January 2024
Box Two Prime 9 drivetrain
25/01/24 23:20 Filed in: Gear
Close to 20 years ago now I bought my first 29r. A titanium hardtail with XT bits providing the gears and stopping. That was my race bike until I got a full-suspension bike for that role and the hardtail was modified to be a singlespeed. Then about 3 years ago I bought a new singlespeed and the titanium bike went in storage. It came back out just before Christmas to become my son's new bike. But he needed some gears.
Box is a company that was known for making high-end BMX gear. They decided to get into MTB and eventually released four levels of related drivetrain components that are all 1x9 (Prime 9 = 1 x 9). The top one is quite expensive and called Box One. The cheapest one is not very nice looking and is called Box Four. The Box Two pieces aren't quite as flashy as the Box One, but much lighter and nicer than the Box Three level stuff. Seems like Box Two hits the sweet spot. Especially when it is on sale when you need it!
One small box contained the derailleur, the shift lever, the chain, the cassette (11-46 range), some cable housing and a shift cable. Instructions were provided online either written or YouTube. It all went together really easily. It did require a lot more B-tension than I expected to keep the upper jockey wheel from hitting the low gear teeth on the cassette. And when I was finished it was not shifting nicely into the second-lowest gear when coming from a higher gear (but it was fine from the lowest gear). No adjusting could quite get rid of that.
I checked the derailleur hanger and it was not perfectly lined up with where it should have been. Once that was fixed, then the shifting was perfect.
In use, the Box Two items work really well. I did find that the amount of pressure required on the shift lever reflected the gear the bike was in - some strange relationship between cable tension and lever effort that suggests Box hasn't nailed every last aspect of their design philosophy quite yet.
It was also my first exposure to anything in the CUES line from Shimano. I put new cranks on the bike because the new owner didn't need my old 180 mm cranks but by remaining in the Shimano brand I didn't have to change bottom brackets. The CUES crank preloads like a SRAM DUB crank, except there is no locking mechanism for the preload collar.
Only having 9 steps for most of the SRAM Eagle gear range means the steps are wider. In use, that seems OK. Especially for a fun bike. XC racing might benefit from more options, and any decent downhill slope (whether XC or Enduro or anything) would benefit from the 10T high sprocket the Box cassette lacks. But for a fun bike, it's great and you pretty much know what gear you need to be in at any time. Given that the entire box-set (pun intended) cost about the same as an XT cassette, it can't be just as refined and light as Shimano's second tier offering.
I like this brand. I'll be curious to see how it fares with use. I'm betting OK.
Box is a company that was known for making high-end BMX gear. They decided to get into MTB and eventually released four levels of related drivetrain components that are all 1x9 (Prime 9 = 1 x 9). The top one is quite expensive and called Box One. The cheapest one is not very nice looking and is called Box Four. The Box Two pieces aren't quite as flashy as the Box One, but much lighter and nicer than the Box Three level stuff. Seems like Box Two hits the sweet spot. Especially when it is on sale when you need it!
One small box contained the derailleur, the shift lever, the chain, the cassette (11-46 range), some cable housing and a shift cable. Instructions were provided online either written or YouTube. It all went together really easily. It did require a lot more B-tension than I expected to keep the upper jockey wheel from hitting the low gear teeth on the cassette. And when I was finished it was not shifting nicely into the second-lowest gear when coming from a higher gear (but it was fine from the lowest gear). No adjusting could quite get rid of that.
I checked the derailleur hanger and it was not perfectly lined up with where it should have been. Once that was fixed, then the shifting was perfect.
In use, the Box Two items work really well. I did find that the amount of pressure required on the shift lever reflected the gear the bike was in - some strange relationship between cable tension and lever effort that suggests Box hasn't nailed every last aspect of their design philosophy quite yet.
It was also my first exposure to anything in the CUES line from Shimano. I put new cranks on the bike because the new owner didn't need my old 180 mm cranks but by remaining in the Shimano brand I didn't have to change bottom brackets. The CUES crank preloads like a SRAM DUB crank, except there is no locking mechanism for the preload collar.
Only having 9 steps for most of the SRAM Eagle gear range means the steps are wider. In use, that seems OK. Especially for a fun bike. XC racing might benefit from more options, and any decent downhill slope (whether XC or Enduro or anything) would benefit from the 10T high sprocket the Box cassette lacks. But for a fun bike, it's great and you pretty much know what gear you need to be in at any time. Given that the entire box-set (pun intended) cost about the same as an XT cassette, it can't be just as refined and light as Shimano's second tier offering.
I like this brand. I'll be curious to see how it fares with use. I'm betting OK.
Braking bumps
23/01/24 21:16 Filed in: Riding
What a difference a couple of weeks can make!
I spent a week at Thredbo ending just a few days prior to Christmas Day. There were zero braking bumps and very little trail damage of any sort. It was very pleasant really.
