Park ISC-4 Internal Seat Tube Clamp Rich’s Rating: Park bills this as an essential tool in preventing damage to bikes with thin-walled or freshly-painted frames when mounting them in a work stand. I actually use it for every repair job on every bike if the task will take more than 5 minutes. On those brief fixes, I clamp the seatpost after determining that doing so will not damage the post. If the post is carbon or thin-walled aluminum or otherwise potentially fragile, I default to the ISC-4 anyway. Here’s what I like best about the this tool: 1. It’s fast to set up. Pull the seatpost, stick the ISC-4 into the seat tube, twist the knob until the expander plugs are firmly pressed against the inside of the seat tube, and you’re done. It’s actually faster than clamping the seatpost, especially on bikes with rear lights attached to the post, seat bags, or minimal seatpost extension above the seat cluster. 2. It’s super-secure. The clamp holds the bike firmly and the stand holds the clamp firmly. This is critical when doing such tasks as removing and replacing headset cups or threaded bottom brackets but it’s a huge help if all I’m doing is fixing a flat tire. It’s also a convenient way to hold a frame I’m painting. 3. It’s secure even when working on heavy bikes, such as tandems, DH rigs, and tourers with racks and fenders. 4. It holds the frame in an area that’s designed to take stress, the seat tube. The midpoint of a downtube, seat tube, or top tube is much more vulnerable. It also eliminates the risk of damage from clamping a work stand over water bottle bosses, cables, and cable stops. 5. It doesn’t tie up any part of the bike. All service procedures can be done easily, which is not true of stands that hold the wheels or part of the frame. 6. It fits any bike with a traditional seatpost. On bikes with seat masts, such as the Fuji SST, you’ll need a repair stand with Park’s 100-3D clamp or equivalent. Two tips. First, mark the seatpost with tape to make sure you reinstall it to the same height. Second, grease the seatpost while you have it out to prevent galvanic corrosion. Carbon frames and carbon seatposts require special attention for this second tip; consult the manufacturer for details. Bikes with seatmasts, such as this Fuji, won’t work with the ISC-4. (Photo from Fujibikes.com.) Park’s 100-3D clamp will work on bikes with seatmasts, as well as those with shaped carbon or hydroformed aluminum tubes. (Photo from Parktool.com.)