Converted 2011 S-works 29r 2*10 to 3*10 system
Converting Specialised SRAM 2*10 to 3*10 on a 29er
The following is how I converted a 2011 Specialized S-Works 29er 2*10 to a 3*10. This procedure changes the 29er gearing to that of a 26er for cadence*speed so you have the same overall gearing as a 26er. (Right click and save this OPEN OFFICE, EXCEL COMPATIBLE spreadsheet to compare gearing). NOTE this will NOT work for a 2*10 system on a 26er unless you want REALLY low gearing! You will need to use non-standard chain-rings on a 29er. I suspect this may work on all 2*10 SRAM 29er systems but cannot guarantee it as have not tried it. NOTE this conversion only works with 20/30/40 front rings.
Why Change: - This is rider specific preference. If you prefer a 3*10 and want an S-Works 29er, you can't get one, or if you prefer to spin your way up long steepish grades, or dont have the leg strength to push a 24*36 29er, then altering the gearing is an option. For me the 2*10 with 24*36 and 29er wheels was just out of my range to get up steepish sections in my riding areas that I could climb on a 26er. If you can push 24*36 up 25% grades – can I borrow your legs
- The current XX derailleur is claimed by SRAM not to be able to cope with three front rings. They also claimed that the angle the derailleur moves is too steep for three rings. NEITHER OF THESE CLAIMS ARE CORRECT IF YOU USE 20/30/40 CHAIN-RING SET-UP. The angle of movement is a slight issue which can be accommodated by a simple mod to the 30T ring, see below.
- The S-Works crank uses two chain-rings on a three ring spider. - so no spider or crank change is required. (The crank is a Specialised crank not a SRAM XX crank).
- The front derailleur is a Direct Mount, Bottom Pull item. There is no vertical adjustment for the derailleur like a seat post clamp style mount.
- There is sufficient lateral movement on the XX derailleur to cover 3 chain-rings.
- However, adjustment via the limiting/adjustment bolts is restrictive, so a small adjustment to mounting is required.
- The 'direct mount' derailleur mounting system sux when compared to a seat tube clamp system for strength, stability and adjustment IMO FWIW!
What you need: NOTE this conversion only works with 20/30/40 front rings
- Chain-rings: 20/30/40 chain-rings. Effect – gives very close (cadence*speed) to a standard 26er gearing with 3*10 (11-36 and 22/33/44 rings) (Right click and save this OPEN OFFICE, EXCEL COMPATIBLE spreadsheet to compare gearing)
- 20 tooth ring from Actiontek or other source (http://www.actiontec.us/prices.htm)
- 30 and 40 tooth rings from Anderson machine. (http://andersenmachine.com/product-info/)
- (I have no connection to these companies) 20/30/40 compared to 24/38 will both lower and raise the gearing.
- A SRAM XO front derailleur shifter (or other SRAM 3 ring shifter)
- Two 5 * 20mm+ torq or allen/cap headed bolts (to replace those holding the derailleur on the mounting bracket.
- 4 washers, 5mm * 1mm thick steel or alloy.
- New power link if you break chain (optional)
- Tools, torque wrench (0 to 34 NM range); 25 torq in a socket; file or lathe; Specialised crank tool.
See next post for how to.
Last edited by Hostilemonk; 03-29-2011 at 11:59 PM.
Reason: title change
How to convert to a 3*10
THE HOW TO:
In removing fittings, torquing, greasing the parts, etc. follow SRAM or Specialized instructions and lubing recommendations.
Go ride it, make adjustments as required to get smooth shifting.(you may need to readjust the rear derailleur also)
- Remove the chain link. Tip: use circlip pliers to squeeze and undo, and reuse the SRAM power link.
- Remove the XX front derailleur shifter and replace with the XO shifter and new cable
- Ensure the cable adjustment screw on the shifter is halfway out so you have adjustment both ways – though you may need to readjust this depending on manufacturing tolerances.)
- Remove the old cable from the derailleur.
