Rims too tight -- sandpaper them down?
#26
Senior Member
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1074 Post(s)
Liked 295 Times
in
222 Posts
Well...
I’ve seen some tubeless MTB rims with a hookless design. Made to seal up between bead and ”shoulder” of the rim profile, just outside the minimum diameter trench running around the rim.
Rims relying on a similar design COULD be milled down some w/o compromising the tire retention.
But AFAIK tubeless road rims still use more of a traditional hook design.
Whether that hook is still functional, load-carrying, I don’t know.
If it is, I wonder if it’d possible to take enough off to make mounting easier, while still retaining enough for it to fulfil its tire retaining purpose.
If I wanted to reduce the OD of a rim on an already built wheel, I’d use a router. These usually come with an adjustable guide that allows you to cut on a set distance from an edge. That guide can be easily modified to allow cutting circles of an arbitrary size. Attach fixture to wheel axle, set your cut and off you go.
Do note that the fixture, if done reasonably well, may trace a more perfect circle than the rim. You may end up with low spots on the rim sidewall.
You might get a more consistent result WRT rim sidewall height by using the sander-and-trainer approach someone already suggested.
I can think of another jig or fixture that would enable sanding down the rim with decent precision, but building it would seem excessively time consuming for the purpose of saving a couple of questionable rims.
What I’ve done on really difficult combinations on occasion is to tape the beads together. It can help in keeping them at the minimum diameter spot and make the final mounting easier. Or If there are people around willing to perhaps get a tiny bit dirty, simply ask them to pinch the beads together on the already mounted section of the tire.
I’ve seen some tubeless MTB rims with a hookless design. Made to seal up between bead and ”shoulder” of the rim profile, just outside the minimum diameter trench running around the rim.
Rims relying on a similar design COULD be milled down some w/o compromising the tire retention.
But AFAIK tubeless road rims still use more of a traditional hook design.
Whether that hook is still functional, load-carrying, I don’t know.
If it is, I wonder if it’d possible to take enough off to make mounting easier, while still retaining enough for it to fulfil its tire retaining purpose.
If I wanted to reduce the OD of a rim on an already built wheel, I’d use a router. These usually come with an adjustable guide that allows you to cut on a set distance from an edge. That guide can be easily modified to allow cutting circles of an arbitrary size. Attach fixture to wheel axle, set your cut and off you go.
Do note that the fixture, if done reasonably well, may trace a more perfect circle than the rim. You may end up with low spots on the rim sidewall.
You might get a more consistent result WRT rim sidewall height by using the sander-and-trainer approach someone already suggested.
I can think of another jig or fixture that would enable sanding down the rim with decent precision, but building it would seem excessively time consuming for the purpose of saving a couple of questionable rims.
What I’ve done on really difficult combinations on occasion is to tape the beads together. It can help in keeping them at the minimum diameter spot and make the final mounting easier. Or If there are people around willing to perhaps get a tiny bit dirty, simply ask them to pinch the beads together on the already mounted section of the tire.
#27
Expired Member
Join Date: Jun 2007
Location: TN
Posts: 11,461
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 3638 Post(s)
Liked 5,316 Times
in
2,701 Posts
I now fully support OP trying this.
Likes For shelbyfv:
#28
I'm good to go!
Join Date: Jul 2017
Location: Mississippi
Posts: 14,811
Bikes: Tarmac Disc Comp Di2 - 2020
Mentioned: 50 Post(s)
Tagged: 0 Thread(s)
Quoted: 6100 Post(s)
Liked 4,732 Times
in
3,262 Posts
This is a really good question.
Also the later suggestion in the post that the tire and rim might be mis-matched BSD's.
Last edited by Iride01; 05-04-21 at 08:26 AM.
#29
Senior Member
Join Date: May 2020
Posts: 490
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 252 Post(s)
Liked 67 Times
in
48 Posts
these are 700cx25mm *used* road tires going onto brand new Chinese rims.
As an aside, I once had a Ford van rear door glass pushed in by thieves, found it laying inside the van with the rubber lining that it is normally seated in. I was very much puzzled how to put it back, basically if you don't know the trick, you are well stuck. I went to this auto shop where they showed me the trick, took just a minute to pop it in. I am sure everybody knows the trick, won't bother to describe it.
