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Motobecane profil 2 Fork Enquiry (sorry repost)

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Motobecane profil 2 Fork Enquiry (sorry repost)

Old 03-05-20, 04:41 PM
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wolololo34
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Motobecane profil 2 Fork Enquiry (sorry repost)

Hi,
I have rebuilt this 1980's motobecane profile 2 (see photos) with veloce components - it came with a mixture of non-original parts so no loss to any collectors out there. It rides really nicely, the lighter components and heavy steel frame make for a really balanced feel. I am 85kg, the bike is steel and aero so its hard going up hill and scary going down hill!

However, I am not too sure about the fork that the bike came with
1) it looks slightly gouged inside the steerer tube, no cracks but hmmm.. maybe a steerer was forced out
2) the stack height is 33mm, velo orange headsets are way to big.
3) the crown race is 27mm, velo orange is 26.5.

I bought the same motobecane fork off of fleabay for 10, it is also French (27mm and French threaded) but the steerer tube is huge, I could cut off the original threads and still have space.

I know most people say that you cannot re-thread a French steerer to iso.

But my capillars say that the tube is just a little over 1". So can I saw off the old threads and put iso threads on an untoched part of the steerer tube or is there something I am missing?
Maybe at some point motobecane used 1" steerer tubes on all their forks to make production easier?






Thanks in advanced for reading, replying and sorry for the bad photos.

sorry for the repost.
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Old 03-05-20, 09:39 PM
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There are more options then those from Velo Orange.

Sounds like the fork you bought isn't the same as it's got different specs.

If you do decide to try rethreading the "new" fork do so with the acceptance of ruining the fork, rethreading a fork can go bad often as most fork dies (almost a pun) are meant to chase/clean up existing threads and not to cut fresh ones. Besides that a French fork die is also likely to be fairly old and thus worn. I suppose you could have a fab shop/machinist single point threads on a lathe but that would likely turn out rather pricy

Steel steerers don't crack often. Bend, bulge, rust yes (although not what I would call often at that) but the only cracks I've seen on steel steerers are at the lock washer's flat or tab groove. Is that where you see the concerning issues?

It seems to me that working with the original fork would be the better path. Having the fork crown race cut to 26.5 is FAR less a job then cutting new threads. Tange offers their Passage headset that has a listed 30.3 stack height and is offered in both crown seat sizes so no crown seat cutting needed. Andy
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Old 03-06-20, 05:14 AM
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There are nicks right at the top of the tube where it meets the flat keyed part. way above the quill so I guess that's fine.
I think someone forced a cone quill stem out of the tube. There are lines that i can feel with my finger going up/down the tube on all sides about 5mm apart

The Tange headsets sound like a good idea, are they good quality?
I'm a little tired of getting half worn french parts.
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Old 03-06-20, 10:48 AM
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Tange makes headsets from what I would call "repair grade" to high end, although of the cup and cone bearing type. The Passage is the basic grade. Likely similar (or even a tad nicer) to the bike's current headset. When threaded headsets and "10 speed racers" were the only game this grade would be found on the (bike shop) entry level, to next step up bikes. As you go up the model line there will be points of cosmetic or mechanical improvements. But also the number of dimensional specs offerings will reduce down (as better headsets are usually thought of as going on more costly bikes which tend to follow a narrower range dimensional standards).

From your written descriptions I suspect the fork is not in doubt. But with no visual to add to the data we really can't definitely say much of anything about the fork. Andy
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