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plantbasedpedaller

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Reply with quote  #1 
Hi all,
(This post has been months in the making so please excuse my extreme wordiness)

I'm looking to start a new bike build and have decided to use Walty to make a custom frame. I have been scouring the threads here and the rest of the internets piecing together my exact specs over the last few months, and now I need a little help nailing down the last few details. I made this decision based on a number of factors, but mostly because none of the bikes out there have all my requirements.

What I want the bike to do:
Perhaps I'm being too ambitious but here goes. I want the bike to do everyday road, mixed surface and gravel riding (everything from well groomed fire trails to non-technical single track), Bikepacking and bike touring (both short and extended), as well as long distance rides (audax, ultracycling, randoneuring, etc.). I have decided the best way to do this is with three sets of wheels ( I have built up a set of Pancenti Forza 700C rims, I'll build up a 650B/ 27.5" set (likely Blunt SS rims), and a set of 700C 50-60mm deep carbon wheels) , I'll attach a Fred Bar with Aerobars for distance riding, and perhaps two forks ( I already have a Curve Cycling gravel fork (https://goo.gl/9aQCVd)) plus another lighter 12mm thru axle fork for ultradistance.)

Current Rig:

I have been riding the gravel and off road around my town for many years on my current titanium bike; a Van Nicholas Yukon. It's a great bike and after almost 10years and three different incarnations (road, touring, gravel) I still love it. However, it's never been the perfect fit and now I want something that can do that little extra. I love underbiking and so the Yukon has been many places it shouldn't. My main reason for the new bike is to get disc brakes and larger tyres. 
20180121_165910.jpg  At a local lookout after a 200m 30%+ gravel pinch20161018_082935 (1).jpg  Bike touring somewhere in Hokkaido

Frame Geometry:

I have attached an Excel spreadsheet comparing my current gravel bike to the prospective new frame.


Stack and Reach:
The issue I have with my current geometry is that I feel like I'm falling forward and putting too much weight on my hands. I also tend to ride with my hands on the transition area between the hoods and tops. This leads to hand numbness. (However, I get hand numbness sitting on the couch as well so this may not be a bike issue). I tried moving my saddle back behind KOPS but this just led to knee pain. I've been focussing on rolling my pelvis forward and keeping a straighter back which feels like it might help in time. 

My body dimensions seem to be within the normal range, but the frame sizes that are usually suggested always seem a little big. For reference I am 172cm/ 5'7.7", cycling inseam 81cm/ 31.5", 66kg/ 145lb, 179cm/ 5'10.5" armspan (longer arms). In most brands' frame size guides, Competitive Cyclist's guide, and a bike fit some time ago, this equates to a frame size of 54cm and an ETT of 545mm or more. However this has always felt a little big. My Yukon is this dimension and was comfortable with a 110mm stem slammed (road and touring format). When I raised it 25mm and shortened the stem to 90mm (for gravel), it was more comfortable but because of the lower speeds and less power I put more pressure on the hands which causes numbness (something I don't think will ever go away.) 

(My current road bike is a Dogma F8 in a 515 size and has ETT of 525mm but a much lower stack. I regularly do 200km+ rides on this bike and always feel comfortable even with the ~10cm/4" saddle-bar drop. However, this aggressive position probably isn't useful when loaded up and hitting the gravel.) 

Perhaps I'm fishing for confirmation here, but do the new measurements on the spreadsheet seem logical in terms of bringing the reach back a little and the stack just slightly higher?

Head Tube and Headset:

My current bike has a 135mm HT, a CK no thread set, and then 25mm of spacers. This yields a total length of (135 + 25 + 25) = 185mm from the crown to the bottom of the stem. 

With the new frame I have all the head tube options open. After doing plenty of reading, I'm no closer to deciding which way to go. The fork I'm using has a tapered steerer (1.5" - 1 1/8"). Am I better off going with a longer, cleaner looking internal headset, an integrated/ zero stack headset, or a straight 44mm HT with the classic looking external cups? Someone sell me on a particular variant. I'd like to end up using no more than 20mm of spacers so that I have the option of removing the spacer, dropping the handlebars (for a more aero position) and adding the Fred Bar/aero bar on top.

