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Tight tires, grind down tight rim to decrease diameter?

Old 12-02-19, 06:58 PM
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Snikerdoodlz
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Tight tires, grind down tight rim to decrease diameter?

My ebike motor's rim is an absolute pain to mount tires on. I know that it's a problem with the rim itself since I've put my exact same tires on another rim with much less effort. Potential DIY defects aside, Is it feasible to grind down my rim to decrease its diameter? I'd rather not spend money on a new rim and service to re-lace my motor.

Edit: The rim in question is the Sun Ringle Rhyno Lite 26x2.00 with 36 holes.
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Old 12-02-19, 07:09 PM
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could try a different tire? you should never modify a rim to that degree especially on a bike you are potentially commuting on.
also if the tire is as tight as you say i would recommend getting help from your LBS.
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Old 12-02-19, 07:14 PM
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Old 12-02-19, 07:17 PM
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Originally Posted by Snikerdoodlz View Post
My ebike motor's rim is an absolute pain to mount tires on. I know that it's a problem with the rim itself since I've put my exact same tires on another rim with much less effort. Potential DIY defects aside, Is it feasible to grind down my rim to decrease its diameter? I'd rather not spend money on a new rim and service to re-lace my motor.

Edit: The rim in question is the Sun Ringle Rhyno Lite 26x2.00 with 36 holes.
no, you can't shave your rim.
Although the center channel of the Rhyno Lite is very shallow, try squeezing the beads together and press them as deep as possible into the center channel on one side of the tire, and then use a tire lever to pry out the tire the opposite side (180 degrees). Once you get a tire lever to pop a small section of a bead out, use a second tire lever to run around the rest of the rim. A rim with a deeper center channel would be easier for removing tires.
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Old 12-02-19, 07:32 PM
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Since this is an ebike and weight isn't a big factor, carry a KoolStop Tire Jack and three really good tire levers with you. Together, they will remove and remount nearly anything.
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Old 12-02-19, 07:33 PM
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Get a tire jack. https://www.jensonusa.com/Kool-Stop-...ck-With-Handle
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Old 12-02-19, 07:37 PM
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If your rim has a thick cloth tape such as Velox, you could try a thinner tape such as Continental Easy Tape or a layer of filament-reinforced packing tape or Kapton tape. The thinner tape should make tire mounting easier by allowing you to get the bead deeper into the center of the rim channel.

Last edited by dsbrantjr; 12-02-19 at 07:46 PM.
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Old 12-02-19, 08:50 PM
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...along with that bead jack (which is an essential tool for the price), using liquid soap or even talc as a lubricant between the tyre and rim surfaces as you finish that final arc in mounting the tyre helps a great deal more than you might suppose.
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Old 12-03-19, 01:21 PM
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Originally Posted by tomtomtom123 View Post
no, you can't shave your rim.
tomtomtom123 is correct. First, the rim mfr did some weight optimization vs strength. Removing metal arbitrarily is going to give you weak rims. On an ebike? Nein danke.

Second, there is no way to do the grinding with sufficient precision, without removing the rim and mounting it on a lathe face plate. Precision metal cutting requires tools and jigs and fixtures that are exceptionally rigid and a spoked bike wheel doesn't qualify.

So, I suspect that you'd end up with an aesthetically unsatisfactory wheel with really uneven grinding marks that would break prematurely.

read tomtomtom123's post: make sure that the wheel beads are in the center well of the rim when you mount the things. I had huge problems with my tires and rims until I remembered this.

