Building Bicycle Wheels

Assembly

Assembly

• gather parts, tools, supplies
• lubricate nipples and/or spoke threads
• lace
• iteratively
  • tension
  • true — laterally and radially
  • stress relieve
• stop when stress relieving makes the wheel lose true

Lacing

• rims often have alternating (zig-zag) spoke holes
• spoke goes to nearest hole
  • worse bracing angle
  • no bend/stress at end of spoke
  • a few rims: spoke goes to farthest hole
• note also zig-zag asymmetry
  • is the first hole forward of the valve hole to the left or the right?
  • spoke nearest valve stem might be from left or right flange
• radial lacing: easy
• cross lacing: get parallel pairs of spokes around valve hole
• avoid "V" of spokes making it hard to get pump on and off
• actually four spokes approximately parallel
• study existing wheels

Lacing process

• insert spoke nearest valve hole if head-out
• or one further if first is head-in
  • start with head-out as they are the hardest to lace
  • especially once head-in spokes are in place
• screw nipple on 1-2 turns
  • leave loose for now, makes lacing easier
• put in every other spoke that flange
• every 4th hole at rim
• examine the wheel
  • every 2nd hole at flange
  • every 4th hole at rim
  • check now, save the trouble of unlacing later
• every other head-out on other flange
• note spoke flanges are slightly rotated
  • e.g., 1/36th turn for 18-hole flanges
• make sure spokes have same relative position at rim and at hub
  • else will twist and ruin center spool of hub
• good time to examine the wheel again
• next: head-in spokes
  • interlace with existing spokes
  • first usually not interlaced (unless 1-cross wheels)
  • weave rest of crosses
• interlacing: bend the spoke along its whole length when interlacing
  • avoid sharp bends
  • bend enough to avoid scratching the rim
  • may take a slight curve — that is okay
• keep checking as you go

Tensioning

• put in truing stand
• screw all nipples on until 1st thread disappears
• wheel will still be a little rattly
• start tightening in big steps (e.g., 1 turn per nipple)
• until spokes starts getting tension
• wheel should be roughly true, spoke tensions roughly equal
• common

Iterate

• true radial
• true lateral
• stress relieve
• increase tension

No need to be very true at first

• radial approx 2mm, lateral approx 4mm
• the tighter the wheel the closer the tolerances
• eventual goal about the thickness of a piece of paper

True radial

• tighten stand's radial adjustment until scrapes
• if bulges out → tighten one or more spokes
• if bowed in → skip
  • will "catch up" by tightening other spokes
  • at higher tensions, may want to loosen some
• notice if bulge is big (4+ spokes) or small (1-2 spokes)
  • big: variation in spoke tension
  • small: minor kink in rim
• can tighten several nipples at once
• small steps and patience
  • maybe 1/4 turn per nipple
  • "sneak up on it"
  • more experience: can tighten more at once
  • but is easy to overdo it
    • tension gets unbalanced
    • further tensioning makes wheel less true
  • so for now go slow

True lateral

• tighten lateral adjustment until scrapes
• if bulges to left, tighten spokes on right
• if bulges right, tighten on left
• at higher tensions, may want to loosen some spokes
• notice that lateral truing will affect spoke tension thus radial true
• that's okay
  • small steps and "sneak up on it"
  • fix lateral next iteration
• can reduce lateral ↔ radial effect
  • tighten one spoke and loosen neighbor
  • both radial and lateral truing
  • but at low tension just skip anything that "needs loosening"

Lateral offset

• want rim centered in dropout
• measure offset with dishing tool
• or fake it by flipping wheel
  • if rim moves left on flip, then re-center to the right
• fix dish by tightening all the nipples on one side
  • every other nipple
• at higher tension, may want to loosen

Stress relieve

• at elbow and at threads there are internal stresses from manufacture
• then we add stresses by tensioning the spoke
• "overload" the spoke slightly — yields (stretches) permanently
• but "slightly" so only the highest-tension parts
• transfers some load to lower-tension parts
• more even load across the spoke section → better service life
• how overload?
  • grab pairs of "parallel" spokes
  • both sides of wheel (4 spokes total)
  • squeeze hard
  • wear gloves so you can squeeze hard!
  • wear eye protection so if a spoke pops you don't get as seriously hurt

Stress relieving and maximum rim compression

• there is about a ton of compressive force in the rim
• at high tension, segments between spokes want to buckle sideways
• slight overload
  • causes slight buckling
  • causes slight loss of wheel true
  • tells you: you have reached maximum tension
  • no need for a tensiometer
• beware for some rims: spoke bed damage before max compressive load
  • especially low spoke-count or low-weight rims
• so check for recommended tension from manufacturer
• most wheels: spokes tight enough stress relieving hurts your bare hand
• dished wheels have higher tension on "flat" side

Stress relieving myth and lore

• mysterious practices
  • bend rim in drawer
  • twist spoke pairs with a wrench handle between them
• misunderstanding of goals
• sharp objects may damage spokes

Iteration

• if wheel is as true after stress relieving
• increase tension
  • 1 turn if spokes "pretty loose"
  • 1/4 turn if spokes "pretty tight"
• if wheel loses true after stress relieving
  • rim is near collapse
  • back of tension slightly
• note that overall spoke tension does not rise in normal use
• so wheel can safely run fairly close to maximum tension

Final truing

• radial: much truer than road surface is good enough
• lateral: avoid brake pad rub
• rims are imperfect, and spokes are discrete
  • hard to get steller precision
  • but stellar precision is irrelevant
• roughly: the thickness of one or a few pieces of paper