Tech Tip: A Simple Cassette Modification That Could Save Your Rear Wheel
by Steve Wentz
Every year there's a new race schedule, new parts, new bikes… lots of cool stuff to drool over. I'm lucky enough to be able to go to some races, ride my bike and have good times with friends. One of the things that I definitely DON'T like is having to do is unnecessary maintenance on my bike. I like that my suspension is awesome, my frames are strong, and my brakes slow me down when I get scared so I can just focus on riding. However, rocks, stumps, and my own mistakes can and have made my back wheels go out of whack from time to time. A wobbly wheel and loose spokes in turn can cause far worse problems, especially with a downhill bike.
This tip is particularly effective for downhill bikes, but four-cross, slopestyle, dirt jump, freeride and even enduro bikes can benefit from it as well.
We've probably all had a wheel eat up a derailleur that goes too far over into the spokes - it literally sucks. This is the last sort of thing I want to ruin a ride or race. To alleviate this potential fun ender, I've been doing the following modification to my bikes over the past few years with great success. I hope this may be able to help some other riders as well.
This is usually free, simple, and not that hard to do. But, I've also got to say that SRAM does not condone this. The cassette was designed to be run with all 10 gears (or 9, depending on the model) and this technically voids the warranty. However, I speed sometimes in my car and I'm not supposed to do that either.
Here is how close a normal cassette setup gets to the spokes on a rear wheel. Not much room. This is the same for 9 speed or 10 speed, SRAM or Shimano. Everything butts up against the end of the freehub, which is very close to the spokes.
For this trick to work, you'll need to use a cassette that comes in multiple pieces. I like using the SRAM PG-1070 cassette because it has some individual gears down low that I can sort through and take out if needed.
Here is what the modified cassette looks like. In this case, I've taken out the 13 tooth cog on the cassette, which allows the rest of the cassette to be shifted over, away from the spoke. Note that there is considerably more room between the derailleur and wheel.
I like the 11-25 spread for DH racing, and now the cassette goes from the 14 tooth cog to the 12, then 11. If I happen to be motivated enough to pedal at 30 mph, that last thing I am thinking of is "am I on the 12 or 13 tooth cog in the rear?" Because my mind is usually concerned with not beefing it, I've never noticed a gear gone from my spread. I replace that lost cog width with a spacer between the 25 tooth cog and the wheel. This makes more space just in case the wheel gets out of whack, I hit something, or who knows what happens in a DH race.
With that extra room, make sure you adjust the limit screws on your derailleur so that the chain won't pop back between the spokes and the cassette. If it does (this happened to me once when I didn't adjust the limit screws correctly) I was able to just shift to a harder gear and the chain came right out without getting jammed.
Be sure to check the limit adjustment a few times, both with the chain off (easiest) and then with the chain on to double check.
Look at all that room! There is now more clearance between the spokes and derailleur. If the wheel gets out of whack or if you happen to smash the derailleur into a rock on accident, it's much less likely to get caught in the wheel and wreak more havoc. As an added benefit, this trick also provides you with a straighter chain line in all the gears you're likely to pedal hardest in.
I hope this trick will help us all keep the mechanicals to a minimum. I went through all last year with a couple of rims and few sets of brake pads. Not bad in the scheme of things. With a few small tweaks to your ride, you can be in the same boat too.
Have a quick tech tip that'll help save a ride from unnecessary mechanicals?
Spread the love and share the knowledge in the comments.
bturman 11/25/2012 8:15 AM
24 comments newest first
The point of the tip is not to keep the chain or upper derailleur pulley out of the spokes, as some of the comments would lead you to believe. This is valuable for the lower pulley and cage of your derailleur interacting with the spokes when either your derailleur or wheel gets out of sorts.
When the going gets tough, the tough get going.
That being said, thanks for providing everyone in the shop today a good laugh.
And maybe a guy as fast as swentz can get away with not running that highest gear (I've tried chasing him before and know he doesn't need it) But for the rest of us mortals its nice to be able to pedal the open sections. Especially given the trend in bike to get lower and lower, requiring smaller and smaller front rings.
PS: It also helps if you build your wheel the right way. Drive-side trailing spokes heads in. The makes it so that the trailing spokes wont drive the chain down further into the freewheel during rotation, but instead push it up. One, this is the way Chris King requires wheels to be built around their hubs, and second, this will also make lacing your wheels easier. When you get to putting in the last 16 spokes (if you use the "Sheldon Brown Method"), because you push the spoke from the inside out, you don't have to weave the spoke in between all the spokes to get your cross.