Ride_Fast

Would there be a problem if an alloy steerer tube is cut 5-6mm below the stem? The tube was cut right below the top stem bolt. I’ve been riding like this for over a year and nothing has happened. I bought a road bike with a full carbon fork that has the same issue and I got into a collision accident where the front wheel was toast and nothing happened to the fork. So what do you guys think? My thought was that the stem would loosen over time.

Amt0571

If the fork steerer is made of carbon, it should protrude slightly over the top of the stem and a spacer should be placed there. Otherwise it can crack. And you don't want your steerer to crack when riding.

If the steerer is alloy, it can be cut slightly shorter than the stem, but I think that 5 or 6mm is a bit excessive. Nothing bad should happen though.

shelbyfv

No, it should not be below the stem bolt.

KenCarlson

If that was my bike I'd take out a 5 mm spacer below the stem. Better to have the bars a little lower than I'd prefer rather than risking a not-completely clamped stem. If it's currently 5 mm short and you take out a 5 mm spacer, then that would leave the top of the steerer flush with the top of the stem, so you would need to take off another mm or two from the steerer to guarantee the top cap can seat properly.

-Ken

mack_turtle

5–6mm sounds too short. use a stem with less stack or use a shorter stack of spacers under the stem. if you effectively remove 3mm of spacers from under the stem, it won't kill you. I doubt you'll notice the fitting of the bike at all. you will, however, notice the effect of your fork suddenly breaking on you.

https://www.parktool.com/blog/repair...icle-section-3

Ride_Fast

You think it will break a fork with an alloy steerer?

icemilkcoffee 

What kind of bike is this? You can buy carbon forks from Craigslist and Ebay all day long. Why on earth would you do something goofy with the stem instead of just buying a fork with the proper length?

mack_turtle

Do you want to find out the hard way?

it probably won't cause the fork to just snap off, but the stem is only clamped with one bolt at that point, so it could shift or tilt off. having your stem firmly attached to your fork is vital.

Ride_Fast

All 3 of my bikes are like this(2 track bikes and 1 road bike). The space is either the same length of the top stem bolt, or below it. I’m actually more concerned about my road bike because it has a full carbon fork but like I said, I was in an accident and nothing happened to the steerer or the fork

I don’t understand how that would cause a fork to snap but the good news is I have options. I could switch out the headset washer for a shorter one then put a spacer on top, or I can keep the stem slammed and put a 3mm spacer on top of it and that way the stem is fully clamped. The third option is to install compression plug that gives the steerer an additional 3mm of clamping surface. They advice the second option on full carbon forks, but you guys can tell me what you think.

Amt0571

I already said that I think that 5 or 6mm below the stem seems excessive. Both bolts should secure the stem to the steerer. Probably nothing bad will happen if the steerer is made from metal though, but are you willing to find out anyway?

On a carbon steerer, having it cut below the stem by any amount is a NO. It should be cut slightly above the stem and a spacer placed there. If it's not this way, your steerer will eventually break, and it will be nasty. That you have been involved in a crash and nothing has happened doesn't mean it won't happen in the future. And BTW, with a carbon steerer you should use a compression plug instead of a star nut for the same reasons.

In any case, steerer tubes breaking or stems coming loose are not jokes. You can get seriously injured or killed if that happens.

shelbyfv

Yep, there are enough other ways to get hurt on a bike. You don't need to add something known to be wrong.

mack_turtle

I can't help but point out one exception to this: Cannondale. This confuses a lot of people and I've seen bikes come out of Cannondale dealers with the stem and headset installed incorrectly. See page 97 of their owner's manual.

I think this is because of the way their SI compression plug is designed. it supports the head tube enough that clamping the stem anywhere lower than right at the top would result in clamping the stem on an unsupported part of the fork.