Riser Bar an '96 Velocity Stem

[Mixi]

Hi!
I'm looking to fit a riser bar on my '96 velocity stem. Any suggestions on how much "bend" I can fit through the stem? Would I be able to fit a bar with 30mm rise for example?

Also: Do the shorter Velocity stems from around '96 turn up here on a regular basis or are they really hard to find? I think a 100mm Stem would be a better fit for me.

Best
M

 

[boxxer]

The way to do it back in the day was to take the face bolt out the stem, pop a penny in the slot and screw the bolt in from the back to lever open the stem to fit a riser bar….

 

[Mixi]

Hi! Thanks for your reply! Unfortunately this will not work with the alloy velocity stem as it has no threads. I think it could work by using an extra nut inserted into the slot.
Still I'm wondering how far I can open the clamp area and whether the bend of a 30mm riser could possibly fit.

 

[Mickeyspinn]

Me I personally wouldn't ever open up an alloy stem.... probably not want you want to hear!
If an alloy stem lands in my hands that looks like it's had this done or the screwdriver treatment it's in the bin! Teeth get expensive when there on the floor! Cromoly stem hmm ok not really the thing to do but 1-1.5mm would kinda spring back !
Stay safe! Find another way

 

[Mixi]

Thanks for your advice! I know that a lot of caution is needed when opening an alloy stem. My question really was: how much rise can i fit through the opening with minimal spreading / opening. Probably not a lot. I certainly would not use any kind of long lever but opening it by hand with moderate force 'should' not do any harm ... i guess ....

Anyways I might have found a better solution: bought a used stem with 100mm and 10 degress to replace the 125mm / 5 degree stem. That might do the trick. Although: What any of those components have experienced in the last 30 years is up to anyone's guess. In gerneral I assume it would be safer to steer clear of any used vintage components.....

 

[Mickeyspinn]

No worries chap,as for how much rise you can fit through ..hmm it's a piece of string! How bars are formed flared and butted varies tight curves are a bugger as would long drawn out curves!
Lots of grease....mount the stem on forks or better still in soft jaws of a vice and only move the bars,trying to move bars and stem at the same time will end up with marring and galling of either or both! It's give it a go time!
And yes when dealing with 30 year old parts that you don't know who else has had a go before you hmmm !

If you do decide to cough gently open them remember pi! A half mm tweak of diam gives over 3 times that on the circumference...again go the other route if you can! I only repeat because I see way too much of set diameters being messed with...when's it's out of round it'll never be a tru diameter again no amount of extra bolt torque fixes it! And theres no difference in being gentle whilst levering a 12" long screwdriver to the force a 6mm stem bolt can apply!
The classic fitting 26 mm bars in 25.4 clamp ooof it's only half a mm mate....er no it's a country mile
Be gentle be safe

 

[Mixi]

Thanks for sharing your advice! At this point I'm wondering: What does an alloy failure look like? Is sudden failure to be expected? Or will it bend before it breaks? I assume probably the former.
I recently bought a used '96 kona and thoroughly inspected all parts before I went for a ride. It's a lovely ride but I will certainly inspect it on a regular basis and I'll cetainly not take it to rougher terrain - I have other bikes for that. At the same time I see so many people commuting on bikes that are far older and have probably never seen any maintenance .... and yet most of them seem to hold up well.....
Better save than sorry - I'll see what I can do with that stem with no or minimal opening and report back.

 

[Mickeyspinn]

Often you can't see a crack or fracture! Or if you can it's thinner than a hairline until dirt gets in it.If the part is anodised you can sometimes see what looks like crazing....but it will be more than that! Anodising is like a micro thin exoskeleton, I avoid battered rubbed and scored lightweight stuff like that! Sometimes you'll hear a creak before it snaps but mostly just goes with a big crack followed by another crack and a ringing sound in your bonce!
My last alloy failure was a head tube ... thankfully it didn't part company and gingerly got me home!
The worst I've had is a BMX stem grenadeing and my solar plexus took the brunt of that...possibly as painful as being knuckledusted by Tyson.

Always look at the face bolt heads seat onto on stems if they're all mashed up that'll tell you lot about previous owner!


Again apologies if I've dampened your fire .... Theres too much put out on the internet for the uninitiated to read and follow ...
If you've got a hi tensile steel stem and matching bars fit em with a lump hammer be alright...thin wall,heat treated,textured stress relieved surfaces, race weight ,anodised ...gently as she blows!

 

[Mixi]

Thanks for sharing your knowledge. Kinda takes the fun away from it all though .... just kidding - I'm always curious to learn and you seem to know your stuff.

I generally avoid lightweight stuff ... even if it's modern and new. What about surface rubbing like on this stem. Thickness of the material is around 2-3mm.

 

[Mickeyspinn]

Haha! I must come across as grumpy ol git...
I can hear that stem ticking from here...run...it's gonna blow! Just kidding!!
Should be ok....I'll send you my disclaimer..