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Trek Multitrack 750 Seat post size?

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Trek Multitrack 750 Seat post size?

Old 01-03-14, 03:17 AM
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Trek Multitrack 750 Seat post size?

Hey all, Paul here I have just got a Trek 750 frame, which came with no seatpost, can someone check theirs for me? Thanks
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Old 01-03-14, 08:53 AM
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I believe it is 26.6 but a cheap caliper is a better answer. Roger
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Old 01-03-14, 09:03 AM
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I don't have a caliper but I think my son's multitrack is a 750. if I remember I'd be happy to eyeball it with a standard ruler, if that would help. but then you can kinda do that with the frame ... there must be a Trek Spec web site out there, no?
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Old 01-03-14, 10:08 AM
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What year? Googling has suggested 27.2, but it wouldn't surprise me if earlier examples were narrower....
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Old 01-03-14, 10:35 AM
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I have a 1990 750 and it uses a 26.8 sp. Congrats on the find, pretty sweet frames. 90-93 the 750 used TT lugged steel. After 93 the frames were tigged so might have changed sp sizing.

Last edited by kaliayev; 01-03-14 at 10:44 AM.
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Old 01-03-14, 12:31 PM
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Surreal that site lists the seatpost for the earlier road bike from the 1970s called 750 not the newer 1990s hybrid 750s which this is. Roger
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Old 01-03-14, 03:39 PM
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Originally Posted by rhenning
I believe it is 26.6 but a cheap caliper is a better answer. Roger
+1

Seriously, OP, go to the big online auction house and invest $5 on a cheap caliper. You'll use it on all your oddball seat post, quill, spacer etc, questions.
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Old 01-03-14, 04:11 PM
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Personally I think the caliper idea is not very good. Unless the caliper is calibrated and you are very proficient at measuring inside diameters, being off by just .2mm means the difference in a sp working and not working. Best to go to your LBS if you are unsure and let them determine the sp size.
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Old 01-03-14, 06:33 PM
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For $10 your can buy a digital caliper from Harbor Freight (most of the time it is on sale for that) that will be accurate enough for your needs. It can be set for for both inches and metric measurement. I have high end calipers but use that one the most because I don't worry about breaking it
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Old 01-03-14, 06:43 PM
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I saw info on 750s' seatposts on a few sites, including this one. Google is awesome that way; buncha results. The 27.2 was for late 90s models...

Many shops have a tapered rod that they can insert into your frame to determine the size.

If the OP tells us the year, or hits up his LBS, we'll be closer to solving this, although even at this point, we can prolly narrow it down to 3 different sizes....
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Old 02-17-14, 08:18 PM
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The seatpost diameter varies from year to year for this trek model. 1991: 27.2; 1993: 26.8.

My advice, if you do not know the year of your bike, or you do know the year but not the diameter for that year, then you will need to use trial and error. Start with 27.2.
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Old 06-11-15, 06:07 PM
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Originally Posted by Bicycle Addict
Hey all, Paul here I have just got a Trek 750 frame, which came with no seatpost, can someone check theirs for me? Thanks
I'm sure by now you've already found the right seat post but if it helps anyone else, I found these pretty specs pretty detailed:
Trek, Fisher, Klein, Lemond bike catalogs, bicycle brochures
I recently came across a 1993 Trek Multitrack 720 with a wrong seat post size (using a dodgy shim), the manual/spec says it should be 26.8mm. Although I found that trying to fit a smaller 26.6mm was way too hard. The seat tube doesn't look too dirty or distorted but going to try to clean it out so see if that helps or just stick with whatever works I guess.
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Old 12-22-18, 03:04 PM
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On my 1995 Trek 750, the seatpost is 26.6mm diameter. Measured with two cheap vernier calipers.
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Old 12-22-18, 08:54 PM
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OP, the size are different throughout the years.

Originally Posted by kaliayev
I have a 1990 750 and it uses a 26.8 sp.
My 1990 520 (same frame as 750) uses a 26.8 seat post, I just purchased a new one for it.
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Old 12-23-18, 07:39 PM
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750 seat post dia.

That's interesting! I took my stock(?) post to Performance Bicycle yesterday, asked the ace repair guy if the 26.8 they had would work, he pointed out that the stocker has "26.6" stamped in it, and said, "Nope." (Note to self: Before comparing various caliper readings, look for size markings on the item itself.) .2-mm is such a tiny difference, had he not told me that I would have tried the 26.8 one. So I came home and ordered one.

Lesson: Remove your seatpost and look at it. There may well be a size stamped thereon.

I surely am going to miss the guys at Performance when they close; they have been gold for me, so much so that I've bought an ebike and a carbon fiber Gran Fondo in the last three months. PB's warranty and support, especially these guy at this one in Beaverton, Oregon, were of such excellence, I wanted to support them. So it goes. They really, really like the commuter I've built out of my 750, by the way.

Last edited by agiyo; 12-23-18 at 07:44 PM.
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Old 12-23-18, 10:13 PM
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hi, use a fabric measuring tape

Measure the circumfrence if possible, or use a thread to measure the opening, then measure the thread. I can use a caliper on my laye 80's early 90's 950. As above just divide the circumfrence by pu (3.14156 or so)
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