Bottom Bracket: 

Am I crazy for going with a T47 BB? Here's my reasoning. 

This bike will be running a mixture of groupsets. I'm determined to run a Campagnolo hydro group with an XT shadow+ 10s RD (with a JTek Shiftmate). It will probably swap between a Campagnolo 50/34 and FSA Adventure 46/30 or 48/32. I've had bb30 in the past and don't want to deal with press fit BBs in a frame. T47 allows me to simply change the cups over between Campagnolo and BB386EVO as well as any other combination I might choose in the future. It also allows for a 34.9mm seatpost and a big down tube.

Angles:

I've always ridden frames with a 74deg seat tube, and this seems standard. 
Head tube angle is 71.5deg on my current yielding a trail of 65mm with 32mm tyres and 45mm offset fork. I'm thinking slackening this to 71deg so that the trail figure is the same with the new 51mm fork and large volume 650B tyres.

Chainstay Length:

I don't like the look of very long chainstays and given that I want to fit 45mm 700C rubber, I think 430-435mm seems appropriate.

Seat Tube Length:

I know that standover height has no bearing on real frame geometry but having shorter legs means that I never end up with much seat post exposed. This isn't just an aesthetic issue it leads to not having enough post for bikepacking saddle bags. However, I'm trying to maximise the front triangle space for a frame bag. My current standover with 32mm tyres is fine but the new bike might have 45mm tyres at times. I would also like the slot for clamping to be front facing. I was thinking of dropping the C-C measurement on my current frame from 500mm to 480mm and the C-T from 540mm to 530mm. I'm not a fan of steeply sloping TTs but it's the only way to get to the goal of more exposed seatpost.

Finishing Kit:

As I mentioned before this will have mixed groupsets in order to get the aesthetic and gearing I want.
Campagnolo H11 brakes, shifters, and front deraileur.
Shimano XT Shadow+ 10s SGS rear deraileur with JTek Shiftmate
Cassette: choice of 11/32, 11/36, 11/40
Cranks: Campagnolo 50/43, and FSA Adventure 46/30 or 48/32
Bars: Easton EC70 AX 42cm
Wheels: 700C 50-60mm carbon rims, Custom 700C Pacenti Forza rims, 650B Blunt SS rims
Stem: 90mm shockstop
The rest is yet to be decided or unimportant.

Whew! That's it for now.

Any help that anyone can give me is much appreciated. Hopefully when I've eventually got the thing together I'll make a post about it.


 
Attached Files
xls Yukon vs Walty.xls (38.50 KB, 15 views)

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mr_slow

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Reply with quote  #2 

I don't think you're being too ambitious. This is about the same thing I was going for, except I wasn't as concerned with the chainstay length, as I ended up with 45cm stays. I've not heard of Walty bikes, but they look quite nice. I will say that I have nearly what you're looking for with the Moots Routt 45 (again, the stays are longer). I did notice that the Moots has less bottom bracket drop than either bike, which might be good for when you slap some 650's on. I have taken mine on some pretty serious single track (black diamond trails in Colorado) with 650's and I did have some pedal strike issues.

That said, I think you're headed in the right direction with the Walty, post some pics once you have it completed.

Cheers,
Greg

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clarksonxc

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Reply with quote  #3 
I am in no poistion to address all your points, so I'll chime in on the two that seem easier for me to cherry pick:
If your road bike geometry is comfortable enough for those long rides, why not try ignoring traditional beliefs and try to replicate some of that on your new rig?  It seems like a lot of people on here actually like a more aggressive position when riding off road, and don't enjoy the slack, long/low geo's that seem to be emerging from the marketplace.  Just a thought.
As for the fork/headset - it just seems like there is always an easy option available for a tapered 1-1/8 to 1.5" steer tube with internal bearings.  For instance, I was looking to upgrade my AWOL fork.  It has a straight headtube with internal cups.  I wanted to go to a 15x100mm TA fork, with bosses on the blades for mounting bottle cages.  Individually there were plenty of tapered options available, plenty of straight HT options, and also 12mm TA options.  But I couldn't find one that satisfied all 3!  With the tapered/internal option, you'll have plenty of aftermarket flexibility.
Good luck and have fun!
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plantbasedpedaller

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Reply with quote  #4 
Thanks so much for the replies.

