Front Mech Seized !

glasgowbhoy

I noticed shifting was very tight on my winter trainer. On closer inspection the tiagra front mech seems to have near seized. I spray it reguarly and keep the chain line clean as much as possible but it seems the winter weather, salt and crud seems to have done the damage. I took it off cleaned it as much as possible and left it soaking in a tub of oil last night but still seems to be really tight at the pivots. Hardly moves at all. Is that it goosed or anything else I can try?
Cheers

rolf_f

Penetrating oil might help. It should feel pretty tight off the bike though - it's a strong spring.

Are you sure it isn't the cables?

glasgowbhoy

Thanks Rolf, yes, changed the cable and it was still hardly moving when set up. I'll try it again tonight after a day of soaking in the oil

wishitwasallflat

Glasgowbhoy wrote:

I'll try it again tonight after a day of soaking in the oil

Make sure you wipe all the oil off your feet though before you walk through to fit the mech

rolf_f

Penetrating oil would be better than normal stuff though. The pivots should be pretty basic so I can't really see how they could sieze up on a permanent basis.

k-dog

They are basic but I've had that happen a couple of times. I managed to get it moving the first couple by cleaning and soaking it but it was never the same.

Replaced it and it's night and day - the springs are stiff but when I got a new one I could move it with my hands - the old one was practically impossible.

I think they get to a point where you can't get all the gunk out the pivots - and I couldn't disassemble mine as it was riveted at that point.

k-dog

Another good tip I had once is heating it up - soak it in really hot water so the metal expands a bit and then in oil (warm oil? - but be careful!) and then do it again. Gets the oil in a bit better sometimes.

keef66

I found with cheaper front mechs that as soon as they started getting stiff that replacement was the only option. I've wasted hours of my time and gallons of various penetrating fluids and lubricants to little effect.

rolf_f

k-dog wrote:

Another good tip I had once is heating it up - soak it in really hot water so the metal expands a bit and then in oil (warm oil? - but be careful!) and then do it again. Gets the oil in a bit better sometimes.

Another option might be an ultrasonic cleaner. Have to admit, I've never had any trouble with front mechs but then mine never get very messy. I always like to make sure that the dirt never builts up.

k-dog

I've got one of those too - but it wouldn't work on that mech. It's really good at cleaning parts that you can see - but doesn't get inside tight joins.

centimani

This may not be relevent to the Tiagra FD, but my Sora FD siezes most winters...if the pivot design is similar you may be able to try this...
On the Sora, look at the mech from the back wheel, you can see the pivot, its a large chrome dome headed allen bolt facing rearwards. Loosen (NOT REMOVE) it, squirt WD on the exposed bolt/pivot and manipulate the mech with your hand, it does come free. Once free, re-tighten the bolt.

It MAY be of use, apologies if its not.

desweller

If you push/pull it through it's full range of motion whilst in oil several times (think 30 to 60) then that should allow it to cart the contaminants out in the oil.

sandyballs

Worst case scenario £23 from Wiggle, other deals are available.