Car belt saves obsolete elliptical from landfill

About twenty years ago, I bought a cheap (~RM500) elliptical (cross-trainer) from Giant supermarket in Bayan Baru. The model is Trojan Strider.

Recently, its rubber belt broke. Unfortunately, there is no local representative for the Trojan brand. I can't use belts intended for other models because they have different length, width and number of ribs.

Elliptical viewed from the right. The broken belt is dangling from the crankarm

The original belt showing 4 ribs running along its length. 

So, the old elliptical appeared to be heading for the landfill. As the thought of scrapping so much steel pained me, I decided to gamble on substituting with an automotive belt. Bando brand of automotive belts come in 25 mm increment. So, there should be one belt that can fit the elliptical.

After experimenting with several lengths, I settled on Bando 3360 which measures 13 x 890 mm. The replacement differed from the original in two respects: 1. ribs that run across the width (as opposed to the original's lengthwise ribs) and 2. ~3x thicker.

Despite the differences, the substitution worked and the elliptical is back to functioning normally. So, the old machine gained a temporary respite from the landfill. 

Replacing Garmin FR70's broken wristband with NATO-style nylon strap

Garmin FR70's wristband is not detachable. So, when the wristband is broken, the watch has to be discarded  (see links below):
https://forums.garmin.com/forum/into-sports/running/running-archive/archived-forums/forerunner-50/5209-?4515-If-your-wrist-band-breaks-Garmin-says-just-go-buy-a-new-watch=
https://www.boards.ie/vbulletin/showthread.php?p=81344694

Garmin FR70 (top) and FR15 (bottom)

Garmin FR70 with broken wristband (top) and Nato watch strap (bottom)

Slip heatshrink tubes over the remnants of the original wristband. After shrinking the tubes, they can be further secured with black cable ties. Alternatively, attach the watch to the Nato strap with cable ties first, and then cover the cable ties and broken ends with heat-shrink tube afterward.

The idea of using a Nato strap to "rescue" a Garmin's broken wristband is not new. However, all the prior arts conveniently fed the Nato/velcro straps thru the remaining oblong holes.
http://www.eduardoramalho.com/2014/05/garmin-forerunner-110-band-replacement.html
https://www.mudandroutes.com/the-beasts-tip-of-the-week-repairing-a-garmin-110-watch-strap/
https://forums.garmin.com/filedata/fetch?id=1164991&d=1402255969


I didn't follow the prior arts because I predict the holes where the Nato straps are threaded thru will likely break in a short time.

Patching running shoes' outsole

Most distance runners do not wear out their shoes' outsoles evenly. Typically, the lateral heel-strike area is first to be worn through [1].

Shoe wear pattern where the lateral heel-strike area wore out first

When this occurs, the exposed midsole will wear down quickly due to its softness. The shoe will then gradually lose shock absorbency as the midsole continues to thin. While it is easy to glue a piece of abrasion-resistant rubber over the worn out area, the graft can shear off when subjected to running's landing impact. Below are steps to achieve a reliable patch.


1. Using a ballpoint pen / permanent marker, outline the area where the outsole has thinned noticeably (a larger surface will increase the patch's bond strength).

Worn out area is marked for patching (top) and would-be graft (bottom)

2. Cut the donor material to fit the marked graft site (see appendix for sources of graft donor).
3. Remove thinned outsole inside the marked area. A heat gun / hair-dryer can ease the removal.

After removal of the thinned area

4. Clean / abrade the surfaces to be joined (I use a brass wire brush).
5. Apply contact adhesive to both midsole and graft
6. Leave contact adhesive to dry for ~15 minutes. Bonding before the solvent has evaporated can lead to a weak bond.
7. Align donor outsole with the marked area and bring together
8. Fit a G-clamp over the graft site and tighten until the midsole is compressed to two-third of its original thickness. Although the adhesive's instruction recommends using a hand-roller / nip-roller  [2], we did not have a good result with this tool as the patches came off later. We suspect when neither midsole nor outsole surfaces are perfectly flat, they can separate slightly after rolling; hence, the unreliable patch. Clothes pegs have been used to clamp the graft [3], but we suspect the reliability will be poor due to the low force. Not enough pressure is a prime cause of bond failure [4].

After grafting, the shoe is then G-clamped to the table

 

Another way to clamp the graft to the shoe

9. Remove the clamp after 12 hours, preferably 24 hours.
 

Donor grafted to shoe 

Appendix: sources of graft donor

The graft donor can either be harvested from car's floor-mat or old running shoes. In the latter case, a heat source (hot air gun or hair dryer) can ease the removal of the outsole.  

This type of floor mat (car) is a suitable graft donor. The flat section is ~ 2mm thick.

 

An old shoe donates its outsole with the help of a hot air gun

If no suitable graft donor is at hand, one alternative is buy a sheet of 3mm thick abrasion-resistant rubber. The below example was sourced online. The advert specified a durometer hardness of 75A [5].

A durometer chart for quantifying hardness. Rubber is usually quantified with the "Shore A" scale

Up to now, we have only considered rubber as the graft material. However, polyurethane (PU) is actually even durable [6]. Unfortunately, we could not find any vendor that is willing to sell one piece and has a reasonable shipping charge.

Polyurethane makes the most durable outsole

Caution

If you hope to extend your shoe life through patching, be mindful of the finding that the midsole (foam) lose s half of its shock absorbency after 500 km [7].