However it is not something you could do on the road unless you were prepared to do it. For the bike it would only solve the initial putting the tire on, then you'd have to hope that the tire would stretch a bit to fit on the rim easier next time, like on the road.
BTW speaking of the impossibility of fixing a flat on the road with this tire rim combination - I once had new tires put on the van in an auto shop and one day, luckily it wasn't by the road side, I needed to remove the wheel and found I couldn't do it with the standard tire wrench. And in those days, I was young and in full strength, although no brute to be sure. Those impact wrenches they use in car shops virtually veld the nuts on and without it, it is near impossible to undo those lug nuts. Meaning if I got a flat on the road, I wouldn't be able to change to spare wheel, similar situation to this predicament here.
As to sanding the rims, I suspect that rim walls are not solid material inside, but are bent 180 degrees back at the very edge of the rim, so the brake surface is actually an outer wall of the rim side, meaning that if you sanded off the thickness of the folded material right in the place where it is bent backwards, the rim would just fall apart?
Last edited by vane171; 05-04-21 at 09:21 AM.
#30
Junior Member
Thread Starter
So thinking about it, how much material would you need to remove in order to produce a noticeable change in the ability to mount a tire on a rim? I'm just guessing based on nothing (or even just the idea that old tires stretch on easier, which everybody knows) that a mm of circumference would be a lot. that's about 1/6 of a mm or 160 microns of radius. The hook is about a millimeter in diameter, so you're not removing all or even most of it, and you don't have to do it all the way around. 160u doesn't need a router or a lathe to achieve, a single piece of 100 grit sandpaper (keep it wet) will take that down in a jiffy. Then smooth it out with 600 grit. I think I would go easy with the 100 grit, because the actual amount you need to remove could be much less.
I thought of a better way to estimate it than pulling numbers out of my sleeve. The critical moment where you have to really start pushing on the bead, it becomes a chord subtending an arc of the rim. You can either remember trig from 7th grade or find a nifty calculator, but either way for a 700c wheel (343mm radius), if the length of the chord is 15cm then the difference between the arc length and the bead length is 1.2mm. Meaning if that tire were 1.2mm longer it would go on with no force. and still seat properly, because the tire is still smaller in overall circumference than the bead. But so maybe you only need half that 0.6mm (600u) of circumference and 100u of radius to be removed. And if you're smart only in one spot, on one side not all the way around both sides. Like I said don't go overdo it with the sandpaper.
But so the 1mm circumference and 150u radius figure I estimated can't be too far off. It's not even hard to imagine that a quick go with sandpaper all around turns a beast wheel into a kitty cat.
The wheel manufacturers want to keep both sets of constituents happy, so they're adding as much material as they dare to the edge of the rims. And tubeless is the new craze (I don't get it, but whatever trips your trigger). But the amount they've added is way more than tubeful users need or want, it's a big disadvantage to us. A tiny bit of aluminum with a big effect if you're sitting in the sun on a highway in Texas with gigantic duallies whipping past you at 80 mph as has happened to me. That's not the time to have to be McGyvering with zip ties or soapy water.
I thought of a better way to estimate it than pulling numbers out of my sleeve. The critical moment where you have to really start pushing on the bead, it becomes a chord subtending an arc of the rim. You can either remember trig from 7th grade or find a nifty calculator, but either way for a 700c wheel (343mm radius), if the length of the chord is 15cm then the difference between the arc length and the bead length is 1.2mm. Meaning if that tire were 1.2mm longer it would go on with no force. and still seat properly, because the tire is still smaller in overall circumference than the bead. But so maybe you only need half that 0.6mm (600u) of circumference and 100u of radius to be removed. And if you're smart only in one spot, on one side not all the way around both sides. Like I said don't go overdo it with the sandpaper.
But so the 1mm circumference and 150u radius figure I estimated can't be too far off. It's not even hard to imagine that a quick go with sandpaper all around turns a beast wheel into a kitty cat.
The wheel manufacturers want to keep both sets of constituents happy, so they're adding as much material as they dare to the edge of the rims. And tubeless is the new craze (I don't get it, but whatever trips your trigger). But the amount they've added is way more than tubeful users need or want, it's a big disadvantage to us. A tiny bit of aluminum with a big effect if you're sitting in the sun on a highway in Texas with gigantic duallies whipping past you at 80 mph as has happened to me. That's not the time to have to be McGyvering with zip ties or soapy water.
