AKAIGAWA TOMO Challenge Cup report

Unfortunately, last year’s fever of the Red Bull Pump Track World Championship didn’t quite come back here this year as the Japan qualifier round in Hokkaido was canceled. To save the locals from the loss and tears, the venue and several members of the local scene have made it happen within the community, and that’s what I was up to a weekend ago.

The race format was the same as the Red Bull event, where there is a single timed run for the qualification round and then a pursuit style dual for the final tournament.

Result-wise, the top two places subject to awards were both taken by the Niseko crew. Fast, consistent and awesome riders.

For myself, despite quite a bit of improvement since last year and some confidence, a series of errors got me eliminated in the first round of the finals. A lot of my friends seemed to have expected me to win, but I just couldn’t cater. Too bad, but lessons were learned nevertheless.

(Hey white line, I haven’t seen you in a long time…)

This is where the biggest losing factor was. I had only been riding here trying to maintain as high cruising speeds as possible from random rolling starts. In this race setup, on the other hand, you need to pedal hard for a few seconds from a still start, then switch to the pumping mode instead of pedaling. I know, it’s something totally basic and I really should have known.

Regardless of the failed start and an accidental french kiss by the stem against my jaw when absorbing a bump, I had to push, and I chose the “jump whatever you can” tactic I came up with this year. They say jumping exhausts you less than pumping, so I just decided to subscribe to that. However, it’s a known fact that manualing and jumping will slow you down if you are just barely keeping the front end up or clearing the distance. I have improved my pump manuals in the last year, but there seems to be way more to learn about jumps. At least I’ve figured something out about race style jump techniques after watching tons of BMX race footage on the next day and onward, and I’m excited to try them later this year.

By the way, there are like 52 roller bumps on this pump track at Akaigawa Tomo Playpark. If you doubled everything, that’d be 26 jumps in a lap. Among which, I managed to make 13, exactly half of them. Considering that there were only three sets I could double around the end of last year, it’s at least some progress, even though I’m still in the “just barely jumping and clearing” phase.

Usually it costs 1,400 yen to ride the course for two hours, but the organizer kindly set a rule to let us ride for hours after the race. At first I was like, “who would actually want to keep riding after a race?” but as it turned out, I was steaming carbon monoxide from my ears when the race was over as I was so far from happily burned out. So despite the drippy weather, some other participants, friends and I ended up riding a lot. I had also brought our official test bike in the Night Forest colorway, and the people there got to try it, from pros to casual bike lovers, leaving quite favorable reviews.

And by favorable reviews, I really mean it. In comparison to, say, model P from company S, J from SC, and T from T, which are all like new, actually really nice bikes produced by large companies that have spent tons of money in R & D, our Tanatos was reviewed as nothing lesser. Or rather, as those who had a taste would occasionally say, actually even better, like, crazy maneuverable, fun, rad, like, wow.

Another discovery came along with a pointer from a friend of mine that the general public may be misled about the rad-/dope-/craziness factor. Apparently, people are scared that such an infectious rad crazy dope ride shall turn their chihuahuas into pit bulls when you buy the bike and casual cruises into bloodbaths when you ride it.

So let me elaborate a little. Certainly, the street/dirt jump/skate park/pump track MTB is a niche genre, within which there have been a number of models with distinct crazy deviant characters in both good and bad ways. Also, it is true that there are many parts of the Tanatos frame that you may call “deviant” based upon bike design norms at the time when I designed it. However, all that “rad deviance” we employed is for the sake of creating a bike that reacts linearly to rider’s input and maximizes the fun of controlling the bike. Just like a good pair of scissors that makes it easy and fun for anyone to cut things precisely, the foremost objective here is to design and make a product that allows you to explore your imagination to whatever extent you may conceive.

Self promotion gets boring so it’s done. Let’s talk a bit about other bikes as well. Amidst the heat of bike swap sessions, I had a chance to try several BMX racers, and they were great fun. Personally I don’t need anything other than our very own Tanatos for my kind of riding on the street and at dirt jumps, and I’m pleased with its versatility to shred in other situations such as at the MTB park at Bankei. Still, the world of 20 inchers like BMX and BTR that have a way bigger maneuver space is somewhat special, fun, and can teach you a lot. For myself as well, there have been so many things I couldn’t have learned, both riding-wise and product design-wise, if I hadn’t been riding BMX bikes pretty seriously at some points. If you have the desire to enhance your bike riding experience with more bike control, this is one great way to do it, whether your main ride is a road racer or full-sus MTB.