Greg The Routt in all it's varieties was one of my main points of data. I like the oversized tubing look and the dropouts are lovely. The longer chainstays aren't really an issue. I just prefer the look of shorter chainstays and after all the volumes written on the effect it has on a bikes handling, the takeaway message for me has been "the front end matters more". 

As for the BB drop. My current bike has 70mm drop and with 32mm tyres (just slightly larger than 650B 47mm) I've never suffered pedal strike. I like the idea of a low bottom bracket but I will probably keep it at the 70mm figure.

ClarcksonXC. I am trying to bring over a bit of that geometry. It's strange but the measured distance from the saddle to the bars is almost exactly the same between frames. (Road: 525mm + 110mm stem vs Gravel: 546mm + 90mm stem). The Gravel is more upright though and I might try removing a few spacers and seeing how it feels. You're right about trend towards more aggressive. From my armchair observations of what's happening in the field, it seems like people are going into two different crowds. Those who are roadies moving over, tend to keep the lower stack, and those that are coming from MTB or touring tend to whack a bunch of spacers on to bring the bars level. I'm aiming for something in between. 

When you say "internal bearings" are you referring to an actual internal headset or internal bearings as in an integrated headset?
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clarksonxc

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Reply with quote  #5 
plantbased - by internal, i mean the bearings that fit into the head tube, that you can't see unless you remove the fork.  Like in the Jamis Renegade photo from this thread:
http://ridinggravel.forumchitchat.com/post/gravel-bikes-a-the-sea-otter-classic-2018-9720534?pid=1303985317

By integrated do you mean one of those fancy stem/bar/headtube systems like Trek and Canyon use for their aero road stuff?  Cause i definitely dont mean that; the model I am talking about uses the plain old 1-1/8" steerer tube and stem.  The bottom of the stem sits on spacers which sit on the headset raceway, with the bearing cup inside the headtube.
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Volsung

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Reply with quote  #6 
Why not just use Campy derailleurs with the h11 shifters? Mixing speeds and brands seems needlessly complicated.
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drwelby

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Reply with quote  #7 
If you go with a 44/49 head tube you could use an AngleSet and then you could have up to 1.5 degrees head tube adjustment which would give you more tuning between road and off-road modes.

If you can figure it out (you need CAD or a big sheet of paper) I'd figure out first where you want your bars, then use that to determine your target stack and reach with an appropriate stem length. Then take your seat position and chosen seat post to figure out the right seat tube angle (you might want to game this, with a zero offset post for "road" mode and an offset post for "touring", combined with a shorter stem). Then "connect the dots" with a top tube of whatever length spans the distance and balances standover needs versus interior frame space for frame bags or bottles.


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chas

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Reply with quote  #8 

First, make sure you get a bike fit before you build a frame, right. My new bike is a little shorter than I am used to, but I find the drop bars so much easier to use on the hoods and in the drops. My old bike might have been set up like your old bike? FYI, I tend to ride a 54 frame and I'm 175 cm. 54 seems too big for you. (simple trick - when you are riding in your typical position - can you see the front wheel axle? The handlebars should block that view for ya. Ideally you should be comfortable in your riding position with little to no weight on your handlebars.

When standing up straight, bend your knees till your back is bent at your riding position. See - no weight on your arms.

I do find that with my shorter reach I am very comfortable with a lower handlebar height. I was kind of surprised.

I'm planning on using a 650b (54mm) on the front and a 40mm on the back. This gives me extra traction and cushion on the front, while keeping the back light, efficient, and distortion free under acceleration.


I like 70mm bottom bracket drop. My bikes range from 80-50mm drop. 50-60 is kind of high, but not really a problem below 70 I have pedal strike. I do find that the higher BB bikes tend to accelerate a lot better.

My seat tubes range from 73 toi 73.5 fyi. Do you have a setback seat post? If so - 74 might be a lot.

