on certainly do wobble.

I've just been to another shop and tried it on a new Giant, and it too moved 1mm.
However a friend's new Bianchi 1885 full Campagnolo doesn't move no matter how long you try to wobble the cassette.

Try the test on you bike and post the result...

Last edited by CmJc; 08-09-08 at 07:23 AM. Reason: Added about hub
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Old 08-09-08, 07:59 AM   #8
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Tighten the cassette lockring. I just tried that on nine bikes at the local shop, only four wobbled, the other five moved noticeably but that was flex in the largest ring, and the other four could be fixed by tightening the lockring.
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Old 08-09-08, 08:08 AM   #9
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I just checked my new Specialized Crosstrail, 9 spd, and it does not wobble at all. The largest cog flexes 1-2mm, but it doesn't wobble. 700-1000 miles on it.
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Old 08-10-08, 08:33 PM   #10
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Thanks for your comments.

This movement is not "flex' in the sprocket, it's movement of the whole cassette. Interesting that so many new cassettes in the bike shop moved Sekine! That's what I find too, the works bike assemblers do seem to allow the cassette a mm or two of movement.

However, If I was to try to remove the movement...

Since my wheel bearings are correctly tightened, and there' no play at all in the wheel itself, it seems there's 3 possible places the slackness wobble could arise.

1) Loose cassette lockring, not correctly seated and tightened to 40Nm. So the cassette moves on the splined freehub body.

2) The large hollow Allen lockbolt inside the hub that anchors the freehub body to the main hub is loose. What Allen key size is this in Formula hubs?

3) The freewheel mechanism inside the freehub has too many (or not enough) shims inside and needs adjusting.

Is this a correct assessment?

Of these 3 my guess it is the last one because I saw the lockring tightened correctly, and it's unlikely the hollow hub lockbolt would work loose. I suspect we will find the hub lockbolt is already fully tight and any play arises from within the freewheel mechanism. So I'll need to have shims ready.

It's a 40km ride to the bike shop so I'd like to prepare in advance for the possibilities.

Once the cassette is removed, how do I distinguish 2) from 3) if there's still 1-2mm play on the freehub? Does the hollow lockbolt have to be torqued to any particular setting, or is it just tightened up until there's no play?
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Old 08-11-08, 11:31 AM   #11
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Without taking my cassette off, it is possible to see where the play is.

When I look from directly above the wheel down at the space between the spokes and the cassette, I can just see the end splines of the freehub body. When I do the wobble test, I can clearly see the freehub and cassette move together as a unit relative to the main hub. So that means it is not slackness in the cassette lockring. Because (I assume) the lockring simply attaches the cassette to the freehub body.

My cassette wobble is therefore due to either looseness in the freehub attachment to the main hub, or excess play inside the freewheel mechanism itself.

I've never seen a freehub freewheel mechanism, but I assume it has its own lockring, which may have worked loose, or the freewheel may need shim adjustment inside.

On the old style threaded (screw-on) cassettes and freewheels, the freewheel lockring (usually with two punch holes in it) does come loose occasionally, or can be tightened by adding very thin bronze shims underneath it.

Am I thinking on the right line?
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Old 08-12-08, 06:18 PM   #12
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Bump...
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Old 08-12-08, 10:29 PM   #13
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Try snugging the axle skewer more/less and see if it makes any difference.
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Old 08-13-08, 08:02 PM   #14
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Thanks Bill, I've tired it at low, normal, and high tension, and it still wobbles, the play seems to be in the hub itself or the freehub freewheel mechanism, which is why I'd appreciate expert advice before we disassemble the wheel.
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Old 08-15-08, 01:54 PM   #15
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a timely thread

Thanks for posting - I have some slight wobble in my Xero hub (2 years old, 2000 miles). I discovered this issue yesterday.

The freehub bolt is tight, but the wobble persists. I'm going to reassemble and just ride it.

btw - Xero hubs are not 10mm hex - On a hunch, I tried my 3/8" socket extension, and that worked!
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Old 08-15-08, 07:41 PM   #16
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Report:

We disassembled the wheel and found, as I suspected, that all the play originates in the Freehub itself.
Both the cassette locknut and the hollow Freehub attaching bolt were perfectly tight.

The SRAM Freehub requires a hefty 12mm Allen key, Shimano uses 10mm.

Since the bike is under warranty, has only done 3,000 km, and has been carefully cleaned, lubricated, and ridden, we phoned the local Asian importer of Jamis/SRAM to ask about a replacement Freehub.