Last edited by WizardOfBoz; 12-03-19 at 01:42 PM.
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Old 12-03-19, 01:58 PM
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These rims (like CR18) are known for having tall sidewalls. A slightly larger OD is one way a rim manufacturer can try to prevent blowoffs without increasing cost, but it leaves much to be desired. Rather than grinding down the rim, thinner rim tape and better technique should do the job.
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Old 12-03-19, 03:06 PM
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Originally Posted by dsbrantjr View Post
If your rim has a thick cloth tape such as Velox, you could try a thinner tape such as Continental Easy Tape or a layer of filament-reinforced packing tape or Kapton tape. The thinner tape should make tire mounting easier by allowing you to get the bead deeper into the center of the rim channel.
tesa 4289 packing tape is supposedly the same material as some of the other big bike brand adhesive rim tape. I've used this on my 26mm interior width and 32mm exterior width rims. The tape works great and it's very thin, so it should give you some extra space for when removing your tires, when compared to thicker plastic rim bands. I used a 19mm wide tape which fits perfectly into the bottom of the channel of my rims. The adhesive tape doesn't have to extend all the way to the beads (if you're using a tube), it only has to extend a little bit further than the spoke holes, as long as you're careful not to lift the tape when inserting the tire lever. Non adhesive bands usually should extend all the way to the bead to prevent it from shifting and exposing the spoke holes, but the band that I used was getting under the beads and in between the tire and rim, causing inflation problems. I wrapped 3 rounds of tape onto my rim, but you only need 2 rounds. 3M also makes packing tape. You can search Google for alternative tape brands to see what other people use that might be available locally.
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Old 12-03-19, 07:24 PM
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Originally Posted by trailangel View Post
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Old 12-04-19, 12:06 AM
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Originally Posted by justinschulz9 View Post
could try a different tire? you should never modify a rim to that degree especially on a bike you are potentially commuting on.
also if the tire is as tight as you say i would recommend getting help from your LBS.
This is probably part of the issue. Ebike tires have much heavier sidewalls than standard bike tires. This will make them tougher to install and remove with standard bike tire levers. I would look into the Kool-Stop Tire Jack or perhaps a set of motorcycle tire levers.
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Old 12-04-19, 07:45 AM
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Originally Posted by Snikerdoodlz View Post
My ebike motor's rim is an absolute pain to mount tires on. I know that it's a problem with the rim itself since I've put my exact same tires on another rim with much less effort. Potential DIY defects aside, Is it feasible to grind down my rim to decrease its diameter? I'd rather not spend money on a new rim and service to re-lace my motor.

Edit: The rim in question is the Sun Ringle Rhyno Lite 26x2.00 with 36 holes.
Sniker--whatever you do, don't grind your rim---but DO please watch this excellent video that shows clearly the technique to work with hard rim/tire combinations
oh, and buy some inexpensive PEDROS tire levers, they are usually yellow and come in a pair, and are super super strong.

but the concept in the video is what others have described, and with some old straps, it REALLY makes all the difference

also, at the very end of slipping the last part of bead on, sometimes putting a bit of soap on the lip edge for a the last 5 inches or whatever can help with that last bit slipping over easier--but gaining those precious extra mm's from the technique shown in video is the main help.

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Old 12-04-19, 08:44 AM
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Originally Posted by Snikerdoodlz View Post
My ebike motor's rim is an absolute pain to mount tires on. I know that it's a problem with the rim itself since I've put my exact same tires on another rim with much less effort. Potential DIY defects aside, Is it feasible to grind down my rim to decrease its diameter? I'd rather not spend money on a new rim and service to re-lace my motor.

Edit: The rim in question is the Sun Ringle Rhyno Lite 26x2.00 with 36 holes.
Use two wraps of 1 mil Kapton totaling 0.005" versus 0.020" for typical rim tapes. 16mm (5/8") works well for traditional road rimes, 19mm (3/4") wide.

Combine that with proper technique, starting 180 degrees opposite from the valve, milking the slack around, and finishing at it.

Manufacturers make rims tighter than they used to, perhaps to reduce liability risk from a flat tire rolling off.

Last edited by Drew Eckhardt; 12-04-19 at 08:58 AM.
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Old 12-04-19, 08:54 AM
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Originally Posted by djb View Post
Sniker--whatever you do, don't grind your rim---but DO please watch this excellent video that shows clearly the technique to work with hard rim/tire combinations
oh, and buy some inexpensive PEDROS tire levers, they are usually yellow and come in a pair, and are super super strong.
The video is wrong. It matters where you start, and beginning at the valve is a handicap..

Rims have a shallow depression in the center.

To get the last bit of bead over, you need the rest of it in that depression.

At the valve hole the depression is occupied by the valve stem so that can't happen.

Start 180 degrees opposite the valve. Finish by continuously moving the bead towards the center, maintaining tension, and milking the slack to the end. Flip it with your thumbs or palms.

You don't need straps if you keep tension on the bead all the way around.

This ignores the gains from using a thinner rim tape. Substituting two wraps of 1 mil Kapton for tradiional rim tapes will get you .0.030" of diameter and 3/32" of additional slack.

Together that's the difference between cussing at tools and comfortably mounting tires by hand.

Last edited by Drew Eckhardt; 12-04-19 at 09:04 AM.
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Old 12-04-19, 09:17 AM
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Drew, I guess we'll have to agree to disagree. Once I saw the technique in the video, ie to gain those crucial mm's that help at the end, it has helped make things easier for me with difficult rim tire combos.

