Earlier today I was puzzled by - of all things - cable ferrules (now sorted…). Here’s another: my bar stem, dating from the eighties, has a clamp dia of 25.5mm. The old bars clamp dia is exactly the same. The newish bars I thought I would use measure at 26mm - are these 2 different standards? Have things changed since 1987? If so, why on earth are they different by 0.5 of a mil? The upshot appears to be that the new bars won't readily fit in to the old stem…
(I tried a couple of searches but nothing helpful was revealed.)
Another puzzler - this time ‘bars
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simonineaston
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Another puzzler - this time ‘bars
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Re: Another puzzler - this time ‘bars
25.4mm is an inch, that's why it's been a standard. Of course those foreigners who refused to use our sensible measuring system came up with their own.
Last edited by PH on 21 Apr 2024, 7:40pm, edited 1 time in total.
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simonineaston
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Re: Another puzzler - this time ‘bars
My go to for all cycle confusion is Sheldon’s pages so I’d already seen that crib sheet - but I’m none the wiser. I said 26mm but its actually less than that - just.
- pesky bar clamp dia…
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Re: Another puzzler - this time ‘bars
25.8 and 26.0mm bars were commonplace back in the day. One size made by ITM the other by 3T. "Bloody Italians" Some manufacturers stated there stems were suitable for both sizes. This link sheds some light on the topic. Some riders squeezed their 25.8mm bars into 25.4 stems. 
viewtopic.php?t=25426#p201264
Oh and i squeezed my Cinelli LA84 bars (26.0mm) into a 25.4 clamp on the tandem for the stoker. I had to spread the stem clamp with a wedge to get the bars in.
viewtopic.php?t=25426#p201264
Oh and i squeezed my Cinelli LA84 bars (26.0mm) into a 25.4 clamp on the tandem for the stoker. I had to spread the stem clamp with a wedge to get the bars in.
Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X2, Raleigh 20 stowaway X2, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840, Giant Bowery, Apollo transition. 
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simonineaston
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Re: Another puzzler - this time ‘bars
That was a helpful read, rjb 
I'll make life easy for myself and just stick with the older bars. There's actually very little difference between them and the newer bars I was complaining about!
I'll make life easy for myself and just stick with the older bars. There's actually very little difference between them and the newer bars I was complaining about!S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Re: Another puzzler - this time ‘bars
Lots of brand new bars in 25.4mm, bars sourced from Nitto or Soma.simonineaston wrote: 21 Apr 2024, 8:58pm That was a helpful read, rjb
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Deutsche Luftschiffahrts-AG
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Deutsche Luftschiffahrts-AG
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rogerzilla
- Posts: 3160
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Re: Another puzzler - this time ‘bars
25.4mm is ISO. 26.0mm is really common for replacement road bars. 25.8mm was supposed to fit either, and doesn't, but you can get 25.8mm bars and stems which do fit each other. Cinelli used 26.4mm for years and Ambrosio dabbled in it too.
31.8mm is pretty standard on better new bikes.
31.8mm is pretty standard on better new bikes.