Low trail porteur 29er discussion optional.
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Here is what I’ve been messing around with.
The design goals are:
28mm tires w/fenders possible (57mm calipers), but not much bigger (want short-ish chainstays). Would want to run 28+ tires most of the time
works with Columbus Hiver fork (45 rake 378 a-to-c).
neutral handling in front (weight back due to setback/slacker STA made up partially by longer stem
slightly more upright but not too faster backwards position (fits now and stem can be flipped up when I’m even more of a geezer)
I don’t know shit about shit. Tell what I’m doing wrong.
my cx bike has 425 chainstays and fits a fender or 35s with space
you should be fine
i have no idea why you are doing htis outside wanting to build your own bike
let someone else stress it
[quote=catdrew f]i have no idea why you are doing htis outside wanting to build your own bike
let someone else stress it[/quote]
I might do that (well farm it out somewhere to have it built), but really I’m just trying to understand how this shit works.
As far as I can tell this is pretty much right in the middle of two stock geometries I’ve mocked up - either of which I think would work fine once I figure out how far down the fred scale I’d want the bike to be.
[quote=tarckeemoon]Here is what I’ve been messing around with.
The design goals are:
28mm tires w/fenders possible (57mm calipers), but not much bigger (want short-ish chainstays). Would want to run 28+ tires most of the time
works with Columbus Hiver fork (45 rake 378 a-to-c).
neutral handling in front (weight back due to setback/slacker STA made up partially by longer stem
slightly more upright but not too faster backwards position (fits now and stem can be flipped up when I’m even more of a geezer)
I don’t know shit about shit. Tell what I’m doing wrong.[/quote]
not sure what the front center is on this
but this is very close to what my davidson is
but with 15mm shorter chainstays and a few mm shorter frame reach
i think this would probably ride just fine and ~425mm chainstays is what i would want on my davidson if i didn’t use a small rear pannier
but yeah, i wouldn’t worry about this if you weren’t building yr own frame…
My surly pacer fits 28’s and fenders or 35 slicks without and it has 415mm chainstays.
That thing is probably within a couple mm of 60cm of front centre based on the difference in reach and rake vs. my cervelo.
[quote=rauce]My surly pacer fits 28’s and fenders or 35 slicks without and it has 415mm chainstays.
That thing is probably within a couple mm of 60cm of front centre based on the difference in reach and rake vs. my cervelo.[/quote]
yeah sounds right
the davidson is 602mm front center and like i said, 420-425mm chainstays would be what i would want if i didn’t need heel clearance for panniers
Just curious, what does your Davidson have?
cs are 435mm
front center 602
ht and sta are 73*
tt is 575
fork rake is 43mm
i forget bb drop, i think it’s 75mm and wheelbase is 1012mm or so…would have to look at the sheet on those
sport tourer/all arounder
edit: oh no, the bbdrop is 72mm and wheelbase 1027mm
Most bike manufacturers would run a 43mm rake fork with a 73HTA giving a little more trail. Makes not a lot of difference. I personally prefer mid-50s in any case, especially if you’re going to run larger tires which increase mechanical trail.
In short, if you get this built and the 42cm stays actually work, then it should handle really nicely.
What’s the BB drop?
seventy
Needs more
How much more? My Charge is 70 and handles pretty well with 28s and I tend to prefer “on the bike” over “in the bike” by a little bit.
i talked to david kirk abotu that exact topic today
it doesnt matter by itself, don’t ask for hte bb drop
either the frame works or it doesnt; ive ridden road bikes with 63mm bb drop to 80mm
all will work if everything else works in sync
erichie didnt lie when he said the frame is the frame
focusing on a singular value is the fasted way to turdrocket imho
That’s asinine.
I’m saying that whole frame with all those angles might scratch some people’s itch with a little more BB drop. However…
If that’s the case, then keep it at 70. I felt the same way about the in the bike vs. on the bike until I rode a 700c bike with fat ass tires and 75mm of BB drop. Not like a few more mm of drop will make much difference in any case.
read this:
http://cyclingtips.com.au/2011/02/the-geometry-of-bike-handling/
dude what are you talking about
bb drop in itself doesnt do shit
you can make a fast handling bike with a low bb, high bb, and mid bb
saying a bike needs more drop doesnt make any sense
the only addition a lower bb has given me, ignoring all other factors is the frame feels stiffer in the bb. as teh stupid baum article stated, you need to work a design parameter in with everything else.
I think the stuff about chainstay length is largely bullshit. But yeah, it all has to work together.
only time id stress it is being super tall
i run a really high seatpost (86cm) and a ton of setback (~15cm)
I rode a bike with sub40cm chainstays, and it was not the rear center that made me dislike the bike.
friggan long chainstays feel a bit weird, but that is just hte overall wheelbase getting out of hand
420 (to me) seems wholly reasonable for what you are wanting to use the bike for
7 is the magic number for a race bikes and racelike bikes atmo atmo atmo. i don’t see any reason to go outside that by more than 5mm for a 700c wheeled bike unless we are talking trail bikes. even for a touring or randomachine. If you like to ride fast you probably like to pedal through corners regardless of what you happen to be doing that day.
but yeah… LOW TRAIL!
HIGH TRAIL!!!
TASTES GREAT!
LESS FILLING!!