Switching from Compact to Standard

kelsen

I want to swap from an Ultegra compact double to a standard double. What components do I need to change and what can I re-use?

(Yes, I know this should be in Workshop, or some other obscure place that no-one visits)

lost_in_thought

You need to change your chainrings.

This is pretty vital for the above.

edhornby

it's not just new chainrings - a compact and a standard has different spacing between the chainring bolts so you would be best getting a new chainset

If you were to get another shimano one (I'm guessing you have one with the external bottom bracket), you could push the old one out (either keep it or ebay it, but I'd keep it..) and fit the new one, and move the front changer and readjust

lost_in_thought

Dude... I know.

greg66_tri_v2.0

Chainrings or (perhaps more likely) crankset.

Lengthen existing chain, or fit new chain. If latter, possibly new cassette if they are both worn into each other. Unless you like chains that jump a lot on the cassette when you apply pressure.

Adjust front mech upwards; possibly re-index.

That's it.

kelsen

edhornby wrote:

it's not just new chainrings - a compact and a standard has different spacing between the chainring bolts so you would be best getting a new chainset

If you were to get another shimano one (I'm guessing you have one with the external bottom bracket), you could push the old one out (either keep it or ebay it, but I'd keep it..) and fit the new one, and move the front changer and readjust

That's the BCD right? So presumably my existing cranks can't be re-used which is what I suspected. Why can't I re-use the BB?

greg66_tri_v2.0

I think edhornby means you can push the existing crankset out of the existing BB, and put a new crankset into the BB.

BCD - you're sort of there. Bolt Circumference Diameter. 110mm for compact; 130mm for standard. It's the width of the circle mapped out by the five bolts securing the chainrings.

You *can* - I've read - find 53/39 chainrings that will fit onto a 110mm BCD spider. However, you've then got a lot more metal between the bolt and the teeth, and so the rings are susceptible to flexing. You're better off replacing the crankset.

desweller

I believe Stronglight do aftermarket chainrings for odd BCDs. Never heard anyone complain, unless you're Chris Hoy chances are that you'll be fine.

fnegroni

What is the primary motivation to go from compact to standard?

Wouldn't you get more benefit to change cassette ratio?

That would allow you to experiment with the higher metric development without incurring the greater overlap and limited range a standard gives.

Unless you already changed the cassette ratio and that's why the next natural step is to go to a standard.

kelsen

fnegroni wrote:

What is the primary motivation to go from compact to standard?

Wouldn't you get more benefit to change cassette ratio?

That would allow you to experiment with the higher metric development without incurring the greater overlap and limited range a standard gives.

Unless you already changed the cassette ratio and that's why the next natural step is to go to a standard.

The bike originally came with a compact chainset, and I'm due to replace the chainrings. Since I've managed ok in the past with 53/39, I thought I'd revert back to standard. TBH, the compact's is fine. I could do without the extra cog shift to compensate for the big jump when shifting between the chainrings but that's really nitpicking.

oscarbudgie

fnegroni wrote:

What is the primary motivation to go from compact to standard?

Wouldn't you get more benefit to change cassette ratio?

That would allow you to experiment with the higher metric development without incurring the greater overlap and limited range a standard gives.

Unless you already changed the cassette ratio and that's why the next natural step is to go to a standard.

Face it, 53/39 is cooler than 50/34

gtvlusso

Personally - I would just change the chainset, making sure that the BB I have is compatible with it - i.e. part of the groupset!

Move your front mech up the seat tube - reclamp it (torque it properly on a carbon frame) - adjust cable/gears.

Job done

biondino

Remember that Chain Reaction still have some excellent deals on chainsets, for example this FSA one at 70% off:

http://www.chainreactioncycles.com/Mode ... elID=28464

This FSA one at 60% off:

http://www.chainreactioncycles.com/Mode ... elID=35741

Or if you want to stick with Ultegra:

http://www.chainreactioncycles.com/Mode ... elID=28436

Or perhaps bargain Dura-Ace (37% off):

http://www.chainreactioncycles.com/Mode ... elID=28436

:

kelsen

biondino wrote:

Remember that Chain Reaction still have some excellent deals on chainsets, for example this FSA one at 70% off:

http://www.chainreactioncycles.com/Mode ... elID=28464

This FSA one at 60% off:

http://www.chainreactioncycles.com/Mode ... elID=35741

Or if you want to stick with Ultegra:

http://www.chainreactioncycles.com/Mode ... elID=28436

Or perhaps bargain Dura-Ace (37% off):

http://www.chainreactioncycles.com/Mode ... elID=28436

:

Cheers Biondino! Would the FSA chainsets work with a Shimano bottom bracket?

greg66_tri_v2.0

gtvlusso wrote:

Personally - I would just change the chainset, making sure that the BB I have is compatible with it - i.e. part of the groupset!

Move your front mech up the seat tube - reclamp it (torque it properly on a carbon frame) - adjust cable/gears.

Job done

Except for the chain being too short. A shot of a bike that has gone from 50/34 to 53/39 and is awaiting a chain lengthen (nb the rear mech):

biondino

kelsen wrote:

biondino wrote:

Remember that Chain Reaction still have some excellent deals on chainsets, for example this FSA one at 70% off:

http://www.chainreactioncycles.com/Mode ... elID=28464

This FSA one at 60% off:

http://www.chainreactioncycles.com/Mode ... elID=35741

Or if you want to stick with Ultegra:

http://www.chainreactioncycles.com/Mode ... elID=28436

Or perhaps bargain Dura-Ace (37% off):

http://www.chainreactioncycles.com/Mode ... elID=28436

:

Cheers Biondino! Would the FSA chainsets work with a Shimano bottom bracket?

I don't know :oops: though I think so, as long as the cranks fit on it, but FSA BBs are reasonably priced too if that helps!

wgwarburton

kelsen wrote:

...The bike originally came with a compact chainset, and I'm due to replace the chainrings. Since I've managed ok in the past with 53/39, I thought I'd revert back to standard. ....

Just change the rings. I'd be surprised if you can't get the sizes you want to fit- Shimano might not sell them but others will.
I run 52t chainrings on a fixed gear (ie much crankage required on steep hills) using an obsolete 86mm BCD chainset- your compact (110mm, yes?) should be fine.
Less hassle, less expense and no worrying about BB axle lengths etc.

Cheers,
W.

bigmat

FSA chainsets work with Shimano bb, well certainly the cheaper ones, top end ones might be more specific. Why switch from compact to double though? Not saying one better than the other, I just think its a lot of aggro for no obvious benefit. If you have an issue with the jump from 50 to 34, just fit a 36 inner ring and you've got the same step as a 53/39. Then make sure you have an 11 sprocket on the cassette and jobs a good'un. Only argument then in favour of a double is because it looks 'ard!