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Both with a 40mm stem.
Im on a G16-GPI so CS are long at 445.
77SA is steep, but moved my seat back a tad on the rails so its not so far forward.
And im around 183cm tal.
For me i think a 475-480 reatch with a 50mm stem, 440 CS and a 76 SA would be spot on.
The way i see it, YT have probably nailed the cizing on ther new Jeffsy. I shuld be on a large cize bike, and ther number match almost perfect.
But if everyone just could stop making seattubes so damn long we culd all just pick and shose more easly. An XL bike shuld never have more then 460mm seat tubes!
Unless you're talking DH and slope bikes in which case make them as short as you want.
For me it was more the other way around, had to almost slam my 150mm e-13 dropper post in my old medium frame with a 460 seat tube.
The smal i have now is a 440mm so now i consider getting a 185mm dropper instead..
Longer post options would be the best tho.
Shorter ST and lower standovers is always good.
939-175(crank)= 764mm 30"
764-560 (seat tube)= 204mm 8"
revive 185 min exposed while extended is 226.7mm + seat = ~250mm seat stack.
so 204mm left and your seat takes up 250mm more, that would mean your seattube is too long.
i bet you pedal with your toes down, run short cranks, wear padded shorts and or roll your hips side to side while pedaling, cause it sounds like youve added a lot of stack to your pedal stroke.
the other way:
inseam + 1/2 Pedal + shoe sole = seat top to pedal spindle length (S-P)
S-P minus Crank arm length = seat to bb length (S-B
S-BB minus Seat tube length (STL) = amount of space that needs filled by exposed post, dropper travel, and seat thickness(~40mm)
revive 185 is 334 max travel extension minimum inserted. plus 40mm saddle stack height =374
200mm dropper is 260+40mm seat so 300mm stack
940mmSeat to pedal length, minus 374 seat and post max stack, minus 175 crank equals 391MM MINIMUM SEAT TUBE LENGTH. (this is assuming a seattube that protrudes directly from bb where effective and actual STA are the same)
My old SB-66c in XL had a 455mm reach on it. My current bike, a Large Nicolai Ion G15 GPI, is sitting at 515mm. However I had to switch the Nicolai from a 35mm to a 50mm stem to make my cockpit feel comfortable and "uncramped" again whereas the SB66c I was on the limits of fitting the XL with the stumpy little 35mm (I stand at 187cm for reference).
It will give you a reasonable comparison of how a cockpit feels if every other number you're comparing between bikes is the same, but it otherwise doesn't properly represent the cockpit.
One of the distances that is almost identical on all my bikes is that between the middle of my saddle clamp and the middle of my handlebar, which makes a whole lot of sense.
I ride a Transition Sentinel with a 450mm reach and a degree head angle. Initially, when I demo'd the bike, I had the same issue as you, I struggled to weight the front end in corners. I wasn't initially sure if it was caused by the slack HA or the longer reach, or something else (brake angle, etc). This was with a 40mm stem. However, as soon as I swapped to a 50mm, I instantly felt central between the axles and had more cornering confidence than on any other bike (literally from the first carve I made in the parking lot). The difference was night and day. I went from feeling as if I had to fight to constantly pull my weight forwards to weight the front wheel, to feeling as if weighting it was perfectly natural and effortless. In my view, minor differences in stem length make a huge difference in the riders weight distribution, and therefore in how a bike corners.
Similarly, I am currently demoing a large Santa Cruz Nomad (460mm reach, 65 degree HA). Initially, I struggled with weighting the front end until I removed all the spacers from under the stem. As soon as I lowered the bars, I got that same neutral, confident feeling in the corners, where I didn't have to shift my body around to weight the bike properly, meaning the bike felt very easy to corner and didn't require a whole lot of body english.
My takeaway? Weight distribution on the bike is the most critical factor in how a bike corners. For me, it was impossible to achieve that neutral, balanced cornering feel before I got on bikes with ~450mm reaches. The reach seems to be far and away the most important factor here. That said, even bikes that fit me with appropriate reach numbers don't corner well until I am able to find that neutral feeling where my weight is between the axles. Stem length, brake lever angle, and bar height all play a role here, as does suspension set up.
