Frame design
- Thread starter Ted Wojcik
- Start date
1x9 is a good way to go - or 1x8 or whatever you so desire in back. But it sounds like Ted has in mind a more versatile design that someone who wanted to run 2 or three rings could utilize.
If we are going to keep this more East Coast specific than a 2x9 with one of those custom Ted Wojcik basguards would be just the ticket.
Ted - where will you be heading in CT?
I live in Burlington - perhaps we could meet for a cup of coffee or something if you'd like.
All the best,
Mark
Another thought for this thread is in addition to a suspension fork, it would be pretty cool to include a rigid fork option as well since many 29er folks enjoy the precision that a rigid fork provides.
Yay rigid!
My idea here is to come up with a design I could ride. I'm 60 now and need all the gears I can get. These challenges face all builders, so if we can find a way to deal with them. I'm sure we will find more usable 29er's in the market place. Of course there will be a rigid fork to go with it. I think that we might end up with some custom fabricated chainstays, slider dropouts, and a geometry that will tolerate adjustable chanstay length. When chainstay length changes, there can be quite an influence on handling. I'll tell you a story about that later in the build. I just want to throw out some fodder for thought here. 27.5" rear wheel?
Hey Mark, we are going to Kensington. (South of Hartford) I will be tied up until Friday on our way home. If there is time in there, I'd love to have a cup of coffee
Hey Mark, we are going to Kensington. (South of Hartford) I will be tied up until Friday on our way home. If there is time in there, I'd love to have a cup of coffee
ted, 27.5 has been tried before on road bikes. never really stayed around. i honestly dont see it becoming a big deal either. a 26 inch rear wheel with 29 front would be better especially when being able to chose tyres
hey let's make it a party... i'm in!
love this discussion, thanks Ted! .. but where was it 2 years ago when i was lookin for a Wojcik 29er?
(I guess I'll just suffer with my Wojcik 650b for now)can you do a curved top tube with steel to provide more standover clearance for the shorty riders? (that's not a request, just wonderin)
oh and ^^^ BARF. in my opinion, 26" rear wheel negates 90% of the benefits of the 29er concept. but if that's your thing, then just have the 26er's geometry customize to account for the bigger front hoop.
The first of the 29er's was really done by Bruce Gordon in the mid 80's. He called them Rock and Road. He used a Hakapallita tire that weighed over 1000 grams and I think that is what prevented it from more popularity. It had quick disconnects on the cables so you could swap back and forth between drop bars and flat bars. Great bike and a great idea that was delayed by tire availability. Scot Nicol and Cannondale did a bike with 26" front and 24" rear. Great bikes to do trials like trail riding. And we can't forget about the 96er thing. A lot of riders like this combo. Motorcyles routinely use different tires front and rear. The thing that will make 27.5" wheels work WILL be tires. 27.5" (650B) is the most popular wheel size in many other countries so I think we will see this gain some acceptance. It will be a better fit for those with shorter legs and gearing is less affected by the big roll out of the larger wheel size. One of the biggest advantages that I have seen for 29" wheels is for single speeds where the inertia of the large wheels keep the bike going through the rough stuff without shifting. Now if we can address the challenges of making a traditional drive train work with big wheels, we will have made a contribution to the sport and bring the advantages of big wheels to a traditional mountain bike. All I'm saying is let's look at all options.
I think 29 front, 650b rear has merit. I was riding a 96er before my 29er and there are some aspects I miss. If the 27.5 truly has a compromised feel between the sizes it would rule on the back. 29 on the front is set for me. I haven't found any disadvantage to that yet. I don't believe the claims that the rear is 90% of the 29er advantage. Anyone who is running a suspension fork on a hardtail has already acknowledged that there is a big difference between the effect of the front end and the rear when it comes to traction, rolling over stuff, and pedalling sensation. I am very tempted to try a 97.5er...
Can I comment, even if I'm from CA?
I'd like to see the frame designed for the Fox F29 @ 100mm of travel. I either want 100mm or rigid (actually I want both, I just don't want to bother with 80mm).
I'd like to see the frame designed for the Fox F29 @ 100mm of travel. I either want 100mm or rigid (actually I want both, I just don't want to bother with 80mm).
Welcome to the Monkey!