And then I returned on January 7. Braking bumps were everywhere, even in places where no one needs to be braking. Big holes on the trails in weird spots. There is this really fast descent off the Gunbarrel chair that was very rough before the holiday season and was completely, hand-hammeringly rough by the first week of January. Luckily it ends on a fire trail which is a great place to shake the hands out before heading into the next bit of singletrack. And this was on my DH bike, which is markedly more gentle on the hands than my Enduro bike (I really noticed it by riding them on consecutive days).
Braking bumps form on dirt due to the way a tyre under braking has a resonant frequency; the tyre is excited by a bump and hammers back into the ground immediately (creating a low spot) which leads to the next high spot, and so on. I noticed when everyone was on 26" DH bikes that riding a 29" Enduro bike on those trails that the big wheels would not "fit" in the braking bumps, so it was quite smooth. Now that almost everyone's front wheel is 29", all the tyres fit all the bumps. The solution is to either pick a line to the side of the braking bump line, or to hit the bumps fast enough to skip over the tops of the sequence. Neither is an option on some lines, but most of them permit one or the other.
Unfortunately, braking bumps are self-reinforcing. You see them, you ride into them, they are so rough you grab a handful of brake, and you then contribute to making them bigger and longer. Or you try to ride beside them with a handful of brake and you contribute to them getting wider. The only solution is no brakes. Which is admittedly very difficult in certain places.
The other thing I noticed in January was the many large holes high up in the berms. I think these are caused by the sheer volume of tyres running under high force up there, breaking the hard dirt surface layer and leaving behind a softer hole that can erode more quickly. Some of them are pretty bad but I was able to either go just above them or, thanks to the DH bike, right through them.
I spent a week at Thredbo ending just a few days prior to Christmas Day. There were zero braking bumps and very little trail damage of any sort. It was very pleasant really.
And then I returned on January 7. Braking bumps were everywhere, even in places where no one needs to be braking. Big holes on the trails in weird spots. There is this really fast descent off the Gunbarrel chair that was very rough before the holiday season and was completely, hand-hammeringly rough by the first week of January. Luckily it ends on a fire trail which is a great place to shake the hands out before heading into the next bit of singletrack. And this was on my DH bike, which is markedly more gentle on the hands than my Enduro bike (I really noticed it by riding them on consecutive days).
Braking bumps form on dirt due to the way a tyre under braking has a resonant frequency; the tyre is excited by a bump and hammers back into the ground immediately (creating a low spot) which leads to the next high spot, and so on. I noticed when everyone was on 26" DH bikes that riding a 29" Enduro bike on those trails that the big wheels would not "fit" in the braking bumps, so it was quite smooth. Now that almost everyone's front wheel is 29", all the tyres fit all the bumps. The solution is to either pick a line to the side of the braking bump line, or to hit the bumps fast enough to skip over the tops of the sequence. Neither is an option on some lines, but most of them permit one or the other.
Unfortunately, braking bumps are self-reinforcing. You see them, you ride into them, they are so rough you grab a handful of brake, and you then contribute to making them bigger and longer. Or you try to ride beside them with a handful of brake and you contribute to them getting wider. The only solution is no brakes. Which is admittedly very difficult in certain places.
The other thing I noticed in January was the many large holes high up in the berms. I think these are caused by the sheer volume of tyres running under high force up there, breaking the hard dirt surface layer and leaving behind a softer hole that can erode more quickly. Some of them are pretty bad but I was able to either go just above them or, thanks to the DH bike, right through them.
Shoes impact your suspension…
19/01/24 22:44 Filed in: Riding
Wait.
What?
How?
I can remember reading at the time when World Cup DH racers were all changing to clipping in that they sit more central in the bike and therefore distribute the load more evenly across the front and rear suspension. Compare that to the same person riding flats who will drop their heels more, pushing their weight further back and loading the rear suspension more and the front less.
I had visible evidence of this after my recent trip to Thredbo on the Sender DH bike with Mallet pedals attached. At the end of the day the fork o-ring was right up at the full travel mark while the shock o-ring was nowhere near the full travel mark. Usually I see the reverse and leave that extra air pressure in the fork for "contingency" issues.
This was despite making a concerted mental shift on every run to attempt to ride just as if I had flat pedals under my feet. Over the day I never achieved that "same" feeling.
A bicycle is more than the sum of its parts. Choices have impacts in the least expected way sometimes.
What?
How?
I can remember reading at the time when World Cup DH racers were all changing to clipping in that they sit more central in the bike and therefore distribute the load more evenly across the front and rear suspension. Compare that to the same person riding flats who will drop their heels more, pushing their weight further back and loading the rear suspension more and the front less.
I had visible evidence of this after my recent trip to Thredbo on the Sender DH bike with Mallet pedals attached. At the end of the day the fork o-ring was right up at the full travel mark while the shock o-ring was nowhere near the full travel mark. Usually I see the reverse and leave that extra air pressure in the fork for "contingency" issues.
This was despite making a concerted mental shift on every run to attempt to ride just as if I had flat pedals under my feet. Over the day I never achieved that "same" feeling.
A bicycle is more than the sum of its parts. Choices have impacts in the least expected way sometimes.
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