So as a whole, despite the sketchy race results on my part, it was a great session with lots of discoveries through fun interactions with the good fellows. Big thanks go to those I rode with, those who cheered, those who captured, and those who elaborated the event and made it happen.

July & August digest

It’s been a pretty good year for me riding-wise.

My left ankle had been in a terrible condition since 2014, but surgeries and rehab seem to have finally started to pay off. Though I’ve been riding bits of street as well as some downhill races in the past five years, those riding days were never complete without tons of taping around the ankle beforehand and crippling pain afterwards. Besides, the pain was a close friend of mine in everyday life that never left me alone on short walking trips to the local supermarket.

That was then and this is now. I’ve recently been spending more time at dirt trails than ever before. And I’m healthy enough to press the clutch pedal on the way home.

(Photo: Hitoshi Watanabe)

However, there is this annual bill you have to pay. This time, it was a metatarsal bone, broken in a stupid daily life accident.

Luckily there was no misalignment where it was broken, so the doctor just taped two toes together to stabilize the part. This was great, as I could just use some masking tape lying around and change it daily. No pain, no discomfort, and no downtime.

Above photo of me jumping was shot about three weeks after the injury, when I was about to forget it. Now at eight weeks, there is no issue whatsoever and I’m soon to completely forget about it.

I realized recently that I don’t tend to remember small injuries in the past. I have a favorable take on that phenomenon, that the brain holds periodic cache cleanup campaigns so as to use its gigabytes for new, fun things instead of the old and painful.

There are several other stories to tell about how I’m relearning pump track riding and dirt trail digging, but let’s save them for later opportunities for now. Anyhow, I hope this summer has also been a fun one for y’all.

Spinner fork actually compatible with 27.5” wheels

Sorry, this article is only available in 日本語.

Tanatos frame actually compatible with Shimano cranks

When we conduct street interviews on Tanatos, the ultimate street MTB frame from our very own Libido Bike Co., we hear voices like these:

  1. “What’s street mountain biking anyway? I’m only interested in pump tracks, dirt jumps, slope style and skate parks, but not that one.”
  2. “They say the top and down tubes are triple butted and the whole frame is post-weld heat-treated to ensure optimal strength and toughness to be expected from chro-moly, right? Yet, the 2.5 kg weight of the frame is way sinful from my lightweight equipment fundamentalist’s viewpoint and thus to be persecuted.”
  3. “Yeah, that one. That stuff with all the nightmares when it comes down to parts to assemble on, huh? Especially, the BB and crankarm area are designed with BMX parts in mind, but I’m a MTBer so I’m clueless.”

Certainly. Let me explain.

  1. Street riding is literally where you jump off stairs, ride walls and so forth in the streetscape. Key points and features in equipment design are almost perfectly identical to those for pump, dirt, slope style and park. Spot on.
  2. Sorry, that was a design error. If only we designed it to weigh around 2 kg just like other aluminum frames intended for similar use, folks would have snapped the frames in several months to several years just as in other companies’ frames when ridden on the street, making us richer thanks to replacement demands. However, many who have had a chance to hop on ours have said “light and agile,” while none has said “heavy.”
  3. We’ve got great news for you today. The Shimano cranks fit.

Yes, you heard me right. Tanatos can actually accommodate MTB cranks made by Shimano. That also means there are rooms for you to try and fit other stuff like RaceFace as long as the spindle size is the same 24mm. Let’s take a look at some photos from our installation test.

Here are the parts required and points to note for the setup:

  1. Grab a 6805-series BB bearing set (= basically Shimano BB minus cups) for the bottom bracket
  2. 24mm ID spacers are needed for crank position adjustment
  3. Use a “Chain Line 3mm Outboard (2×11-speed)” crankset, a.k.a. Boost-compatible model, available in XT and SLX component series
  4. Use the original 24T or 26T front sprocket
  5. Choose any rear sprocket, typically 11 to 12T

Now let’s cover all the details.

#1, BB bearings.

Though you could hammer the bearings out of threaded Shimano BBs, there are tons of identical bearings w/ ID sleeves sold after market, so why not get them? If unsure what fits, whisper these magical words: “for Trek’s BB90.”

On the right you see the bearings with 24mm ID sleeves I got for this.

The plastic sleeves had a flange larger in diameter than the bearing, which need to be trimmed. To any size smaller than bearing OD. There seems to be a design intent to add extra sealing, but it’s just optional. The definitive sealability is ensured by the bearing itself.

Thus, there is no need to fine-trim it like this. I just wanted to, being hyped for the demo assembly this time. Then, press in the bearings and you’re done. Much easier than BMX-type BBs where you need to insert a metal sleeve between the bearings.