Last edited by jesnow; 05-04-21 at 09:32 AM.
#31
Senior Member
Join Date: Sep 2017
Posts: 7,768
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,873 Times
in
4,637 Posts
So far I have zero helpful responses. And zero point five tip or tricks I didn't already know decades ago. I asked a simple question: Has anybody actually tried milling the rim a little,
A helpful response would be "I know a guy who tried it, got his tires on just fine using his pinkies, but had a blowout and died on a descent". Or "I saw that some cheap rims just have very rough grooves along the braking surface and those might be what's making it so hard to work the tire on. Maybe you just need to knock those down a little bit on the side".
A helpful response would be "I know a guy who tried it, got his tires on just fine using his pinkies, but had a blowout and died on a descent". Or "I saw that some cheap rims just have very rough grooves along the braking surface and those might be what's making it so hard to work the tire on. Maybe you just need to knock those down a little bit on the side".
You want to dictate the terms of a "helpful response" -- and then ignore (and complain about) any and all other responses from people who are trying to help you.
Nice.
Likes For Koyote:
#32
Randomhead
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,664 Times
in
2,497 Posts
I feel like the OP has gotten lots of helpful replies, but he was seeking affirmation, not answers.
I have had occasion to wonder if I could remove some rubber from a tire and get it to seat more easily. Some tires seem to have a lot of extra rubber at the bead. I would never touch a rim, they break.
I have had occasion to wonder if I could remove some rubber from a tire and get it to seat more easily. Some tires seem to have a lot of extra rubber at the bead. I would never touch a rim, they break.
#33
Senior Member
Join Date: Jul 2006
Location: San Jose (Willow Glen) Ca
Posts: 9,856
Bikes: Kirk Custom JK Special, '84 Team Miyata,(dura ace old school) 80?? SR Semi-Pro 600 Arabesque
Mentioned: 104 Post(s)
Tagged: 0 Thread(s)
Quoted: 2304 Post(s)
Liked 2,741 Times
in
1,499 Posts
So far I have zero helpful responses. And zero point five tip or tricks I didn't already know decades ago. I asked a simple question: Has anybody actually tried milling the rim a little, and people say things like "oh you must be an idiot" (which maybe I am) or "just use a little soapy water, works great for me!". Like I didn't know your favorite tip or trick already in the 1970's. But OK, nobody so far has tried this idea, with good *or* bad results. I'm kind of surprised, you'd think people would have a little more imagination than fixating on the tire as the source of the problem. But maybe I'm the idiot and am about to ruin a perfectly good set of wheels. I think I should probably roll out the new wheels and a few of my old ones to see if there's an actual difference in circumference at the bead. If not I better think twice before modifying anything.
Anybody want to make a prediction?
A helpful response would be "I know a guy who tried it, got his tires on just fine using his pinkies, but had a blowout and died on a descent". Or "I saw that some cheap rims just have very rough grooves along the braking surface and those might be what's making it so hard to work the tire on. Maybe you just need to knock those down a little bit on the side".
To be fair I should have mentioned: these are 700cx25mm *used* road tires going onto brand new Chinese rims.
Cheers,
Jon.
Anybody want to make a prediction?
A helpful response would be "I know a guy who tried it, got his tires on just fine using his pinkies, but had a blowout and died on a descent". Or "I saw that some cheap rims just have very rough grooves along the braking surface and those might be what's making it so hard to work the tire on. Maybe you just need to knock those down a little bit on the side".
To be fair I should have mentioned: these are 700cx25mm *used* road tires going onto brand new Chinese rims.
Cheers,
Jon.
I don't know about you, but I find I learn things in areas where I thought I knew everything all the the time
One of those things i learned was that in some cases I needed a tire jack (not levers) Koolstop is the one i used to mount tires. if you have not tried this, which is not clear that you have, your should before going on to destructive options
__________________
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
Likes For squirtdad:
#34
Method to My Madness
Join Date: Nov 2020
Location: Orange County, California
Posts: 3,546
Bikes: Trek FX 2, Cannondale Synapse, Cannondale CAAD4, Santa Cruz Stigmata GRX
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1877 Post(s)
Liked 1,413 Times
in
979 Posts
Riding on a highway with 80 mph traffic seems like even a worse idea. You cannot avoid that route?
