Help please, rear derailleur snapped, recommendations?

[drossall]

By the way, is the back wheel definitely still true? As Bob says, the point of a hanger that snaps off is to protect other, less easily replaced parts (including the frame and back wheel).

[Colin_P]

Drossall,

Thank you for the most informative and detailed reply, many thanks.

As is typical for me I've asked questions before properly looking for answers myself.

However since posting my last, I've been inter-netting and have found what looks like the hanger for £7 plus delivery. I've already ordered a replacement derailleur, did that last night but didn't realise the hanger was separate. I'm about to order the hanger that looks the same...

Bit of pot luck with the parts but hopefully they will fit.

I'll look into to the re-indexing and fine tuning but would assume the default position (with the spring) would be 7th or top gear. That is from my experience thirty odd years ago on classic 10 speed racers that used the sachs huret or simplex gears, they always went to top gear when the cable snapped or wasn't fitted. On mine assuming the same applies the starting point would therefore be index to top gear, set the limit screws and........

And, I'll have a look online for a guide.

Again, many thanks for your reply.


And Bob, thanks for yours.

[drossall]

Yes, default is top. I'm not actually sure what the exceptions are. There are some recent odd specialist Shimano parts that are not so inter-compatible - you need a real expert for those. I think the latest stuff is also not so easy to mix and match (especially between road and MTB), but I've never got beyond 9 speed, and it took me ages to go indexed at all, so I haven't tried everything.

There were some strange front mechs, before indexing, that pulled the "wrong" way as well, not to mention bottom-pull and top-pull designs. I never had to do anything with any of those, so never got my head around them.

[Colin_P]

Thanks again.

I've just ordered two of those hangers now knowing they are sacrificial parts.

Just hope they are going to be the correct ones. Done by comparing a photo vs the broken bits on me knee.

[Colin_P]

Many thanks to;

Gaz
Drossall
531 Colin
Bob

The plot thickens.

Taking the advice to check the wheel to see if it is true, picked it up and things felt a bit weird.

Turns out the axle / spindle has snapped / sheared as well.



I've measured the spindle at approx 145mm and the distance between the dropouts at 133mm, am I right that I need a 145mm spindle? Again I'll go away and do some searching.

Bit surprised at the damage that has been caused by this incident!

[[XAP]Bob]

135 is likely right - My "mostly" was unfortunately required

All the spokes still sound about the same when tapped with a small spanner/allen key?
No wobble when you spin the wheel (harder now you don't have an axle in there....)

[Brucey]

I would say that your axle was most likely broken well before the mech tangled; axles like yours break often in normal use, but if in good condition before a prang, they usually just bend.
This whole episode might have been a blessing in disguise; had you not found your broken axle, the next thing to break might well have been the frame.

The broken axle might well have allowed the wheel to flex enough to cause the mech to tangle with the spokes in bottom gear; if that is when it happened it might have had something to do with it.

If you want your axle not to break again, think about getting a cassette hub; not cheap, but they are much stronger.

cheers

[[XAP]Bob]

I would say that your axle was most likely broken well before the mech tangled

Quite possible. I know I rode on one for a good while before I got round to looking at it (100's of miles)

[Colin_P]

Bob and Bruce,

Yes.

I think you might be right, I did post up a week or two ago about a 'noise'. The axle may well have been broken before. The bike did ride and function perfectly though and only the day before I bombed down 'the' off road hill I use a lot at a max speed of 28.2mph according to my 'omputer. Looks like I've been very lucky and it also points to axle being the cause of the problem, the wheel probably did move and as a result the derailleur caught into the wheel.

I cannot check the wheel until I get a new axle in it but the spokes feel ok.

Many thanks again.

[drossall]

I'd be looking for an axle of the right type for the hubs. What are they? Also check the bearing surfaces in the hubs and on the cones. This is a good chance to replace the lot if needed (and if you're replacing bearing surfaces, get new bearings too).

If you can't replace the axle or the wheel is structurally damaged, it is a chance for that upgrade - new wheel and derailleur needed anyway, just a new gear control, cassette and chain and you're away!

Although you have to be careful with such extensive replacements that a new bike wouldn't be cheaper, especially with end of season deals coming onto the market...

[Colin_P]

I've done a little under 1,000 miles only on the bike which was new in 2011 so don't to replace it just yet. The thing with these Giants, you get the same frame on the Roam 1,2,3 & 4. With mine being the 4 it has the lower end components. Saying that it has been a great bike and I think this could have happened to any.

I've ordered a new axle and new skewer and have already ordered a new hanger and derailleur so I'll see how it goes. I'd hope not to have to replace the wheel.

Thanks everyone for all of your help, I'll update as and when the new bits arrive and get fitted.

[Colin_P]

The new axle, skewer and hangers turned up today so this evening I've fitted them. Hopefully the new derailleur will turn up tomorrow.

Got the bike back together with the old derailleur still fitted and amazingly it still rides despite the derailleur being a bit twisted! Who says cheap stuff is bad, it still works!



I think that all that was holding it together was the skewer and I may have been riding it like that for a week or two. Quite lucky and an advantage of having quick release, there again if it had been a solid axle it probably would not have snapped.

Derailleur to fit tomorrow hopefully and the joys of learning how to set up he indexing.

[tim_f]

re

Derailleur to fit tomorrow hopefully and the joys of learning how to set up he indexing.

see http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur is a good source of generic instructions.

[Colin_P]

Thanks Tim.


I've not fed back on this to add some closure.

I got the new derailleur fitted and the indexing was a very straight forward process. I set the cable hand tight in top gear, set the low and high limit screws and in 10 minutes the job was done, works perfectly. Probably just got lucky but it was not too dissimilar to doing sachs huret derailleurs as I did back in the 1980's.

One thing though that is bugging me is that one of the axle cones had a bit of pitting on the bearing face so won't last much longer. Not sure if it was caused by the snapped axle or if it is due to wear and tear. The cones that came with the axle are small and if fitted would have exposed the bearings to the elements so I fitted the old cones onto the new axle.

The cones are about 20-25mm in diameter and the hubs are joytech items. I cannot seem to source them anywhere online. I do need to measure them but the existing ones are 20-25mm in diameter the replacements that with the axle were about 15mm (again not measured just a guess).

Anyone got any idea what I need to search for?

[531colin]

http://wheelsmfg.com/tech/PDF/wheels_cone_chart.pdf

Scroll down for "Taiwanese" as opposed to Shimano.