Your comment on the Fox fork makes me wonder if somewhere down the line we'll see a Fox 29er Talas model on the market.
My thoughts on fork and components:
Fork: Fox. The Reba is probably due for a change soon. The jury is still out on whether Manitou has got their QC and customer service back on track. That said I really like the Minute 29" fork I rode a few times. That leaves us with the Fox, or maybe the RST, which seems to be a heck of a lot of fork for the money.
Components: We are pretty much locked into external bearing 2 piece cranks if we want off the shelf parts. I say stick with proven stuff, something at the LX or XT level, perhaps for the whole bike. I've been testing a bike with an almost straight LX grouppo (including hubs) and have very little to complain about.
I've tried 2 27.5 bikes , and I have rims and tires waiting for hubs and spokes to finish the build. While tire selection will never be great, the one tire out now is just about perfect for east coast style trails. Deeper tread, real cornering knobs, should shed mud acceptably. I would have no problem going to a 27.5 tire to get shorter chainstays and front derailer clearance.
Fork: Fox. The Reba is probably due for a change soon. The jury is still out on whether Manitou has got their QC and customer service back on track. That said I really like the Minute 29" fork I rode a few times. That leaves us with the Fox, or maybe the RST, which seems to be a heck of a lot of fork for the money.
Components: We are pretty much locked into external bearing 2 piece cranks if we want off the shelf parts. I say stick with proven stuff, something at the LX or XT level, perhaps for the whole bike. I've been testing a bike with an almost straight LX grouppo (including hubs) and have very little to complain about.
I've tried 2 27.5 bikes , and I have rims and tires waiting for hubs and spokes to finish the build. While tire selection will never be great, the one tire out now is just about perfect for east coast style trails. Deeper tread, real cornering knobs, should shed mud acceptably. I would have no problem going to a 27.5 tire to get shorter chainstays and front derailer clearance.
How about one of each and we can do a comparo.
If this is going to be an 18" seattube design - then perhaps it makes the most sense to stick with the original concept of a 29er. Since the "challenge" part of making a frame like this work and have it be geared is part of the "fun" of this excercise.
Just my two cents.
With that said - I wouldn't mind giving a 27.5er a try - especially at my 5'9" height at some point to see how it works for someone like me.
it that why he comes off so grumpy, because he doesn't get credit for the first 29er?
come on, pal, crack a smile! DW looks more pleased than BG.
Ted - Feel free to send me an email or private message and I'll give you my telephone number.
Safe Travels for the Turkey Day Festivities!
I know that Davis Carver of Carver Bikes and www.bikeman.com Bath Ski and Sports up in Maine has tried out this 27.5/29er combo on one of his Carver hardtails. That seems to be a better combo than 69er in my eyes, but I've also been on a couple of 69ers that I cobbled together and although it wasn't as good as a 29er - with the right frame and fork - it was better than dual 26" wheels to my estimation and my riding preferences.
I've got no problems with the 29/27.5 combo. It's not for me (I like the full 29 thing), but I've got no problems for it.
I do agree with MMcG, though on doing the "full 29" treatment on this bike. I kind of feel that if this is a "learning process" to see what compromises have to be made and what creativity came come about to make this thing work, using a 27.5 rear to gain that tire clearance on shorter stays is a bit of a copout.
What kind of stay length are we talking about here?
I know all you East Coast guys seem to like super short stays and high bbs, but I've found with good design, you don't have to have 16.5" stays on a 29er. My Rock Lobster had +/-17" stays, and my Badger has 17.75" stays, both with +/-12" bb heights. The Badger is a better climber AND descender. We've got plenty of tight and twistys in KC, and we have no shortage of rocks. I used to be in the "must have the shortest stays I can get" camp, but this new bike has me re-thinking some of that.
So what kind of chainstay length are we actually talking about here?
I do agree with MMcG, though on doing the "full 29" treatment on this bike. I kind of feel that if this is a "learning process" to see what compromises have to be made and what creativity came come about to make this thing work, using a 27.5 rear to gain that tire clearance on shorter stays is a bit of a copout.
What kind of stay length are we talking about here?
