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12 posts • Page 1 of 1
can you reverse chainrings?
i'm building a bike up out of old spares which i intend to give to my brother for a xmas pressie and am looking at whether to buy a new crankset or whether i can get away with reversing the worn rings on an old crankset.
so far i've discovered that:
1. the mounting points and teeth are not in the same plane, so when you reverse a chainring, the spacing between the next one (this is a triple chainring) goes out of kilter. i'm thinking maybe i can pack it out with a thin washer?
2. there is a pin on the outer face of the outer chainring, which seems to stop the crank arm from fouling the chain ring (can't see that happening though?) when i reverse the chainring, the pin is then on the inside and would block gear shifts between middle and outer ring. solution - 30 secs. on bench grinder
3. the chainrings have 'profile shifting' ramps or whatever shimano calls them, presumably to smoothen shifts between chainrings. reversing them would mean losing the benefit of those - no big deal i'm thinking?
has anyone else tried this? spare chainrings are not that cheap and my brother isn't about to enter the Tour de France so i thought i'd save a buck.
The pin on the outside of the big ring is to stop the chain jamming under the crank on an over-shift. I managed to overshift somehow this week, with a car up my clacker. I'm very glad the pin was in the right spot.
I'm not sure I'd contemplate the idea. Maybe upgrade yours now and give him your hand-me-downs
On the other hand, if you really don't like your brother ... go for it
so it is.. oh well, his problem
mine's pretty new Deore. this is my commuter bike so i don't really do upgrades, it's too expensive to put quality bits on it, as i wear them out pretty quickly. chainrings last ~ 1 year.
could be funny
i've still got a bit of time to play around before i hand it over.
i replace my chainsets when they will not transmit any decent torque anymore, with a worn chain. they're pretty useless by that stage - they just slip.
Plus the rings are recessed for the ummmmmmm I can't remember the correct name for them but the bolts that hold them in place!
I don't suffer fools easily and so long as you have done your best,you should have no regrets.
Yes, if you're running Rohloff, Alfine or SS and you have a Thorn chainring (designed for reversability - no ramps or pins, and the ring is symetrical side to side)
Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.
Don't cut the chain drop pin off, drill it out from the other side with a 2.5mm drill. You can then tap it to M3 and install it on the other side of the ring. To keep it clean, use a countersunk screw.
I did this when I was fitting new 10 speed rings to an old C-Record crankset and didn't want to pay Record prices. The C-record cranks' arm position differs from the usual crankset so the pin ended up 36 degrees out of kilter.
Maybe try a WTB thread. There are plenty of guys on hear with lots of old parts. I've got a couple of old NOS Shimano 5 bolt MTB Chainrings that I'd give you for post cost if they suit.
Always looking for new rides & ride partners in SE QLD area
Ribble usually stocks Stronglight chainrings which are pretty cheap.
Keep your eye out though sometimes whole cranksets on sale are cheaper. I have been known to buy a crankset just for the rings before.
12 posts • Page 1 of 1
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