This came up in another post (Coker crank length/road grade) so I’m starting a new thread to answer any questions.
Miyata plastic bases are rather flimsy, as many of you know. I recently made a metal plate that replaces the thin sheet metal plate on top of the base. The one I made extends from the seat post mount all the way to the handle bolt holes. In this case I made the plate for a Coker unicycle using a “GB Handle”. After installation the rigidity was comparable to a carbon fiber base.
I’m currently in the process of designing a universal plate that will accommodate every handle currently available (GB Coker handle, RH and LH Reeder muni handles, and the stock Miyata handle). The plate will go on top of the plastic base and have existing holes for all of the above mentioned handles.
I’ll be getting these laser cut, probably out of 10 GA. steel (for rigidity). Laser cutting is very precise and clean. All of the holes will be 0.25 square holes to accommodate 1/4" carriage bolts (which will probably come with the plate). This will eliminate the current Miyata base problem with spinning bolts.
These will be available from Unicycle.com in a few weeks. At this point, I hope for them to sell for $10 or less (including mounting hardware), though this figure could change. You don’t need to call Unicycle.com asking when they are available; I will post here as soon as they are.
Cool! That’s a very needed seat option. Especially now that the Miyata seats have the spinning bolt problem.
One thing to think about. I have cracked a Miyata seat base in the back where my butt sits on it. If the reinforcement plate goes all the way to the back of the seat it would help. And if it could follow the roundish outline of the back of the seat that would be even better.
Glad you can do it so cheaply. I was thinking of buying a $130 punch and die set for our turret punch to punch 1/4" square holes and then roll the plates to the 8" radius that would match the Miyata seat. You’re talking about the square holes and a set of holes to accommodate all kinds of other stuff and for $10 or so. A bargain indeed. You rock, dude!
I’ve considered this. What’s holding me back is the weight and cost that this would add.
The density of steel is about .283 lb/in^3, so take this times the area of the steel you want to add times .135 (the thickness of 10 GA) to find the weight of the addition. I don’t have my design finalized yet, but I think the weight was already up around 0.35 lbs. Would you want to see this addition at the expense of a heavier seat?
Also, the final cost of the plates more or less comes down to the volume of steel per plate. The difference in cost would likely be fairly small, but I suppose it’s still a factor.
The Miyata seat base that cracked in the back was on my Pashley muni. On a muni having the plate go all the way to the back of the seat would be nice. On a Coker an extended plate would not be necessary.
The seat that cracked was reinforced with an expoxy sandwich made with two Miyata seat plates epoxied together. It worked well enough to keep the nose of the seat base from collapsing, but didn’t keep the back of the seat base from cracking. The seat cracked right along the edge of the reinforcement plate.
> gbarnes wrote:
> > *John,
> > I’ve considered this. What’s holding me back is the weight and cost
> > that this would add.
> > *
> The Miyata seat base that cracked in the back was on my Pashley muni.
> On a muni having the plate go all the way to the back of the seat would
> be nice. On a Coker an extended plate would not be necessary.
> The seat that cracked was reinforced with an expoxy sandwich made with
> two Miyata seat plates epoxied together. It worked well enough to keep
> the nose of the seat base from collapsing, but didn’t keep the back of
> the seat base from cracking. The seat cracked right along the edge of
> the reinforcement plate.
> john_childs (at) hotmail (dot) com
> john_childs’s Profile: http://www.unicyclist.com/profile/449
> View this thread: http://www.unicyclist.com/thread/19112
For MUni, and perhaps some freestyle and racing, where weight is important, the CF would be much better. For other applications, where weight is less important, say long-distance, the add-on stiffener should be more cost-effective, especially for people that already have a plastic Miyata seat.