I would recommend trying that 460mm reach bike again, but going to a 50mm stem. It might sound like a minor change, but for me it made a major difference. Lots of people seem to think stem length is just a tool to fine tune reach numbers, but for me 10mm in stem length seems to have a way bigger impact on ride characteristics than 10mm of reach. It is likely you don't need to "re-learn cornering" or adapt your riding style to the bike so much as you need to get the bike to adapt to you.The 460/40mm bike you tried probably requires a more forward biased riding position with the shorter stem, so to get a similar feel, go for a longer stem and try and ensure other factors like bar height are as similar as possible.
Hope that helps!
https://www.pinkbike.com/news/lee-mccormacks-guide-to-perfect-bike-set-…
But they confirm it in that article.
reach is one important isolated piece of geometric angle to discern fit. all parts the same ie same stem bar etc. variable and/or numerical reach paired with, headtube height, stack, axle to crown can tell you a lot about a hypothetical bikes weight distribution and cockpit feel.
Axle to crown + headtube length - sag @ headtube angle = will give you a horizontal length, probably somewhere between 220mm(xc) to 320mm (29er dh) this horizontal distance, plus reach and fork offset, is your front center length! something like ~730mm. your front center divided by rear center (450mm) will give you a % of weight distribution standing on pedals without weight on hands on flat ground ie, 730/450=1.62 = 162% weight on rear wheel. this number will be smaller with bike pitched downhill, on brakes, leaning forward & weighting handlebars. the % weight on rear wheel number will be bigger when climbing, accelerating, leaning/ hanging back, frequently hitting all weight on rear wheel when you wheelie, loop out, or get in the back seat cause your a scared squid and loose control of the front wheel. personally im shooting for 150-160% weight on rear whee on flat ground, based on my experience on many many bikes.
you cant have traction without ground pressure, no matter the tire. if your bike is a xl process 153 with 425 chainstays 510 reach 66ha and 834 fc youll have a 196% as much weight on the rear as the front... that sucks. your gonna have to work hard to get that front wheel to lead the way! thats why they put the motor in motorcycles, sportbikes and dirtbikes alike, as close to the front and low as possible, to weight the front wheel!
Consider myself a fairly good and fast rider.
Why your asking?
I currently have a 150mm KS dropper which is 440mm long (the shortest out there as far as I know) but at minimum insertion the saddle isn't high enough. I end up running a quick release seat collar to compensate. I would love to get a 180 or even 200mm post but then the post is way to long to insert into my interrupted seat tube.
Its 226.7mm to rails when slamed.
Starting off, I have gone from - to:
-2015 Giant Reign 1, Large - Bird Aeris AM9, XL
- 27,5" - 29"
- 458 mm reach - 522 mm reach
- 1217 mm wheelbase - 1292 mm wheelbase
- 160 mm travel - 150 mm travel
- 125 mm seatpost travel - 170 mm seatpost travel (it's important)
- 50 mm stem - 40 mm stem
Me:
-190 cm (or 6'3" in the weird units that don't make sense)
-91 cm inseam
-I think a bit over 190 cm of arm span
Yes, I am tall. Yes, this puts things i will be saying below into a different context and changes some stuff, massively. Yes, I’ve been saying steep actual seat tubes are a must on the internets for a while now. And yes, this is true for the XL squad and less so for the M/L squad (given the way virtual seat tube angles are measured, people with an inseam around 10 cm over the stack height get the advertised seat position). This is because the height of the seat we XL guys need and the amount of it getting over the stack height, which changes the actual seat position massively.
Giant facts:
-Yes, the large Giant was too small. But:
.-my previous bike was also a (too small) Large (I found the L Giant comfortable at the time of purchase)
.-I tried an XL Reign before buying my L and I didn't like the cockpit (less so than the L)
.-It took a while before I got to the conclusion that I don't like slack seat tubes and/or the L Giant
.-riding the Bird for two weeks now going back (after preparing it to sell) I still don't like the cockpit of the Giant.