Exposed seat post makes a HUGE difference with a good carbon seat post. I have a CGR that did nothing for me at its minimum insertion depth. Now I have a bike with a lot of seatpost exposed, and it works wonderfully. Night and day difference.

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NoCoGreg

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Reply with quote  #9 
A few random thots...
In my experience if one feels too much weight on one's hands it's either because the saddle is pointed too far down or they're not engaging their abs. More drop (saddle to bars) should help get the abs to engage.  An expert bike fitter should be able to help you sort out this issue.

As far as bike geometry and fit across multiple bikes - there is a triangle formed by the saddle-bars-bottom bracket (assuming the same length crank).  If this triangle is duplicated between bikes then the fit will be identical.  If you haven't already, check out the fit calculator at BikeGeo: http://www.bikegeo.net/

I'm not a fan of mixing parts between companies, but I agree it can be done successfully. 

Taper forks seem to be the future.  I like the larger bearing race for greater durability (more balls to spread the load) and the wider HT makes for a stiffer and more solid front end for more precise steering.  That said, I still see lots of folks doing just fine in gravel with an old school steel frame/fork with a 1" headset.  You can still get good carbon 1-1/8" (not tapered) forks, but if the fork needs replacing in the future it may be more difficult.

Threaded bottom bracket (IMO anyway) is definitely the way to go - that's one of the key features in my choice my new Raleigh Roker.  I like the T47 concept but it's new and hopefully will become standard.  In case you didn't hear, Specialized went back to a standard threaded BB for the 2018 Stumpjumper.   It'll be interesting to see how long before other manufacturers go back to threaded BB's.  Just yesterday I was talking with a mechanic at a local Trek dealership and he was going on about how much time the shop sometimes spends on a problematic press fit BB.

Happy shopping,
Greg
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plantbasedpedaller

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Reply with quote  #10 
This is all fantastic help. Thanks so much.

ClarksonXC - Yes that's an integrated HT. There is a forum post here (https://goo.gl/VFGwd2) that goes through each of the styles. I just think integrated is simpler and more aesthetically pleasing. The potential long term wear to the inside of the HT is really a non-issue in spite of what Chris King says. I've got over 40,000km on my road bike with an integrated HT and it's as good as new.

Volsung - I would love to use Campy everywhere. However, I can't achieve the gear ratios I like with just Campy. On my current gravel bike I run a 50/34 with an 11-40 XT cassette. I use the medium cage Potenza derailleur and a road link. It works great but I did destroy a derailleur commuting back from work one day. I'd hate for this to happen off road so the safer system is to use the XT long cage which can handle an 11-42t with a max chainwrap of 43t. Mine will be 45t  ((50-34) + (40-11) = 45t) but we'll see how we go. 

drwelby - I did consider offset HT bearings but would just prefer the simplicity of an integrated HT. I've always used an inline post with the saddle all the way forward for road and back a few cms for gravel. It's worked well and is basically what you are describing. 

chas - I wish I could get a bike fit. However, the nearest bike fitter is a 4hr drive. My fit is fine it's just trying to balance two competing goals. At the end of the day I think these expensive bike fits are great for setting up new riders and eking out the last 2% of power efficiency. I've had a few done, but they always end up putting me in the exact position I've arrived at through my own adjustments. The frame geometries that I've worked out should work for a rider my size. 

NoCoGreg - My occasional hand numbness is, as you say, mostly due to being lazy with my spine and not using it to support my weight and having a constant death grip on long descents (I'm a roadie still getting used to the lower traction of gravel descents). I went for a bikebacking trip two weeks ago with no issues.  I already have the taper fork so it's really just a question of integrated vs cups. I'm going with integrated. It makes for a longer HT thus more room for a frame bag. I've only had one frame with bb30 and I had to pull the bearings every so often and reapply grease to stop creaking. I'm going with T47 and hopefully the standard will catch on. It's got some big names in support but that doesn't always mean anything. I like the look of larger tube sizes and having a larger BB shell means that the joint has more more welding area and looks a little neater.