He claimed only bike frames are covered by warranty, and said that "SRAM Freehubs only last 1,000 kms", and suggested buying a Shimano Freehub instead.

It would be interesting to hear what SRAM have to say about this.

We reassembled the wheel using the original parts, still with the 2mm wobble.

The SRAM Freehub does not have a lockring on the back, its a sealed unit, so there's no way to tighten it up. However, the bearing cup in the Freehub does have two special notches so that it can be tightened with a custom tool, but I suspect it is already tightened down properly and would not remove the play.

Anybody from SRAM here?
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Old 08-17-08, 07:29 AM   #17
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I've emailed both Jamis HQ and SRAM HQ about this and have given them this thread.

It'll be interesting to see what they make of their Asian Distributor claiming Jamis SRAM freehubs only last 1000km, and are not covered by the Jamis warranty.
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Old 10-21-08, 06:17 PM   #18
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Update: Good news!

My enquiries to SRAM produced no useful result, other than they agreed that the Freehub was defective. But Jamis HQ responded to my nudging by sending a replacement Freehub at no cost. It looks identical to the defective one, but the lateral play is much less, only about 0.5 mm when you wobble the cassette, compared to 2 mm on the old one.

The gear change is crisper too.

It arrived in time for my first UCI road race here in Asia, and the Jamis Ventura Sport performed very well.

I would like to publicly thank Carine at Jamis HQ for looking after her customers wherever they are.

I am very pleased with my Jamis road bike, now approaching 4,000km in six months.

My conclusion is that the SRAM Freehub fitted to the new bike was manufactured below standard, and I hope the replacement will last far longer than 3,500km.

We shall see!
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Old 10-21-08, 09:32 PM   #19
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Most freehubs have 2 sets of bearings in the cassette body, and as they wear the body will wobble relative to the axle, so when you ride in certain gears the cassette will make a clunking news. Stuff wears out....as you now know.
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Old 10-22-08, 09:05 PM   #20
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Merlin55: You missed the point that this is a new SRAM Freehub, the Jamis is still under warranty, only 4 months and 3000 km old when the Freehub began to wobble excessively.

Freehubs should not have to be replaced every 4 months, even SRAM Freehubs should last longer, as both SRAM and Jamis have confirmed to me.

Last edited by CmJc; 10-23-08 at 08:01 PM.
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Old 10-23-08, 12:14 AM   #21
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I just fixed something similar to this just this evening...

Solution: Make sure the smallest cog is properly lined up with the splines on the freehub when you tighten down the lockring.

Problem: My cassette was loose and i could wobble around all the individual cogs except the small one. I thought perhaps the lockring wasn't tight (it was) and maybe i had even crossthreaded the lockring (it wasn't). I pulled off the cassette and reinstalled everything and lo' and behold, everything was tight. I'm guessing the small cog wasn't lined up with the splines and while probably off only afew degrees, it was enough that the cog actually got sandwiched between the end of the splines and the lockring.
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Old 10-23-08, 08:00 PM   #22
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That could be caused by a bit of crud on the splines, so whoever assembled the cassette before you didn't clean it properly.

Good point to mention, but wasn't the problem in my case, it was a sub-standard brand new SRAM Freehub installed by the manufacturer Jamis.
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Old 10-23-08, 10:06 PM   #23
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Originally Posted by capwater View Post
Cassette should have zero wobble if the lock ring is properly tightened. Take the cassette off and now check if the hub wobbles. Could be the culprit. Could also be a spacer issue depending on the wheel manufacturer.
Whether they should wobble, or not, many brand new bikes have a very noticeable wobble in the cassette and it's not because the lockring is not tight. Been there, checked it out, tightened the lockrings, and they still wobble. If you chased the manufacturers for every case of this, a significant percentage of bikes would never get out on the floor.

In most cases - even with a noticeably wobbling cassette - the drive train works smoothly and just fine.
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Old 10-23-08, 10:07 PM   #24
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Originally Posted by seanoc View Post
cassettes wobble. on everything. campy, shimano everything i have worked on.
Exactly what I have observed.
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Old 10-23-08, 11:03 PM   #25
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You would have to reshim the freehub if you want the wobble out of it.Better a little too loose than a little too tight.I bought brand new 105 hubs about 3 months ago and had the same thing,brand new.It worked fine but bothered me so I took it apart and corrected the clearance.
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