Wider rims

[rayivers]

My MXR now has 18 x 2.50 and 21 x 1.85 Warp 9 rims, with a 19 x 2.50 wheel waiting on a tire. I've had 3 rides on the bike after the swap (new tires too, NOS Dunlop MX-31 120/90-18 and Bridgestone M59 80/100-21). Conditions were hardpack / rooty - rocky trails / loam / sandy loose dirt, most with a coating of wet leaves.

I expected little change, but I was wrong. For me, usually the first ride on new tires is a semi-sketchy break-in deal till the rubber nibs wear off, but instead the bike felt more 'planted' and stable than ever, with less fishtailing and better initial (pre-wheelspin) traction. I've had the same rear tire before on the bike - I love it, too bad it's discontinued - but this time I was easily able to wheelie over every single large puddle - and there were many - without the usual instant spin-up and front wheel coming up too late to do any good, despite the wet dirt and leaves everywhere. The following rides in dryer conditions were even better. The Bridgestone M59 is now my favorite front tire - it tracks straight and true, with little deflection or hunting (don't know how much the wider rim contributed to this, but I'm sure it didn't hurt).

Swapping rims is kind of a pain, and if you're going to 18" I'd suggest buying a complete Warp 9 wheel, but the 19 x 2.50 was my 6th lacing job so it can be done. PM me for details/tips if needed.

Warp 9 has a 20%-off Black Friday sale (checkout code warp92020bf) that ends Sunday 11/29 midnight (PST?). I went a little nuts last year, but saved a bunch.

 

[Philip]

What are the stock MXR rim widths, front and rear?

I have been running the front Bridgestone M59 on one of my bikes since the NE 24-hour race last year. I think it is okay. The Dunlop MX32 seems to have taller knobs and it grabs better in the foamy conditions, but the M59 does not chunk on the Arizona hardpack like the MX32 does, so it is a more universal tire for me.

One thing I don't like about the Bridgestone M59 is that it has very thin beads. It is easy to mount, but it kept spinning on the rim because the stock rim lock couldn't punch the beads properly. I lost two inner tubes to this issue. So, I am now running it with a Nitro mousse instead. Just ordered a second Nitro mousse for my second bike too, also for an M59 tire.

I wonder if your wider rims also require wider rim locks?

 

[Philip]

BTW, wider rims on cars have always been known to increase traction. But bike tires lean into the turn, so I am suspecting that wider is better only up to a certain point.

I think there is a very good case for using wider rims with the 18" tires. They have a very tall sidewall, so they should use a wider rim too in order to maintain the lateral stiffness.

 

[rayivers]

My stock rim widths were 2.15" rear, 1.60" front. Yes, the wider rims need wider locks; I used Emgo 16-26010 (front) and 16-26080 (rear) units, which are a little heavy but work well. I like the MX32 front tire too.

 

[rayivers]

Philip - perhaps the wider Emgo front lock might work better on the stock Alta 21" wheel? Just throwing this out there in case anyone wants to try the M59 but is worried about slippage. The oversize locks fit the bigger rims better than the OEM locks fit the OEM rims, with more grip area and 'crush' against the inner sidewalls.

FWIW, my MX-31 rear measured @ 9mm wider than the identical tire on a 18 x 2.15 rim. As far as I know, American tires are made for the generally-narrower US rim widths (the MX-31 definitely is, it's in the specs), so maybe they benefit more from the wider rims.

Here's an interesting chart set of tire profiles for various rim sizes - not directly applicable to my 2.50 rim, but the trend is visible. There's also an FIM chart, demonstrating pretty clearly why I no longer buy them.

 

[rayivers]

Here's a tire-size-vs-rim-size chart - had no idea there was a 140/70-21 tire

 

[Philip]

Here's a tire-size-vs-rim-size chart - had no idea there was a 140/70-21 tire

View attachment 6253

Wow! So this table is telling us that the rims that we are running with stock tires are barely within the width spec and are on the very low side of the spec.

