Why are my gears slipping?

[Majorslow]

I have an old road bike (1987). When I have to stand on the pedals to get up steep hills (and the not so steep when i'm knackered) the gears slip down one, then a few rotations later will slip down again.

The cables are the original ones, so are they worn out? stretched? so can't handle the load any more?

I have had a few pass me over the last few weeks complementing my "retro" bike.

It has a shimarno 600 gear set on it, and compared to modern bikes weighs a ton!! (maybe once I weigh less I will consider a newer bike), but it works better than I do....and I like it, just wish the gears did not slip

[Harpoon]

It could be one a few things, for instance if your rear derailleur is out of line that could be trying to pull the chain under load. It's also classic symptoms of a worn chain / cassette / chainrings and it could be one, two or all of them combined.

Has the bike (especially the drivetrain) been serviced much? How old are the parts?

[colin_p]

Most likely to be a worn chain and cassette (or freewheel knowing the age).

Change both at the same time and it should cure the issue. And a fresh set of cables wouldn't do any harm either.

[BrundanBianchi]

I’d pretty much guarantee the rear mech hanger isn’t straight either. You could straighten it, or replace it ( which is what I’d do given the age of it ). So re cable ( inners and outers ) new chain and free wheel / cassette, new hanger, see if that sorts it.

[outnumbered]

Assuming it's friction shifting, then the friction bit of the lever can fail, and give you the exact symptoms you mention. Is there a way to tighten up the front shift lever ? They usually have a screw with a wire loop to turn it. You need to balance being able to move the lever at all, with not slipping under load.

[Justin S]

BrundanBianchi said:

I’d pretty much guarantee the rear mech hanger isn’t straight either. You could straighten it, or replace it ( which is what I’d do given the age of it ). So re cable ( inners and outers ) new chain and free wheel / cassette, new hanger, see if that sorts it.

Having a rear mech hanger tool, I can guarantee most bikes dont come with a straight rear hangar as out of 10 in my garage 9 weren't straight, especially with replaceable dropouts being softer and sacrificial to fail than damage the frame.

[BrundanBianchi]

Justin S said:

Having a rear mech hanger tool, I can guarantee most bikes dont come with a straight rear hangar as out of 10 in my garage 9 weren't straight, especially with replaceable dropouts being softer and sacrificial to fail than damage the frame.

I’d agree with you as well. I’ve had hangers knocked out of shape on trains / parked at work / in communal bike sheds, and only noticed when the shifting went to crap. I regularly realign the hangers on my bikes as part of routine maintenance these days.

[Majorslow]

Thankyou all for the replies,

I have to admit shamefully it has never been "serviced" properly (unlike my cars), but it is in good condition

"outnumbered" has suggested the fix i could do first of all.

I wouldn't know how to straighten the hanger.....but it is likely that it ain't owing to it's age

The chain set and chain are the original (1987) so are likely to be worn and tired out.

I had new rims and spokes for the bike about 7-10 years ago, and the original hubs had to be reused owing to the age of the bike. I am concerned that as it is so old getting parts to fit it now may be difficult and expensive.

I think I had best take your advice and and get these things looked at by a professional bike mechanic who first hand will be able to look at all your suggestions, and see what it will require to getting the bike back to 100 %. To me it would be worth it as I have had it so long....but within reason

First today though I have a nice 35 miler to enjoy this afternoon before the rain comes

I'll take it to the guy in town tomorrow

cheers for the helpful advice

Edited by Majorslow on Friday 24th July 08:39

[HiAsAKite]

Out interest (my road bike is an old '91 steel framed bike) - does anyone know where you can actually get rear cassettes now that still fit in these frames?

[outnumbered]

HiAsAKite said:

Out interest (my road bike is an old '91 steel framed bike) - does anyone know where you can actually get rear cassettes now that still fit in these frames?

Sjscycles.co.uk would be my starting point.

[gazza285]

anonymous said:

[redacted]

That is a freewheel, not a cassette.

Seven speed cassettes are still available, but getting rare. I haven’t seen any six speed cassettes for years. The spacing between sprockets is the same as the eight speed cassettes, so I usually just buy an eight speed and grind out the rivets, allowing me to remove the big sprocket and a spacer, so I can use it as a seven.