Re: Patching TPU innertube

On Wed, 22 Jan 2025 09:51:38 -0600,
  AMuzi <am@yellowjersey.org> wrote:

 On 1/22/2025 8:49 AM, Ted Heise wrote:

I don't go out on the bike when it's below 30 F, or if there
is chance of icy patches.  Instead I ride a set of Kreittler
rollers in my garage (which has itself been damn could with
the recent sub zero outdoor temps).
 
Speaking of the rollers, I wanted some resistance when I got
them (25 years ago?) but wasn't that interested in the fan
options offered by Kreitler, So I cobbled the mag resistance
unit of my previous junky set of rollers onto the new ones.
 
Part of the flange on one side of the pulley on that unit has
broken off.  I glued it together, but it broke of again. 
This time I found a washer about the size of the outer side of
the flange, and glued it against the side of the pulley with
JB Weld.
 
Seems likely to be pretty durable, but I've been trying (with
no luck) to get a replacment from McMaster-Carr as a backup. 
It seems the shaft is a hair over 3/8" so the pulleys with
3/8" bore won't slide onto the shaft.  I tried drilling out
the bore hole, but don't have a drill press so the wider bore
wasn't perfectly straight (seems the pulley wobbles a bit when
turning).
 
Is there such a thing as 1 cm bore pulleys?  I'm not finding
anything that's clearly along those lines.
 
The next largest U.S. spec pulley is a 1/2" bore, which would
be too big.  I suppose I could look for tubing that would fill
the gap between the shaft and a 1/2" bore pulley, but that
seems like a long shot (and maybe hard to track down).
 
Any other ideas from the brain trust?

 The Minoura mag unit is the most prevalent so I'll assume it's
 that or rebranded Minoura. Just measured one and yes shaft is
 10mm.  Yes, 10mm shaft pulleys do exist, less common in USA.
 Here's the first result in a search for "10mm shaft V belt belt
 pulley"
 
 https://www.ebay.com/itm/166027767983?itmmeta=01JJ7AA3FF2XYFAEBFF678FJ8Y&hash=item26a806b0af:g:gzwAAOSwluNkNQ9L&itmprp=enc%3AAQAJAAAA4CodCO1vSDjg2xNOt8By6oBgR14HEvUANdveTIGUdj6NMd1fACLg%2BRCzbf6L91sTNHKYOrljqUaZp5RMRFVzGjGxIFKbuRpr5ZQfoefrhVRzDAUWxReRP8ijDHyQx4svlv7EkC11oUYDkfmelh7oipr6ABeXf%2FDo1NgxSfXecUuKQVumqPo%2Bt6L04aSVKHAX65q%2B7LF5DDnONpjOWBUpCWA4T218i19rkSnTeTojywjUWgAXPZwUQai609rJCciheafJjhAz3e542GwEEWQQMAJ3djLtjgh2f2FCQD%2FpEOaO%7Ctkp%3ABk9SR_S3qOqRZQ&var=465531361750
 
 Which is for a round band, same size as your Kreitler drive
 belt, not a V belt.

Very, very helpful, Andrew, thank you so much!

I think my old junkier rollers probably were Minoura, at least
that name rings a bell.

I had searched only on 1 cm bore, and kept getting mostly 1 inch
bore results.  10 mm makes more sense, as does eliding the space.

From the McMaster pulleys I tried (and sent back), I narrowed down
the pulley as being for a 3L type V belt.  Should have shared that
bit of info too.

 Poly bands are easily shortened and spliced if you have a worn
 spare handy. Light both ends and press together firmly. I have
 a section of Kreitler roller band on my sewing machine for
 example.

Ooh, also good to know.  I just replaced the Kreitler band a few
years ago when it broke.  Sounds as if I could have repaired it,
darn.  I really hate throwing stuff away.

 Most 10mm belt pulleys seem to be splined for notched belts:
 
 https://www.precisionwormgear.com/photo/pc21405533-aluminium_internal_and_external_splines_timing_belt_pulley_rohs_approved.jpg
 
 which are probably not helpful.

I'm having trouble pulling up that site, but yeah, most of what I
did find with metric bore was notched for timimg belts.

 Arbor adapters are common and cheap (we have a lot of those
 here) in myriad diameters but I could not find any between
 metric shaft and SAE bore in a quick search.

Ah, good to know the proper term.

 The simplest solution would have been a 10mm bit or reamer in a
 drill press. Too bad that didn't work out. The next would
 probably be another 3/8" shaft V pulley (cheap) and someone
 else's drill press.

Yeah, that makes sense.  My former employer (who I still consult
for) probably has a drill press.  The question will be whether
they would let me use it.  Think I will go this route.  I'm also a
bit pleased to know my idea wasn't wacky.

Thanks again for the help.  I was hoping you would respond.

--
Ted Heise      <theise@panix.com>       West Lafayette, IN, USA