Wanted: compact crankset

martyc5674

Have a trek 1.2 and looking to change the crankset to a compact(not sure if I've te right terminology here!!)

Basically I don't need it so high geared but I'd like the gears to be closer.

Anyone got one..do I need to change front and back?

It's a standard double on front 9 on the back
Thanks
Marty.

TheBlaaMan

I've done this recently, so here's what was necessary:

• change crankset - ensure new crank is not just a compact, but compatible with the existing bottom bracket, or else you'll need to change that too.
• chain will now be too long (chainrings are both smaller diameter on compact crank), so you'll need to get hold of a chain breaker to remove a link or perhaps 2
• front derailleur will be too high on seat tube (again due to chainring diameter differences), so you'll need to drop it. Many are 'bolt-on' but others are 'braise-on' - I'm not too sure what entails in moving the latter
• rear derailleur and sprocket dont need replacing, but may RD may need adjusting so,
• adjust FD and perhaps RD to ensure all gears are available and indexed properly and away you go

A few hours work.

vertigo1976

I have an FSA gossamer compact crankset, 50/34 with 172.5mm crank arms. It's done about 200km and is in perfect nick, would pass for new! Bottom bracket included.

The cheapest I can find it online anywhere works out about 140 delivered. You could have it for 100.

Let me know what you think. I can take some pics and send them on to you.

Hungrycol

TheBlaaMan wrote: »

I've done this recently, so here's what was necessary:

• change crankset - ensure new crank is not just a compact, but compatible with the existing bottom bracket, or else you'll need to change that too.
• chain will now be too long (chainrings are both smaller diameter on compact crank), so you'll need to get hold of a chain breaker to remove a link or perhaps 2
• front derailleur will be too high on seat tube (again due to chainring diameter differences), so you'll need to drop it. Many are 'bolt-on' but others are 'braise-on' - I'm not too sure what entails in moving the latter
• rear derailleur and sprocket dont need replacing, but may RD may need adjusting so,
• adjust FD and perhaps RD to ensure all gears are available and indexed properly and away you go

A few hours work.

That's good info. I've ordered a new bike with a compact and I want to put a standard on it. No option to change it in store so I'll have to sell it when I get it and replace it straight away, I'll probably make a loss on the change over! Alternative is I get a 39t small ring.

martyc5674

vertigo1976 wrote: »

I have an FSA gossamer compact crankset, 50/34 with 172.5mm crank arms. It's done about 200km and is in perfect nick, would pass for new! Bottom bracket included.

The cheapest I can find it online anywhere works out about 140 delivered. You could have it for 100.

Let me know what you think. I can take some pics and send them on to you.

Cheers all for the info.

Where are u based vertigo??
Not sure if u can stump to 100 tho...must look now at what size is on it to gauge if I can get up them hills without needing a granny ring!!
Marty.

martyc5674

martyc5674 wrote: »

vertigo1976 wrote: »

I have an FSA gossamer compact crankset, 50/34 with 172.5mm crank arms. It's done about 200km and is in perfect nick, would pass for new! Bottom bracket included.

The cheapest I can find it online anywhere works out about 140 delivered. You could have it for 100.

Let me know what you think. I can take some pics and send them on to you.

Cheers all for the info.

Where are u based vertigo??
Not sure if u can stump to 100 tho...must look now at what size is on it to gauge if I can get up them hills without needing a granny ring!!
Marty.

Ok I just checked what's on it and it'd 52/34 so I wouldn't be gaining any lower gearing which is kinda what I was after..few steep hills round here.

Am I looking for the right thing??
Would I be better off changing the rear instead?

Thanks
Marty.

vertigo1976

I'm based in Dublin midweek and Cork at the weekends.

Maybe a change of rear cassette could help. Depends on what you've got on at the moment.

The jump from a 52 to 34 ring seems pretty gappy in my opinion.

martyc5674

vertigo1976 wrote: »

I'm based in Dublin midweek and Cork at the weekends.

Maybe a change of rear cassette could help. Depends on what you've got on at the moment.

The jump from a 52 to 34 ring seems pretty gappy in my opinion.

I'm sure your right as I'm not up to speed on what's normal for recreational use.
I'm not sure what else exists..48/30 perhaps...
Just counted the back sprocket and it's 11/26..
Would such thing as a 12 to 28 exist?
Be cheaper surely and give me lower gearing.
Cheers
Marty.

vertigo1976

It depends on what groupset you have. Presume a Trek 1.2 is 9sp? There are rear cassette options up to 32T if your derailleur can take it.

macnab

The Trek 1.2 comes with a 34/50 front and I think a 11 or 12 to 26 on the rear. An 11 to 28 is your best option, if you are still having trouble then a treble (30/34/50) front chainring is an option. However an improvement in fitness and strength will come when you have a few more miles in your legs and then you will be fine.

martyc5674

vertigo1976 wrote: »

It depends on what groupset you have. Presume a Trek 1.2 is 9sp? There are rear cassette options up to 32T if your derailleur can take it.

Cheers
Yes it's 9 speed.. The DR is Sora and it's from 2009.
Would an extra 2 teeth back there keep me in the saddle!!?
Cheers
Marty.