Fixing a rack - steel or alloy bolts?

geebee2
geebee2 Posts: 248
edited September 2011 in Workshop
Hi

I'm fiitting a rack to my old bike to carry some panniers.

It's not ideal - the bike is an old Trek 2100, carbon tubes but with aluminium rear stays.

It has pre-drilled holes, but they are 4mm rather than 5mm ( which is the size of the bolts supplied with the rack ). I guess these holes were possibly intended for a mudguard rather than rack.

So I'm planning on using 4mm bolts, in fact bottle cage bolts seem to fit the bill.

My question is : should I use alloy or steel bolts?

Steel would be stronger, but could cause corrosion from using in aluminium holes.

The rack will only be fitted for a short time ( 3 days ).

Is there a risk of corrosion in this short time?

Will alloy bolts probably be strong enough anyway ( I'm a bit concerned they might shear off under the weight of a loaded pannier ).

Comments

  • loaded pannier- steel bolts.
    no corrosion in 3 days,
    use a wee bit of grease on the threads.
    stop worrying quite so much!

    I'd use alloy bolts on mudguards - I've got a few steel bolts stuck in frames on commuter bikes in the past. IT's a pain in the bahookey to drill them out
    Commute: Langster -Singlecross - Brompton S2-LX

    Road: 95 Trek 5500 -Look 695 Aerolight eTap - Boardman TTe eTap

    Offroad: Pace RC200 - Dawes Kickback 2 tandem - Tricross - Boardman CXR9.8 - Ridley x-fire
  • It's steel, surely it will survive three days... it's not a banana left skin-less in bad weather
    left the forum March 2023
  • MichaelW
    MichaelW Posts: 2,164
    My alu frame has had steel bolts for 3 years, no corrosion.
    Use stainless steel, greased, with a washer. You may need a serrated, anti-rotation washer.
    Alu bolts are for non-loadbearing applications; they will not support a rack.
  • Yossie
    Yossie Posts: 2,600
    Steel with copperslip.