53/39 to Compact

shinsplint

My double chainset suits me fine for 95% of my riding, but i've often fancied getting a compact for the odd sportive.

My bike is Felt AR2 with Dura Ace 7900 chainset, with Shimano Hollowtech-II bottom bracket.

Rather than going to the lbs every time I want to change it, I want to buy the necessary tools to swap it myself. Could someone please advise what I would need, and also my options i.e. which chainset and bottom brackets are compatible.

Thanks for any help !

smidsy

Just change the inner ring to a 36 and get the best of both worlds (assuming you mech will allow it).

If you went to a compact you may need to move the front mech down the seat tube to compensate.

markos1963

You haven't said what your current cassette is. If it's a 12/25 then it would be cheaper to fit a 11/28 or a 12/27 or even a 12/30! The first two options will fit easily and the third might just work with some adjustment of the B screw.

shinsplint

Cheers guys,

I changed the cassette to a 12/27.

I like the idea of a 36 inner ring. I presume its possible to change them without removing the cranks?? The bolts are on the inside of the dura ace rings.

dawebbo

You can't fit a 36t inner chainring on da 7900 cranks. http://sheldonbrown.com/cribsheet-bcd.html

Swapping the chainset is far quicker than changing chainrings anyway. It takes a couple of minutes max, you just need an allum key and one of these http://www.wiggle.co.uk/shimano-crank-i ... owtech-ii/

Though if it was me, I'd stick with one chainset and change cassettes according to the ride.

shinsplint

dawebbo wrote:

You can't fit a 36t inner chainring on da 7900 cranks. http://sheldonbrown.com/cribsheet-bcd.html

Swapping the chainset is far quicker than changing chainrings anyway. It takes a couple of minutes max, you just need an allum key and one of these http://www.wiggle.co.uk/shimano-crank-i ... owtech-ii/

Though if it was me, I'd stick with one chainset and change cassettes according to the ride.

Cheers for that. Yeh I just read something similar - 36 ring not an option.

I'll have a look for a cassette with a 30 sprocket... and hope no one notices :oops:

drlodge

Changing a Hollwtech BB is easy, you just need a tool like this and an allen key



- Using small plastic round part of the tool, remove plastic threaded plug on left hand crank
- Using allen key take off the left hand crank
- Pull right hand crank and spindle out through BB

- Insertion of crank is the opposite, except once you have loosely fitted the left hand crank, before tightening, use the small plastic round part of the tool to screw in the plastic plug into the left hand crank hand tight, in order to pre load the bearings
- Tighten up left hand crank using allen key.

The main part of the tool is used to remove the bearing cups, which you won't need to do.

shinsplint

Cheers fellas.

Can't find a 12-30 cassette, so its looking like drlodge's method.

So when I buy the compact chainset, will I need to buy another hollow tech bb, or would this come with the chainset??

drlodge

The chainset consists of both cranks, and the hollow spindle is attached to the right hand crank. The BB itself with the bearings stays on the bike, so you just need the chainset and "reuse" the BB bearings.

markos1963

ShinSplint wrote:

Cheers fellas.

Can't find a 12-30 cassette, so its looking like drlodge's method.

So when I buy the compact chainset, will I need to buy another hollow tech bb, or would this come with the chainset??

If you look for a Tiagra 10sp cassette you should be able to find one( I have one on my new Jamis touring bike)

markos1963

Have a look here
http://www.chainreactioncycles.com/Mode ... elID=67228

drlodge

FYI, I got an Ultegra compact chainset from this place http://www.roadbikeparts.co.uk/product_ ... cs6750.htm and it was even cheaper off their Ebay site, £135 I think.

shinsplint

Cheers fellas

mrushton

11-28 is also available and don't forget SRAM cassettes are compatible. The new DA chainsets are compatible with both standard and compact chainrings hence the move to 4 bolts but a new chainset from the 2013 catalogue will be expensive

themekon

Why would you want to change such a brilliant chainset for a more inferior one. A complete waste of money.I think you can fit a 38 to Shimano.