Frequently Asked Questions
1. What’s a ‘hop-up kit’ and why should I buy them?
2. Are Titanium (Ti) bolts as strong as the steel ones they’re
replacing?
3. Are aluminum bolts as strong as steel?
4. Is ’galling’ a problem when using Ti?
5. How much weight can I save by installing Ti fasteners on my bike?
6. How can I figure out how much weight I'll save with my bike?
7. How do you measure and classify bolts?
1. What’s a ‘hop-up
kit’ and why should I buy them?
A hop-up kit is a set of bolts, nuts and
fasteners designed to replace the stock steel ones in a given component or accessory. They
are usually made of Ti with the occasional incorporation of aluminum. The point of the kit
is first to save weight off existing high end components. Even Dura-Ace, Record and XTR
have a lot of heavy steel bolts in them. SRP’s hop-up kits also greatly increase the
components corrosion resistance. People who ride in the mud or rain a lot or those who are
lucky enough to live by the ocean love this feature. And finally, our bolts are precision
machined, good looking and a pleasure to install and adjust. Call us weird or perverse,
but it just feels good sliding an allen key into a beautifully crafted part with tight
tolerances and a beautiful finish.
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2. Are Titanium (Ti) bolts as
strong as the steel ones they’re replacing?
For the most part, yes. Ti is as strong as
steel in sheer strength (twisting torque) so you can tighten it just as tight as you can
tighten a steel bolt. And due to its superior corrosion resistance, you actually get a net
gain in overall integrity when installing our Ti fasteners. Be careful, though, as Ti is a
little softer than steel so you can strip it just a bit easier. ALWAYS use a fresh Allen
key with no signs of rounding on the edges. Even an expensive ball-end allen key can round
off so always be sure to visually inspect the key before inserting it. And be careful and
make sure it is inserted all the way in before you apply torque on it. 99% of stripped
bolts are caused by either round allen keys or by shallow key insertion.
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3. Are aluminum bolts as
strong as steel?
No, they are not. That’s why in our
hop-up kits we spec aluminum only where strength is not a major issue. Chainring bolts,
water bottle bolts, rear derailleur hanger bolts etc. are fine in aluminum. But you would
not want a brake cable clamp bolt or center pivot bolt made out of aluminum. At the trade
shows you’ll see a couple of super-lightweight bikes decked out with all aluminum
hardware. Scary. These bikes are for hanging on scales and not to be ridden.
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4. Is ’galling’ a
problem when using Ti?
No, not if you use a metallic anti-seize
lubricant. Finish line makes stuff it calls ‘Ti prep’ that works great or you
can go to an auto supplies store and buy some in a big jar for a lot less money. Just put
on a thin coat--enough to lightly coat the threads--before installing any Ti screw and you
should be fine. And make sure not to cross thread the bolt when you get it started. If you
don’t have it in straight and torque down on it, it will pretty much weld itself into
place. That can be a real hassle.
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5. How much weight can I save
by installing Ti fasteners on my bike?
That depends on what kind of bike you have and
how thorough you are in replacing all the fasteners. On the average, you can shave between
1/4 and 1/2 a pound. With some full suspension mountain bikes, your savings could be even
higher.
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6. How can I figure out how
much weight I’ll save with my bike?
That depends. With many of our kits, we have
already calculated the savings. For example, a Dura-Ace full-hop up kit will save 92 grams
and an XTR brake kit will save 28 grams. But you might not be able to use the full hop-up
kit and we haven’t calculated the weight savings for all our kits for stems and seat
posts etc. So in that case, you can follow these simple rules of thumb: A Ti bolt weighs
about 1/2 what a steel one weighs and a aluminum bolt weighs about one 1/3. Pull the bolts
out, throw them on the scale, do the math and you’ll have a good estimate of your
actual weight savings.
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7.How do you measure and classify bolts?
Bolts are measured by shank diameter, thread pitch and shank length. They are classified by head
type. The 'shank' is the long, skinner part of the bolt. The bolt 'head' is where the allen key or wrench fits on. The shank is divided
into threads and 'grip'. The 'grip' is the non-threaded part up by the head. Shorter bolts will usually be threaded all the way to the head,
longer bolts will have some grip. The amount of grip varies and is most of the time irrelevant. The shank is measured first by it's "major
diameter" (hence the 'M' in the first part of a bolt description). Common sizes for bike fasteners are M5, M6, and M8. Next comes the
thread pitch which usually corresponds to the major diameter. M5 bolts usually have a .8 thread pitch, M6 bolts usually have a 1 thread pitch,
and M8 bolts usually have a 1.25 thread pitch. Finally, there is the overall
length of the shank. Measure grip plus thread but don't include the head. This will give you all the dimensions for a common bolt
type. For example, a "M6x1x15mm" would be a bolt with a 6mm major diameter, a thread pitch of 1 and a shank length of 15mm. Notice that
in none of this is there mention of the size allen key used to work on a bolt. That is NOT relevant to how you measure a bolt.
Then you need a head description. Common head types are as follows:
- Socket heads: a larger cylinder on top of the shank that you fit an allen key into. An example of a socket head bolt would be the ones that
you find on most stems or head set caps.
- Low-profile socket head screw. Just like a socket head, but with a shorter head. You'll find
these screws on the brake arches of Marzocchi and White Brothers forks.
- Tapered socket heads: a socket head that is cone-shaped and tapers in at the top where the allen key fits in. An example of a tapered
socket head bolt is a derailleur cable clamp bolt.
- Button heads or cap head screws: a bolt with softly curved head that resembles a
mushroom from the side. Example: water bottle bolts.
- Flat head screws: In profile, these would look like an inverted triangle on top
of the shank. They are designed to fit flush into a recess. Examples would be and SPD cleat bolt or the bolts that attached the brake arches
onto older Rock Shox forks.
- Finally, there are hex head bolts. Unlike all the types above, these are worked on using a wrench and not
an allen key. You don't see them on bikes much anymore with the possible exception of some crank arm bolts.
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