35.8mm seat post clamps?

MartinYorkshire

Retro Guru
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Evening all,

Does anyone happen to know if 35.8 is anything close to a regular size for an MTB seat post clamp? My sons QR clamp is marked 35, but the outside diameter of the frame at the seatpost tube is 35.8 on my calipers. It seems to be a very odd size.

Could I get away with a hope clamp in 36.4 or am I looking for a more specialist item?

His frame is aluminium.

As always, your collective wisdom is much appreciated.

Thanks
 

velomaniac

MacRetro Rider
Not that I question your calipers but a 35.4mm clamp size exists, 35.8 does seem unusual. My solution would be to use shims to bodge the difference between the next clamp up. Other than your Hope clamp, next clamp up tends to be folding bikes like Dahon or Tern.
 

MartinYorkshire

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velomaniac":106wv3y6 said:
Not that I question your calipers but a 35.4mm clamp size exists, 35.8 does seem unusual. My solution would be to use shims to bodge the difference between the next clamp up. Other than your Hope clamp, next clamp up tends to be folding bikes like Dahon or Tern.

Thanks for the reply and suggestion. Shimming with a coke can takes me back to the days of USE seat posts, pile of crap that they were (even if looking great).

I sent an email to Marin tech about this and they said the correct size is 35mm which is what is stamped on the OEM QR. The odd thing is, when I measured the frame, its coming up 35.8 on the calipers (mitutoyo's). They are (were..) calibrated, so I'm a little bit stuck, unless they have fallen out of calibration. Marin put it down to thick paint, but I measured the frame after removing the OEM clamp, so its where its sitting rather than including any paint thickness.

All a bit odd.

I will find out in a few days because I've ordered a Hope QR in 34.9 which if its truly 35mm, should fit and I need to take a close look at the calipers!
 

MartinYorkshire

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Close look at calipers needed. The 34.9mm hope QR seat clamp fits the Marin San Quentin 24, but only just.

(written out in full for the benefit of future Googlers)
 
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