Can't Get #@!!@ Tire On Rim

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Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 14 2020 10:49pm

I just LOVE looking like a complete Newb. I really should stop buying things from Ebay, but anyway, here is the situation: I bought a 500 watt Das Kit 26" conversion kit on Ebay recently, so I could use the motor/wheel as a plug-in replacement for the really noisy Das Kit 500 watt 26" motor/wheel on my Magnum Metro Step-Thru. I also bought a new brake rotor and tire, so I could use the still-functional old wheel with the new kit, to convert an old EZIP later on. The tire I bought is a SCHWALBE Big Ben Race Guard Wired Tire, 26 x 2.15-Inch E-bike tire - the same tire the bike came with. I already had a Schwalbe 26" tube suitable for this tire size, along with a few other new or newish tires. Last night, I started to mount the tire and tube on the new wheel. And failed utterly, despite numerous attempts, most with an assistant. The tire and rim LOOK compatible, but with about 24" linear of sidewall left off the rim, the tire is stretched so far down the side of the rim that it won't budge. The tire is labeled that it is for "crotched rims" only. It's my understanding that all new rims are "crotched." This is also the same tire (except in a different color) that is on the bike now. I've mounted a few tires in my time - not a lot, but maybe 5 - and never had this much trouble. Is it really hard to mount to a "crotched" rim? To further complicate matters, there is a label on the rim tape that says "27.5 20". I was thinking "Crap! This is a mislabeled 27.5" rim!" But when I measured the circumference with string and did the math, I got something like 22.6" for the rim diameter. This is a 26" or slightly larger rim, but not a 27.5" rim...right? Was I really an awful person in a past life? Any other time I could drop everything off at a bike shop and say "Do this, please" and that would be it. But now, it looks like I'm on my own. Any help would be appreciated. Any insults should at least be amusing.

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Re: Can't Get #@!!@ Tire On Rim

Post by amberwolf » May 14 2020 11:18pm

Well, there's actually several sizes of "26"" rim, so maybe you have one of the ones your tire cant' fit.

What exactly does it say on the side of your tires? First, the one that came off the rim you have a problem with. Next, the one that you're trying to put on. It may have additional numbers molded into the side of the tire than just what is printed on it.

FWIW, 22.6" is 574mm, and doesn't match any of the sizes I know of, but is closest to what the wiki article linked below calls a 650C (571mm). (some other sites say a 650c and a 26" 559are identical, just to be confusing).

Per this page (and others)
https://en.wikipedia.org/wiki/Bicycle_w ... ike_wheels
the common 26" is 559mm, and 27.5" is 584mm.

This part of the page
https://en.wikipedia.org/wiki/Bicycle_wheel#26_inch
shows several other sizes:
650 - ISO 32-597 (26 x ​1 1⁄4) - Older British sport bikes. Schwinns with narrow tires.[44]
650A - ISO 37-590 (26 x ​1 3⁄8) - Common on many vintage frames ranging from American-made Murray and Huffy as well as English and French manufactures like Raleigh and Peugeot.
650B - ISO 40-584 (26 x ​1 1⁄2) - Also 650B demi-ballon. French tandems, Porteurs, touring bicycles; enjoying a revival.[40] (584 mm rims with large volume ISO 56-584 knobby tires, aka; balloon, are also known as 27.5 inch mountain bike wheels)
650C - ISO 44-571 (26 x ​1 3⁄4)

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 14 2020 11:54pm

The new rim with hubmotor came with no tire or tube - just rim tape. I'll get out the magnifying class and post what's on the sidewall of the new tire a bit later. I'll also try to read what's on the tires on the bike. As I wrote, though, this is, as best I can tell, the same tire model the bike already has on it, front and back. The rims also appear to be the same. The "manufacturer" says that it uses the Das Kit. I also eyeballed a couple of other new tires I have on hand against the rim, and it looks like they'd all be too small to go on. One was maybe more possible, but it's a skinny Continental street tire with little knobs that I think would be too slippery. Assuming that what I need is a new, taller "26 inch" tire, how would that tire be labeled...?

