Working closely with Cervélo and their wind tunnel testing results, XLAB developed an aerodynamic single rear system specific to Ritchey clamp seat posts with a 10 mm horizontal rear hole.
If the saddle is in the rearward position, you may want to look at the DELTA SONIC XL

Aerodynamic Design

The DELTA SONIC allows the bottle to be close to the saddle, hiding in the rider’s draft and provides clean air flow.

Reliable & Customizable

The DELTA SONIC fits snug into the seat post providing a sturdy non-sway bottle mount, for fast and safe access to your bottle. The DELTA SONIC rod can slide along the seat post for the best-customized fit for you. XLAB recommends a 1" insertion minimum into the seatpost.

Compatibility

XLAB has found these bikes to be compatible with the DELTA SONIC. 
Cervelo P5 & 2013 P3, Scott Plasma, Kestrel 4000, Fuji D6 & Norcom, BH Aero

XLAB VEE CLAMP helps support the seat post to keep mounting rod locked in place.

all3sports.com ships throughout the 50 continental United States via UPS (United Parcel Service). We typically ship items immediately as they become available. Our goal is to inform you when an item is not available for immediate shipment. While you may receive more than one shipment per order, there is no additional shipping charge. We process orders on a first-come, first-served basis. In-stock items on orders placed before 3 PM EST will typically be shipped out the same day.

UPS does not ship to APO/FPO or P.O. Box addresses however we will gladly ship to APO/FPO addresses for members of the armed services using USPS. Please note in the special notes section of your cart that you require the order to be shipped to an APO/FPO address. Please be aware that the shipping rates shown during checkout are for reference only and that further costs may need to be added to insure the value of the items you have ordered.

Attempts to ship to a P.O. Box will delay and in most cases prevent delivery of your order.

Returns and Exchanges Procedures:

There is no need to contact all3sports.com prior to returning an item. Use your order number included on your packing slip as a RMA and mail to:

All3sports.com
Returns Department
8601 Dunwoody Place, Suite 420
Atlanta, GA 30350

Refunds

all3sports.com processes refunds once your returned item(s) have been received and inspected by our Returns Department. Shipping and handling charges are nonrefundable. If you received free shipping because your original purchase totaled more than $99 and your return brings the order total below $99 all3sports.com will deduct the original shipping cost from your refund.

A refund will be credited back to your original method of payment and will post approximately two or three days after the date of processing. Please note that it may take up to two billing cycles for the credit to appear on your monthly credit card statement. Most returns will process in approximately two weeks, depending on your method of return.

Exchanges

If you have ordered an item that does not fit, feel, or look right, follow these easy steps to exchange the item. Simply login to your account and place a new order for the item you need. It is best to place a new order as soon as possible to ensure availability of the alternate item. At your convenience, return the item you do not want for a full refund. Once the returned item is received byall3sports.com, a refund is applied and your exchange is complete.

Working closely with Cervélo and their wind tunnel testing results, XLAB developed an aerodynamic single rear system specific to Ritchey clamp seat posts with a 10 mm horizontal rear hole.
If the saddle is in the rearward position, you may want to look at the DELTA SONIC XL

Aerodynamic Design

The DELTA SONIC allows the bottle to be close to the saddle, hiding in the rider’s draft and provides clean air flow.

Reliable & Customizable

The DELTA SONIC fits snug into the seat post providing a sturdy non-sway bottle mount, for fast and safe access to your bottle. The DELTA SONIC rod can slide along the seat post for the best-customized fit for you. XLAB recommends a 1" insertion minimum into the seatpost.

Compatibility

XLAB has found these bikes to be compatible with the DELTA SONIC. 
Cervelo P5 & 2013 P3, Scott Plasma, Kestrel 4000, Fuji D6 & Norcom, BH Aero

XLAB VEE CLAMP helps support the seat post to keep mounting rod locked in place.

all3sports.com ships throughout the 50 continental United States via UPS (United Parcel Service). We typically ship items immediately as they become available. Our goal is to inform you when an item is not available for immediate shipment. While you may receive more than one shipment per order, there is no additional shipping charge. We process orders on a first-come, first-served basis. In-stock items on orders placed before 3 PM EST will typically be shipped out the same day.

UPS does not ship to APO/FPO or P.O. Box addresses however we will gladly ship to APO/FPO addresses for members of the armed services using USPS. Please note in the special notes section of your cart that you require the order to be shipped to an APO/FPO address. Please be aware that the shipping rates shown during checkout are for reference only and that further costs may need to be added to insure the value of the items you have ordered.

Attempts to ship to a P.O. Box will delay and in most cases prevent delivery of your order.

Returns and Exchanges Procedures:

There is no need to contact all3sports.com prior to returning an item. Use your order number included on your packing slip as a RMA and mail to:

All3sports.com
Returns Department
8601 Dunwoody Place, Suite 420
Atlanta, GA 30350

Refunds

all3sports.com processes refunds once your returned item(s) have been received and inspected by our Returns Department. Shipping and handling charges are nonrefundable. If you received free shipping because your original purchase totaled more than $99 and your return brings the order total below $99 all3sports.com will deduct the original shipping cost from your refund.

A refund will be credited back to your original method of payment and will post approximately two or three days after the date of processing. Please note that it may take up to two billing cycles for the credit to appear on your monthly credit card statement. Most returns will process in approximately two weeks, depending on your method of return.

Exchanges

If you have ordered an item that does not fit, feel, or look right, follow these easy steps to exchange the item. Simply login to your account and place a new order for the item you need. It is best to place a new order as soon as possible to ensure availability of the alternate item. At your convenience, return the item you do not want for a full refund. Once the returned item is received byall3sports.com, a refund is applied and your exchange is complete.