-The seatpost is a limiting factor descending because the seat gets in the way being dropped down. I figured this out in the past year and wasn't prepared to swap it out given I was about to buy a new bike.
Now, like I mentioned, the difference in reach between the two bikes is a massive 64 mm. Given the opening post in this thread, this is about three frame sizes. Granted, accounting for the stems this difference does get taken down by 10 mm. But what do you think the difference in cockpit length, from centre of the bar to the point where the seatpost pierces the seat (which is what I’ve been saying matters) is? Less than 30 mm but definitely more than 25 mm. So where did the massive 64 mm in reach difference go? Taken out by the seat tube angle, the actual one.
Seat tube angles: from Giant - to Bird:
Virtual: 73° - 76°
Actual: 69° - 71° (Giant's is taken off a press photo, could be even slacker comparing the two bikes. Bird's is official)
Effective: 72,07° - 75,02° -> at seat height! (calculated given above two angles, stack height and needed seat height)
This is what over 800 mm of seat height gives you, it's a territory most designers don't think about (I can understand them, given the volume of XL frames) and most people don't experience. Those who do, mostly don't care or don't know what they are missing.
Bird - going up:
Why does the effective seat tube angle at seat height matter? Climbing performance. The bike climbs like a champ. I had problems and I never actually succeeded in clearing a relatively long (for the grade), very steep, rocky and rooty climb with the Giant. I cleared the same climb with not a single problem, issue or wobble, never got hung up or had a skid of the rear tyre, in my first try on the Bird. And I tried many times with the Giant, looking for the optimal line (took the final, most optimal line with the Bird), tried it in multiple surface conditions, but always got hung up on stuff, lost traction, etc. Granted, I took three pauses to catch my breath (lacking in cardio fitness), but this was the same as on the Giant, I also took pauses there, even more of them if anything.
The grade? Over 30 % average grade on the steep part, ~15 % average over the 1,7 km of climbing with a height difference of 244 m. Nothing world class, but definitely not easy.
Now, my shape was largely the same in all cases. I had a new Aggressor on the rear of the Bird with a not new, but definitely not worn out High Roller II on the Giant in all cases. The tires are then are not a factor here. A benefit for the Bird was that I knew the optimal line, but I attempted the same line multiple times with the Giant.
Technically a benefit of the Bird is the fact that it's a 29er. The rollover performance is insane. But the main factor? The seat tube angle. I was relaxed in an upright position much longer and had to move forwards on the seat and bend over the bars much later than on the Giant to weigh the front, when the climb got really steep. While the 10 mm longer chainstay has an effect here as well, the effect of it is much less than the seat tube angle. I was pedalling comfortably, unlike on the Giant, where I felt like I was kicking the doors down (pedalling 'forwards', not down) because of the slacker angle.
Bird - going down:
Descents? You’d think the extra 75 mm of wheelbase would show itself. That the reach would be too long. That the bike would be lazy with the 29er wheels. Only the last part was true. Only on the first ride. I even excitedly told how smooth, calm and grippy the bike is but that it's lazy going into the air to a 29er fan, who's a friend of mine. He was surprised. I took the laziness comment back after another ride or two. Since then, I’ve been popping roots and rocks and other small fun, even popping it right before and into turns, which I didn't do before. I rail turns (berms or off camber nasty stuff) confidently where I was awkward before. With like a flick of a switch, overnight (by changing the bike) I’m much faster, more confident, have a better position on the bike. A friend of mine was amazed at my 'progress', which is caused by the bike. A lower seat is most definitely the main factor here, WideTrail tires probably account for quite some confidence by providing more grip and giving tons of confidence. But...