I'm just trying to work on tube shapes and sizes at the moment. I like the look of larger round tubing and will probably stick with that. The Moots Routte 45 and the Bearclaw Thunderhawk are the look that I like.

I'll obviously have 12mm thru axles and like the simple look of the dropouts on those two bikes but are there any other styles of dropouts that I should consider? I'm adding rack/fender mounts as well.

Are there any other little details/features that people like to see on frames? I've added a chain keeper tab as I find them useful. I'm also considering a split seatstay for a belt if I ever choose that.

Thanks again for the input. Here's another bikepacking pic of my current frame.

20180513_084348.jpg 



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NoCoGreg

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Reply with quote  #11 
Sounds like your bike is really coming together! [thumb]

To your question on other details...
- I love having unlimited air for fixing flats and a pump peg is nice for that. But frame pumps are all but useless for tubeless.

- Mounting points for racks and fenders are nice should you decide to go that route.

- Shift cable adjustment mounts.  On old school bikes the cable stops attached on the downtube shifter mounts are really convenient for on the fly derailleur adjustments. MTB derailleurs do not have cable adjustment barrels as these are incorporated into the shift lever mechanism.  IMO the in-line adjusters are more problematic and have much less range than a barrel adjuster. All this is moot if you get electronic shifting. 

- Similarly it is nice to have cable adjustment mounts for brake cables...  However hydraulic brakes don't require cable adjustments.   

- The Tout Terrain has a very cool handlebar stop which prevents the bars from rotating around and damaging the frame.  Here's a link to some pic's
http://www.peterwhitecycles.com/tout-terrain.php

One additional thought...
I've been through the custom bike process several times and over the years I've gotten to know several frame builders.  I would suggest that instead of trying to spec the tubes, let the builder know what you want to optimize and ask for their recommendations.  Ti builders who have been in business for a long time (Moots, Seven, Dean, others) can give you very detailed explanations on the tradeoff of various tubes (ex. wall thickness and diameter).  One of my wife's bikes was spec'd from a bike she had that fit perfectly and rode great when she rented it.  The process was simple, we just got the frame geometry, her fit measurements, and explained to the good folks at Dean what we wanted (light, fast but also not too stiff so it would be comfy on long rides).  They selected the tubes and the bike turned out great!  Either way you go, custom is lots of fun.  BTW, if you're still looking at potential builders, Black Sheep Bikes in Fort Collins combines form with function.  If nothing else, they have a fun gallery worth checking out.
http://www.blacksheepbikes.com/

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chas

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Reply with quote  #12 
Quote:
Originally Posted by NoCoGreg


- Mounting points for racks and fenders are nice should you decide to go that route.



I never really thought of that.  Do you say that because the bead will not seat with a hand pump?

I have yet to get a flat tubless (although I got a fair amount of punctures this spring after the snowmelt).  I assume I would just stick a tube in there if I had a bad cut - although with some tight bead tires like the G-One I would probably just give up and call Uber).  On long rides I carry extra sealant and have some tire plugs for larger holes (I've done that a lot on cars, not yet on the bike though).  

I do carry CO2, but like to carry a pump if I uses up all my O2.
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NoCoGreg

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Reply with quote  #13 
Quote:
Originally Posted by chas


I never really thought of that.  Do you say that because the bead will not seat with a hand pump?

I have yet to get a flat tubless (although I got a fair amount of punctures this spring after the snowmelt).  I assume I would just stick a tube in there if I had a bad cut - although with some tight bead tires like the G-One I would probably just give up and call Uber).  On long rides I carry extra sealant and have some tire plugs for larger holes (I've done that a lot on cars, not yet on the bike though).  

I do carry CO2, but like to carry a pump if I uses up all my O2.

Just one experience where a guy burped his tire (aka flatted and pulled the bead out) and couldn't get it to seat with a mini-pump.  I doubt my Zefal frame pump would've been any better. Fortunately another rider had CO2.

With sealant and tubeless I'd be comfortable with a few CO2 cartridges and an emergency tube.  But I'm almost always in a group and cell range (aka Uber).

