well poo on me
Lahr Carbon Gear Box bike
- Thread starter NY_Star
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Yep we always call them either female or male molds.
We pretty much machine all mold patterns from tooling block, the tooling block patterns are pretty much the shape of the finished part, they're machined on big 5-axis CNC beasts and then hand finished. We then make a LTM carbon mold from that. LTM meaning Low Temperature Moulding. It's basically a coarse woven carbon/epoxy composite that can be cured at low temps so they don't distort the pattern. The LTM Carbon molds are capable of then being used at the final cure temps needed for the final composite parts.
For those that wonder why we call the male or female - you laminate inside a female mold or around the outside of a male mold.
We pretty much machine all mold patterns from tooling block, the tooling block patterns are pretty much the shape of the finished part, they're machined on big 5-axis CNC beasts and then hand finished. We then make a LTM carbon mold from that. LTM meaning Low Temperature Moulding. It's basically a coarse woven carbon/epoxy composite that can be cured at low temps so they don't distort the pattern. The LTM Carbon molds are capable of then being used at the final cure temps needed for the final composite parts.
For those that wonder why we call the male or female - you laminate inside a female mold or around the outside of a male mold.
where can I send my deposit... as long as it a gearbox bike of course
Gridds, use of Ti instead of Al in the bonds will significantly up the price, doesn't it?. Not to say it may be really difficult for home frame builder to get to Ti. What about trying to avoid the usage of metal inserts in places like HT, seat tube or even som simpler pivot designs? Like SC did the HT in new C V10, without Al inserts for HS cups, just plain laminate? Is kevlar required for this?
Yes Ti instead of Al will up the price, but over the whole cost of a carbon frame, that increase will be small and you will have the added bonus of it being done properly and you'll end up with a longer lasting frame. Why go to all the effort of making a nice carbon frame if you know it has a design flaw in it that will limit it's life?
Of course you could design it with minimal requirement for metal inserts, but you'd still need them in some places. The BB shell is one place you'd almost certainly need it. You could get away with no inserts for the headset cups and a layer of Kevlar or even glass would be ok. Personally I'd still use a Ti insert for durability and longevity.
I use a glass scrim.
I would love to use Ti as well, and may well on future projects. But it is cost prohibitive and my designs are overbuilt anyway. not to mention most adhesives have a bond of over 2000psi shear. The loads the differences in expansion would place over something bike related (in length) would be a LOT less than that?
What are the real world ( differences in CTE
I agree the differences seen in a bike component would be small but not insignificant.
We still get problems on Carbon/Al bonds on suspension and chassis components and these would be around a simlar size you'd see on a bike frame.
We can get bond shear strengths over 5000psi in a static situation. When looking at fatigue strength though a joint with that kind of static strength may only have fatigue strength of around 1000 - 2000 psi. Small loads have a large effect in fatigue, particularly with aluminium. It's not just how strong the bond is but also things like how stiff the adhesive is for it to cope with the differential strains and how will it cope in harsh environmental situations etc.?
You also have to consider how your part is made, is the insert co-cured or secocndary bonded? Co-curing it will see some fairly high temps just in the manufacture. CTE plays a factor here.
Some real world CTE figures:
Carbon/Epoxy composite around 2 to 3 x10-6 °C-1.
Ti is around 9 x10-6 °C-1
Al is around 23.5 x10-6 °C-1.
It's not all about CTE though. Stiffness, corrosion and fatigue and combinations thereof all play a significant part. Al is not good at any of these.
Although for things like prototypes it would be fine...
I'm not saying it can't be done. I'm just saying I wouldn't do it in my design of a bike frame. Which should last a lifetime!
We still get problems on Carbon/Al bonds on suspension and chassis components and these would be around a simlar size you'd see on a bike frame.
We can get bond shear strengths over 5000psi in a static situation. When looking at fatigue strength though a joint with that kind of static strength may only have fatigue strength of around 1000 - 2000 psi. Small loads have a large effect in fatigue, particularly with aluminium. It's not just how strong the bond is but also things like how stiff the adhesive is for it to cope with the differential strains and how will it cope in harsh environmental situations etc.?
You also have to consider how your part is made, is the insert co-cured or secocndary bonded? Co-curing it will see some fairly high temps just in the manufacture. CTE plays a factor here.
Some real world CTE figures:
Carbon/Epoxy composite around 2 to 3 x10-6 °C-1.
Ti is around 9 x10-6 °C-1
Al is around 23.5 x10-6 °C-1.
It's not all about CTE though. Stiffness, corrosion and fatigue and combinations thereof all play a significant part. Al is not good at any of these.
Although for things like prototypes it would be fine...
I'm not saying it can't be done. I'm just saying I wouldn't do it in my design of a bike frame. Which should last a lifetime!
interestingly the lahar uses no inserts anywhere. the bb uses bearings direct fit in the carbon (just like the headset) - similar to a bb30 system. seems to be doing the trick so far.
aren't they GLUED in though? I would think at some point you may want to swap bearings/brands/etc. Having a threaded insert would allow for that. Where's BCD when you need him...
Nice to see people know their stuff around here...
Yeah I do like the Lahar design, a lot. Always have. In fact I find it pretty hard to fault other than looks and maybe a bit too long CS, but that's just being fussy.
As far as I'm concerned Lahar is the benchmark design for a DH frame.
I'm curious, have you ever ridden a Lahar? Years ago when I was working on the GBOXX 1 standard, Karl sent me one of the Nucleon's to ride for a couple seasons, the second generation one with the welded swingarm. A guy here on the East Coast had a Lahar and we traded bikes for a few runs in West Virginia. It was an interesting bike, not terrible for it's time, but I can't imagine it being a very formidable weapon today with it's geometry and suspension feel.
Not sure if Derek Lahr has chimed in here on this, as I remember the bike in the pictures earlier in the thread was supposed to be the testbed for his CVT design. I remember he was testing the bike without the box, as it wasn't finished quite yet. You can see the CVT is not in place in the pictures. Did he ever get the design working and in the bike? He seemed like a good guy, I was rooting for him to get this thing done.
Why? Because it doesn't have a 'DW link' or one of your ridiculous patents slapped on it? Have a day off.
Sure the goemetry could be tweaked to something more modern but there's nothing wrong with that suspension design. In terms of materials and design concept it still beats the sh!t out of many many bikes that have been made since and even now.
was that the last generation (m9)? geo still feels pretty solid (considering it's 4yrs old now). bb is a bit high by current standards ~14.25, but not bad for a 9" bike. h/a is ~63.5 (ahead of his time on that front). not as much anti squat as one of your multi link designs, but it's a monster bump eating machine. still an amazing bike by todays standards, imo.
sandwich - re: the bb bearings - yeah, they're epoxied in. aaron told me to use a bit of araldite with replacement, but the fit is snug enough that just pressing in the new ones was adequate. the old ones just tapped w/o much problem. dead simple & light yet effective interface. uses standard bearings (as with the h/s). makes you question why we even need headsets & bottom brackets. aaron, despite his faults, had lots of great ideas.
that's cool on the BB bearings. I thought it was a "one and done", hope your bearings never fail sort of deal. Great strides have been made in cranks in the last few years, so I would expect to have to change things once in a while.
As to the lahard, mega long CS's are the biggest detriment, although the HA is probably way ahead of it's time. High pivots are definitely rider preference matter. I loved the way my brooklyn went through rock gardens, but the sunday is an excellent sprinter. I never felt too bad on the brooklyn mostly because I didn't pedal it like a turd, which is when it gets bad. The lahar is quite a bit like the link bike I had before, just lower, carbonerer, and rohloffier. I wish (zerode) somebody (superco) would make a more modern version of that design, preferably with a IG hub (alfine 8speed).
yeah, lengthly cs (esp. on a high pivot) makes for a not so easy to manual ride. it terms of a pure go fast racebike, it works great, but i personally prefer the more 'playful' aspect of a shorter cs.
you know, i was really impressed w/ the pedalling ability of the silencer; not sure how it compares w/ the racelink kinematically, but it puts the power down pretty effectively.
you know, i was really impressed w/ the pedalling ability of the silencer; not sure how it compares w/ the racelink kinematically, but it puts the power down pretty effectively.
It has nothing at all to do with my ridiculous and obviously frivolous rubbish suspension designs and patents.
Why? Because it doesn't have a 'DW link' or one of your ridiculous patents slapped on it? Have a day off.
Sure the goemetry could be tweaked to something more modern but there's nothing wrong with that suspension design. In terms of materials and design concept it still beats the sh!t out of many many bikes that have been made since and even now.
I rode the bike and I just feel that even at the time there were other bikes on the circuit that outperformed it as a World Cup race bike from both a geometry and suspension standpoint. (Turner DHR, Intense M1, Iron Horse SGS (won WC overall that year))
Don't get me wrong, I love the concept of carbon construction and I spent literally years of my life working on the GBOXX 1. I see and appreciate the technical merit of both, I just was not sold on the ride of the one particular bike that I rode. Perhaps there are better examples of that one bike there, I won't discount that at all.
You know, I am about 99.9% sure that it was the fist model LAHAR, as this was 2003, but I don't have the model names 100% dialed in my head. It was definitely the only one I've ever seen on a mountain. The guy that owned it used to post here way back..
There's no doubt that the lahar is fast! the long chain stays do hold back the fun factor but for a bike with such long stays and wheel base it sure does turn well for a bike with those dimensions.
the lahar is still far from perfect and if I a choice between one with a gear box or with out I would have gone for no gear box, only reason I got one was for the hi pivot.
The fact that the main frame pure chunk of carbon is evey well done!
but maybe you could machine up the inserts from some of that super hard thermoplastic??
the lahar is still far from perfect and if I a choice between one with a gear box or with out I would have gone for no gear box, only reason I got one was for the hi pivot.
