miyata nuts stripping

I have a red miyata seat. I bought a 400mm seat post so I can ride my daughters’ 20" and 16". When trying to undo one of the 4 nuts underneath, the screw is turning too.

I stopped immediately. Now what? 3 haven’t been touched, so are still tight. The stripped nut never did loosen. :thinking:

I just dealt with this same problem and I tried all kinds of things. I ended up cutting the carriage bolt off with a Dremel. Here’s a list of things you can do, in the order you should try. If I get something wrong, I’m sure somebody can correct me.

  1. Stick the saddle in the freezer overnight before trying to get the rest of the nuts off. Your probably already screwed with the first one, but putting the saddle in the freezer should keep the plastic and metal plate that the carriage bolt locks into from stripping out when you try to take the others off. You’ll have to skip straight to the next step for the bolt that is already spinning.

B) If that doesn’t work, you need a Dremel. You can try cutting the the extra bit of bolt that’s sticking through the nut, then cutting a horizontal line (perpindicular to the seat frame) through the bolt, for a small slot-head screwdriver. Then hold the bolt in place with the screwdriver while turning the nut with an open-face wrench. This is a technique developed by Yoopers, and he’s got pictures in the gallery that make a lot more sense than my rambling. I found that if you try to start turning the bolt directly after cutting the screwdriver slot, the metal might still be hot and soft. Better wait a while, so you don’t round out the slot with the screwdriver when the dang thing doesn’t want to turn.

III) If its still stubborn, you have to take the seat cover off. Of course, you’ll have to take of the handle/bumpers to get the seat cover off, which means another five possibly problematic carriage bolts. You may want to have a quick chat with Jesus before you launch into this. Plus, you might stick the whole caboodle in the freezer again, for good measure (no offense to Jesus). If you can only get one bumper off, you may be able to peel the seat cover up enough to get to the head of those seat-post carriage bolts anyway. Use your dremel to cut a new, bigger, stronger flat-head screwdriver slot in the head of the bolt. This should give you a better grip.

Fore) If it STILL won’t come off (my situation) your going to have to cut the bolt in half with your Dremel. What sucks about this is it can be hard to get the Dremel’s cutting wheel to fit in that tight space on the underside of the saddle. I actually had to cut the nut in half with a cutting line parallel to the seat frame, then cut the remaining part of the nut open with a cutting line perpendicular to the seat frame. I couldn’t find metric carriage bolts to replace what I cut off. I had to settle for the closest-sized american carriage bolts, which I think is OK, since they are a little bit larger, they lock into the metal plate inside the saddle a little better.

All in all, the whole activity is less fun than it should be.

Great explanation. There is one you forgot:

Phyve) Buy a new seat with the right post on it. They usually ship within 24 hours.

I like the freeze it technique. I have a Dremel.

Has anyone mentioned this problem to the Miyata people?