The new tubeless rims and tires can be extremely difficult to remove as many form an excellent connection (hook-up?) between the tire's bead and the rim.  If the bead/rim isn't separated all the way around the rim it can be impossible to get sufficient movement to pry the tire off.  I've often seen this problem with non-tubeless tires on tubeless rims and occasionally on non-tubeless rim & tire setups.  Bottom line - if the bead is not broken free from the rim (all the way around) it's going to be difficult to impossible to pry the tire off.

Greg
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chas

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Reply with quote  #14 
Yeah, my G-Ones took a long time to get on my rims.   I could not do it with a tube, without putting a hole in the tube.  Some tires/rims are easier than that.  I doubt I could stick a tube in the G-One on the side of the road.  My ramblers I probably could.

That is one nice thing about the skinnystrippers (latex liners) that I use.  The tire is easy to inflate by hand even if there is a total loss of air and the bead is unseated.  
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jever98

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Reply with quote  #15 
@OP: a couple of thoughts on your geometry:

- If your Pinarello fits well and you want to replicate the fit, maybe with the option to be higher, I would set the stack and reach so that you arrive at the same handlebar stack and reach with the setup "slammed" (no spacers, small top cap, appropriate stem, e.g., 110mm, -6 degrees). It's simple geometry to work out the frame stack and reach from that - PM me for an excel, if interested.

- Chain stay length: I have 410 on one road bike and 420 on a cyclo / gravel and my endurance bike. The handling differs quite a bit - the longer chain stays make the handling more muted and slower. I personally don't want to try longer than 420. Another thing to look out for is BB drop. The bigger the drop the more stable and muted the ride (also lower clearance). 70mm is fairly standard, less is going in the direction of "traditional" CX bikes.

Cheers
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TimmyR

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Reply with quote  #16 
Following....I am now in the market to build / design a new bike. Much like you, it'll be a gravel/touring/road bike...no cross...I suppose it could see light easy single track, but that'd be rarely.  My Crux is just not the right fit for me anymore due to change in riding and hip mobility.  Good luck on the new bike!


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chas

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Reply with quote  #17 

It is “trail” that determines the handling.  I have a bike with 420mm chainstays, and it is super agile.   Another bike has 371mm chainstays and is relatively stable – being a track bike it’s goal is to hold a steady line on a 166mm track.  On the track bike, the 30mm offset fork does the trick of balancing out the short chainstays, but a slack head tube would do the same thing.  Some designers are keeping short chain stays but making a longer top tube (with shorter stem) to increase the wheelbase while still giving the responsiveness of shorter chain stays.

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jever98

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Reply with quote  #18 
Quote:
Originally Posted by chas

It is “trail” that determines the handling.  I have a bike with 420mm chainstays, and it is super agile.   Another bike has 371mm chainstays and is relatively stable – being a track bike it’s goal is to hold a steady line on a 166mm track.  On the track bike, the 30mm offset fork does the trick of balancing out the short chainstays, but a slack head tube would do the same thing.  Some designers are keeping short chain stays but making a longer top tube (with shorter stem) to increase the wheelbase while still giving the responsiveness of shorter chain stays.



Sorry, failed to say if other things are being held equal, then longer chain stays and lower BB tend to make for slower handling.
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plantbasedpedaller

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Reply with quote  #19 
NoCoGreg - I will have a tubeless set up. Whilst I will have a pump, it'll be for topping up and the worst case scenario (read: adding tubes). Love them on retro builds though. The build will be hydro and entirely internal (I know,I know! but I can't stand the look of external cables, and don't think it's all that much of a faff to do the install.) I've never had any issues with Campagnolo inline adjusters (only needed for FD). However, I will need one for the RD in the new build. I like that HT frame protector tab. I wish there was something simple like that to lock the front wheel when leaning/ standing etc. (that is one thing that frustrates the hell out of me.) I will be letting the builder select the tubes. It's more the overall shapes etc. that I want to have some input on. BTW I love that 36er from Black Sheep!

