Evening,

My geometron was making a right racket, which turned out to be a loose chain stay pivot. I replaced the bearing and thought that would be the end of it.

The loose pivot has bashed the chain stay out of shape. It should be a round hole with a round pivot locking into the frame. As the pivot has bashed about it has made the hole (in the frame) slightly oval.

I had it in to 18 bikes in hope today and they pointed the ovalalisation of the chain stay.

So, I’m going to email nicolai ad see what they say. I guess they will suggest a new chain.stay. As the frame was second hand and the damage was caused by me not keeping the pivot tight I guess I’ll be footing the bill.

Any suggestions on how to bodge it so it’s rideable, hopefully long term, but ideally in the short term until I get a chain stay organised.

Cheers!

Difficult to advise without pics, is it the bearing hole that is ovalised? Or is it the hole the bolt screws into?

If the first, could you shim (coke can naturally!) The bearing to fit the whole.
If the second, then drill/machine out the hole and helicoil it.

The chain stay is on the outside of the pivot, the seat stay containing the bearing is on the inside. A little pivot passes through the chain stay and bolts into another part of the pivot that is bolted from the other side.

The actual chain stay hole is ovalised.

To shim it I’d have to have a thin shim at the oval.ends, and nothing in the middle.

I notice Nicolai have change the design and now the end of the chain stay can be replaced!

loctite bearing ft might work or JB weld. With the loctite you just fit the bearing with it in – its a grade designed for this sort of aplication but can only take up a small gap. JB weld is a epoxy stuff that you would fill the hole with then machine it out. Or build up with weld and then recut the hole

Can’t see your pic but from your description you must have a first generation Geometron.
Second generations have the mutator chip you seem to be describing.
If it is a first gen it’s just an Igus bush that sits it there which is adjustable or easily replacable if it’s totally worn.
Try emailing Paul at Geometron he’s really helpful.

Bearing fit, its what its for. degrease, apply bearing fit, insert bearing.

How oval…

I’ve pin punched hubs on card to get the wheel bearing to drive In tight before now.

Or machine it out n press a steel insert in

Should say cars

Thanks all!

I’ve emailed nikoli and will see what they say.

In the mean time I’ve bought some bearing grade lock tite.

I might try the punch before moving on to building the weld up and machining it down.

Cheers!

I would try drilling it out slightly and sleeving it.