Regardless, the bike just motors down the trail. It's calm, confidence inspiring, I feel completely at one with it. I fit in it. I've actually missed my PB/KOM on a local trail by only 4 second on my third ride with the bike while passing a hiker (slowly and carefully on the high speed, loose section), going for the slow, but fun route (instead of the faster Strava line) and generally just cruising about, learning the reactions of the bike, evading the effects of the forestry on the lower part of the trail, etc. The KOM was set 2 months before in prime grip conditions while clearing my head from the stress of work both going up and going down, where I was in a perfect state of flow and aggressiveness, genuinely enjoying myself while setting the KOM.
Tight turns where you have to front pivot (I still can't do that properly anyways) or jack-knife yourself? It's about the same as with the Giant or maybe even less awkward. Maybe due to an increased confidence from the new bike. Generally the three sizes larger reach is NOT an issue and is not something I noticed. The same goes for the 75 mm longer wheelbase.
64 mm more reach is not too much reach:
So, 64 mm longer reach, a much steeper seat tube angle and I’m loving it. Would I go longer or steeper? Steeper definitely, longer I don't know. Maybe. I was looking at Pole's Machine, but it was around 1000 € too expensive to justify the purchase, regardless of me having the money to spare or not. But having finally ridden a bike with a steep seat tube angle, finally drinking the Kool-Aid I’ve been spewing on the internet for so long, I can confidently with no doubts say that this is it.
I am fully aware of the fact that I am in a special, small part of the population, but given this fact, there are 6 frames I would be thinking about buying if I had to buy a new bike. Given that I’m a 29er convert (and I was playing the 'I want a fun, poppy bike, not a freight train' record before trying the 29er, plus I can't be helped with my size), realistically there are 5 frames I would buy. that I would buy. These are:
-Bird Aeris AM9 (29")
-RAAW Madonna (29" - the minus is a relatively short cockpit, even more so given the steeper seat tube angle than my Bird)
-Nicolai G1 (in 29" of course - but there is no water bottle, so a minus here. It can be bodged together though)
-Pole Machine (€€€...)
-Pole Stamina (€€€€ and I kind of prefer the looks of the Machine. Plus 180 mm of travel could be a bit much?)
-Custom geometry MDE Damper (29" of course - there is also no water bottle option)
The sixth would be Bird's Aeris AM145, which is a 27,5" bike. The seat tube on the 145 is actually even steeper than on the AM9, by about half a degree for my height. I would have to take a closer look at Yeti's SB150 regarding the actual seat tube angle, but it does also look a bit short in the cockpit area, though longer than the RAAW.
Conclusion:
Given the above list, I’d go for the AM9 again. It's right on the border regarding the seat tube angle and I’d prefer a steeper one, but it ticks all the other boxes, mostly the price one (and their online configurator with an excellent choice of parts, given my preferences). Given unlimited finances or 'you can get anything you want', I'd go for one of the machined Poles. Third option would be a custom geometry MDE Damper 29", that also has an actual, effective, seat tube angle of around 76°. But I want the option of the water bottle.
And, to clarify again, I’m talking about XL frames for riders of around and mostly above 190 cm. This is an area I’m most familiar with and feel the issues of the most. If you're thinking I’m talking shit, I’ve had three other people tall enough for an XL frame (one of them is riding a Large Meta V4) commenting how nice the Bird feels in a parking lot test. That it's not big at all. Another (not so tall) friend contemplating the same AM9, but deciding between their Medium-long and a Large tried mine and instantly decided to go Large.
Steeper seat tube with a much longer reach is better, at least for me. But this is a perfect example showing how utterly useless the reach number is for the feel of the bike.
I'm 5'9" with long body/arms and short legs (29" inseam) and have found my Stumpjumper Evo S3 fits better than anything before it (with a 35mm stem fitted). But I've also found that while I'm faster by a good margin (up and down), my upper body has definitely felt more tired, and I've always been strong after years of competitive swimming.
A few weeks of a new kettlebell programme and I seem to be improving, but it's a consideration many wouldn't think of. A dramatically longer bike needs more "work" or else you can feel like a passenger..
So I convinced myself that I need a longer bike to sit comfortably, using a 50mm stem.
