When I make a batch of bikes, some parts of it I know exactly what I want to do, totally committed. Then other parts take a while. While the basic structure has been worked out some time ago, some assemblies I am seeing for the first time. I wanted to align the forces more directly on the rear shock mounts and improve the clearence for turning the adjusters. I had an idea that I wanted to try that would not only increase the strength but also achieve the goals mentioned above.
From purely a engineering perspective this machine is really unusual. Not that it should be. It's just surprising that no one has "discovered" it as the new best thing. The shorter swingarm helps rigidity and because the chainstays do not have to "squeezed" so narrow they are still tube and stiffer than a narrower solid section. The whole rear of the frame weighs less than just the R9 swingarm. I am pretty sure it is at least 2 or 2 times the stiffness. I was able to move the bearings outboard quite a bit. I used to feel that narrower Q-factor was much better for making power. I still feel that way but the wider 83mm BB shells and Q factors make some good things happen. I am using these huge 30mm double-row bearings that are spaced a full 50mm apart with a 17mm axle. The drops are 150mm apart are MAXLE ready and are light and solid burl. Pinch bolts are NOT required on fully triangulated swingarms.
I slightly under-drove the shock to take better advantage of what new dampers have to offer. You can set this bike up tight at the ends of the stroke and it will sprint like a hardtail and take hits with grace and control. The low frame weight is a result of a drastic reduction of machined parts and hardware. The gussets have actually increased in thickness by 15%. The frame weight of these machines will allow a drastic reduction in the amount of work required to bring the bicycle up to speed. In addition, it's reduced initial leverage allows easier "lifting" to backside objects so much so that you can "pop" and fly over stuff with amazing ease. The chainstays aren't short with a tape measure but riding the bike, again because of the rearward pivot it feels short and very snappy.
Needless to say I am beyond excited to ride my F-bomb. I have all new parts on the way for my own bike and I will be attending races and tuning sessions so we can get dialed early.
For more on the evolution of the F-Bomb from FTW himself, first impressions and rider reviews and builds continue to check back here and on our Forum at
The questions, interest and comments about the new 2009 Sinister F Bomb from Frank The Welder has been incredible. Many of you have asked for more information about the build and the final design so stayed tuned for the 'Making of the F-bomb' series that we will be putting on the blog over the next few weeks. For now, download the PDF below to take a closer look...
Download F Bomb Dims_Final
Now that the start of the 2009 season is right around the corner, this series of posts will also include rider reviews and opinions and of course all those sweet builds. So keep checking back for more info or visit our forum:
Sinister Bikes Forum
Sinister Team Rider, Knight Ide, has been testing the prototype F - Bomb for some time. He has been providing FTW with design feedback and has written up a great technical review that he shared with us from Boulder City, Nevada.
Sinister Bikes recently unveiled the prototype of their newest offering at Highland MTB park’s end of the season party. There was quite a buzz created by the prospect of a new design from the legendary Frank The Welder. It was my first look at the F-bomb and I got pumped! My fervor could be attributed to the large amount of alcohol I had consumed, as was the 4 hours of dry heaving later in the evening. Beyond the inebriated zeal was a genuine excitement for a new Sinister downhill race bike
Imagine my level
of stoke when Bruce asked me if I would test it out during my upcoming trip to Bootleg Canyon in Boulder City, Nevada
F-bomb close up
Anyone who owns an R9 knows that Frank found the sweet spot for the pivot to eliminate pedal bob. Now imagine the same feeling on a bike that is four pounds lighter.
I didn't spend much time on BC’s gnarly jump lines but I did get a handful of runs.
The R9 is the standard against which I compared the F-bomb and that is a high bar to meet. Bootleg is a yearly destination for me so I was familiar with the trails and the Vivid is the same shock I run so I feel the comparison is accurate. Here's how they stack up.
I had heard that Mark had offered us the use of Highland for some test runs. Needless to say, I wanted to get the bike out and do some back to back comparisons between the R9 and the F-bomb. Max, one of my guys from the shop was kind enough to assist me as did Wilson who snapped a few pics.
First thing we did was get the new bike set up for Max's riding preferences. It wasn't too difficult as he built up the bike last week. We knew already that it pedals really well so I loosened the damping quite a bit to start with. I don't think the same settings would work on a normal day, it was 20 and the wind was blowing.
