79pmooney

I picked up a Nitto Pearl 13 in good shape yesterday. Obvious scratches but in very good shape otherwise. It's a 25.4. I want to use it with 26.0 pista handlebars. So, what are your thoughts on the best way to enlarge the stem by hand or with simple power tools to enlarge the stem accurately enough to be fully usable and safe. (Sure, I could take it to a machine shop, but that would put it well past what I would pay for a new one.)

I know that reducing a 26.0 back to 25.4 can be done easily with a Coke can shim. Done it many times. So, if I do this right, I haven't ruined its use with the handlebars for which it was intended. And if I cannot do this, well it will just have to wait until I find a sweet 25.4 bar that needs a 140mm stem. (A Nitto Pearl 13 measures 130mm from the HB center to perpendicular to the steerer centerline and is almost exactly 140mm when measured traditionally. So, those Pearl 13s are really the only available production 140mm stem out there.)

So, ideas? I"m listening.

Ben

HillRider

Get a 7/8" dowel and wrap it in medium grit sandpaper, rough side out, and use it like a round file to enlarge the opening.

TimothyH

Get the right stem or a different bar.

Enlarging the hole with power tools or sandpaper will not be safe.

Do it right or don't do it at all.


-Tim-

Kontact 

While you'd only be removing .3mm, I also agree that it is a poor idea. You may end up with bar-fatiguing stress risers or the wrong final angle. The world is not running out of 26.0 stems or 25.4 bars - find a better mate for your stem.

wesmamyke

Never mind any safety issue. Having a bar stem combo that slips because it won't clamp right is possibly the most annoying thing in the world.

79pmooney

I guess this is the thinking that made America great. You have a bike part that could work if you removed 0.011" of material. Aluminum. On a part that weighs most of a pound. Nothing skimpy about it. Guy goes on the internet to ask about the best approach to go about this. Answer, phrased three different ways - "don't even think about it".

The out-of-roundness I measured on the bar was roughly half the material I am considering removing. Yes, the Nitto Pearl stem is precision made. But that precision doesn't carry over to the rest of the stems and handlebars that have been ridden quite successfully for generations.

Iride01 

Well you did add that word "safe" to your question.

Not sure about your math. (26.0 - 25.4)/2 doesn't equal .011".

OOOps that's me....... mm, inches.... my mistake.

Kontact 

Really? If you knew what you were doing well enough to simply remove that .011" of material, you would have done it by now. But you don't know what you're doing, so you asked - and then you don't like the answers.

I am certain a machinist could do this with no issues, as could many handy people. But those people aren't even going to ask.


And having asked, the advice your getting is not just that it isn't a great idea, but that there is no reason to bother when the world is full of alternatives that don't require bubba mods.

dabac

I’ve got a set of adjustable reamers that’ll do that kind of job very nicely.
Here’s an eBay link to the right kind but the wrong size:https://m.ebay.com/itm/High-Speed-St...QAAOSwTM5Y7awk
I’ve done that mod, and ridden the finished item several times.
Bad things have utterly failed to happen b/c of that.
YMMV though.

TimothyH

You asked. Next time don't ask questions if you are only prepared to hear agreeable answers.

If you have generations of experience with stems and handlebars then you should be able to figure out how to ream the hole and get it to work. Let us know.


-Tim-

fietsbob

find a Machine Shop, so reaming will not be leaving the bar 'cattywampus' ..

70sSanO

The dowell approach does work well. Just take your time. No one will vouch for safety. I did have a couple of mishaps, unfortunately I broke but the stem didn't... YMWV.

John

ThermionicScott 

I'm not sure if I should share how I did it, but I've also opened up a 25.4mm stem for a set of 26.0mm bars. Quite a few years later, I have no reason to suspect that either part will fail, and the bars are being held securely.

79pmooney

I knew full well these answers were coming. I even guessed correctly a couple of the poster. This is Bike Forums after all. My skin is plenty thick enough so it isn't an issue. I could figure out a method that would work. (I already knew about the sandpaper on dowel approach.) But I also guessed there were other approaches that might be either easier or more accurate.

Ben