- Take the 30T ring and remove about 25 to 30 thousandths of an inch from the OD of the teeth. You can do this in a lathe or with a file and vice as I did (patience!). Recreate the chamfer that was on the teeth before the 30 thou removal (patience!) or if no patience, don't . This will still leave the teeth as deep as those on a standard ring. Why: due to the angle of movement the XX derailleur cage will catch the centre ring teeth when on the large chain ring. The cage will clear the centre ring if approx 25 to 30 thou is removed from the OD.
There are slight variations in the mounting system due to manufacturing tolerances. I found 30 thou was fine for my bike, others may need less or slightly more but it is unlikely you will need more than 40 thou. The only way to test this is to mount the system and see if the cage clears the chain-ring. (patience!) (see below for details)
- Note that when you sit on the bike this clearance between cage and middle ring will increase as the derailleur bracket is bolted to the swing arm (!) and pivots so only when the back wheel is airborne will clearance be at minimum.
- The depth of the teeth is still more than those on Shimano and very close to SRAM's
- Remove the crank and two rings and replace with the 20/30/40 rings.
- Remove the XX derailleur from the direct mount bracket.
- Undo the limiting/adjustment bolts so they are fully retracted.
- Remount the derailleur with two 1mm washers between the derailleur and the mounting bracket on each bolt. Use the two 5mm replacement bolts to mount the derailleur to the bracket. (NOTE: you may get away with one washer for each bolt depending on production tolerances)
- These washers are the adjustment that pushes the derailleur out so all its movement can be used to cover the three rings.
- Note: the two original bolts are too short with washers fitted so longer ones needed. The left bolt as you look at the derailleur can be as long as you want as it goes through the centre of the swing arm pivot so swing arm pivots around it. The right bolt needs to be long enough to use the whole thread in the mounting bracket but not too long so it touches the frames down tube. Note this bolt moves down as swing arm moves up, so check clearance from the frame. Use standard torque values.
- When you torque up the derailleur push it as high as it will sit on the bracket to get maximum clearance from the rings.
- Connect the shifter cable to the derailleur and test for movement so all three positions are available. (tighten cable clamp but don't torque it up yet)
- You may need to adjust the outer cable to get the three positions on the front XO shifter to 'click'. If you can't get the outer (large ring) position on the shifter back off the cable adjuster until you can and you hear it click for the 3 positions. Adjustment is a little bit finicky but is easy once you try it.
- Refit the crank (don't torque up yet, just tighten slightly) leave the chain off.
- Test the derailleur in each of the 3 positions and check there is no interference between the cage and the rings. Spin the crank especially with the derailleur in the large ring position.
- If the middle ring is rubbing against the bottom of the derailleur cage then you may need to take a few more thou off the OD of that ring. (patience!)
- Fit the chain, don't torque the crank yet.
- Test the shifting for all three rings – ensure the adjusting/limiting bolts are backed right off.
- If the chain drops off the small or large ring use the adjusters to limit the cages movement as per normal. Yes, there is more than enough movement in an XX derailleur!
- Once everything is working ok, ensure you greased everything that needs greasing and torqued everything up, including the derailleur cable and crank.
Go find a steep grade
The shifting I find quite good and more than adequate – it is not as nice as the original 2*10 system but is as good as my Shimano 3*10 system. Part of the issue is the Andersen rings aren't as well ramped as the SRAM rings IMO, but really the difference I believe is negligable.
Hope the above is adequately clear, it is worth every cent you paid for it
Last edited by Hostilemonk; 04-02-2011 at 12:27 AM.
Somebody's been working hard in the lab Very interesting. Gonna post a pic of this setup ?
Pics after a ride and before a clean
Ignore dates on pics - cant be bothered resetting date after battery replacement
I like what you have done. Makes a lot of sense for me to do what you have. I wish the rings were made by more manufactures.
Now only use one washer spacer as found it does not drop chain when shifting into granny with 1mm washer rather than 2.