Getting the tire into the deeper mid part and staying more or less there is what ends up accumulating with that extra slack at the end.

This is my experience anyway.
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Old 12-04-19, 09:34 AM
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Starting at the valve isn't "wrong" if you're still able to mount the tire without issue. It's just that current thinking has swung toward finishing at the valve since it helps a tiny bit.
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Old 12-04-19, 09:47 AM
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I prefer starting at valve to avoid the forcing the valve if it's at an angle, if some movement has occurred during mounting.
Am I right it wrong? Who knows, it works though for me.
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Old 12-04-19, 09:49 AM
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as mentioned above,

a touch of liquid soap+water.done.
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Old 12-04-19, 06:28 PM
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What tires are you using? I have a set of wheels with Rhyno Lite rims and have found it to be a challenge to mount new Kevlar bead tires. I almost never have to use my VAR tire jack but did this time. The tires seem easier to mount now that they're stretched a bit. Follow the excellent advice posted by others above, stay patient, and you'll do fine. Building up your thumb muscles is always useful.
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Old 12-04-19, 08:29 PM
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Originally Posted by Moe Zhoost View Post
What tires are you using? I have a set of wheels with Rhyno Lite rims and have found it to be a challenge to mount new Kevlar bead tires. I almost never have to use my VAR tire jack but did this time. The tires seem easier to mount now that they're stretched a bit. Follow the excellent advice posted by others above, stay patient, and you'll do fine. Building up your thumb muscles is always useful.
I'm using Schwalbe Marathon road tires. Those tires are already tighter than usual, so the combination was brutal. I used to use Maxxis Gypsies, which were still unreasonable.

People are saying to guide the bead into the central depression. Does it not do that automatically when you pull on it when flipping tire levers?
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Old 12-04-19, 08:40 PM
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Originally Posted by Snikerdoodlz View Post
People are saying to guide the bead into the central depression. Does it not do that automatically when you pull on it when flipping tire levers?
Not really. You have to manually press the bead into the center channel on the opposite of the tire lever and also massage the slack from the pressed area towards the lever. If you apply an incredible amount of force to the lever then it may pull the bead into the center, but there is a risk of damaging the rim or tire, and it depends on the shape of the channel and whether it not the rim tape gets in the way. That's why people are recommending thin rim tape for you.

Have you ever seen a YouTube video about how radial deep groove cartridge bearings are assembled? Have you ever wondered how they get the balls in between the 2 rings? It's the same principle as removing a tire from a wheel. By moving 2 concentric rings so that one side is closer together, it increases the gap on the other side.
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Old 12-04-19, 08:42 PM
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Originally Posted by Snikerdoodlz View Post
I'm using Schwalbe Marathon road tires. Those tires are already tighter than usual, so the combination was brutal. I used to use Maxxis Gypsies, which were still unreasonable.

People are saying to guide the bead into the central depression. Does it not do that automatically when you pull on it when flipping tire levers?
as per the video, my experience shows that by pushing the tire into the deeper section, and making sure you keep the tire in the middle as you work your way around, you accumulate a tiny bit more slack as you work your way to the end.
By not doing it, when you use the levers, it doesnt automatically do it ALL around the tire.

my take on this technique is that the difference is small, but by gaining those crucial mm's of extra room, plus maybe some wet on the last bit of rim to help go against the sometimes natural "sticking" of the rim and bead, to help it slide over a smidge easier, plus some good strong levers--all these small details make the difference.

but of course, every tire and rim combo is different, and some people have much stronger hands and fingers than others.
the few times I've encountered a real bugger of tire/rim mixes, it has helped using straps because they physically squish the tire in and keep it in place, it doesnt spring back, but usually I can just use my hands and make sure the tire stays in the middle as I work my way around.
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Old 12-05-19, 06:40 AM
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This is a good thread. 👍 I recently had a tough situation, while changing my tires & tubes onto different rims. The whole issue was caused by Slime inner tubes, which didn't want to deflate all the way, due to that sealant jamming up the valve stem. 🙄🤔 I finally gave up on one, and used my spare. And couldn't deflate that tube any more, even outside of the tire & rim, to store it in my pannier as a spare. 🙁

Anyways, there's something else to complicate the issue even further. 😁😉 Another good reason to always carry a spare tube or two.
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