I know all you East Coast guys seem to like super short stays and high bbs, but I've found with good design, you don't have to have 16.5" stays on a 29er. My Rock Lobster had +/-17" stays, and my Badger has 17.75" stays, both with +/-12" bb heights. The Badger is a better climber AND descender. We've got plenty of tight and twistys in KC, and we have no shortage of rocks. I used to be in the "must have the shortest stays I can get" camp, but this new bike has me re-thinking some of that.
So what kind of chainstay length are we actually talking about here?
I definitely think 96 kills a regular 26. Like I said, the 29 front seems like all positive, no negative as long as you have the geometry right. I've done bike switches on rides and found that a 29 wheel on a decent rigid fork feels almost exactly as compliant as a 26 wheel with a 3 inch travel fork, however the 29 wheel then adds its ability to roll over features that would stop a 26.
The problem with 29ers and acceleration is that even if you make the wheel light the inertia is going to be disproportionately greater because it increases with the square of radius. For that reason, the 650b will feel much closer to a 26 when accelerating while still being a (hopefully) good compromise in rolling effect. Since some of the mechanics of wheel performance are exponential and some are linear there should be a critical point where the inertia vs rolling resistance strikes the optimum balance. Since wheel size has been pretty arbitrary, it seems that it would premature to assume that one of the current sizes has pegged that point precisely. Maybe it's 27.5, maybe it's 29, maybe it's 28.1...That balance point will be shifted based on the average size of obstacle that the wheel has to overcome, i.e. what kind of trail you ride on...duh.
The problem with 29ers and acceleration is that even if you make the wheel light the inertia is going to be disproportionately greater because it increases with the square of radius. For that reason, the 650b will feel much closer to a 26 when accelerating while still being a (hopefully) good compromise in rolling effect. Since some of the mechanics of wheel performance are exponential and some are linear there should be a critical point where the inertia vs rolling resistance strikes the optimum balance. Since wheel size has been pretty arbitrary, it seems that it would premature to assume that one of the current sizes has pegged that point precisely. Maybe it's 27.5, maybe it's 29, maybe it's 28.1...That balance point will be shifted based on the average size of obstacle that the wheel has to overcome, i.e. what kind of trail you ride on...duh.
I think that is what is cool about this thread. We have ideas but in a sense it is somewhat of a blank canvas. I doubt we'll see a frame with a 17.9" chainstay - yet I also doubt (maybe not) that we'll see something with a 16.5" chainstay either. We'll get to decide what "works best" perhaps.
I would love to hear about rider size/height and chainstay length. Does it make sense to have slightly longer stays for those folks who may be pushing 6'4" and up let's say. For example, if a rider is 6'9" tall - would longer stays (within reason) make sense for that person compared to the chainstay length that might be "optimal" for someone my height at 5'9" tall? Or doesn't that matter?
I think it makes a big difference, and I wish that production bikes in different sizes where all different. Currently production frames are too similar, and the smaller sizes get the worst compromizes.
I'm not into the 27.5 idea, only because I think we should prove what can be done with 2 29" wheels. 278.5 should be another project. I also don't want to think about 2 different wheels and tires etc.
I'm sorry for being away, but I have bikes to make during the day. We have a great discussion going here. First what I would like to do is determine how short we can make the chainstays with a given tire to give adequate clearance with the tail of the front dérailleur. If we can't reach an acceptable design here to make a traditional (read Shimano) drive train function, we will decide if we want a 29"wheel only design or do we want the ultimate mountain bike without restricted wheel selection. Let's decide on a rear tire and size. I have a new XT crank on order and I will make a bottom bracket chainstay assembly to check and verify how much room we will have based on the tire chosen. I talked to Fox today and I cannot buy a 29er fork as an OEM, but I can have a local bike shop get me one as an aftermarket part. They did give me an engineering drawings so we can design the frame.
Ted - so you want to work with the most current XT or equivalent front derailleur available correct? I thought I read somewhere that Shimano had made some recent changes in their front derailleur designs to help provide a little more rear tire clearance - I'm not positive, but maybe it is something a fellow Monkey could look into for this thread.
As for a rear tire - I wonder if we can get Kenda to "buy" into this thread and provide a Nevegal or Small Block 8 or something else in their line-up.
It would be really cool if we could get MikeB from this forum to join in on this thread. He's a STan's employee - maybe a good source for the wheelset? Just thinking out loud here.