I did a lot of measuring and calculated that I should have a frame with 460mm of reach. So I got a custom hardtail frame built with that exact reach number. I loved it, rode it a lot, but ended up not liking it anymore.
After that I got a Production Privee Oka. I wanted a size large, but got an XL frame, as the previous owner did not know exactly what frame size he had bought...I had to chop off 20mm of the seat tube to fit my dropper post and convinced myself that this is exactly what I needed. It was not.
I ended up buying a Production Privee Shan size large, which has around 30mm less reach. And I finally can ride it the way I want to ride a hardtail.
Besides that I got a 2015 Mondraker Foxy XR (carbon frame) with 483mm of reach and it's pretty good overall. Feels appropriate on 90% of trails for me.
Apparently there is the theory that you can go with 30-40mm more reach on full-sus bikes as the reach gets shorter with sag. And it's the other way round on hardtails. They get longer with reach.
I did not read this whole thread, so sorry if this has been discussed before.
I've been on a 29er for a few years now, my other bike is still current, which is a 19.5" Trek Fuel EX 9.9. prior to that, funnily enough I was on a Reign Advanced 0 for years.
Reason I went for a big 29er was, i've raced enduro & regional DH on the same bike for probably the last 7 or 8 years now (last DH bike was an IH Sunday). My poor Fuel was taking an absolute battering, I had long shocked it so it was just shy of 140mm rear travel & ran a 150mm fork, it was surprisingly good but the frame was too light for what I was putting it through & it cracked. Trek replaced it & i've since built it back up to a 26lb trail bike, for which is absolutely rips at. Seriously it might be the best bike i've ever owned in it's current setup.
Sizing wise, it's probably whats considered about average these days, but it is considerably slacker than Trek advertise. it's still my go to bike for 90% of my riding & will still be used for local enduro races where the RAAW is just far too big & cumbersome.
With the RAAW I run a 170mm fork on it & a 65mm stroke rear shock which takes it to just over 170mm travel on the back. It's not light, and when it's lent up with other bikes, it almost looks like a comedy thing, it's so big. Reach between the two is quite a bit different but due to the steep SA the saddle to bars numbers are almost identical. Much like the recent PB review, it does climb well for its size, but that's the geometry doing it's thing - I get a lot less front wheel lift & wandering than I do with the Fuel, but that makes up for it by being ~8lbs lighter.
They are very different bikes though. The Fuel is light, nimble, playful & a bit of a handful when it gets fast & rough. It's an easy bike to ride. The Madonna by comparison, is an absolute monster truck & you really need the terrain & speed to make it work. The long stays & low BB can make it hard to throw it around, but like everything, it's a trade off for outright speed & stability - it just wants to go hard & fast everywhere.
If I could only have one bike, it would be no contest - the Fuel wins hands down for the vast majority of my riding, and does double as a surprisingly competent race bike for the UK. But, i'm racing a few EWS's again this year, doing a month in Whistler & a few weeks in Finale Ligure later in the season & for those, the RAAW makes perfect sense.
For me, i've found the limit, I can't imagine I would ever need something bigger. I would prefer it to be lighter, but i'll trade reliability for a bit of extra weight, given it's intended use.
I go to phys therapy and I do a lot of stretches/workouts but still not really sure what I need to do / what actually works. I've had back pain since i was around 16, almost 30 now. I have my seat slammed forward and I roll the bars back in a 40mm stem to get them close as possible for climbing.
My goal is to ride everyday, I've been trying to achieve this for 3 years now, average ride is 1000-3000 ft. Last week my back finally felt good, like didnt hurt at all, I hit the bikes so hard and rode perfectly for 7 straight days. Come day 8, Im inexplicably destroyed and I haven't been able to really ride for 3 days, bummed! Im in the best shape of my life and not overweight, Im sure i have massive muscle imbalances though.
TL;DR: Will a shorter frame make my back hurt less often? It's hard to ride with back pain, it tightens everything and limits my movement.
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