References

[1] T. D. Noakes, Lore of running, 4th ed., pp. 763
[2] "Bostik contact bond",  ver. 5, Mar. 2017, Available: https://www.bostik.com/globalassets/tdsdocuments/bostik-contact-bond-tds_australia_en/technical-data-sheet/bostik_contact_bond_tds_01032017.pdf
[3] "How to fix a pair of old running shoes with contact adhesive". Available: https://almost-a-technocrat.blogspot.com/2015/01/how-to-fix-pair-of-old-running-shoes.html
[4] "15 Frequently Asked Questions About Contact Cement", Available: http://www.cpadhesives.com/contact-cement-faq

[5] https://www.ebay.com.my/itm/3mm-1-9-Thickness-6-152mm-Square-Rubber-Sheet-Chemical-Resistance-High-Temp-/391668455110?hash=item5b314256c6:g:ygEAAOSwnHZYbM2g
[6] "Polyurethanes in footwear", Available: http://www.polyurethanes.org/en/where-is-it/footwear
[7] R. Verdejo, N. J. Mills, "Heel-shoe interactions and the durability of EVA foam running-shoe midsoles", J. Biomechanics, 37 (2004) 1379-1386

Repair Garmin FR15 / 70's broken wristbands

Garmin FR15/70 wristbands are susceptible to breaking after a year or two of daily use. Clone FR15 wristbands are available from China sellers. However, shipping & custom clearance may take several weeks and so, an interim fix may be required, especially if one is a daily exerciser. As for FR70, the wristband is part of the watch body and therefore, is irreplaceable; so, hacking a solution is mandatory.

Material list: cyanoacrylate glue ("Superglue"), heat shrink tube (dia. 16mm), contact adhesive.

1. Clean the broken ends.
2. Apply cyanoacrylate glue to the ends and then bring them together.
3. Hold for ~60s while the glue hardens.

At this stage, the wristband has been rejoined, but the butt joint's small contact area is unable to withstand much tension load (pulling). To increase the joint's resistance to pulling, the joint area is enlarged in the subsequent steps to create a double lap joint.

Gluing the wristband's broken ends forms a butt joint. However, the joint's small contact area is unable to withstand much tension load (arrows)

Heat-shrink tube over the wristband approximates a stronger "double lap joint"

 
4. Cut a piece of heat-shrink tube with sufficient overlap to cover the break.
5. Clean the wristband surfaces that will be later covered by the heat-shrink tube.
6. Slip heat shrink tube over the wristband, but slightly away from the break.
7. Apply contact adhesive to the wristband' surfaces (contact adhesive allows the joint to flex).
8. Apply contact adhesive to the inside of the heat-shrink tube.
9. Leave contact adhesive to dry for ~15 minutes
10. Slide heat-shrink tube over the break.
11. Apply heat (e.g. hair dryer) to the heat-shrink tube.
12. Leave overnight for the bond to cure to full strength.

opening a stuck battery cover on the Polar Wearlink transmitter

The battery cover of a Polar Wearlink+ transmitter (T31) is intended to be opened by turning the slot with a suitably-sized coin. Considerable force is required to rotate the cover, but the cover is made of soft plastic and its shallow slot is easily sheared by the coin edge. After the slot is damaged, the coin will slip when turned. So far, I have already ruined two covers.

 Battery cover









 Polar Wearlink+ transmitter and soft-strap (textile electrode)






On a website lamenting about the same problem, a commenter suggested drilling two holes on the cover and using long-nose (needle-nose) pliers to turn the cover. However no detail is provided.

Here's my iteration of the aforementioned suggestion. First, I drilled two 1.5 mm blind holes on opposite sides of the cover. I chose the hole diameter to fit the tips of long-nose pliers that I own. To prevent water ingress, the holes are supposed to penetrate only part of the cover's thickness; i.e. blind holes. But the cover is only 2 mm thick and it is hard to control the depth of the drilling. Anyway, if by accident, a hole penetrates the cover completely, it can be plugged with silicone glue.

two 1.5 mm holes drilled into the top and bottom of the battery cover

More Mizunos with fragile uppers

Previously, I have blogged about the Mizuno's uppers being prone to tearing. The Mizuno Wave Impetus (photos below) has this problem too. Below are different coloured variants of the same model. The red shoe is in worse shape than the blue one because the former has been worn longer. Again there is still plenty of life left in the outsole despite the torn mesh.

An attempt to patch the hole. Sew a piece of cloth over the hole but can't tell how long will this hold up.

Mizuno Crusader 7, after +1 year

Unlike my other running shoes, this Mizuno Crusader 7 still has a lot of life left at the outsoles even though the uppers have long disintegrated. 

I wore this pair for more than a year until the gaping holes in the forefoot area forced me to retire them.

But the outsoles' heel-strike zones still have some life left in them!

New Balance W590V2's outsole peels off

New Balance W590V2's outsole peels off

 NB shoes have an issue with glue failure - see blog describing NB827 midsole separating from the upper.

After many years of staying away from NB, I took the plunge again thinking that they would have solved the glue issue. This W590V2 has been worn less than a dozen times when the outsole (light blue rubber) peeled off from the midsole. 

side view

"SF120731" This tongue label info indicates the date of manufacture?