Jever98 - That's pretty much how I've arrived at those geometries. I've used both the published and measured variables on my current bikes and then used the excel spreadsheet in the original post to compare them (as well as online ones). "Rough" guide: Pinarello is 525mm ETT w/ 110mm  stem (635mm total), Yukon 546mm ETT w/ 90mm stem (636mm total). From axle to handlebars on the Yukon ~560mm (370mm fork-crown, 25mm headset, 135mm HT, 30mm spacers), new bike ~560mm (400mm fork-crown, 150mm HT, 5-10mm headset & spacer). I'd rather have a slammed stem (aesthetics and for the purpose of holding a handlebar bag.) However, I'm considering a 140mm HT with a 10mm spacer to lower the TT a little at the front. (I'm not the biggest fan of sloping TTs.) It also means I can drop the handlebar down a little further for using aerobars. I'd love the ETT/ reach to be just a little shorter but my issue is size 45 feet. I already get toe rub on 28mm tyres, even more so on 32mm. With 35mm plus rubber its potentially going to be annoying. The new fork is 51mm offset vs current 45mm which will go a little way to helping this. I also don't want to go any shorter on the stem either. I like the way it handles,looks, and fits handlebar bags. Having said that I'm still considering reducing the ETT to 540mm.

As for the chainstay length, overall stability of the bike, and handling. 430mm seems to be the standard for these kinds of bikes. (3T Exploro is shorter of course but is more race oriented). In order to fit big rubber (maybe up to 50mm 700c, 2.2+" 650B) I'll need that extra length. (BTW Riv bikes' roadbike chainstays start at 440mm and go out over 500mm. That's huge!). It's only 5mm longer than my current bike which I'm happy with. I'm trying to match the trail of my current bike across a wide range of tyre sizes. My trail currently is 63-65mm (71.5deg, 45mm offset, 25-32mm rubber). The new fork has 51mm offset so I'm thinking of either slackening the HT angle or simply just learning to live with a shorter trail (71.5deg, 51mm offset, 25-50mm rubber yields a trail of 57-65mm (60mm on 35mm tyres and 57mm on 47mm 650B tyres)). If I slacken the HT I gain a little toe room and also yield a trail closer to what I currently have. I'm leaning towards leaving the HT angle as 71.5 (like most makers use in my size) and maybe I won't even notice the change in trail. 

Still a work in progress. Although, I've recently bought the shifters and brakes (Campagnolo H11 160mm front and rear). I have almost everything now. Only missing a frame!

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drwelby

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Reply with quote  #20 
It can tougher to get short chainstays on ti bikes and have low Q so you might want to think going longer just to make everything work out with less compromises. 

More rake plus slacker head angle is the classic was to fight toe clip overlap. Just be wary that if you match the trail between two fork offsets the higher offset fork will have more wheel flop. In some cases that can help (in 29ers it gives you a little "power steering" in switchbacks) so you may not notice if you're running bigger tires. Wheel flop also increases when you have more weight on the front tire, which will happen if you stretch the chainstays out.

The current thinking on handlebar bags is to have a longer top tube and shorter stem to get the center of gravity of the bag closer to the steering axis. The low trail set-ups are becoming more popular for bikes that always have a front bag. That configuration does work extremely well for a lot of people but you are committed to having the bag on there. If this bike was to have bags on it a lot of the time then going a little lower trail could be a good design compromise. I think lower trail would also be balanced out by bigger tires which seem to be the direction everything is going.

Have you done your fit calculations using just stack and reach? I've been mislead by just using ETT and now try to ignore that number.

Re-reading your older posts and looking at your bike still makes me think you're sitting too far forwards on the bike. Is there a way to test this out before you commit? Do you live in an area where it's easy to find old bikes to mess with?
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jeanjacques

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Reply with quote  #21 
The head tube angle is an interesting question, if the gravel geometry isn't a copy of endurance / CX bike, we see some manufacturer get inspired by MTB geometry with a high trail (compensated by the stem lenght) with slack head tube. For example, the Lauf Tru Grit, 70,5°, good reviews on the geo. Also Kona Rove 70,5°/71,5°, Scott Speedster 70,5°/71°, Kinesis Tripster ATR 70,5°.