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Re: Can't Get #@!!@ Tire On Rim

Post by amberwolf » May 15 2020 12:50am

LeftieBiker wrote:
May 14 2020 11:54pm
The new rim with hubmotor came with no tire or tube - just rim tape.
Does it have any markings on the rim itself? Either stamped or engraved or printed? Usually reads something like "ISO/ETRTO" and a number.
As I wrote, though, this is, as best I can tell, the same tire model the bike already has on it, front and back. The rims also appear to be the same. The "manufacturer" says that it uses the Das Kit.
Well, "Das Kit" appears to be an ebike kit "manufacturer" (meaning, they badge stuff they've bought in large lots, most likely), at this page:
http://das-kit.com/
They have several kits, and unless I missed it you didn't say if it's the front or rear. But both front and rear are available in either 26" or what they call a 28" for at least two of the kits, and another is available in both those and a 27.5", and I would guess that you probably have the 27.5" or 28", and not the 26".
http://das-kit.com/Products/R3_Rear/wheel_set/24.html
http://das-kit.com/Products/R3_Front/wheel_set/20.html
http://das-kit.com/Products/D5_Rear/wheel_set/25.html
The way they call out the model numbers sort of sounds like it indicates the rim size.
RM600S6-RX2C-22
RM650S6-RX2C-22
RM700S6-RX2C-22
FM600S6-K6
FM700S6-K6
RM600S6-RX2-45
RM700S6-RX2-50
but 600 doesnt' match any of the 26" wheel sizes, so I don't know why they use that number (the only 600 I have seen is a 24" wheelchair size). 650 is any of three different sizes, only one of which is the 27.5. 700 is also several different sizes, only one of which is the 28.
I also eyeballed a couple of other new tires I have on hand against the rim, and it looks like they'd all be too small to go on. One was maybe more possible, but it's a skinny Continental street tire with little knobs that I think would be too slippery.

If those are also "26"" tires, then it almost certainly means it's not a common "26"" rim.

Assuming that what I need is a new, taller "26 inch" tire, how would that tire be labeled...?
That depends on exactly which rim it really is. If the rim is completely unlabelled, then try remeasuring it. I'm sure you're already doing it this way, but just in case:
https://www.sheldonbrown.com/rim-sizing.html

Since you probably can't measure directly across the rim because of the motor, then:
You may measure the circumference of a rim by wrapping a measuring tape all the way around the rim. You derive the diameter from the circumference.

A narrow, metal tape measure -- 1/4 inch or 6 mm wide -- will fit into the well of the rim. (A wide metal tape measure won't fit into the well of the rim and and won't curve smoothly around the rim.)

Don't trust a fabric measuring tape as used in fitting clothing. This kind is usually inaccurate, because the fabric stretches.

Use the metal tape measure as shown in the image below.
Image
Here are the steps to measure using the circumference:

The tape has a tab at the end. Hook the tab into the valve hole and wrap the tape all the way around the rim, measuring the total circumference at the bottom of the well.
Divide the circumference by pi (3.142) to get the diameter of the well.
If the tape measure is divided in inches, also multiply by 25.4 to get the diameter of the well in millimeters.
Add twice the height from the well to the bead seats (see instructions below).

If you don't have a narrow tape measure, you could wrap a length of thin, flexible electrical wire or bicycle cable inner wire around the rim, mark two places on the wire which line up with one another, lay the piece out flat and measure the distance between the two marks.

Our example rim is a hook-edge rim without clearly-defined bead seats, so we'll measure from the well (but not the bottom of the recessed spoke holes) to the outside of the rim and then subtract twice the typical flange height. Our highly-sophisticated tool for this task is a bicycle spoke. We are also using a small ruler as a bridge across the rim flanges. Holding the spoke with a thumbnail against the ruler gives us a good enough measurement for our purposes.
Image
The measurement can be transferred to the ruler:
Image
Now, calculating, the circumference of the well measured as 64 1/8 inches, (64.125 inches). Multiplying by 25.4 gives 1629 mm; then dividing by pi (3.142) the diameter is 518.5mm. 16mm additional (twice the depth of the well) gives 534 mm, but the bead seat diameter is be about 10 mm smaller, and this is a 520 mm rim.
These are two other good pages to help figure it out:
https://www.sheldonbrown.com/26.html
https://www.sheldonbrown.com/tire-sizing.html

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Re: Can't Get #@!!@ Tire On Rim

Post by Tommm » May 15 2020 2:41am

Channel the edges of the tire in the middle of the rim all around, except where you are working on it.
Since the middle of the rim is of lesser diameter, you will free up some material.
Put some soapy water on the edges of the tire.
Completely deflate the inner tube if you haven't already.
Doing these it should be quite easy.

