captainhastings
Guru
- Location
- West Wales
Seat post for old Specialized Rockhopper mountain bike
- Thread starter captainhastings
- Start date
Page may contain affiliate links. Please see terms for details.
Ajax Bay
Guru
- Location
- East Devon
Take out the seatpost and with luck (and a clean) you should find the diameter lightly engraved just below the minimum insertion marking: ||||||||||||||||||
34 is a fair way from 31.6. 34.9 is closest (making no recommendation). Has to be dead right. If no marking need to find someone with measuring calipers.
34 is a fair way from 31.6. 34.9 is closest (making no recommendation). Has to be dead right. If no marking need to find someone with measuring calipers.
Last edited:
Not really. Did you measure the internal or external diameter?
Sheldon gives a number of seat post sizes for Rockhoppers, but none of them are near to 34 mm.
If in doubt, take it to your LBS and ask them to measure it.
OP
OP
captainhastings
Guru
- Location
- West Wales
mmm yes there was no old seat post sadly. I used a tape and yes I did see the sheldon page
OP
OP
captainhastings
Guru
- Location
- West Wales
I thought allowing for my iffy measure a 31.6mm would be close enough. I will remeasure it
Ajax Bay
Guru
- Location
- East Devon
RichardB
Slightly retro
- Location
- West Wales
Absolutely. I bought a pair of these (dial, not digital) when I was making cabinets and they make measuring stuff so easy. Accurate to 0.02 mm. I still use them regularly (bike, car, round the house) and I don't know what I would do without them - apart from buy some new ones, obviously. They should be part of anyone's toolkit, and you can get a perfectly useable pair for less than the ones linked to above.
My seatpost - 25.4 mm. My handlebars - 25.4 mm. No guessing involved.
Pale Rider
Legendary Member
I have an old vernier gauge, trouble is I've forgotten how to read it.
Still handy, because once set I can offer it up to the new component.
Still handy, because once set I can offer it up to the new component.
Yellow Saddle
Guru
- Location
- Loch side.
Real men don't use digital. They read vernier scales. Up your game man.
OP
OP
captainhastings
Guru
- Location
- West Wales
RichardB
Slightly retro
- Location
- West Wales
Should have added - vernier calipers will measure inside as well as outside diameters.
S-Express
Guest
Yellow Saddle
Guru
- Location
- Loch side.
Measure twice, buy once.
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
You can get mechanical ones for about £10 from retail park builders' suppliers, they're usually good enough for bikes (you might sometimes be 0.2mm out) and - the biggest plus - they don't ever need calibrating.
Ajax Bay
Guru
- Location
- East Devon
My advice was directed at the OP, who sounds as if he needs it. Mine's a vernier. OT, I still miss my circular slide rule, which neatly fitted in my school jacket pocket while others had their 11+" long one sticking out of their bag. Both gave the same full 10" calculation distance.
I reiterate: you have to get the right one. Close enough won't do: closest seatpost diameter to 34mm is 34.9, but if it is 34.9: how about this seemingly expensive (alleged RRP £59) one (but @ 94% off) on CRC - Crank Brothers Cobalt 2 Straight Seatpost.
Better punt than e-bay. If you go to the CRC seatpost page and scroll down a bit, you'll see a list of all the diameters of seatpost they sell (to give yourself an idea of the size range and options).
Last edited:
