Noob question on road bike transmission

[ocrx8]

Hi guys

Runner by trade but thought I'd get a road bike for a different type of cardio hit.

Picked up a (new) Giant Contend 2 last week, which comes with a Shimano Claris transmission - completely entry level from what I can make out. Took the bike out for a go on Friday and found the front cassette really rattly on the outer ring.

Tried again on Sunday after lubing the chain and it was still the same. However, discovered if I use the shifter to shift "up" again, even if it's already on the outer cog, the rattle disappears (despite nothing visibility altering within the transmission). Does anyone know what it's doing?

The bike came with a free 6 week service so I'll mention it to the shop, but just wondered if anyone more knowledgeable than me is familiar with the above.

Thanks.

[WinstonWolf]

ocrx8 said:

Hi guys

Runner by trade but thought I'd get a road bike for a different type of cardio hit.

Picked up a (new) Giant Contend 2 last week, which comes with a Shimano Claris transmission - completely entry level from what I can make out. Took the bike out for a go on Friday and found the front cassette really rattly on the outer ring.

Tried again on Sunday after lubing the chain and it was still the same. However, discovered if I use the shifter to shift "up" again, even if it's already on the outer cog, the rattle disappears (despite nothing visibility altering within the transmission). Does anyone know what it's doing?

The bike came with a free 6 week service so I'll mention it to the shop, but just wondered if anyone more knowledgeable than me is familiar with the above.

Thanks.

I think that's 'trim', you can shift gear then move the shifter out of the way. You're not riding 'crossed out' are you, ie on the smallest cog front and rear?

[Barchettaman]

+1

The FD is moving to the big ring on its 'trim' position.

The extra click puts it in its correct position.

Claris is good stuff, improved still further by using a 9-speed chain and posh cables and housing.

Enjoy the bike!

[lufbramatt]

yep as above

just to add you should be able to do the same thing on the little chainring, the shifter should have 4 positions in total.

[paulrockliffe]

Yeah, it's the trim, when you're in the big ring at the front it'll rub on one of the derailleur plates if you're low in the range, or high in the range at the back. The trim is there to stop that rub.

It'll obviously be worse if your'e crossing the chain, but it'll rub in acceptable gears as well due to the limitations in the geometry of the derailleur.

The derailleur has to have a small gap between the plates and extend far enough backwards that it can drop down below the top of the inner ring to work and the width of the cassette means that the change in angle of the chain must cause it to rub on one of the plates. Unless you trim it.

In practice you should find you have enough overlap when shifting up the gears that you go straight into the trimmed position when shifting up, but coming down the other way you'll tend to hold the big ring longer, and you drop the trim when it rubs.

[Slushbox]

The rear and front mech cables also stretch for a while on new bikes. They eventually settle down.

The rear mech cable adjuster might need half a turn out during the stretchy period (red arrow) :

[ocrx8]

Grand, thanks everyone!