msl109

Folks, I have a 3T stem, I think it's the first one they made, and the GB Map of Britain bars mated - They are obviously not the same clamp size, so I shimmed them with a .2 and .1 mm shim (used a digital caliper to measure a beer and cat food can. ) .3mm x 2 = .6, I figured, would make up the 25.4 to 26mm difference. That's assuming the GB is 25.4 - it measured that, and the 3T is 26, not 26.4. But I can't get it tight enough - bars rotate when I lean hard into the drops. Complicating matters is the clamp bolt on the 3T has buggered up the notch that keeps it from spinning in front. I had grabbed it with a vise grip around the edges to hold it while I turned the nut. Seems they redesigned this later and did a better job - recessed it for one thing. Anyway, suggestions? Is the clamp possibly made to Cinelli standards, 26.4? In that case, I'll try a larger shim. And any suggestions as to a replacement clamp bolt that I could grab from both ends? I can live with a hex on the front of the stem. Was also thinking of using a lock washer, but that's probably not enough. Pics below should give you an idea. Very much appreciated, as always ...

3speedslow

I would skip the 3T and go with a GB, like to like.

msl109

Have one of those, but it was intended for another project. And this is going on a 68 Paramount - don't care too much about original, but wanted to keep it in the right era - all the ones I've seen have this type of stem. Does that GB go back to '68?

old's'cool

Be advised that, unbeknownst to me at the time, the cycle shop that sold me my 78 Motobecane GJ combined a 25.4 stem and 25.0 bar, without a shim. Tightening the clamp enough was no problem, but several decades later, the clamp developed a crack. When I saw this, I deduced the cause, using knowledge about French sizes gained here. I had the crack repaired with a very high quality prep & weld, and the stem is back in service with an 0.2mm shim, going strong for 7 years. I filed and polished the welded area, so the stem looks just like new.
I'm just mentioning this since it's possible with your setup, that latent damage has been done to your stem; something to keep an eye out for.

CV-6 

If you are okay with maybe not being 100% period, pay a visit to your local hardware store and buy bolt which has an Allen head on it. I have a button head bolt I use on one of my Pivos to solve a similar tightening problem. Granted it will not directly solve your bar rotation problem, but with shimming it might help you get the stem tight enough.

msl109

Thanks, that makes a lot of sense, but this is actually a NOS stem. The stem bolt notch was just underengineered and once it slips, it chews up the aluminum and won't stay put ..

msl109

I'd be ok with that, could even use a hex had to keep it more period, but my concern with hardware store stuff is that a lot of the time, the bolts are made out of cheap pot metal and don't do well under stress. Maybe if they have stainless ...

3speedslow

Hey, sorry it took so long to get back. That stem was 1970 on. GB supplied girder style stems to Schwinn which would look killer on your 68 Paramount.

msl109

I agree - and I'm pretty sure I know the stem you're talking about - more like a T girder than an I, right? Just saw one listed on eBay but according to the listing the clamp is 24mm ...

Tempted to use the GB I have, even if it's 2 years too young. Or try again with the 3T. Or give up on the 3T. Or ... you know how it goes.

msl109

Well, with a bit of help from Pabst Blue Ribbon, I increased the size of the shim by about.15 and she's holding enough for me to put my whole weight on it, feet off the ground. I also used a needle nose pliers to hold the shaft of the bolt from betwee the opening in the bottom of the clamp. The shims were not easy to line up and were certainly not loose but the bar still could be moved easily before I tightened the bolt, so I'm not worried about .1mm stressing the clamp - these early stems don't look like the tolerance on them was very precise anyway.
But I'm going to keep an eye out for one of those GB girder stems now that you put the bug in my ear.

msl109

Is this the girder stem you're referring to? I see it called a gooseneck.

Metacortex

The girder style GB made "S" stems did "look killer" but note that they were only used by Schwinn from 1973 on.

msl109

Ah, but were they in production in '68? And is the pic above I posted earlier today the stem we're referring to? I'm attempting to keep it era correct for the most part, but I'm not too concerned about original specs as delivered in '68. (Have Mafac Competition brakes on it, for instance, which are a bit too new and not very Weinmann, but I don't have to go through retaping bars if I change my mind about those.)

3speedslow

Velobase refers to that stem as a Nova. Info says was in the 73 cat but no catalogs have it before that. The girder style GB stem with " British Made " was in use from the 40's to 70's. Pricy I bet.

As always, up to you. I am perfectly content to use a 70's set up on my early 80's? English Dawes.

Would love to see pics of that Paramount!

Metacortex

The stem you pictured above was called "Nova" by GB and "Girder Design" by Schwinn. I believe it was produced by GB both in "GB" and "S" branded versions from 1973 through 1978. Note that the Schwinn branded version of that stem came only with a 21.15mm diameter, not suitable for an original Paramount fork. Note that "gooseneck" is a universal slang term for stems in general.

msl109

Thought it was either a universal term or was referring to short extension stems. - good info, would be frustrating to find out the hard way about the diameter. thanks

msl109

Certainly will post pics (the chrome will be a challenge) - probably will be built by the end of the week, aside from the rear brake cable and bar tape Yeah, I try not to make a build an anachronism of style, if you get my drift. Beyond that, I haven't been too particular. If I need to research it to discover whether the component was in production at the time, then it probably doesn't look out of place aesthetically, except to a historian. That said, I appreciate completely someone trying to keep things historically correct and am tempted with this build, but it's going to be more like a '68 Paramount as it could be built in '74 ... It's a NR modified to triple crank that I haven't even checked the date code on, a Rally rear, Mafac Competition brakes, and Weinmann levers that are a few years too new - I had them lying around, they have adjusters that work, the generic hoods fit, and they're more distinctive looking than the stock Weinmann levers of the time.
Aside from those bits, it will be pretty '68 correct ...
Btw, toying with the idea of a GB spearpoint on there .. thoughts, anyone? Otherwise, the 3T stays ... and I save probably about $75 bucks ...

msl109

Here you go, as requested - just took it for a spin yesterday. Velvet ride. Went with the GB Hiduminium stem and avoided the shim situation entirely - found one at a reasonable price, had some scratches which I managed to grind out and polish. Top tube was a little long for me, so going to the 75mm stem was a perk.

3speedslow

Bravo! You have a very nice looking Paramount there. Glad to see it all together and read that it has rolled out the door for rides now. I'm happy to have been able to assist with your questions.

The stem choice is really classy. The GB spear points are just dripping with British character. They can be hard to find but not impossible, even better if the one found is the right size. The one I have came to me on a 61-62 Raleigh Gran Sport.

Enjoy your fine bike and rebuild efforts with a well deserved ride and a beer afterwards!

msl109

Thanks, yeah, pleased with the outcome, and the spearpoint is definitely one of the classiest of the era. Not sure if it was still being produced in '68, but close enough. '61-2 Gran Sport - nice, cottered crank, I'd imagine. I have a '69 Competition in parts stashed in the garage. When I clean out the garage and there's a place for all these bikes, I'll build it ...