Likes For SoSmellyAir:
#35
Duke Ulysses
Join Date: Jul 2013
Location: Southern California
Posts: 800
Bikes: An old orange one for dirt, and for the other stuff: a white one, a kinda mint green one, and a black one.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 165 Post(s)
Liked 175 Times
in
86 Posts
I know someone who did just this. The tires went on great, but he had double blowouts and died on a descent.
Are you happy now?
Are you happy now?
Likes For growlerdinky:
#36
Junior Member
Thread Starter
You got the most helpful response in the very first reply, by cxwrench. He said, "No."
You said you already know all the tricks. Why would someone try to give you advice? You don't need it, and yet, you cannot get the tire mounted.
You now consider a helpful response to be one validating your idea to sand down, or mill the rims. In that case, I cannot give you a helpful response, but it you bring the rims over, I'll mount the tires for you.
You said you already know all the tricks. Why would someone try to give you advice? You don't need it, and yet, you cannot get the tire mounted.
You now consider a helpful response to be one validating your idea to sand down, or mill the rims. In that case, I cannot give you a helpful response, but it you bring the rims over, I'll mount the tires for you.
You clearly didn't read my post or my responses to the other posts. I said very clearly, it would be helpful to say "Here's the math, it wouldn't work" which nobody has. It would be helpful to say "people have thought of this and tried it, but it didn't work or had unintended and costly consequences". Those are helpful, even though they would shoot me down utterly. I would welcome that.
What's unhelpful is to say "I've never heard of this and can't imagine it so you must be an idiot". Which is what you're saying. I don't care about that, I have a thick skin. At least the guy up the thread who speculated (wrongly) about the hook being formed by bending the aluminum over was thinking about the problem. I'm starting to see people catching on to what I'm saying.
But I also have an imagination, and a lot of experience. I'm not going to venture more than walking distance (in cleats) from my house with rims that are super hard to mount tires on. Yes I used my experience and knowledge to get them on there in my own shop though my thumbs are still sore. But that doesn't matter out on the road. So if you will accept the proposition that I'm not going to use shop tips and tricks out on the road ("oh just warm them up with a hair dryer!"), and that these rims are truly beasts to mount a tire on, it seems like my choices are modify the rim or send the wheels back to China. My wife very wisely wants me to send them back, and just pay for proper wheels. I suspect that wheels have just gotten tighter (on purpose) in the intervening decade since I bought my current ones. So I could likely spring for the 1:1 replacement wheels to what I have now (Dura Ace C60) and be right back where I started, because everybody is going tubeless-ready these days for new wheels. It's the new standard.
I'm not sure but I suspect that sanding down the rims carefully may become just what you do when you get new wheels and don't intend to go tubeless. Like grinding off the lawyer lips and taking off the legally-required reflectors and spoke guard on a new bike, or finding the right length stem extenders. But in the future probably all bikes will be tubeless and we'll all be ubering home if we flat. Technological retrogression.
Or maybe I'm completely full of a certain substance similar to tubeless tire sealant. But so far nobody has come up with anything convincing to say either way.
#37
Duke Ulysses
Join Date: Jul 2013
Location: Southern California
Posts: 800
Bikes: An old orange one for dirt, and for the other stuff: a white one, a kinda mint green one, and a black one.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 165 Post(s)
Liked 175 Times
in
86 Posts
I know a lady who tried this. everything was going great until the double blowout. She was pancaked by a semi.
#38
Duke Ulysses
Join Date: Jul 2013
Location: Southern California
Posts: 800
Bikes: An old orange one for dirt, and for the other stuff: a white one, a kinda mint green one, and a black one.
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 165 Post(s)
Liked 175 Times
in
86 Posts
I knew a dude who knew his maths, and all the tricks. He was legit! WAS legit. Double blowout sent him into a retaining wall at 50mph.
Likes For growlerdinky:
#39
Junior Member
Thread Starter
I don't ride at all in Texas anymore, but in Louisiana, where there are just as many 80mph duallies, and they are also on *every* road, the only difference is the roads here are narrower and less well paved. At least there is less cycling here, so having 20 smelly guys unhappy about waiting for you watching you do it all isn't as much of an issue.
