Rearward weight bias, frame sizing and stem length question.
I've been testing medium and large Norco Bigfoots and seem to be right between sizes. This is always the case for me and I have a pretty good handle on the pro and cons on my trail bikes but am new to Fat Biking
and am unsure of the tradeoffs on snow, which is the primary reason I'm buying one of these bikes.
I have bad knees so I tested them with a laid-back Thompson post with 16mm offset and one of my extra saddles, which I slid all the way back in the rails. This is how I ride all of my bikes and it puts a lot of weight over the rear wheel.
There is a 2cm difference in top tube length between the medium and large. I assume if I bought one or the other I'd run a stem longer than the stock 90mm on the medium and shorter than 90mm on the large.
Any thoughts as to which would be a better choice for riding on snow?
I spent some time searching this forum today and seems to get mostly hits about bar length but did find this statement:
"If you're riding a higher percentage of time in the snow it probably makes more sense to run a long stem and get more weight over the front tire to equalize the weight and minimize the rear tire sinking. "
It was from post #22 of this thread: Stem/Bars: Long and narrow or short and wide?
The poster writing that indicated that he/she didn't do any riding on snow, however.
Appreciate any input. I'll keep digging through previous posts. Want to make my decision quick as these Bigfoots seem to be selling quick.
I think the most useful way to approach it is to think in terms of which bike allows you to shift your weight around the most. Snow riding is so incredibly variable that putting hard and fast rules in place is not workable. There are times when you need to keep all of your weight back and dig in for max traction and float the front just to keep moving. Then, sometimes you need to seriously weight the front wheel to keep it under the bike. Then there are rides where you have to do all of it, and sometimes even then no matter what you do it does not work. Bottom line is, I like to have a roomy cockpit so I can move all over the place, as needed. That can be achieved with stems and seats to some extent, but I do not prefer to work it that way unless I have to (meaning the frame is wrong for me in the first place!). I think it is better to shorten a bike with stems and seats than to lengthen one. In a perfect world, I want a proper Front Center to get the room I need.
Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
- John Hajny, a.k.a. TrailMaker
Yeah what Trailmaker said! Some people like a smaller frame for winter but I prefer a little bigger since I am usually bundled up a lot more and like to have the extra room to move around. Plus it gives me more frame bag room.
I have a cross bike that's ever so slightly too big for me. My fat bike is ever so slightly too small.
Originally Posted by DITCHMAN
I much prefer the smaller. A larger frame tends to "snap" loose under me, while with the smaller frame, I can really throw my weight around and allow the bike to slide around beneath me more progressively.
I say go for the smaller frame and adjust the fit with the setback post and stem.
I have a small Bigfoot, yet should -- by height -- be a medium. I ride on snow and have had no issues with weight over the front, even on short, billy-goat style climbs. Rear sink will happen, no matter what you do LOL.
Disagree with me on what you prefer size wise is fine but adjusting a bikes reach by using a setback post is totally wrong. What determines the type of post needed is the correlation of ones feet while on the pedals to ones knees. Like I said it's all personal preference and how and where you ride.
Originally Posted by simonj
I agree with Trailmaker, very wise advice!
Originally Posted by TrailMaker
Amen, Ditchman. The setback post also helps accommodate disproportionately long femurs. Trust me -- long femurs + a short torso = extremely limited bike options.
Been kinda impressed with the dropper seatpost for being able to shift weight distribution. certainly no magic bullet, but dropping my seatpost an inch definitely shifts my weight distribution to the back when I need it...
THIS!!!!! I have struggled for years with bike fit mostly because i did not realize that the bike mfrs do not size their bikes for these proportions. My biggest problem was for years bike shops would "put me" on bikes that were simple too small. So then I end up with an elevated seatpost (actually managed to split one, but excellent service from the shop!) and a ridiculously forward weight bias. Endos were so common that they became almost boring lol.
Originally Posted by Eaglehawk
How do you handle bike fit with this issue? It seems to me that Surlys seem to fit better for those with longer legs/short torso due to their longer seat tubes and shorter effective top tubes but are there other mfrs that would work better? Thanks
Team Honeybadger, I'm 5-7, but have a 33" inseam similar to those 6-2 and taller. Add in the disproportionate femurs and I'm a nearly impossible fit. I know your pain.
Long femur length makes cockpit choice REALLY important. The moment you offset the seat post to accommodate the femurs, you pike forward. This changes the pelvis tilt and puts pressure on the cervical and thoracic spine because of the reach and crank you put on your neck to see where you're going. I have to get my torso up higher -- a more upright position helps. Some of the brands offer this. Yes, shorter effective top tube has been my saving grace, but this must be combined with a shorter, more upright stem position and an offset post. And a seat that flares up at the back to essentially keep the pelvis locked into the position that optimizes the pedal stroke. It's not aggressive, but that's OK by me.
I've worked with my LBS to measure all the angles and lengths of my summer ride (which fits like a glove) and we're mimicking it on the fattie. I tested Surlys, KHS and Norco, and stood over the Charge. I ended up with the small Norco because both the angles and ETT were the closest (despite my height suggesting I should be on a medium). Then we flipped on a 10 mm offset post and upped the stem angle. Plus a wider, flared-up seat that's set way back. Oh yah -- we cut the bars, too. It's better to reduce the scapular load and I can still lever the front end well. The stock bar is 740!! Insane.
The Surly? I felt like I was really stretched out. The KHS was remarkably long, even on a small. So was the Charge. The only other one I found that came close (by measurement) was the Beargrease and I didn't have that kind of coin. The Bigfoot is reasonably spec'd and a crapload of fun. Seriously fun. Like never pry the grin off your face kind of fun. The extra cash left over let me upgrade the seat and the tires.
Bottom line? Test, test, test. And don't be afraid to select an option that some people think isn't a "true" fat manufacturer. One place I looked badmouthed the mainstream manufacturers, but hadn't seen any. I get it they'd been in the biz for a while and probably didn't like the competition for market share, but at the end of the day, the best bike is the bike that fits right. No matter the name.
BTW, the seat tube length hasn't been an issue. The Q factor seems different because of the width of the bottom bracket and my seat needs to be a little bit lower than my summer bike. If only by a few millimetres, but it's still lower.
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