#2, spacers.

You will also need some 24mm ID spacers, which, again, you can just buy anywhere, whether being genuine Shimano parts or aftermarket. Your BB kit may also include some. You’ll need about 10mm thickness in total. If you’re a handy type, you could chop some 24 ID piping into spacers, turn stuff on the lathe, or even find 15/16″ washers that fit. By the way, 15/16″ may sound like but not really is such an odd number: you’ll find it in most BMX sprocket bores as well as brake master cylinders on some sports cars like 32 skyline, JFYI.

Sorry for the messy notes, as I was juggling between Boost-compatible and non-Boost cranksets. Anyhow, the final spacer setup was 7mm on the right and 2.5mm on the left. Though slightly dependent on individual frames, these are about the right numbers that ensure sprocket-to-frame clearance, correct chain line, equal Q-factors between right and left, and maximum engagement of the left crank arm onto the spindle. Which means, you can add a few millimeters worth of spacers if desired.

You get this much clearance with a 26T. As bike frames and parts deflect under stress, you’ll need at least about 1mm gap here. Currently it’s around 1.2mm.

Chain line measures at 49mm, matching that of 50mm at the hub. Roughly put, larger differences like 3mm or 5mm may (depending on the chain and sprocket) cause issues. Although, some people ride with like 10mm offset, and no instant failure is likely. That 1mm here is, from the bike engineering point of view, within the tolerance range of zero.

Then #3, the entree, the crankset.

B is your lucky letter of the day. It means it’s dedicated by the global giant Shimano to Li”B”ido Bikes.

This Boost specification is essential, as sprocket/frame interference will be an issue otherwise. If you avoid it by adding more spacers, you’ll run short of the engagement margin on the left crank. So just stick to the gift of “B.”

That’s it.

I kind of over-elaborated on it for the fear of misunderstandings, but it’s nothing more than a breeze for pro shop mechanics to assemble Shimano cranks on our frames.

*More unnecessary extra information from here on*

So for the black magic approach to just make it work, you’re all set. In case you had more whys and hows in your curious mind, I’m addressing further details below.

The keys here are BB standards and bearing compatibility.

Let’s start from basic industrial knowledge. Industrial bearings are standardized respectively for metric and imperial series with several selected ID and OD sizing. Application-specific standards like bike bearings may come with larger or smaller ID than normal, but still are based on some standard sizes in most cases. Among such standard OD sizes is 37mm, which applies to both “Spanish” BB bearings employed on Tanatos and Shimano’s Hollowtech 2 bearings, albeit the different IDs.

Now about BB standards on frames that accommodate them. I actually learned recently that the BB shell I designed for Tanatos is quite similar to the “BB90″ standard from Trek.

Here’s my take on what BB90 is. It’s an integrated BB shell combining a threaded shell and outboard bearing cups. Historically, 68/73mm threaded shells were the golden standard for some time, which housed loose-ball bearings inside. However, through the transition from skinny, square tapered spindles to the fat and hollow ones for the sake of greater rigidity marketed by Shimano, the bearings were eventually chased out of the shell and found home outboard. The Hollowtech 2 era comes. In terms of bearing placement, it’s similar to traditional headsets, despite the difference of press-in and thread-in cups. Now, someone may have thought, “why not integrate the external bearing housing part into the frame as in the recent headtube innovations?” and voila, that renders about the exact dimensions of BB90 on the drawing board.

The BB90 and the “Spanish +” on Tanatos share the same 90mm shell width and 37mm bearing OD, with the only difference being the press-in depths. 7mm-wide 6805 bearings are used for BB90, while we use 9mm-wide 6904-based Spanish bearings. BB90 features flush mounting, while we press bearings 10mm in (1mm recess from shell edge), so there is just 3mm difference on either side if 6805 is pressed into our shell. Now, it’s so simple – just add spacers.

There also is an opposite hack called “Shimanish BB” where you press 6904-series bearings onto Shimano’s outboard BB cups to accommodate BMX cranksets. Either way, parts selection is key to success, in such manner as to ensure proper chain line, Q-factor, etc. For Shimanish, BB spindle length is probably the biggest requirement. For our case, front sprocket/frame interference was the highest hurdle, which just became solvable thanks to the release of the Boost-compatible cranks. I really appreciate all the requests, hints and information I have received from people that led to this fitting test.

The parts needed for this setup, like the BB bearings, are not our regular stock. However, there may be cases we can help you with if procurement is too difficult for you. Please don’t hesitate to ask.

Happy press fitting, everyone!

Real cause of recent tailgating craze

Sorry, this article is only available in 日本語.

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