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Re: Can't Get #@!!@ Tire On Rim

Post by alfantastic » May 15 2020 3:25am

If it's any consolation, I find my wired Schwalbe Marathon GT 365's to be a pain to fit. My trick is to seat a section of the tyre into the beading groove and cable tie the tyre tightly against the rim. Then I use a strong plastic tyre lever to feed the wired section into the groove as I move around the tyre. The last bit needs extra muscle to pop the wire into the groove, but the cable tied section prevents the tyre from slipping back out of the bead groove. Once all in and seated correctly, just cut the cable tie.

Hope you get what I mean :confused:

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 15 2020 5:14am

I already measured the circumference, guys, with a nice flexible length of small diameter rope. IIRC I got 71" after subtracting half an inch for what I think is 1/4" rope. That yielded the 22.6 diameter. As already noted, that doesn't indicate a 27.5" rim, even though the rim tape says 27 x 20. I suspect that maybe it's a rim tape from a larger rim.

I will examine the rim for any markings.
Last edited by LeftieBiker on May 15 2020 2:53pm, edited 1 time in total.

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Re: Can't Get #@!!@ Tire On Rim

Post by dogman dan » May 15 2020 6:12am

If it is a 26", but bigger than most, I have found I had problems will bottranger cruiser type tires on several bikes. Too big, they don't grab at the rim so great, and then creep causing stem rip flats.

There is a trick for getting just normal, but tight tires on the rim. You have to get the bead all the way down touching the spokes on one side, to get the last bit on the rim opposite. That zip tie trick sounds good.

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 15 2020 6:15am

No markings on the rim other than a 'QC Rim" sticker. The rim tape sticker actually says "27.5 x 20." Also, the box it came in measures exactly 24" square. I will take pictures of the new tire tonight, so I can try to read the tiny markings.

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Re: Can't Get #@!!@ Tire On Rim

Post by Tommm » May 15 2020 9:42am

Well, you're not putting 26 rubber on a 27.5 rim, that's for sure. :lol:

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Re: Can't Get #@!!@ Tire On Rim

Post by spinningmagnets » May 15 2020 10:40am

The part where the tire bead seats on the rim, and the part where the spoke nipple seats...they are two separate and completely different measurements. Here is an image of a deep "aero" rim for a road bike:

Image

I posted that to inform the casual reader (many months from now) that one rim is not the same as another rim of the same tire "nominal diameter rating".

The center-line of a rim (bike, motorcycle, car) is typically a smaller diameter than the actual bead-seat. If you take the section of tire that is on the opposing side from the part you are trying to install, and then you clamp it together...there is a chance you can then pull the clamped end deeper, and as a result you can then move the "install end" farther out, making the install easier...

Image

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Re: Can't Get #@!!@ Tire On Rim

Post by 2old » May 15 2020 10:46am

Did you measure the old rim and compare to the new one? If they're the same it's just a "bad" combination that occurs occasionally. One of the main considerations is what would happen if you get a flat while you're riding. I would look for a different tire, and probably one with a kevlar belt which would be more flexible. FME, Bontrager tires (Trek) seem a little easier to mount than others, and I've mounted hundreds.

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Re: Can't Get #@!!@ Tire On Rim

Post by MadRhino » May 15 2020 11:30am

Few years ago I have had a Schwaalbe tire that wouldn’t fit the rim. It was a Bloody Mary 26’’. Just to make sure, I did compare this tire with another Bloody Mary when I had a chance to have another one in my shop. The first was defective, smaller than the other 26’’ despite having exactly the same sidewall markings.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 15 2020 2:56pm

MadRhino wrote:
May 15 2020 11:30am
Few years ago I have had a Schwaalbe tire that wouldn’t fit the rim. It was a Bloody Mary 26’’. Just to make sure, I did compare this tire with another Bloody Mary when I had a chance to have another one in my shop. The first was defective, smaller than the other 26’’ despite having exactly the same sidewall markings.
Interesting! I'll do some bead diameter measurements of the tires I have on hand, plus the new one.

