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Fat tire attempts on 70's Moto GR

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Fat tire attempts on 70's Moto GR

Old 05-04-21, 08:45 PM
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mcgregorj 
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Fat tire attempts on 70's Moto GR

I just got some 700c wheels from Velomine for my 70's Motobecane Grand Record, which came with 27" wheels. I've been hoping to get some wider tires than the 27x1-1/4" Panaracer Paselas that I was using. The Moto seems to have a good amount of space, including crimped chainstays in the back.

I have several WTB Nano 40 tires kicking around that I decided to try on a lark. I was using these on my Surly LHT until switching that over to WTB Riddler 45's. The Nanos were a super tight fit on the front - the center knobs rubbed the backing piece for the centerpull brakes. I trimmed the knobs and was able to get the wheel to spin, with maybe 2mm clearance - too tight. I borrowed a few other tires from friends this evening, here's what I've tried so far:

(1) WTB Nano 40 - untrimmed - 38mm wide - 0mm clearance
(2) WTB Nano 40 - trimmed - 38mm wide - 2 mm clearance
(3) Schwalbe Marathon Plus 38 - 36mm wide - 2 mm clearance (these must have a super-thick tread - so heavy!)
(4) Panaracer Gravelking SK 35 - 33.5mm wide - 8 mm clearance

These are all on Sun CR-18 rims. I took some photos - the four above are shown left to right, below. Here's the big question - what do I order for this bike? I'm wondering if a Gravelking slick or SS 38mm or Rene Herse Barlow Pass 38mm would fit (the Gravelking SK 35 fit with plenty of room and a knobbier profile) or if I'm stuck with 35's... (not the worst outcome, I suppose)

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Old 05-04-21, 09:07 PM
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nlerner
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I’ve had the Gravel King slick 38mm and the Barlow Pass 38mm tires on the same rims, and the PBs were several mm wider and taller. I switched to 35mm Bon Jon Pass tires and have been extreme happy with the ride.
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Old 05-04-21, 09:14 PM
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+1 on 35mm Bon Jon Pass tires. They work well even on relatively well maintained gravel roads with a bit of washboard. I've got them on two bikes.


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Old 05-05-21, 09:21 AM
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Thanks, nlerner and gugie. Sounds like the Rene Herse tires run very true to size. Probably will give the Bon Jon Pass a go and see what the Herse tire love is all about!
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Old 05-05-21, 10:08 AM
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my gravel 'becane project

I'm in the process of turning my '73 Motobecane Grand Record into a gravel bike. The paint has crackled on it so it's a fine platform for a rough stuff bike. It's 2 x 5 and I'm running a 50/34 nervar 631/633 crank and a 13-28 5 speed freewheel.

I'm running schwalbe marathon mondial 700 x 35c tires. The tires are plenty wide enough and there is sufficient clearance all the way around. They measure 35 mm and the tightest spot is along the seatstays as that is a bit narrower than under the front fork. I didn't do much research on the "right" gravel tire. These tires came to me as part of bunch of stuff I picked up in a package deal and they're fine tires. You aren't going to go wrong running schwalbe marathon mondials on rough roads. You can buy a pair of these for the same price as one Rene Herse Bon Jovi tire (less if you shop around) but they weigh right around 200 grams more per tire. Still the total weight of my Moto GR with these tires is 25 lbs which isn't bad.



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Old 05-05-21, 11:06 AM
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Nice, bikemig! I'm headed in an all-road direction with mine - you have to ride a lot of pavement to get to the gravel here in NJ! I swapped the 52/42 TA 3-arm crankset out for a 46/30 and have a IRD 5-speed 13-32 on the back with the longer SOMA cage on the Nuovo Record rear derailleur.
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Old 05-05-21, 10:06 PM
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Originally Posted by bikemig View Post

That crackled enamel paint is spot on!
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Old 05-06-21, 12:17 AM
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Originally Posted by gugie View Post
That crackled enamel paint is spot on!
And I thought only the YELLOW moto paint was prone to such "cracleur", apparently they were onto something in the Moto paint shop in the early '70s.My black/red mid '70s Moto GR shows no such tendencies in it's paint. They must have re-formulated.
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Old 05-06-21, 01:22 PM
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Hmm. I have a '72–'73 Le Champion, also black w/red, and no such craquelure. The paint seems rather thin, though, and it's got other advanced-beausage qualities.
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Old 05-06-21, 05:27 PM
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Originally Posted by gugie View Post
That crackled enamel paint is spot on!
Yeah I've thought once or twice about selling that bike because of the crackled paint. But honestly it's just perfect in an ugly duckling kind of way.
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Old 05-06-21, 06:27 PM
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I understand completely. I have a couple well-loved ugly ducklings. I was not casting any aspersions on craquelure vs anything else, in fact it looks appealing. It was simply an observation intended to give some more data.
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