Boulder Bicycle Defiant?

Hi, new here but appreciated finding all your posts about Boulder Bicycles. I recently acquired a Defiant (?) I believe, not sure what year. Serial number is 70029 and it has a front badge sticker, rather than the embossed badges I am seeing on here. It also has a support on seat post and looks like a spring on rear shock. Anyone have any idea what year this is?

I am trying to get it in working shape. Ordered new tires, etc. I tried to raise the seat post but it was frozen. I have a DEFIANT seat post! ha ha. Twisting it caused separation between the post and stem sleeve? I drilled it and used leverage to remove. I am left with alloy lining the frame stem post frozen in place which I need to remove.

Anyone have any ideas for clean removal before I do damage to the frame post? I drilled two more holes to get something in there to try and leverage it out and have been soaking it with Liquid Wrench before I go ape on it.

Thanks in advance. The bikes I have seen on this site are amazing. Not sure what I will do with this bike but what I have seen is is absolutely inspiring!

Cheers, - gio

Caustic soda. But I would strip the frame first and remove the shock/damper assembly. Then put a tape around the seat tube, cover the rest of the frame in a plastic sheet so the soda wont be able to touch the paint.
Hopefully there is no hole between the seat tube and the rest of the frame. But if so, you should try to close that, before filling in the caustic soda.

Caustic soda will dissolve aluminium and rust. But be warned. It's a bubbling mess.

Re:

Welcome to the site and cool Defiant!!

Your frame is quite interesting. Is the head tube 1 1/4 or 1 1/8?

I'm going to guess and say it's a 1992, possibly late 91. The RS1 forks are from 1991 (and probably 1 1/4), internal rear cable routing is also a early detail. The small support tube is not a detail i've seen on the earlier frames so i'm a bit stumped.

Good luck with the seat post, don't give up!

Re:

Hi, thank you both for your helpful replies. I am being patient and applying Liquid Wrench. If that does not work I will try and caustic soda.

Here are a few more photos. I am baffled too. It seems like they would have added the seat post support on later year models if they experienced failures.

When was the front badge a sticker?

Was the spring shock older or later years?

How can I tell if the head tube 1 1/4 or 1 1/8?

I ordered a seat post 26.8 size, sound correct?

What size seat post clamp do I need to the bike?

Thanks! This is turning into a fun project.

Re:

Seatpost size is either 26.6 or 28.6. Frames after serial number 00200 should use 28.6, according to my literature.

XC Pro build and RS-1 forks point to either 91 or 92. A 1 1/4 head tube would verify this.

Your rear sus unit is the older spring/oil style. Apparently you can still buy a replacement air unit from Risse Racing, though I haven't looked into this.

Here is my wild guess at the history of your frame. Probably a late 91 model outfitted with a 1 1/4" RS-1. Bike might have been repainted at one time and the seat tube support tube added at that time. The head tube badge could have been lost, kept by prior owner, or possibly was never installed on the frame.

Pull the stem, drop the forks and take a look inside of the head tube for traces of a different color (measure the quill on your stem at the same time).

Very cool bike, keep us updated!

It can be really hard to precisely "detail" a boulder, the way it would be tricky to identify stuff from any custom builder. From what machines I have (and have had in the past), I think it's a Gazelle, the precursor to the defiant, based on two particular details. On the machines I have had, gazelle is 1 1/4" head tube with a square tube by the BB, which needs a suntour mech with the requisite depth to fit above this tube.
Defiant's I have in front of me have 1 1/8" head tubes, and a higher bracing tube (and round), with room to fit a Shimano f.mech under this tube.
That is indeed a spring/ oil shock. Air shock is indeed available from Risse. I have done this on one machine. It comes with very small valve orifices and needs tweaking for the boulder- but it works really well once set up.

Nice to see another boulder on the site!

Re:

As Elite504 mentioned it is difficult to date Boulders.

I've come up with a few timeline and construction details that might be helpful, though there are no steadfast rules it seems when it comes to Boulders.

Here is what i've found based on the Mombat history page and web searches.

1991-92:
Boulder Gazelle introduced. 1 1/4" head tube. Early frames had a bend in the rear subframe, rear brake cable runs along the drive side of the seat mast, can have a stepped seat tube (26.6) or straight (28.6), after frame 200 most if not all are 28.6. Internal rear cable routing in sub-frame.

Sometime during 91 the bend in the rear sub-frame was changed to a straight tube.

1993:
Defiant introduced. 1 1/8" ht, rear brake cable now on non-drive side of seat mast, rear der. cable not internal. Other "improvements) have been made to frame. The square subframe support seems to be on early Defiants, not sure when they switched to round.

That's all I have. I wonder if the serial numbers added a "7" prefix when Defiants were introduced?

It would be nice to have a timeline of these bikes, including serial numbers.

Cheers!

Re:

Looking again at Gio's Boulder I do see a mix-up of details I thought would ID the year.

Early(ish) sub-frame. Later rear brake cable routing, including rear the brake stop. Then there is the seat mast support.....

I'm at a loss but will stick to my repaint theory (because there is no model name on the frame, lacking head tube badge, and interesting seat tube support). And also guess that yours is a 1993, 29th Defiant made (70029).

Could somebody with a Defiant verify or discount my 7 prefix guess?

Also, please let us know if your frame has a 1 1/4 or 1 1/8" head tube. Just pull the fork and measure the diameter of the forks' steerer tube. Take a peek inside of the frame ht at the same time. And take pictures.

No luck getting the mangled seat post out yet so I took it apart today. Looks like the head tube is 1 1/4. I can't get an accurate reading on the seat tube inner diameter yet with the alloy in the way but exterior of that tube looks like 32mm.

Yes, it does have the spring which looks in good shape. Air shock might be nice. Is the value of an air shock the lighter weight or performance too?

I got the rear assembly apart except for the pivot axle which I am supposed to drive out with a soft brass or aluminum "drift" (?) slightly under 7/16" in diameter??? Anyone happen to have one of those handy? I guess I will improvise something. Soaking it with Liquid wrench overnight. I might have to use caustic soda soon on these parts but I found an interesting list of products to free stubborn bolts, etc. that includes a 50/50 mix of automatic transmission fluid and Acetone. See attached.

Here are the latest photos. Let me know if it reveals any more clues about the year built. To me, it does not look like the frame has been repainted. Photos include shots from top and bottom into head tube and I see same color in there.

Re:

Very cool!

Must be a fairly early Boulder, Gazelle as Elite504 predicted given the 1 1/4 ht.

Also looks like it could be original paint, double bonus.