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C38T25 Carbon Tubular Set

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For many years 38 mm carbon wheels were the standard for road racing - the Zipp 303 wheels, for example. Now the bulk or racers are opting for something a little bit deeper - 50 mm in most cases. But there is no right or wrong. These would be a little bit lighter if you generally climb more. They also have a nice bullet shaped rim profile that is better in side winds (than the traditional V shape). The 25 mm width also gives you a wider bed for the tire for better performance.

Specifications

Size: 700C Tubular (glue on tires)

Weight 1320 grams (without skewers) weights can vary by about 50 grams a set due to rim, spoke, and hub weight tollerances.

Rim (for more information on rims and wheel building go to the carbon rim page)

Rim Material Carbon UD (unidiredtional finish). Braking surface is pure basalt ceramic that not only dissipates heat but also tolerates it well

Drilling: 20 hole front and 24 hole rear

Rim Weight 380 grams

Rim Dimensions 50 mm high 25 mm wide

Rim ERD 565 mm

Spokes

Spokes if Sapim CX Ray 4.1 grams each bladed aero. Blade is 2.3 mm x 1 mm

Spokes if Sapim Laser 4.1 grams each Double butted 2.0-1.5-2.0

Spoke Length Front: 267 (Radial)

Spoke Length Drive Side Rear: 267 (2X)

Spoke Length Non Drive Side Rear: 259 (Radial)

Spoke Tension Front: 110-120 KGF (on a Park Tensiometer 13-14 for CX Ray and 18-19 for Laser

Spoke Tension Rear Drive Side: 120-130 KGF (on a Park Tensiometer 14-15 for CX Ray and 19-20 for Laser).

Spoke Tension Rear Non Drive Side: There is no spec for this because it is whatever it is to pull the rim to the center of the wheel. They will always be looser than the drive side spokes and often by quite bit.

Note: Wheels come with extra spokes and the exact length is indicated on the spoke package. We occasionally substiture when we are out of a particular length.

Spoke Prep

We use Loctite 242 on the non drive side spokes and on the front spokes during the building process (no lubricant). On the drive side rear spokes we use a lubricant to build (nothing special - just something slippery) and after the build put some Loctite 242 in to finish them off. The Loctite 242 will make the spokes harder to turn but will not sieze them.

Spoke Nipples

Front Nipples Alloy 14 gauge uses Park Black Spoke wrench

Rear Drive Side Nipples Alloy 14 gauge uses Park Black Spoke wrench

Rear Non Drive Side Nipples Alloy 14 gauge uses Park Black Spoke wrench

Spoke Washers

Used internally on the drive side rear spokes. I have them custom made by Boker's in the US. They provide an extra layer or durability while adding almost no weight. Weigh less than 1 gram each.

Hub (for more information on hubs and servicing go to the hub page)

Front over lock nut dimension 100 mm

Front flange diameter: 32 mm

Front center to flange: 32 mm

Rear Over Lock Nut dimension 130 mm (standard road)

Rear Drive Side Flange Diameter: 58 mm

Rear Drive Side Center to Flange: 14 mm

Rear Non Drive Side Flange Diameter: 45 mm

Rear Drive Side Center to Flange: 38.5 mm

Campy Cassette body - 9,10, or 11 speed compatible

Shimano/Sram Cassette Body - 8,9,10,11 speed compatible

Cassette Body Bearings: 6902 (Two) Abec 5 sealed cartridge bearing with seals

Front Hub Weight 80 grams

Front Hub Bearings: 6900 Abec 5 sealed cartridge bearing with seals

Rear Hub Weight 245 grams

Rear Hub Bearings: 6802 (both drive and non drive side) Abec 5 sealed cartridge bearing with seals

Note: On Shimano-Sram cassette bodies (they are one in the same) you will need a spacer if using it with a 9 speed cassette (which is included in the spoke package), for a 10 speed cassette (which is narrower than a 9 speed) you will need the included spacer and the one that came with your cassette. If your cassette doesn't have one you can get them at any bike shop. They are 1 mm wide.

Skewers

Skewers weight 46 grams front 50 grams rear.

Tire Recommendations

With the wider rims, you can use pretty much any tire width you want - from 19 mm all the way up to over 30 mm. I like 25 mm wide tires simply because they hold more air and are more comfortable. 23 mm tires are probably the fastest and are the most aerodynamic. As you get bigger tires, the limiting factor is the frame. Typically the tires will first rub on either the brakes (on the top of the tire) or with the rear tire hitting the seat tube. Most road bikes will fit up to 25 mm tires, a few bigger ones, and many won't even fit a 25 mm tire.

The rim is 50 mm deep but the tubes rests in the rim cavity. I suggest using tubes with removeable cores. The wheels come with valve extenders (see below) for tubes with removeable cores. You can get valve extenders that will work with tubes without removeable cores but there is no way to lock the valve stem. Note that not all tubes have removeable cores. In fact, most don't

Valve Extenders

We provide valve extenders that work with tubes with removeable cores. If you are not familiar with them, the trick is to remove the valve stem core from the tube (it will have two flat sides - you can remove it with needle nose pliers or a very very small wrench). Thread the valve extender onto the base of the valve - extending it - then thread in the core into the end of the extender. I recommend using a piece of electrical tape around the core where it adjoins the rim. If you don't the core will click against the rim - driving you crazy.

Tire Pressure Recommendations

With the wider rims you can generally run at least 10% less pressure than with a narrower rim because the system holds more air. Less pressure is better because you have a bigger tire patch and will roll over the bumps in the road instead of bounce over them (it's that sidewall flex that gives you better rolling resistance). Most people run too much pressure in their tires because they believe they are faster (and they feel faster at first). If the roads were perfectly flat that would be the case but they all have lots of bumps so lower pressures make sense. Generally speaking a 160 pound rider should be around 80-90 psi in the back tire and 75-85 in the front. If you have been running higher pressure you will immediately notice how much more comfortable the ride is and how much better the bike handles around corners.

Documentation

When you receive your wheels it will include a package with the extra spokes, skewers, a spacer (if a Shimano-Sram cassette is ordered) and some documents. The documents will list the builder and on alloy wheels a serial number (which is under the rim strip near the valve hole on both wheels). Also included is a spec sheet showing the type and length of spokes used and the spokes tensions for your wheels). There is also some maintenance info and whatever else I want to throw in there along with a copy of your invoice. We keep a record of your info here so you can contact us with either your invoice number (preferred), serial number (also OK), or your name and we can pull up your records.

$895.00

Reviews

C38T25 Carbon Tubular Set

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Featured positive reviews:

C38T25 Carbon Tubular Set

Great wheels 10/06/2015
By Brad C
These wheels arrived and I was impressed by the build quality. The nice wide rime makes installing tubular tires easy. These wheels have taken the abuse of 4 CX races and are still in great condition.