Travers Ti frames - pay what you can afford.

[johnnystorm]

Glad I haven't just paid £1800 for one about 6 weeks ago

All you have to do is buy another 20 and you'll have only spent an extra 40 quid a frame. Much more palatable.

[FLV]

Anyone know who builds them?

(I know this doesn't matter to some people, but it *might to me)

Also, anyone know the reach and stack figures?

[mountainbaker]

Except Pressfit isn't proven junk. There are some awful implementations of it but done properly, PF is a perfectly fine standard. Bashing brands that can manufacture correctly is fine, but bashing the standard makes no sense.

Because there wasn't a problem with threaded BBs, so it's a pointless standard, totally deserving of bashing. Perfectly fine isn't perfectly good. So why bother?

Because it's easier to get a Chinese factory to produce things with less critical tolerances.

Do you put pf on your hand built frames, or only the ones from China that you paint? If so, why?

[stevenshand]

Except Pressfit isn't proven junk. There are some awful implementations of it but done properly, PF is a perfectly fine standard. Bashing brands that can manufacture correctly is fine, but bashing the standard makes no sense.

Because it's easier to get a Chinese factory to produce things with less critical tolerances.

I'm not sure what you're saying here. If you're saying it's easier for a Chinese factory to make a PF BB than a threaded one then I'm not sure that's correct. In fact I know it's not. All the poor implementations backup the fact that it's harder. And as far as tolerances go, the tolerances for a PF are tighter than they are for a BSA threaded shell.

The issue with the threaded standard (which I have nothing against) is that it's not as well suited to modern materials (CF, thin wall large diameter steel and aluminium). If we were all still riding around on skinny steel tubes I'd be on your side.

Do you put pf on your hand built frames, or only the ones from China that you paint? If so, why?

Well, firstly we've never had any Chinese frames. We have had some carbon frames from Taiwan that we painted and we currently have a steel frame from Taiwan that comes to us already painted. About 90% of the handbuilt steel frames we make here in the UK have PF shells, the CF Taiwanese had a mix (same frame but the BSA threaded version had a bonded-in aluminium threaded insert which was awful). The current imported steel frame has a BSA threaded because it's cheaper and we're trying to hit a price point.

[In Reverse]

Anyone know who builds them?

(I know this doesn't matter to some people, but it *might to me)

Also, anyone know the reach and stack figures?

They're built here: http://www.titancycles.com/

I can send you the .dwg for mine if you're interested?

[JohnClimber]

There’s a definite DIRTi type itch

[whitestone]

The issue with the threaded standard (which I have nothing against) is that it's not as well suited to modern materials (CF, thin wall large diameter steel and aluminium). If we were all still riding around on skinny steel tubes I'd be on your side.

Steven, that's the first argument I've heard in favour of PF that makes sense from an engineering perspective rather than the marketing BS ("It's stiffer", etc.) that's normally trotted out.

But ...

How much extra weight/cost is a suitably thick walled steel or aluminium tube over a thin walled one when it comes to the BB? I've a Cotic Solaris Mk1, thin walled steel and it's got a threaded BB and it's been no problem so presumably Cy has specced a thicker tube for the BB. Similarly I've a Spesh Roubaix (SL2 from memory) that's ten years old, CF frame but with a threaded BB shell. I replaced one of the bearings last year after 24k km. N=1 (or 2) and all that but it can be done.

[Piemonster]

There’s a definite DIRTi type itch

Do one. That’s not helping

TBF, I ordered a few items yesterday for some long rides later this year so I might be safe unless the deal is still in place next payday. Then I’m in trouble.

[stevenshand]

The issue with the threaded standard (which I have nothing against) is that it's not as well suited to modern materials (CF, thin wall large diameter steel and aluminium). If we were all still riding around on skinny steel tubes I'd be on your side.

Steven, that's the first argument I've heard in favour of PF that makes sense from an engineering perspective rather than the marketing BS ("It's stiffer", etc.) that's normally trotted out.

Sure , but remember, it's not really the frame/bike makers telling you that PF is 'stiffer etc', it's component companies that are telling you 30mm crank spindles are stiffer than 24mm spindles and you can't (really) get a 30mm spindle into a BSA threaded bottom bracket and play nice.

But ...

How much extra weight/cost is a suitably thick walled steel or aluminium tube over a thin walled one when it comes to the BB? I've a Cotic Solaris Mk1, thin walled steel and it's got a threaded BB and it's been no problem so presumably Cy has specced a thicker tube for the BB. Similarly I've a Spesh Roubaix (SL2 from memory) that's ten years old, CF frame but with a threaded BB shell. I replaced one of the bearings last year after 24k km. N=1 (or 2) and all that but it can be done.

