Which M6 Stem Cap Bolt Length Fits Your Stack?

Ever tightened a stem cap bolt and felt it bottom out before the cap sits flush? Or worse — the thread barely catches, and you're riding with a loose headset wondering if the front end will hold. The stock bolt that ships with most bikes is a one-size-fits-all compromise: it works for the factory build, but the moment you change stem height, add spacers, or swap to a different cap, that single length is either too long or too short.

That's the real problem: one length can't cover every setup. And the material — usually steel — adds unnecessary grams at the very top of the bike where every gram counts.

Four Lengths, One Purpose

TiNE Tech machines stem cap bolts in Grade 5 Ti-6Al-4V at four lengths so you pick the one that matches your stack height, not the other way around:

Each length adds roughly 0.4 g per 5 mm step — the titanium weight penalty is negligible even at the longest size. A stock steel bolt in the same M6 thread typically weighs 5-8 g depending on length, so the lightest TiNE option saves around 60 % compared to steel.

Steel vs Titanium: More Than a Weight Number

Weight is the obvious reason to switch, but there are two practical issues steel bolts create that titanium solves:

That corrosion point matters more than most riders think. A steel bolt threaded into an aluminum steerer tube is a galvanic corrosion recipe — after a season of wet rides, that bolt can seize so badly it strips the star nut or expander when you try to remove it. Titanium is chemically inert against aluminum, so it backs out cleanly even after years.

Which Length Do You Need?

Measure your current bolt's thread length (not the head) with a ruler or caliper. If it protrudes past the cap when fully seated, go one step shorter. If it barely catches, go one step longer. The 30 mm length covers the majority of road bikes with 1-2 spacers under the stem.

Color That Matches Your Build

TiNE anodizes these bolts in eight colors — gold, blue, rainbow, silver, black, pink, green, and purple. The anodized layer is a surface oxide, not paint, so it won't chip or fade. It's a small detail, but on a bike where every visible fastener is either black or silver, a single gold or rainbow bolt at the stem cap can tie the whole cockpit together.

The Verdict

If your stem cap bolt is either bottoming out or barely catching, the fix isn't to force it — it's to get the right length. TiNE's four-size range in titanium means you can match the bolt to your stack, cut weight, and pick a color that fits your bike. At 2.0-3.3 g each, the weight savings alone justify the swap; the corrosion resistance and color options are the real bonus.