Mark
As for a rear tire - I wonder if we can get Kenda to "buy" into this thread and provide a Nevegal or Small Block 8 or something else in their line-up.
It would be really cool if we could get MikeB from this forum to join in on this thread. He's a STan's employee - maybe a good source for the wheelset? Just thinking out loud here.
Mark
The Shimano site does claim that the new XT front derailleurs have been redesigned for better tire clearance both for the cage tail and behind the seat tube.
If it had modular dropouts like this Sinister, you could run any size wheel you wanted in the back, geared or single, etc...The dropout for a 26" wheel would have a hole or slot far forward and way down, the 27.5 would be in the middle and the 29 would be back and up. That way the rest of the bike wouldn't change, BB height, HT angle, standover would be constant regardless of rear wheel choice. In addition, if each dropout size were slotted the owner could adjust chainstay length for different handling or tire clearance. It would actually be pretty simple and perhaps make a bike that pleases most of us? Then we can argue about paint schemes!I'm cheating...FTW, Darrell and I just chatted about this on the Sinister 29er a few months back
to keep a sub 17" seat tube angle the seat tube got a nice dogleg in it.
I spoke with Chris a week or two ago, sounds like you guys are kicking ass!
RJ
The big problem is always going to be the front derailleur. I believe that there is the possibility of a semi-cageless design that could free things up for 29, but we're obviously talking about a non-standard part... so you either have der cage tire overlap or you don't.
If you don't then you're stuck with long WEST-COAST stay lengths, and we don't want that. Even 650b out back will increase stay length over a traditional 26er. The greater traction of the larger tires will help to mitigate some of the losses due to the length, but they still harm the balance and quickness of the bike.
Since the 29er wasn't considered when multi-speed components were designed, I see this as an area where it's OK to have proprietary pieces, like a special chainline crank or funky front der. The bike will be compromised without it. Someone smart (like me
) with money (not me :-( ) should develop a new standard front der for 29.
Or there's Schlumpf. Or Rohloff.
If you don't then you're stuck with long WEST-COAST stay lengths, and we don't want that. Even 650b out back will increase stay length over a traditional 26er. The greater traction of the larger tires will help to mitigate some of the losses due to the length, but they still harm the balance and quickness of the bike.
Since the 29er wasn't considered when multi-speed components were designed, I see this as an area where it's OK to have proprietary pieces, like a special chainline crank or funky front der. The bike will be compromised without it. Someone smart (like me
) with money (not me :-( ) should develop a new standard front der for 29.Or there's Schlumpf. Or Rohloff.
And most builders are making the mistake of running a straight seat tube down to the BB. This gives an inappropriate angle for the front der because those ders aren't designed for so much BB drop.
(I know that Shimano now offers the XT -and maybe others- in two different CS-to-ST angles. I haven't checked them to see if either is appropriate for 29er)
Curving the bottom of the ST increases clearance and corrects for front der angle.
But it takes a mighty thick tube to heat-bend it and a mandrel-bent tube can get pricey for tooling set-up.
(I know that Shimano now offers the XT -and maybe others- in two different CS-to-ST angles. I haven't checked them to see if either is appropriate for 29er)
Curving the bottom of the ST increases clearance and corrects for front der angle.
But it takes a mighty thick tube to heat-bend it and a mandrel-bent tube can get pricey for tooling set-up.
I wish I could afford to have some custom dropouts machined for this project, but I can't. The closest thing to that is going to be Sliders by Paragon. I can't post the first of the drawings yet, but 17.5" chainstays, 2.5" BB drop with 73 degree seat tube will allow the use of a Shimano XT front der. M771 or M773. They are for a seat tube chainstay angle of 63-66 degrees. Do we have a consensus on the tire yet? Right after Turkey day, I will make a mock up to check the clearances.
I've been pretty happy with the Nevegal. Going wide enough to fit this tire would leave plenty of room for everything smaller.
How about a 3 piece seaat tube with cut, mitered and welded lower sections to effectively "bend " the seat tube in the front derailer clamp area?
ted you have a pm
but doesn't pushing the rings out induce a lot of chain dropping?