Edit: and if you want to adapt the trail at your practice / tire / ground, there is the Cane Creek Angleset headset, 0,5 to 1,5°: http://www.canecreek.com/product/angleset/
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chas

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Reply with quote  #22 
Quote:
Originally Posted by jeanjacques
The head tube angle is an interesting question, if the gravel geometry isn't a copy of endurance / CX bike, we see some manufacturer get inspired by MTB geometry with a high trail (compensated by the stem lenght) with slack head tube. For example, the Lauf Tru Grit, 70,5°, good reviews on the geo. Also Kona Rove 70,5°/71,5°, Scott Speedster 70,5°/71°, Kinesis Tripster ATR 70,5°.

Edit: and if you want to adapt the trail at your practice / tire / ground, there is the Cane Creek Angleset headset, 0,5 to 1,5°: http://www.canecreek.com/product/angleset/


Hmmm.  My bike has short trail (steep head tube) with a short stem (inspired by MTB geometry).  

That adjustable trail headset looks intriguing...
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NoCoGreg

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Reply with quote  #23 
Looks like your project is coming together nicely.  I really like to avoid toe overlap on gravel bikes simply cuz there are times I'm going really slowly and making sharp turns (yeah the perfect situation for touching the front tire).  That's one of the big advantages my Raleigh Roker has over my Dean CX bike.  

I'll have to look into the Campy in-line cable adjusters.  I'm not a big fan of the SRAM in-line adjusters simply because there isn't a lot of range.  Just one man's opinion...

Cheers,
Greg

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plantbasedpedaller

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Reply with quote  #24 
DrWelby - Thanks so much for your thoughts. Most of the geometry is copied from various bikes I like in my size. Each has a slight variation in chainstay length, but apart from the Routte 45 (450mm) and the Tripster ATR (440mm), most are just either side of the 430mm that I'm going to spec. The maker (Walty) uses one of the fancy chainstay yolks to achieve the 68mm shell size with wide tyres and a mid-compact double. The toe overlap thing isn't really a problem, until it is. I've always lived with it, but it has bucked me off or made for a hairy situation on more than one occasion. I don't really want to fiddle too much with trusted geo just to fix that problem. Currently my thoughts are just to stick with the 71.5deg angle and settle for a little less (but still higher than neutral) fork trail and the negligible amount less flop. As you say, I could change the HT angle to match the trail but then I'd have to deal with extra flop which won't be the best when I do have front weight (fork bottles). I prefer to rear weight my bike (when necessary) so the flop is probably less of an issue. I do have bags on the front of course but it's not the bulk of the weight. My sizing is based on stack and reach (Reach ~380 & stack ~570). The ETT stuff is just convenient when the seat tube angle is consistent (which it is for most smaller frames). I'm interested to know why you think I'm too far forward. Since reading your comment I've been moving back on the saddle at various times to test it. There is a definite point where it is clear I'm too far back but for the most part I'm comfortable and efficient across the whole length of the saddle. I like to move around on my saddles a lot anyway. When doing efforts or TTing on my road bike I'm often way up over the BB and other times I like to sit way back and grip the drops right on the ends. 

JeanJaques - It's interesting you mention the Tripster ATR. I actually have a brand new size 54cm frame just sitting here that I bought during a sale. This whole thing has been spurred on by that particular frame just not being quite right. 

NoCoGreg - All of my shoes have wear marks on the toes from overlap. It's only ever really been a problem when stopping or slowing at traffic. Other than that I don't notice it. I don't think Campagnolo inline adjusters are anything too special. It's just that they have a really fine threading/adjustment and a wide range. The spring inside also has notches that provide a kind of positive stop. It prevents them from unwinding.


I'm not too far off now. I have a few component questions that I might put in a different post in the more appropriate topic area.

 


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jeanjacques

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Reply with quote  #25 
Quote:
Originally Posted by plantbasedpedaller

JeanJaques - It's interesting you mention the Tripster ATR. I actually have a brand new size 54cm frame just sitting here that I bought during a sale. This whole thing has been spurred on by that particular frame just not being quite right. 


V1 or V2 ? And did you ride it ? The V1 is one of the lightest ti gravel frame due to butted tube (even on custom frame, it's not common).
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