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Re: Can't Get #@!!@ Tire On Rim

Post by Dauntless » May 15 2020 10:11pm

spinningmagnets wrote:
May 15 2020 10:40am
Image
OMG Mr.Magnets, where DID you get that tire tool? Do you know a proper name so I can search for one?
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Re: Can't Get #@!!@ Tire On Rim

Post by MadRhino » May 15 2020 10:27pm

That is a tad extreme for a bicycle rim, but if you want to try a manual bead press, this one should be more than enough.

Image
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Can't Get #@!!@ Tire On Rim

Post by Dauntless » May 15 2020 11:21pm

That won't work on a motorcycle wheel.
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Re: Can't Get #@!!@ Tire On Rim

Post by MadRhino » May 15 2020 11:49pm

Both are made for home motorcycle tire service, and are enough to crack a bicycle rim.

A small wood clamp could be used on a bicycle tire without too much of a risk for the rim but really, best is to use tire levers.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 15 2020 11:56pm

Can anyone suggest really great tire levers? I was using a pair of cheap plastic ones. They helped, but not enough.

EDIT: here is what I ordered:

https://www.ebay.com/itm/Bike-Hand-Inst ... 0972.m5489

The reviews in another listing for it seem very positive and real.

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Re: Can't Get #@!!@ Tire On Rim

Post by Balmorhea » May 16 2020 12:32am

The bead seat diameter of a 26" MTB rim is 559mm, which is 22". How much farther the rim sidewall comes up beyond that is arbitrary, within a small range. I just measured a brand new 26" rim here at 22-9/16", or 572mm overall. Since a 27.5" wheel has a bead seat diameter 25mm bigger, the same rim would measure almost exactly 1" larger in overall diameter.

The channel in the middle of the rim can vary in depth by quite a lot, so its diameter/circumference are also somewhat arbitrary. I would not depends on that measurement for anything.

I say, lay a tape measure as straight as you can across the diameter of the wheel you're working with. If it's any more than 22-3/4" overall, you are definitely working with the wrong diameter rim.

Pro tip: NEVER use tire levers to install a tire. If you really need leverage to get them on, then you will not be able to get them off later without destroying something. Just make sure the wire beads at the edges of the tire are bunched up together in the middle of the rim channel. Use toe straps or zip ties to hold them there if necessary, as you work your way around. But don't pry them on; you'll regret it.

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 16 2020 1:42am

I can get a radius for the wheel more easily than a diameter because of the axle. That's maybe a hair over 11". My guess at this point is that I have a rim on the large side of normal, and a tire or two on the small side - with one tire that might fit but would be too narrow and slippery for the bike.

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Re: Can't Get #@!!@ Tire On Rim

Post by Balmorhea » May 16 2020 2:02am

Also, if you have more than one layer of tape as a rim strip, get all the extraneous junk out of there. It all competes for space with the tire when you're mounting and dismounting it.
Last edited by Balmorhea on May 16 2020 12:10pm, edited 2 times in total.

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Re: Can't Get #@!!@ Tire On Rim

Post by LeftieBiker » May 16 2020 4:34am

It looks like a single layer of tape.

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Re: Can't Get #@!!@ Tire On Rim

Post by MadRhino » May 16 2020 6:17am

Balmorhea wrote:
May 16 2020 12:32am

Pro tip: NEVER use tire levers to install a tire. If you really need leverage to get them on, then you will not be able to get them off later without destroying something...
We normally fit bicycle tires by hand alone but, do you know a single bike shop in the world that never use tire levers ? There are some (DH tires especially), that are PITA to fit on some rims without the levers.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Can't Get #@!!@ Tire On Rim

Post by 2old » May 16 2020 11:07am

LeftieBiker wrote:
May 15 2020 11:56pm
Can anyone suggest really great tire levers? I was using a pair of cheap plastic ones. They helped, but not enough.

EDIT: here is what I ordered:

https://www.ebay.com/itm/Bike-Hand-Inst ... 0972.m5489

The reviews in another listing for it seem very positive and real.
Pedro's, which are yellow, beefy and probably for sale on Amazon. If those don't work, you'll need aluminum motorcycle ones (used once to remove a recalcitrant fat tire.

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