It's not really about the wall thickness of the BB shell. Cy won't have specced a thicker wall BB, it'll be about 38mm OD, the same as most BB shells. The issue is the surface area of the welded region. When we were all riding bikes with 32mm down tubes, they mated up fine with a 38mm BB shell. As materials got better (stronger), walls got thinner which meant tubes needed to go bigger diameter to be stiff enough. So now you have a 38mm DT (or bigger) mating to a 38mm BB shell. This isn't necessarily bad but you also need to get 2 chainstays and a seattube on there too which means there's bigger compound mitres (where two tubes intersect each other as well as the tube they're joining, in this case the BB shell). A PF30 BB shell is close to 50mm OD which gives much more room.

I’m not saying that a BSA shell and the big tubes in my example will fail or it’s a terrible idea, it’ll be fine, but as a designer and fabricator, if there’s another option to choose from with a bigger shell then I’ll go for that everytime. However, I can only confidently go for that if I know that I have the ability to control all of the other variables needed to make sure that a PressFit system will work in the way it’s intended. These variables are shell width, accurate internal diameter and crucially, the bores on each side of the shell being totally concentric.

Going off topic slightly but I also think it’s worth addressing an attitude I see pop up often, about BB shells but also the other standards that are introduced from time to time. I see comments (including in this thread) that the factories are only doing stuff like this because it’s cheaper/easier/quicker. The factories are only making what their customers are asking for. They’re not the ones pushing these new standards. I would imagine having to tool up for these newer standards are more of a headache for them. My dealing with factories in Asia isn’t extensive but I’ve never had a conversation where my design has been influenced (in this context) by what the factory finds easiest to do. JamesO will have had much more experience than I have, it would be interesting to hear his thoughts.

Finally, as this has turned into a long ramble, it’s worth noting that when it comes to bike design it’s not all black and white and often marketing decisions are at conflict with engineering solutions. One of the bikes that Shand do that used to have a PF shell has gone back to using a BSA shell. The only reason for this was sales/marketing pressure. There were enough people saying that they have little confidence in buying a PF frame that the company felt they were losing sales. I should also say that wasn’t my decision (I don’t get to make those sorts of decisions anymore!) and it’s not one I would have supported, I think it contributes the misinformation out there about PF frames.

I have waaaayyy more to say on the subject of BB shells but I think there’s enough thread drift here already.

[Lazarus]

it's component companies that are telling you 30mm crank spindles are stiffer than 24mm spindles

This one i dont get push hard on your cranks and the wheels and chain stays deflect - who out there was moaning about how flexy their cranks were ? Its the least flexy part of the systems even your chain ring will deflect more - assuming you have vaguely exciting levels of power] Had anyone ever complained about this ?

The factories are only making what their customers are asking for

their customers being the bike manufacturers rather than the paying public- again I dont recall anyone wishing bottom brackets were fitted like headsets

I could fruther argue the industry made bigger BB and then bigger cranks to fit them to solve problems no one had - [ also makes your old frame/ bike/ BB /cranks obsolute and requiring [full bike rather upgraded parts replacing ] though i get why you end up with this due to having to use bigger BB due to tubing size changes

i dont want to appear like I am having a dig as i appreciate the honest input from the industry and a builder but I dont think you will find many outside the industry who thinks that we the paying public demanded these new and ever varying standards that achieve, from a functional working bike perspective - nothing and often create probelms the older standards never had

[In Reverse]

Worth pointing out that his newer frames have a T47 BB shell, and trying to get one of those to fit an mtb crank is "interesting" at the moment. I'm pretty sure I managed to buy the only one in the country to fit SRAM DUB, and that took a few days to find.

[stevenshand]

Worth pointing out that his newer frames have a N47 BB shell, and trying to get one of those to fit an mtb crank is "interesting" at the moment. I'm pretty sure I managed to buy the only one in the country to fit SRAM DUB, and that took a few days to find.

Assuming you mean T47, what are the issues trying to fit a crank? The only difference between the T47 and the PF30 is that one is threaded, the actual ID of the bearings and the width should be the same so I'd be interested to hear what the issue is.

[In Reverse]

Worth pointing out that his newer frames have a N47 BB shell, and trying to get one of those to fit an mtb crank is "interesting" at the moment. I'm pretty sure I managed to buy the only one in the country to fit SRAM DUB, and that took a few days to find.

Assuming you mean T47, what are the issues trying to fit a crank? The only difference between the T47 and the PF30 is that one is threaded, the actual ID of the bearings and the width should be the same so I'd be interested to hear what the issue is.

Apologies Steven that wasn't very clear (including the actual name ). It's the buying bit, not the fitting. Supplies seemed to be very thin on the ground a few weeks ago, genuinely thought I wasn't going to be able to get one.

