Checking frame alig...
 

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[Closed] Checking frame alignment

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New frame, something’s out of line, but how do I narrow down what it is?

If I squint down the bike from the nadlebars to back, with the headset top cap bolt lined up with the toptube/seat tube junction, the seatpost and the tyre are not in line in a vertical plane. The difference at the saddle is between half a centimetre and a centimetre.

I’m satisfied it’s not the wheel or the tyre, I've seen the same difference in angle wherever the tyre is, and I’ve fitted and refitted the wheel a few times and the angle remains the same.

Options
1) It’s the dropper post
2) It’s the frame - seat tube
3) It’s the frame at the dropouts (difference somewhere along the stays)
4) It’s a mis-drilling/fitting of the nut/adapter that the thru axle threads into/or the adapter itself.

I can check 1) by buying/borrowing a solid post, but I don’t know about sorting out the others. I can set the bike in the stand and use a spirit level to check vertical/horizontal. If the seat tube is vertical and a level laid across the chainstays is horizontal, then I guess that means the issue is in the adapter or the drilling.

Bit of thinking aloud post, but any help/tips advice would be gratefully received.

Cheers!


 
Posted : 17/09/2019 8:58 am
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String. Start by looping from the dropout, over the head tube and back again. Measure the gaps between string and frame tubes. Might show something up.


 
Posted : 17/09/2019 9:06 am
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Is the wheel dished correctly? You've not switched from a non-boost to a boost frame, changed the end caps but not redished..?


 
Posted : 17/09/2019 9:10 am
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Cheers, Colin. I'll try that.

frogstomp, new wheels too. Hunts, correct spacing for frame.


 
Posted : 17/09/2019 9:13 am
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Check endcaps are in wheels right way round. Mine weren’t on Hunts.


 
Posted : 17/09/2019 9:14 am
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That would mean the whole wheel would be shifted over, wouldn't it? - still vertical when the seatpost is vertical, but offset to one side? That's not how it looks. shifting is find and disc is where it should be too.


 
Posted : 17/09/2019 9:25 am
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I'd start by flipping the wheel and seeing if the issue is present on the same side. Just to 100% rule out the wheel.


 
Posted : 17/09/2019 9:42 am
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I had something similar to this with one of my hardtails,the bike wouldn't ride in a straight line without leaning it over a bit(looked/felt like an old cut n shut crabbing along the road ).A long straight edge run right across rear and front wheels with bike upside down revealed they were out of alignment. Scotsroutes string method then showed the headtube to be off center.


 
Posted : 17/09/2019 9:47 am
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what did you do about it? back to the mfr?


 
Posted : 17/09/2019 9:50 am
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Yes Ned got a new frame-problem gone bikes great as it should of been.


 
Posted : 17/09/2019 9:56 am
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Is it an Orange...?  They told me having a seat post 5mm out of alignment was within tolerance.  Oh how I laughed!


 
Posted : 17/09/2019 10:50 am

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