We will try to keep the chainline as close to the 50mm that Shimano recommends as possible. Monday, I will order the parts to build a "mule"
Do to the Holiday ext week, things will slow down a bit, but bare with me here, and I will share the process of building a true custom frame. Ride Monkey will have control of the helm as this ship sails into unchartered seas. Kinds' corny, huh?
Do to the Holiday ext week, things will slow down a bit, but bare with me here, and I will share the process of building a true custom frame. Ride Monkey will have control of the helm as this ship sails into unchartered seas. Kinds' corny, huh?
How are the tubes bent for say the Karate Monkey - is that a difficult and costly process for a custom builder to undertake? IF the newer Shimano front derailleurs provide more clearance, the bent seat tube idea may be worth exploring a little bit more. When I ran my Karate Monkey (a small) I was able to run a Bontrager Race wheel with an Exiwolf in back and an older XT front derailleur with the rear wheel all the way forward in the horizontal dropouts (I didn't need to use their Monkey nut to move the rear wheel back a little) in a 2x9 set up and the bike shifted just fine in all gears.
The thing that irked me the most on the Karate Monkey for these parts (Connecticut) was the low bottom bracket. I know some guys are running 170 and even 165mm cranks to address this issue - but again - this is another compromise that this Ted Wojcik Project could address.
Ted - do you want this to be a total in house thing or would you be willing to have collaborators contribute. For example - you may have to go with Paragon Sliders - but perhaps there is someone here on the Monkey with the ability to produce a different type of sliding or adjustable or multiple dropout set up.
Just thinking with the collective power of the Monkey and the web and the riding community - perhaps folks wouldn't mind stepping up to the table to assist with items/hard work/parts for this project.
Best to all,
Mark
The thing that irked me the most on the Karate Monkey for these parts (Connecticut) was the low bottom bracket. I know some guys are running 170 and even 165mm cranks to address this issue - but again - this is another compromise that this Ted Wojcik Project could address.
Ted - do you want this to be a total in house thing or would you be willing to have collaborators contribute. For example - you may have to go with Paragon Sliders - but perhaps there is someone here on the Monkey with the ability to produce a different type of sliding or adjustable or multiple dropout set up.
Just thinking with the collective power of the Monkey and the web and the riding community - perhaps folks wouldn't mind stepping up to the table to assist with items/hard work/parts for this project.
Best to all,
Mark
Fred (Wolfhound) & I have been discussing the challenge of adding a front der. to his split ST frames....one way we discussed was using an E-type with the backplate removed....like such:
We'll see how effective it is over the long haul.
We'll see how effective it is over the long haul.
Attachments
I would welcome inputs on this project, but lets try to be able to repeat the component. Doing a one time design that would be too expensive to repeat won't help this thing go forward. Paragon sliders are not a problem, bent tubes are. I would like to use some of the air hardening steel that is available to keep the frame light and strong. That tubing isn't not going to like being bent. I'm pretty conservative in my frame designs. I hate returns. I'm definitely a "form follows function" guy. But whatever ideas are thrown out there, let's take a look. I'm willing to learn, too. Remember every time we deviate from the norm, it will probably require some special fixtures for construction. The frame needs to be straight and stay straight. As the frame flexes, let's make sure the wheels stay in plane, that is no head tube or rear axle twist. Too much flexibility will make the bike feel unsteady through stutter bumps and lose precision in tight technical stuff. Also, we don't need fatigue cracks showing up later.
I think the e-type could be the best front derailleur option if this frame is to have a straight seat tube.
Probably OEM items but I noticed today while visiting a shop that Specialized is using a sort of bolt on front derailleur (pseudo e-type?) on their FSR Stumpjumper 29er and a few of their other FS bikes (like their new Pitch 5.5" travel bike).
Since this isn't a true "custom" frame for one specific individual - what were you thinking of in terms of top tube length for the 18" seat tube frame?
Probably OEM items but I noticed today while visiting a shop that Specialized is using a sort of bolt on front derailleur (pseudo e-type?) on their FSR Stumpjumper 29er and a few of their other FS bikes (like their new Pitch 5.5" travel bike).
Since this isn't a true "custom" frame for one specific individual - what were you thinking of in terms of top tube length for the 18" seat tube frame?
The derailers found on the Specialized bike are E-types with the bracket removed and a Custom mount on the frame which should be easily recreated...