650b Blunt rim cracking

[Gat64]

I was cleaning my single speed commuter today and noticed cracks on every spoke hole of my velocity Blunt rear rim - none on the front. This would have been the third season of use, but I do put on a lot of kms - maybe a total of 10-12k kms on the set. The wheels have been great - no truing needed and dead straight (still is).

So, is this a reasonable life for a rim that is intended for mountain biking? My use has been on road it's whole life, but ridden hard (much climbing), and with light paniers on the rear.

If this does seem flawed, does anybody have advice for strong alternatives? I am a fan of the wide rims:
- Stans Flow EX
- DT Swiss M480
- Velocity P35 (but 35mm maybe overkill)

Cheers

[rice rocket]

So I'm assuming you don't have a brake on the rear?

I use Pacenti TL28s (http://www.bikelugs.com/store/index.php?strWebAction=item_detail&intItemID=343) on my MTB, they lace up super easy. It was the first wheelset I've ever built and it was a breeze, and has stayed true through my MTB use and plenty of crashes. They're eyeletted, which may help avoid some cracking.

[Gat64]

Yes, sorry - they disc. Those rims look like good Blunt replacements - same width. Thanks - they might just be the ticket.

So I'm assuming you don't have a brake on the rear?

I use Pacenti TL28s (http://www.bikelugs.com/store/index.php?strWebAction=item_detail&intItemID=343) on my MTB, they lace up super easy. It was the first wheelset I've ever built and it was a breeze, and has stayed true through my MTB use and plenty of crashes. They're eyeletted, which may help avoid some cracking.

[stuckey]

Drive side spokes? Velocity will warranty it, just e-mail them.

[Gat64]

Actually, it both sides - almost every one has a crack. And since it is a SS, it should have less stress on the drive side shouldn't it? Not being so dished?

Drive side spokes? Velocity will warranty it, just e-mail them.

[Peter P.]

The wheel could have been overtensioned. With the information you've provided, I can't conclude the rims are flawed in design or defective. I think it's worth relacing the wheel with the same spokes and an identical rim, just to see if it occurs again. After all, other than the cracking it sounds like you're happy with the rim.

Tip: Use an engraver to etch the build date on the inside of the rim, as I always do. That way you can keep track of how old the wheels are.

[Gat64]

That is what I was thinking, though the LBS that built the wheels are pretty experienced, though mistakes can happen I suppose. Doing a little research does show that there are cases like mine, but all all were MTB usage.

I have sent a note to Velocity to see what their response is.

Cheers.

The wheel could have been overtensioned. With the information you've provided, I can't conclude the rims are flawed in design or defective. I think it's worth relacing the wheel with the same spokes and an identical rim, just to see if it occurs again. After all, other than the cracking it sounds like you're happy with the rim.

Tip: Use an engraver to etch the build date on the inside of the rim, as I always do. That way you can keep track of how old the wheels are.

[oldpotatoe]

I was cleaning my single speed commuter today and noticed cracks on every spoke hole of my velocity Blunt rear rim - none on the front. This would have been the third season of use, but I do put on a lot of kms - maybe a total of 10-12k kms on the set. The wheels have been great - no truing needed and dead straight (still is).

So, is this a reasonable life for a rim that is intended for mountain biking? My use has been on road it's whole life, but ridden hard (much climbing), and with light paniers on the rear.

If this does seem flawed, does anybody have advice for strong alternatives? I am a fan of the wide rims:
- Stans Flow EX
- DT Swiss M480
- Velocity P35 (but 35mm maybe overkill)

Cheers

Rims need to be built properly, including proper(not excessive) tension.

I have built many Blunts w/o the issues you see. If you do replace, the second 2 mentioned would be good choices..I'd stay away from number 1(stan's anything-rim wise).

[Kirk Pacenti]

Rims need to be built properly, including proper(not excessive) tension.

I couldn't agree more.

Cheers,
KP

[pdxharth]

I just found similar cracks in my O/C Synergy rim after 1.5 years. Velocity's customer service is good, but this is my second replacement rim on the rear (first one was because rim was small and it was a challenge to get tires to stay on for mounting, which sucked for changing a flat in the rain!). Wheel was professionally built by reputable shop.

Previous rear wheel lasted a long time under the same conditions, so I'm getting a little frustrated with Velocity rims. Fingers crossed.

Good luck with your wheel - hope they replace that rim for you.

Cheers,
Harth

[Mr Cabletwitch]

I had a set of Blunts that I used for a total of 2 seasons of MTB riding. The rear showed cracks but I never had an issue with it. At the end of the first season I had a wreck and ripped a spoke right through the rim on the front which also showed cracks, so I had the rim replaced and by the time I got rid of the bike the rims were showing cracks again, but the only time I had a failure was after a pretty hard crash so I wouldn't worry about it too much. After that I went with a set of Stans Flows and haven't had much of an issue yet aside from some broken spokes on the rear.

[Hank Scorpio]

I had the same problem with an early pair of the A23's within the first season of use. Rear cracking only I inserted it into the trash and replaced both with a set of Belgiums that are going strong after two seasons of winter abuse.

[HillDancer]

...anybody have advice for strong alternatives? I am a fan of the wide rims:
- Stans Flow EX
- DT Swiss M480
- Velocity P35 (but 35mm maybe overkill)...
What size tire are you running? If nominal 42mm or wider I endorse the P35 for durability and side wall support (less slip angle for this tire width than when mounted on narrower rims).

I don't have experience with Pacenti's DL31 650b (http://www.bikelugs.com/store/index.php?strWebAction=item_detail&intItemID=408), but this rim should be strong too.

[Gat64]

I was running Gran Bois Hetres, but they were a little too tight in my frame with fenders, so I went to the 32mm Nifty Swiftys.

What size tire are you running? If nominal 42mm or wider I endorse the P35 for durability and side wall support (less slip angle for this tire width than when mounted on narrower rims).

I don't have experience with Pacenti's DL31 650b (http://www.bikelugs.com/store/index.php?strWebAction=item_detail&intItemID=408), but this rim should be strong too.

[HillDancer]

I was running Gran Bois Hetres, but they were a little too tight in my frame with fenders...
The Hetre will be 47mm + when mounted on the P35 and worn.

[Gat64]

Yeah - I loved them, but it was a no-go with fenders.

The Hetre will be 47mm + when mounted on the P35 and worn.

[grndskpr]

There have been a few sets of 650's run locally built by very well know por's. All have cracked and all have gone to Stans. It seems more prone to riders over 2 bills

[Gat64]

Update: Velocity has agreed to replace the rim under warranty! :banana:

Thanks stuckey for the suggestion to contact Velocity - it seems they have great customer service. Like I said, even though there are cracks forming, the wheel is still true after 2 years of many kms (aprox. 10-12k).

Cheers,
Scott