Ishiwata exo magny quadruple
08-17-20, 04:16 AM
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Ishiwata exo magny quadruple
Can anyone give some advise if its worth buying a classic bike with ISHIWATA EXO MAGNY QUADRUPLE BUTTED FRAME. There's this ITOI handmade lugged frame being sold to me and it has a decal PRIVATE 1101. Cant seem to find any reference on the bike, but it has a decent well preserved lugs and dropouts. seat tube is in VG condition. I wish i can post pics already 
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08-17-20, 05:55 AM
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If it helps put things in perspective, the low end Fuji racing bike I bought in the late '80s for around $400 (Shimano low end parts, SR steel handlebars, etc) frame was Ishiwata Quad butted
08-17-20, 06:09 AM
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I'm wondering if ITOI is actually ITOH, the Japanese trading company aligned with Bridgestone? Regardless, EXO was a series of seamed, quad butted tubesets developed by Ishiwata in the mid 1980s. The Magny (carbon-manganese alloy) version was the lowest of these tubesets and had a claimed weight of 2.4 kg. It was typically found on upper, entry level models.
08-17-20, 08:13 PM
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I'm wondering if ITOI is actually ITOH, the Japanese trading company aligned with Bridgestone? Regardless, EXO was a series of seamed, quad butted tubesets developed by Ishiwata in the mid 1980s. The Magny (carbon-manganese alloy) version was the lowest of these tubesets and had a claimed weight of 2.4 kg. It was typically found on upper, entry level models.
08-17-20, 08:17 PM
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I'm wondering if ITOI is actually ITOH, the Japanese trading company aligned with Bridgestone? Regardless, EXO was a series of seamed, quad butted tubesets developed by Ishiwata in the mid 1980s. The Magny (carbon-manganese alloy) version was the lowest of these tubesets and had a claimed weight of 2.4 kg. It was typically found on upper, entry level models.
ibb.co/v1JRXSg
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Ibb.co/z8JCRYn
Ibb.co/1nLDSw3
08-18-20, 09:47 AM
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Ishiwata had three EXO CrMO tubesets, weighing from a claimed 1.95 kg to 2.14 kg. Ishiwata never published the strength specs for their alloys but it's not unreasonable to expect they were similar to the offerings from other Japanese manufacturers, in which case, CrMo is only ~5% stronger after brazing. The extra weight Magny comes from slightly thicker tubes which, in most cases, more than compensates for the reduced strength, resulting in lower stress and greater durability. Of course, that is all theoretical, as the greatest impact on durability comes from the skill of the person doing the brazing.
08-21-20, 07:03 PM
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Ishiwata had three EXO CrMO tubesets, weighing from a claimed 1.95 kg to 2.14 kg. Ishiwata never published the strength specs for their alloys but it's not unreasonable to expect they were similar to the offerings from other Japanese manufacturers, in which case, CrMo is only ~5% stronger after brazing. The extra weight Magny comes from slightly thicker tubes which, in most cases, more than compensates for the reduced strength, resulting in lower stress and greater durability. Of course, that is all theoretical, as the greatest impact on durability comes from the skill of the person doing the brazing.
08-22-20, 12:53 PM
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quadruple butting was a marketing term made up by Ishiwata. it just means that the ends of the tubes
are stepped twice. usually resulting in being more heavy. but it sounded good in ads: 4 butts has to be better than 2 right?
are stepped twice. usually resulting in being more heavy. but it sounded good in ads: 4 butts has to be better than 2 right?
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08-23-20, 03:14 AM
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Thanks for this, i also saw one thread on mangaloy frames here and its a ton of info. Thanks
08-23-20, 03:20 AM
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Ishiwata had three EXO CrMO tubesets, weighing from a claimed 1.95 kg to 2.14 kg. Ishiwata never published the strength specs for their alloys but it's not unreasonable to expect they were similar to the offerings from other Japanese manufacturers, in which case, CrMo is only ~5% stronger after brazing. The extra weight Magny comes from slightly thicker tubes which, in most cases, more than compensates for the reduced strength, resulting in lower stress and greater durability. Of course, that is all theoretical, as the greatest impact on durability comes from the skill of the person doing the brazing.
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08-23-20, 10:42 AM
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Generally, the bicycle has to be something special to warrant chroming in the USA. It's become very expensive, due to the hand labour (polishing) and environmental concerns. Hopefully, it's still reasonable in the Philippines.
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08-23-20, 07:24 PM
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Yes, Magny can be chrome plated. It is just a different alloy of steel.
Generally, the bicycle has to be something special to warrant chroming in the USA. It's become very expensive, due to the hand labour (polishing) and environmental concerns. Hopefully, it's still reasonable in the Philippines.
Generally, the bicycle has to be something special to warrant chroming in the USA. It's become very expensive, due to the hand labour (polishing) and environmental concerns. Hopefully, it's still reasonable in the Philippines.
08-24-20, 07:22 AM
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For instance, an Ishiwata 022 downtube uses 0.9mm butts at both ends with a 0.6mm centre section. EXO-M, which was the quadruple butted version of 022, had 0.9mm butts and the centre section started at 0.6mm adjacent to the butts but gradually tapered down to 0.5mm, resulting in a lighter tube than 022.
Here's a cross section for an Ishiwata quadruple butted down tube from an Ishiwata catalogue. For EXO-M, T1 & T4 = 0.9mm, T2 = 0,6mm and T3 =0.5mm. Since T1,T2 and T4 are the same as for an 022 down tube, which has no thinner T3, the EXO-M down tube is lighter than the comparable 022 down tube. An EXO-M tubeset was 60g lighter than 022.
Quadruple butting operated of the premise that stress is gradually dispersed along the length of the tube, the further you get from joints. Optimally, the centre section of the tube should be progressively thinned. The one flaw in this argument is that torsional stress actually increases at the centre of the tube. Torsion results in twisting and subsequent misalignment between the front and back ends of the frame. In excessive amounts, this can lead to handling issues.
It should noted that only the down tube had the double tapers. The seat and top tubes used a single progressive taper.
Last edited by T-Mar; 08-24-20 at 07:27 AM.
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