Ended up buying direct from a UK manufacturer (Rideworks) and they had just one left in stock.

[stevenshand]

Worth pointing out that his newer frames have a N47 BB shell, and trying to get one of those to fit an mtb crank is "interesting" at the moment. I'm pretty sure I managed to buy the only one in the country to fit SRAM DUB, and that took a few days to find.

Assuming you mean T47, what are the issues trying to fit a crank? The only difference between the T47 and the PF30 is that one is threaded, the actual ID of the bearings and the width should be the same so I'd be interested to hear what the issue is.

Apologies Steven that wasn't very clear (including the actual name ). It's the buying bit, not the fitting. Supplies seemed to be very thin on the ground a few weeks ago, genuinely thought I wasn't going to be able to get one.

Ended up buying direct from a UK manufacturer (Rideworks) and they had just one left in stock.

I see. It was the BB you were struggling to get, not the crank. That makes more sense. The Rideworks parts are great. He makes his own seals for the bearings too.

[mountainbaker]

their customers being the bike manufacturers rather than the paying public- again I dont recall anyone wishing bottom brackets were fitted like headsets

I agree with this. Factories make what they are told to make by bike designers. Who make decisions on both merit of design and the bottom line, cost. All designers have different bias toward quality and function/cost of course.

I just see PF as a cheap option. Admittedly I had terrible experience with PF on a cheap On-One lurcher, there weren't many BBs available at the time, and I got through 3 in a year. Sold it and never going back.

[stevenshand]

I just see PF as a cheap option.

I'm genuinely interested in this outlook and where it comes from. From a small volume builder perspective, I'm pretty sure the material cost is higher with a PF frame, I know I was paying more for either raw tubing to make the BB shell or in fact if I was buying finished to size (and threaded) shells, PF was more expensive. The post manufacturing machining/reaming/chasing is certainly more expensive in terms of tooling and time to deal with PF frames than it is with threaded.

Are Pressfit bottom brackets themselves cheaper?

Maybe Pressfit just needs a better PR person!

[fatbikephil]

I think my biggest disappointment with press fit BB's is the fact that they come in a separate shell. If the bearings just pressed direct into the frame that would be much better. The ICT has a PF41 and my issues have been around the crap placcy shells on the shimano BB's that can randomly creak unless you bung them in with loctite, which makes remval a PIA. If the shell had a 42mm ID you can get a bearing that would press directly in. Hope's 30mm ID bearing for PF41's is a special made one that does just that. I'm going to get one of these next and just use converters for my 24mm crank but it would be nice if you could just bash a nice big bearing in, with a centre spacer and then press in the crank spindle and bolt it up FO tight. In fact I designed just such a thing for the Jones 60mm BB. The bugger is that you can get a bearing with a 25mm ID but not 24.....

[TraversBikes]

People seem to be getting a little off topic, I was trying to make a genuinely nice, fair and creative offer, share a little love and give back a bit but things seem to have descended into the old "the standard BB I like is better than the one you like" argument!

For what its worth my reasons for using the PF30 on the DIRTi and RUSSTi frames are:
You can use a Eccentric Bottom Bracket in it (to convert to single speed)
Its stiffer and gives a larger weld area for the adjoining tubes
Every crank on the market will fit in it (I know there are option now for the English thread BB but there weren't when I designed the frames)
It gives flexibility...you can thread it and turn it into T47

I am not trying to convert anyone but simply pointing out the reasoning behind the choice, I am not forcing anyone to buy any of these frames. There are plenty of Ti frames on the market with English thread BB's if that's your choice...I also make custom frames where you can spec any BB.

Now back to saying how much of a nice bloke I am....

[lune ranger]

Very nice indeed, I’m just gonna go and find the kids’ piggy banks

[JohnClimber]

Now back to saying how much of a nice bloke I am....

OK, you're a very, very, very nice man.

[Piemonster]

I was trying to make a genuinely nice

...way of maxing out my credit card

[TraversBikes]

I was trying to make a genuinely nice

...way of maxing out my credit card

No clearing mine

[sean_iow]

People seem to be getting a little off topic

I'm sure it's not your first time here, what did you expect? We made it from sewing projects to Toyah's tee shirt on another thread in 4 pages

For what it's worth I've never had an issue with PF and as you say you can fit an eccentric. I also like the idea that with the right dropouts/mech hanger you can have a frame without any threads to damage, well apart from the bottle bosses but I can't think of a way to engineer those out.

[lune ranger]

Wasn’t aware that ‘off topic’ exists here. I’m more worried that we’re heading towards 10 pages of introspection about whether PF BB’s are going to feel welcome posting here...

[fatbikephil]

We got off topic deliberately to avoid all those nice shiny bikes