#41
Junior Member
Thread Starter
The answer to your question from all responders is obviously "No, we have not tried sanding down rims." That tells you something about the wisdom of your idea.
You want to dictate the terms of a "helpful response" -- and then ignore (and complain about) any and all other responses from people who are trying to help you.
Nice.
You want to dictate the terms of a "helpful response" -- and then ignore (and complain about) any and all other responses from people who are trying to help you.
Nice.
Cheers,
Jon.
#42
Senior Member
Join Date: Jun 2018
Location: SW Ohio
Posts: 2,409
Mentioned: 93 Post(s)
Tagged: 0 Thread(s)
Quoted: 1103 Post(s)
Liked 1,824 Times
in
878 Posts
Let me save some of you kind souls some time and aggravation.
YOU CANT HELP SOMEONE WHO HAS ALREADY DECIDED WHAT THE ANSWER TO THEIR "QUESTION" IS.
YOU CANT HELP SOMEONE WHO HAS ALREADY DECIDED WHAT THE ANSWER TO THEIR "QUESTION" IS.
Likes For nomadmax:
#43
Junior Member
Thread Starter
It would be interesting to measure the actual diameters of rims that are tough mounts vs easy mounts.
That kind of accuracy at home would be tough. ... (post shortened)
I'll leave this to someone else. My Vittoria tires mount easily on my non-tubeless ready Open Pros and when those rims expire, I'm going back to tubulars.
That kind of accuracy at home would be tough. ... (post shortened)
I'll leave this to someone else. My Vittoria tires mount easily on my non-tubeless ready Open Pros and when those rims expire, I'm going back to tubulars.
I hear you about the tubulars. I used to use those too.
Cheers,
Jon.
#44
Junior Member
Thread Starter
There have been a couple of very helpful comments! From the point of view of helping move the question forward, not stoking my ego, which if I wanted that I would get a dog.
#45
Junior Member
Thread Starter
One last thing. If you do pull this off, you can never sell or give away those wheels to anyone. When you are done with them the rims get destroyed. If someone else uses a different tire and it comes off at high speed, or the rim fails from removal of material, you will be responsible since you altered the rim. It will take the OEM 2 seconds to discover that.
John
John
#46
Expired Member
Join Date: Jun 2007
Location: TN
Posts: 11,461
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 3638 Post(s)
Liked 5,316 Times
in
2,701 Posts
Lots of rims no longer have hooks. You may not need them either. Grind the hook off one side of the rim in less time than reading this thread!
#47
BMX Connoisseur
Join Date: Jun 2016
Location: Canada
Posts: 774
Bikes: 1988 Kuwahara Newport, 1983 Nishiki, 1984 Diamond Back Viper, 1991 Dyno Compe
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 399 Post(s)
Liked 108 Times
in
69 Posts
I had some modern BMX rims like this where they seemed like 3mm too wide on the rim wall. The answer was a motorcycle tire lever. If you look at a rim the edge is finished in a nice round edge. If you were to file it down then you would have a sharp flat edge rubbing constantly into the sidewall of your tire.
Likes For cbrstar:
#48
Senior Member
Join Date: Aug 2009
Posts: 2,592
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1541 Post(s)
Liked 1,702 Times
in
956 Posts
Take a picture of the inside edge of the rim. Let's see how much 'hook' material exists first. If the hook is plenty thick then sand away. If the hook looks marginal to begin with than you're SOL.
#49
Junior Member
Thread Starter
Yes I know this trick. These particular tires (conti GP 5K) were mounted for several months on my track bike. Ridden many times at the velodrome at high pressure. Contis are known for being a little tight to get on, especially the foldable ones. But I always use them, I have them on my current rims (Dura Ace C50) my TT bike (well, gatorskins, but they're tight too). But the thing is: all of my current wheels predate the tubeless craze, when manufacturers seem to be deliberately adding material to the rim. Several posters above have spoken to this, so I'm thinking it's not just my imagination.
Likes For jesnow:
#50
Junior Member
Thread Starter
I think this is a good idea. I can maybe get my calipers on there. I don't know what "looks marginal" means, but maybe I can find some metrics. These rims are carbon with an aluminum braking surface. I could measure the width of the braking surface and not take it down more than X which could be 0.1mm and I could still measure it.