I had Max session some rough sections that had been shreaded by riders in the rain and had frozen that way. The bike tracked awesome and had no tendency to pack or drift in high frequency stutters. We headed to a nice steep rock garden and noticed the fork was soft and we were a bit deep in the front travel but it was OK. Same thing, he drilled it several times on both bikes.
We then worked on some slow sprints through the rough,
then we sampled a section of hellion (a new BMX top to bottom run) Max was able to nail a step-up twice, one he had never cleaned before. He then fired off several runs over a BIG jump into a steeply banked, very rough turn.
Here are my findings from this brief early test.
Pedaling, someone who has ridden more bikes than I will have to be the judge. It pedals very flat with no chain growth or torque reaction at all.
Rock gardens It's very good and easy to change lines, no drifting and minimal speed loss (this is something to watch other bikes for) We didn't find the big square edge we were looking for but so far, so good. I also feel that the slacker head angle has a nice effect in extreme steep and rough. We ran very small tires (not the 2.7's that it was weighed with) and it was very fast in the rough.
handling the flickability of this bike is amazing. I watched Max over do bunnyhops and side moves, the bike responds quickly and effortlessly. It turns well and compresses far less that the 9 in big g-outs.
Summary Max loves the bike and I felt like I could ride extremely fast with confidence. While the straight-rate rear shouldn't be as plush as the 9, perhaps the greatly reduced un-sprung weight had major effect. Could be the shock is tuned to open bypasses at lower pressures, I don't know but it works very well even in freezing temps. As you know the frame is under eight lbs. with a steel spring shock. it's made from the same tube as the R9. It just has has less machined parts and only one small steel bolt and two double-row bearings. I have major confidence in it's construction and it's freakishly stiff with ZERO flex in the rear stays ...ZERO... and it's apparent the moment you nail the gas. I really can't wait to see people ride this and try to keep a straight face.
Thanks to Mark, Max and Wilson for todays efforts, thanks to my sinister family for the fire in my belly and thanks to the future F-bomb owners who have supported this rewarding effort. I tip my hat to you..
As we mentioned, since this is the prototype design, we will not be releasing too many specifics until we get closer to the production model. Many of you knew FTW was working on a new design and we couldn't wait to release some image!!
As far as the design intent and dims...hear it from the man himself
The proto frame is a small, the chainstays are 17.5" and the head angle is 65 where is sits now. That may change when I see where the fork rides in it's range. As with any design I do, I am looking for something in the overall performance....good weight balance, the right grip under braking and tracking through bumpy turns. One of my goals upon starting this bike was to build a bike that would be faster and easier to ride fast.
Right now, I expect to pull the head angle in about 1/2 to one degree from where it is now in the range of fork adjustment you can only go slacker...perhaps a degree steeper. The cool thing about the F-bomb is the tubing is still burly and the parts are not creepy thin.
It's so friggin stiff my Ridge is not stoked
Keep checking back, there will be more to come
Mark and the Crew put on another great end of year video party last night at the Highland Mountain Bike Park. We want to thank them for allowing us to roll in the Prototype Model for the New Sinister Downhill Race Bike. We couldn't think of a better place to unveil the new FTW design especially in the presence of our team riders Dane, Knight and Sasha (Heal up D-Rock!)
The F - Bomb is another stunning creation from Frank "The Welder" Wadelton and will be available in 2009. We will be releasing specs on the F - Bomb later this year following the extensive testing of the Prototype Model that is currently ongoing.
We have been getting a lot of requests for Gruitr demo rides and rider reviews. We know that you all can't be on the East Coast to meet up with one of the Sinister Crew, but we will do our best to put you in contact with someone in your area so get hooked up on the Forum and ask around. As for the review, we welcome you all to take a minute and let us know what you think. There is a lot in store for the Sinister Family so keep checking back and we promise you won't be disappointed. For now, here is an excellent review from one of our local riders and from FTW himself. If the reviews are any indication of the ride you can expect from the GRUITR you should try one out TODAY!
Thanks to our friend Transition Man for the most comprehensive review yet!!
"OK I finished the Gruitr on Monday and took it out today for the maiden voyage at Lincoln Woods. Started off with a quick little bump around in the parking lot area. Immediately I could feel a weight difference. Took a few little jumps to make sure the shock had somewhat near the proper air pressure. Then I rode a couple sit down wheelies to get a feel for the rear end. Let me say that the stays are nice and short and the bike balances better than any FR bike I have owned.