The fact that the main frame pure chunk of carbon is evey well done!
but maybe you could machine up the inserts from some of that super hard thermoplastic??
Hi Scott,
Do you mean PEEK? Or even short fibre carbon reinforced PEEK? Hmmm. I'm not sure it's hard enough to have durable threads for repeated use by ham fisted DHer monkeys but might be ok. We generally use threaded inserts on it (helicoils etc) and it seems to be ok. However tests I've done on it have shown it's actually quite difficult to bond to reliably. Also pretty pri$$$ey. Not a bad suggestion though.
(still love my bike btw)
the older lahars were pretty horrendous. The new one is less of a trainwreck but somewhat less so.
The long chainstays are more of a problem because of the high pivot. As you get deeper in travel they get even longer. IIRC, the lahar's start at 18.2". That's huge. At sag you're probably at 19+, and fully bottomed 20. That makes for pretty terrible tight corners. My linkbike was terrible at highland because of all the tight berms. The sunday is phenominally better there with it's shorter back end (not to mention 20lbs lighter).
PS I'm glad you took that quote out....I poke fun but I'm not a hater.
The long chainstays are more of a problem because of the high pivot. As you get deeper in travel they get even longer. IIRC, the lahar's start at 18.2". That's huge. At sag you're probably at 19+, and fully bottomed 20. That makes for pretty terrible tight corners. My linkbike was terrible at highland because of all the tight berms. The sunday is phenominally better there with it's shorter back end (not to mention 20lbs lighter).
PS I'm glad you took that quote out....I poke fun but I'm not a hater.
I'm with you dude, so many cool bikes out there at the moment but there's not a chance I'm swapping my Sunday 'till I see something along this lines
Gridds, build it, they will come!!! I'd be interested to see what you'd come up with compared to more standard designs!
I agree, FWIW I use a specialist carbon/alloy adhesive, pricey but man it sticks! http://www.atlcomposites.com.au/atl_composites/epoxy_products/adhesives/techniglue_r5_toughened Most bearing seats are what.. 50mm long? And a bike is working in a 50 deg c temp range. So what's that? 0.0000000000000000000000000000000000000000000000000000001mm??!! Hardly an issue.
Think that's a bit harsh mate. DW has a right to chime in there too
Why? Because it doesn't have a 'DW link' or one of your ridiculous patents slapped on it? Have a day off.
Sure the goemetry could be tweaked to something more modern but there's nothing wrong with that suspension design. In terms of materials and design concept it still beats the sh!t out of many many bikes that have been made since and even now.
I like the Lahar's bearing idea in theory too. But as a production item I think asking someone to glue in a bearing without getting epoxy everywhere is a bit impractical. Just my opinion. The consequences of poor preperation before bonding and spinning a bearing in a carbon seat could get nasty.
If your interested You can see on my bike the alloy between the pivot and the BB, serves not only as a bearing plate, but also aligns the BB pivots etc. http://www.facebook.com/photo.php?pid=4666826&id=106494828315
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The Lahar just requires a bit of araldite, to help fill any miniscule imperfections, hardly messy. And if you stuffed the surfaces you could get it redone anyway I believe. If everything's done up before araldite dries, it's in correct possition.
Your bikes looking great, all holding up as antisipated?
Working on the next gen yet?
Critisizing a bike design based on geo isn't really making a point when discussing it's desing, construction, and materials used. results don't say too much either, and statcisticly per capita results wise, the Lahar doesn't have much to worry about.
With 9" travel a 14.25"BB would be close to sub 14 on a 8" bike wouldn't it? The Lahar's head angle is still current.
Just the chainstays were too long for me, and the tracks I ride.
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does anyone know exactly what happened to lahar? after hearing a few years ago about people getting screwed by them i didnt hear much else. did they ever resurface? its really too bad because they were years ahead of their time, and its always excieting to see someone pushing the envolope.
'they' was solely aaron franklin, and despite having great ideas & mad carbon manipulation skills, he didn't have the organization to actually go into production with these things in any sort of volume, and he bit off more than he could handle in taking a bunch of pre-order deposits. last i heard it sounded like he was working on completing the last order, this was a long time back though. seems he's since vanished. lots of rumours circulating of course. i corresponded w/ him a bunch, and yes, he had his eccentricities / was dealing w/ personal problems, however i don't think he had any ill intent in mind when things went sideways. unfortunate, yes.
*edit* - granted, my perspective is based on a positive experience w/ aaron. the initial build was lengthly, but the subsequent support was great.
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Last I heard there was 1 outstanding order, and a negative thread on here fuelled by Hamwich^ and others pushed away a potential investor that would have completed that order. Not sure what happened after that. Nore can I validate this, just what I heard. Shame for sure. Pitty Arron wasn't in USA or somewhere that a company could have tapped into his brain for design only.
Looks good, D. Thanks for chiming in.