Gemcrest CF Bases, How are they?

I did some searching, and have found that people have them, but didn’t find much discussion on them.

I am looking at the Gemcrest CF bases on UDC, and I will be getting it made into the KH style of a saddle, so I can transfer my foam and other components onto it easily.

I know Ill have to drill it myself, which shouldn’t be too hard, cause ill just use the same pattern as my KH plastic base. But any drilling tips would be appreciated.

Now, my main question is: How does the Gemcrest compare to the Scott Wallis Base. What are the main differences in them, and what makes one cost more than the other. Is the Gemcrest weaker or something?

I hope everyone with this base or that knows about it can chime and and tell me how well it has been holding up.

EDIT: If I can get enough money I will get the SW De-rail base, but with the money issues I am in, this seems like the only choice. IT will be good to learn about it as much as I can before I commit to buying it.

#1 drilling tip… measure, re-measure, and measure again. You have one chance to drill so make sure you’re right on the money. If you can use a drill press with a vice, do it… this will allow you to make the most accurate hole pattern.

If you want to be extra-careful, use a very small drill bit (much smaller than the final hole) to create “pilot holes”. Hold your seatpost over the pilot holes and make sure they line up exactly. If not, you will likely only be off by a little bit and you can re-drill your pilot hole without screwing up the final product. Once the pilot holes are spot-on, drilling the final holes will go easily.

The SW base is superior to the Gemcrest because a lot more work goes into the SW base. The Gemcrest base is simply a piece of carbon fiber while the SW base includes (as an upgrade, which is well worth the money) stainless steel threaded inserts. You don’t have to drill the SW base nor do you need carriage bolts… just add screws and your handle and bumper are attached!

The biggest advantage to getting a SW base is the seatpost attachment. The SW base is designed to mate with a rail-type seatpost WITHOUT THE RAILS! Isn’t that cool? You can adjust the angle of the seat by screwing or unscrewing a couple allen screws and that’s it. Check out the pictures at

All that being said, a well-drilled and well-mounted Gemcrest base should hold up just as well as a SW base. In buying the SW base, you’re paying for work you’d have to do yourself to setup the Gemcrest base. If you’re in a pinch for funds, go for the Gemcrest base and do a good job mounting it. You’ll end up with a super-strong and durable seat, along with the pride of doing it yourself!

Other than cost, the only downside I can imagine is the inability to adjust forward/back positioning. But come to think of it I think on a uni that problem would be irrelavent.

Man that W.D. setup must be light, though :sunglasses: !

The most difficult part of drilling the Gemcrest CF base is finding a suitable square file to file the holes square for the carriage bolts. Square files are hard to find. And if you do find one they can be expensive ($16, $20, or more).

With the proper square file, making the square holes for the carriage bolts won’t be too difficult. Drill a small hole, then use the file to expand it to the right size for the carriage bolt. If the pilot hole is off a little bit you’ll be able to move the hole while you file it. With a careful iterative process you’ll be able to get the important holes all lined up properly.

I did my first three CF bases with a triangular file. Not ideal. The square holes are only rough approximations of a square. It was more difficult than it needed to be. I now have a proper square file so if I make any more CF saddles I’ll have a proper file and it will be easier.

I bet a dremel tool with a small circular saw blade would work as well.

If you are going to be using a rail adapter and don’t already have one the Wallis base is cheaper.

$80 - CF Base
$70 - Rail Adapter

$125 - S Wallis Base, if you do your own drilling

If you are fiting the KH carbon-fiber base to a Kris Holm saddle, you will need to use a Kris Holm Rail-Type Adapter which are only $30 not $70 on

The Scott Wallis is a much better base if you can afford it though


Except that the rail adapter costs much less now than it used to ($30, £17)

Having said that though, the Wallis base is a much neater solution. It’s a pity it’s miyata style bumpers not KH, rather than being a drop-in replacement for a KH base, because that means you have to buy expensive replacement handles with it though.

I did ask Roger why the gemcrest ones aren’t like the wallis design ones as standard, and he said that it’s because the stuff you need to do brings the cost up so they end up costing tons more, like the wallis ones do.


Thanks for all the replies and info guys. =p

I am gonna hold out on the gemcrest and go for the SW De-Rail base. That was my original plan but I was starting to get desperate for a CF base. Hence the decision of the Gemcrest.

It will be worth saving up more to get the SW base, specially when you dont need an adapter on it, and you ca have SIF grips. :smiley:

Ill probably get a Gemcrest for another uni though, latter on. Just so I can have the experience of drilling and setting up one on my own.

As a side note, I’m pretty sure that the newest KH rail adapter no longer uses rails. It just bolts straight to the seat base and allows for tilt adjustment, just like the Wallis base.

The big advantages of the SW rig is craftmanship and durability. Durability is often misunderstood in terms of hardcore Muni. If you’re really going at it hard, no piece of Muni gear (excepting some axels) lasts very long. Rims get bent or fall way out of true; cranks bend; frames eventually weaken and bend or break; pedals wear out. Maybe only a Thompson seat post will last forever. Anyhow, the SW rig has lasted eveyone in SB for going on two years and that’s a lot of bashing on the rocks. So yes, the SB rig works grat, but maybe best of all, it lasts awhile. In the end if you’re on the rocky stuff it is probably cheaper to go with the SW because you’ll break the other stuff in a quarter of the time.


The new seat post do you mean?

It is a bike post adapter that bolts on to the seat and has the same kind of attachment as the swallis base. The kh one is just metal, not CF. I don’t think it is going to be on the kh unis yet, Kris said they were still working on the design I think.

I’d avoid using a dremel, especially with a blade… their high RPMs make them quite “skittish” when trying to do detailed work, and they can take off too much material if you don’t pay close attention to what you’re doing.

You’re best off with a drill press and a vice: you hold your work in place and select your bit such that you know EXACTLY where your hole is and EXACTLY how much material is removed.

John, can you compare / contrast your SW CF base experiences with the Gemcrest? Has anyone in your crew ridden on the Gemcrest base?

Something like this?: no-rail seat adapter 1 no-rail seat adapter 2

Exactly like that.

I ride a Gemcrest KH form CF base, but have no experience with the Wallis. I use a Reeder handle. The Gemcrest a great setup, except for the much-discussed downsides to using a rail adapter (SIF sucks).

Jess Riegel is the man to ask from our group about the differences, since he has ridden both setups extensively.

that’s it exactly. kris said they might be out around march of 07.

Any more news on this new rail adapter?