We started up the warm up trial which has a decent climb. Right off the bat I could tell that the bike was going to climb extremely well. I played with the propedal function and played with the rebound a bit. The first decent was a little different than the BR handled usually does but felt good. Mostly I was trying to find the balance point and get a feel for the different geometry.
After a couple more trails I started to feel comfortable and the bike was starting to become more predictable. We hit the sketchy trail and that was the test trail. There are a couple of drops on that trail that really let you know if the bike is performing. We hit it every ride so I really know how the impact feels on other bikes. The one drop in particular has a roller-drop rock where I usually have to really lean back to land both wheels together. This time I leaned back just slightly and leanded rear wheel first. The next little section usually bounces you around and I just leaned back and pumped through.
As the ride went on I could really notice differences in climbing. Not once did I break traction with the rear wheel and I was trying to. It climbs so well I thought I was on my old Merlin XC from years past. Front end comes up easy to get over stuff and the weight is awesome.
So what's the differences? First off is weight. The bike feels nimble, maneuverable and very pedalable. Second is geometry. The slightly shorter stays and longer tt is exactly what I was looking for. Third is that the bike climbs very well. Decending the wheels stick to the ground and the suspension soaks up everything. I had it in the 5.5" setting to start with. Similar to the BR, it feels like more travel. All in all the bike is exactly what I was hoping it would be. The frame is a little flexier than the BR, but that was expected. By no means is over flexy or even flexy really. Just slightly more than the BR.
All in all I am totally stoked to have it. I can throw on some single ply tires and go for a XC ride no problem. Now I have a tough decision as to which bike to bring to Highland. Thanks again to Bruce for answering all of my questions along the way.." Look at this sweet build!!
And Yes...from FTW himself!!
"I got my Gruitr rolling finally (thanks max and Bruce) and took it yesterday and rode Kenda bikefest. The build was a typical FTW XC build, MTX wheels, DH cranks, heavy wire bead tires and a Pike up front. Typical because I don't usually ride light parts. The first shocker of the day is the bike rode really light. It was hot,raining off an on and the trails were slippery. Normally, I would feel tangled in such conditions, glasses fogging etc. The Gruitr had me feeling good, weightless one might say. Getting used to a new machine first on a paved, steep climb then on a fresh-cut single track isn't the best conditions. I took to it pretty quickly. It's pretty hard to go wrong with a basic SP bike but none the less, I wasn't going to go easy on it. The bike stayed tight and solid in the worse conceivable conditions with me absolutely torquing with all "me worth", drifting and sliding the muddy trails. I was able to pop the front up at will and whip the thing around as needed.
The bike was good but until I got into some really sketchy stuff that I felt my first "connection". It was steep, really steep, off camber, roots, full gnarl and I was able to hold my line and from full stop, pop and drop to the firm ground at the bottom..amazing.. pics soon, good job men! I got home and weighed her for the first time..35 lbs..I am like, stoked as they say.."
Visit the Sinister Bikes Forum for more ride reports and great builds...you'll like what you see
Hey how's Derek doing????? A lot of you have been asking for updates on D-Rock's condition after he fell from the sky at Highland a month or so back. As you would expect Derek is on his way to recovery and still busting balls on the forum... We wish Derek a speedy recovery and look forward to having him back SS and on the DJs soon!
Ahhhh where do we begin..hahahaha
So went to my knee specialist today and gave him some more of my money in exchange for some good and BAD news.....good news i can walk and do some light duty crap...woooo hooo!!!....oh and the pills arn't bad either...lol
and of course the bad.....my PCL is completely gone and will take surgery to fix..my ACL and MCL are frayed/sprained etc and swollen...one wrong little fall or careless anything will tear them very easily and then will require surgery for those too....but as far as right now i will be starting physical therapy next week for 6-8 weeks and then if things haven't improved then i go under the knife for sure......so no biking and unfortunatly no snowboarding either this winter....and if i have to have everything replaced in my knee then prolly no biking for a season or two...so no good news either way...
oh and i forgot to mention the hairline crack in the lower part of my femur near my knee that they failed to see in my first round of X-rays and my miniscus between my upeer and lower leg being effed up.....ahhhhh lets just keep em comming for christ sakes...lol peace kiddies
Derek is all over the forum so give him a shout. Heal up Bro!!!