Trashed another rim.

[NeilP]

Must have done 4000 miles on it though

Mavic EX721.

Rim started breaking out, and on stripping away. See it has a crack all around the inner wall

Lucky I kept the old one from August 2011, ..it has a bit of a flat spot, but it is not collapsing, so re laced it to the wheel this evening .

Trouble is I can't get another the same from Rose.de in Germany, and getting another rim means new probably different length spokes. So even after I get a new rim, if it is not the same, can expect another month or so wait for new spokes...bugger bugger ..
View attachment 4



See the crack? it runs all the way around the inside... big piece missing in the next picture

 

[mlt34]

impressive failure. Hit a sudden pothole or just fatigue over time?

Do you recall the effective rim diameter or is it still marked on a sticker on the rim? If so, I'm sure you could find something within a few millimeters of it and salvage the spokes for the new rim. And if not, after 4000 miles, new spokes couldn't hurt either.

 

[Ypedal]

switch to a sunrims mammoth or alexrims DM24... or better yet.. disk brakes !.

 

[NeilP]

It is using disk brakes. never had a set of rim brakes on that rim, or this bike at all for that matter

 

[NeilP]

Surprisingly I found one on first hit on Amazon..£53 delivered.

ERD as I think 526mm spokes were 88mm

Guessing fatigue over time. Bike built in Jan or Feb 2011. trashed first rim July/August the same year.
Just clocked over 7012 mies on it ..so may well be more than 4000 miles now I think about it.

Obviously new rim and spokes is the answer, but this is my only real transport now, so for this week I have put the old one back on, till new one arrives.

Once the new rim arrives I can build it back on that and start looking out for a new stronger rim

any suggestions?

 

[Ypedal]

What tire pressure do you run?

 

[NeilP]

35 to 40psi..on 2.3 inch..think they are 2.3 Crazy Bob's to give a bit of a softer ride..so not hard

 

[NeilP]

In the words of both BRITNEY SPEARS

Oops! ...I Did It Again


and Queen....Another one bites the dust.

trashed another EX721






View attachment 1

 

[cheekybloke]

Surprisingly I found one on first hit on Amazon..£53 delivered.

ERD as I think 526mm spokes were 88mm

Guessing fatigue over time. Bike built in Jan or Feb 2011. trashed first rim July/August the same year.
Just clocked over 7012 mies on it ..so may well be more than 4000 miles now I think about it.

Obviously new rim and spokes is the answer, but this is my only real transport now, so for this week I have put the old one back on, till new one arrives.

Once the new rim arrives I can build it back on that and start looking out for a new stronger rim

any suggestions?

Sun double wide rims are 46mm wide i think.
I have one its like a girder.
Darren

 

[NeilP]

Not sure I'd fit a 46mm in the frame.

plus I 'd need a new tyre.


Pretty sure I have already bought the spokes for what ever new rim I d have. Seem to think it is a Sunringle Rhino ;its XL

 

[Teh Stork]

I've seen this kind of failure from too high tire pressure. Then again, these rims do look old - and rims do have a finite life.

 

[NeilP]

Yes, it is just over a year old, about 3000 miles,
Running at about 35 psi


last build was may 2013

 

[Ohbse]

That's pretty well destroyed! I can't say I've had even a crack appear in my Mavic EX729 and I've done similar mileage to you - highly recommended. Otherwise the other wide and strong rim I've heard good things about is the Halo SAS, I've just ordered a 24" for the rear of mine.

I realise that rims have a finite lifespan - however this seems alarmingly regular and quite catastrophic when it goes. Maybe you're just a rough bugger? :wink:

 

[MadRhino]

I'd say running too low PSI for the terrain and speed that you ride, is that possible ?

If you like riding low pressure, use a much wider rim.

 

[sigimem]

Have you considered running a moped/motocross rim and tyre?
much stronger and more rubber(tyre) around the rim to save it. What motor do you use and how havy is it?

 

[NeilP]

Pretty much all road use
Alwsys take aboid curbs and potholrs as much as possible.
30-40 psi max never more possibly less

no m/c rim that will fit the frame. Too narrow at seat tube end.

Motor Xlyte 5304 at about 8000 watts since I devtuned it Originally 100 volt at 140 amps, but now run it low powerrd at 84 volts and about 90 amp max.

In the ; years with this bike I've gained about 4/lbs weight, so 200lbs now. So it has a lotno put up
With

 

[johnrobholmes]

I bet you could fit a 19 in it with a 2.0 or 2.25" tire. What spoke gauge are you running? If its 13, you will get better bicycle rim life by redrilling your spoke holes closer together and using 13/14 butted spokes.

 

[riba2233]

Sooo, thinking about mid motor? :lol:

 

[NeilP]

No none of those options appeal.
Mid drive means you loose the triangle for battety pack and other electrics etc. Thennextra drive trsin strain.

All of those suggextions are a complete new bike build , new electrics everything. Consider I have two other project builds on the go, one for the past four years for one still incomplete, and another about a year in, I'd never get a complete redesign abd rebuild done by this afternoon.

Fitting mid drive to the current bike really means scrapping the bike and starting again. If that was the only option I'd just guve up on e-bikes and go back to the car everyday.

A re lace into to the New Rhino lite XL wirh the new butted spokes that are sitting there, I'll be back on the road in 4 hours.

Definetly no m/c rims thst will fit, well the rim may fit , but I'd have to ride it with no tyre. I looked before and never found a 19 inch x 2 inch m/c tyre


This is actually the third rim I think, first got dented by a mate, second failed like this and I caught it before it blew. Tried with the stainless steel nipple inserts totally removed or reamed out.

Got different rim and thinner butted spokes this time . Previous were 12 gauge, think these new ones are 13/14.

 

[The Stig]

I'd say running too low PSI for the terrain and speed that you ride, is that possible ?

This was my thinking too. I get pinch flats if I run under 30-40psi, which means the rim is hitting the ground. inevitably we're bound to hit some potholes etc which may crack the rim, leading to a failure later.

 

[NeilP]

No, not hitting anything that hard,

just a fatigue crack, The same happened to the first rim these rims are just not designed for the constant weight and abuse they get even on a commuter, that this is. No off roading , no jumps etc. Not my style, this is just an every day road bike.

The constant 'pumping' in / out of the side walls, the rim just splits between the spoke nipple head holes.


Rebuild done this afternoon. Timelapse of the rebuild just uploading now

View attachment 3



View attachment 1

 

[NeilP]

I bet you could fit a 19 in it with a 2.0 or 2.25" tire. What spoke gauge are you running? If its 13, you will get better bicycle rim life by redrilling your spoke holes closer together and using 13/14 butted spokes.

Ehh? drilling spoke holes closer together? I used 13/14 on this last build with polyax nipples, so virtually no bend of the spook out the nipple.


I looked at that option last time. There are just no motorcycle tyres that I can find that are narrow enough the body of the tyre has to be no wider than 2.2 max. The last tyres I had were Crazy bob 's and they were i think 2.35's and they just cleared the frame. Are there any m/c tyres thinner than that?

 

[NeilP]

[youtube]2MhBpxPldaY[/youtube]

 

[The fingers]

I've taco'd a couple on the rear, but they were the cheap $19 steel replacement ones from the LBS. Usually a spoke breaks, then another, then a couple more and by the time I stop there's a birds nest back there and I'm doing the walk of shame. Lots of weight on the rear of my bike.