It also tells that if you like running a 120mm rear, like I do, then the rear rim should be a whopping 3" wide instead of the stock 2.15".

 

[F451]

Also keep in mind not to over tighten the rim lock as over tightening it can deform it and it loses its gripping force. Its counter intuitive, but it makes sense if you think about it. I've heard "two finger tight", "snug", etc. Perhaps the rim lock mfrs have a torque spec for it, but I always go with the "two finger tight" method and have had good luck with it.

 

[snydes]

One thing I don't like about the Bridgestone M59 is that it has very thin beads. It is easy to mount, but it kept spinning on the rim because the stock rim lock couldn't punch the beads properly. I lost two inner tubes to this issue. So, I am now running it with a Nitro mousse instead. Just ordered a second Nitro mousse for my second bike too, also for an M59 tire.

I wonder if your wider rims also require wider rim locks?

Interesting, I’ve been running the M59 since the 24hr as well. Also have the same opinion of it as far as the lack of chunking. It’s been my front tire of choice ever since. Haven’t had the spinning issue though.

 

[rayivers]

Wow! So this table is telling us that the rims that we are running with stock tires are barely within the width spec and are on the very low side of the spec. It also tells that if you like running a 120mm rear, like I do, then the rear rim should be a whopping 3" wide instead of the stock 2.15".

Yes! but good luck finding 36-spoke Honda-style rims wider than 2.50, at least this side of the pond. Excel certainly doesn't have them, don't think Warp 9 does either. The MX-31 looks so much more 'normal' on the wider rim, as if it was a 100/100-18 tire stretched sideways; on the narrow rim it looks like a round hot dog with knobs.

 

[evh1]

I had the guys at Dubya set up some extra rims and they recommended the same sizes rayivers had for optimum use offroad on my EXR. I felt the stockers were too narrow. I can feel the gription, lol,, difference I believe in a more planted turning bike and I'm running Dunlops. Those guys seem to really know their stuff!

 

[wwmotors]

Wow! So this table is telling us that the rims that we are running with stock tires are barely within the width spec and are on the very low side of the spec.

It also tells that if you like running a 120mm rear, like I do, then the rear rim should be a whopping 3" wide instead of the stock 2.15".

Dont You feel the heavier rims and tyres in a worse acceleration/loss of range? We tried with the Quantya E-bikes 10 years ago to run tubeless and You could feel the better acceleration without tubes very clear! The difference of wider rims plus wider tyres must be several times worse!

 

[rayivers]

Dont You feel the heavier rims and tyres in a worse acceleration/loss of range? !

I don't feel that at all. What I DO notice is better acceleration & traction in all directions plus a slightly lighter-feeling front end, and being more in-control of the bike. I'm very much a lighter-is-better kinda guy, but this small amount of added weight was a very acceptable trade-off for me (ymmv).

 

[Philip]

Dont You feel the heavier rims and tyres in a worse acceleration/loss of range? We tried with the Quantya E-bikes 10 years ago to run tubeless and You could feel the better acceleration without tubes very clear! The difference of wider rims plus wider tyres must be several times worse!

It depends on your riding. If you are traction-limited, then more traction would give you a better acceleration. I primarily ride motocross, short 15-minute motos, so range and fuel economy is not my main concern.

 

[wwmotors]

It depends on your riding. If you are traction-limited, then more traction would give you a better acceleration. I primarily ride motocross, short 15-minute motos, so range and fuel economy is not my main concern.

Exactly range and ridingtime is my problem. In a 5 hour opening on our tracks here in Germany, i can do a maximum of 2 hours riding. Sometimes I want to go more, but with the chargingtime this is not possible. So I care for saving energy and weight on my MXR. Sometimes, when the battery is completly full, i gor for a longstint and empty it on one stint (40-50min) !

 

[Motophyllic]

I don’t get any slippage with my m59 while running tubless in it. I found that green slime with the tubeless install seals everything up and works great. I hear it’s a big mess though when changing out to a new tire.