Mongrel MTB build - major headset headache!!

SherifH

Evening all!

Some help solving a headset conundrum would be appreciated.
Currently building a new xc bike out of a frankly ill fitting kit of parts, including a quite rare Decathlon Rockrider 8XC frame I have recently acquired (bear in mind there is literally zero info on the original bike online anywhere).
Needed to order a new headset to fit my forks, and having taken all the necessary measurements and consulted the Nukeproof and HOPE guides, opted for the integrated IS41 HOPE headset top and bottom, but having tried to fit it today, it is a micron out - I guess integrated headsets should just drop in place but this doesn't - looks like it would need to be pressed in almost, which leads me to believe it isn't an integrated headset I need, but no other standards appear to fit!
Photos below FYI - would appreciate any help for a baffled bike building beginner!

The Rookie

Looks like it's ZS44 to me, what is the measurement of the internal diameter?

I thought the 8XC was carbon, that looks like aluminium!

SherifH

The Rookie wrote:

Looks like it's ZS44 to me, what is the measurement of the internal diameter?

I thought the 8XC was carbon, that looks like aluminium!

Internal diameter is approx. 39/40mm. External diameter is 45mm
There was also an aluminium special edition built back in 2009 I believe - the frame is pretty light compared to what I have been chugging along on - just 1.8kg in an XL frame!

The Rookie

You'll need better accuracy than that, then look here
http://www.parktool.com/blog/repair-hel ... -section-5

SherifH

The Rookie wrote:

You'll need better accuracy than that, then look here
http://www.parktool.com/blog/repair-hel ... -section-5

It does indeed look like the headtube is designed for an integral, rather than integrated headset. My only issue here is still with the dims.

All of the guides state an internal diameter of 43.95 - 44.10mm to accept the cups for this type of headset. I've measured a hundred times over now, and whilst the external diameter of the tube is within this range (just over 44m), the internal diameter is very definitely just under 40mm. Baffling (for my simple beginner mind anyhow).

The Rookie

External diameter is completely irrelevant, for example a carbon frame would have thicker material for the same headset bore.

SherifH

The Rookie wrote:

External diameter is completely irrelevant, for example a carbon frame would have thicker material for the same headset bore.

I appreciate that it is indeed the case, however that doesn't detract from the fact I appear to have a 40mm internal diameter which doesn't seem to correlate to any standard headset. This surely can't be right?

The integral headset looks the closest bet, but with it quoted at either 34 or 44mm, surely this isn't going to work.

The Rookie

Well it can only be IS41 or IS42 of that list.

supersonic

Have you got any more pics of the frame as a whole?

SherifH

supersonic wrote:

Have you got any more pics of the frame as a whole?

Sure...hopefully the below helps?

JBA

That's a 2009 8XC. There is a basic list HERE.
Not much help with headset sorry, but gives you an idea of how the bike originally looked.

The Rookie

https://www.google.co.uk/search?q=2009+ ... 7zKlUvtImM:
Enlarge the top photo and it clearly shows external cups.

SherifH

The Rookie wrote:

https://www.google.co.uk/search?q=2009+rockrider+8xc&rlz=1C9BKJA_enIN603IN603&hl=en-GB&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjm6tKrsvPRAhUDJ8AKHRPIC-8Q_AUICCgC&biw=1024&bih=653#imgrc=ZStM7zKlUvtImM:
Enlarge the top photo and it clearly shows external cups.

Apologies for being thick (I am still learning about this bike building fun and games), but the manufacturers' dims and the variances are what is confusing me here.

Internal diameter is obviously the key dimension, yet the one headset I have found that appears to work is an FSA Intellaset Pro, which quotes outside diameters! Doesn't appear to be consistency at all, so for a newbie it is pretty mind-boggling!

The below is now what I suspect will fit based on measurements taken. This is the only technical spec from any manufacturer I have seen thus far which quotes that all important 40mm internal diameter....this is what I can't understand.

The Rookie

Perhaps it's indicating the minimum OD for the bearing to be stable, I don't know but as you say you have the ID there and its an external cup as per that link.