Morning all,

Is it possible to stiffen the BB area on a Ti frame buy changing the cranks & BB?
I’m currently running a square taper Ti BB with Middleburn cranks, I know the newer external bearing cranksets are stiffer, but would adding them stop the actual flex in the frame? I’m thinking its not possible, but I thought I’d ask the question.
Thanks in advance.

The new cranks will be stiffer but this won’t alter the stiffness of the frame. Not a lot you could do other than trying to find someone who works in Ti to maybe weld some gussets/reinforcing plates on.

you could spray expanding foam into the DT and ST via the bb shell holes.. fair bit more stiffness but it may break as it’ll just concentrate the stress elsewhere

New cranks will not affect frame flex.

stiffening foam LOL111

So, you have a frame made from Ti, a material that people always eulogise over for its suppleness and give – and you want to make it stiffer..?

Crazy person.

😉

some ti frames, particularly early ones, were silly flexy.

Some newer ti frames *still are* flexy. 😉

why not try 10mm bolt thru rear hub?

what would that achieve?

A higher resale value, I suppose.

Out of interest, how do you know it’s BB flex? Genuine question – are you getting tyre rub, noticable flex or something else?

stiffening foam LOL111

Some road companies actually use this for the frames used by pro roadies…

http://www.bikeforums.net/archive/index.php/t-334043.html

In fact, they’ve since started using it in their production frames:
http://www.bianchiusa.com/technology.html

Structural Foam Injection is a 2-component non-toxic foam developed by Henkel Spa Surface Technologies and patented by Bianchi for specific cycling applications, i.e., as a tube strengthening material.

The results obtained through the introduction of SFI have been noteworthy: a weight increase of only 20 grams yielded a 15% improvement in stress resistance, while resistance to fatigue doubled in the bottom bracket area.

All this was made possible by the special properties of this foam, which is able to distribute the loads evenly, avoiding fatigue build-up in high stress areas and in welded parts whose composition has been thermally altered.

Who was the huge guy who rode for bianchi in the (late?) 90’s?

His Paris-Roubaix had a plain guage DT and the whole thing was filled with foam to keep it stiff.

Bolt through (or even just better QR’s) will hold the rear triangle more rigidly, but generaly make getting the rear wheel out a PITA and dont make much differenc on a HT which are rigid compared to full sussers (where they ake a massive differance).

Only other way to go is stiffening it by adding more tubes and plates, expensive, and probably liable to fall apart.

furry muff. I thought he was suggesting “no more gaps” or simila, available at Halfords to transform the handling of any bike.

FYI Cynic-al expanding foam can be used to reduce flex, just ask anyone that’s built a box framed westfield, you can spray the expanding foam inside the chassis to stiffen it up

You could put a wrap of carbon fibre mat with epoxy resin. Titus do this with their exogrid frames and Dean also make a carbon/Ti frame.

Regarding Bianchi, they have been doing this for years with their EV frames.

cynic-al = Uber Noob.

Viagra 🙂

Even with HT 2 cranks, the frame will still flex under the force but a little more equally than HT1.

I did notice the creaking disappeared upgrading from HT1 cartridge BBs to 2 pc HT2 cranks.

Also you could lose some weight if you’re heavy or buy a super stiff aluminum frame.

Thing is the ride will be harsh compared to the forgiving nature of your Ti frame.

Also check your wheels are not flexing under the power too. Mine used to flex under power or uphill till I bought custom built wheels.

thisisnotaspoon – Member
Who was the huge guy who rode for bianchi in the (late?) 90’s?

Magnus Backstedt?

Thanks for all the replies, it got quite serious for a while, very amusing 😉
Can you actually buy that foam, or even carbon wrap for that matter?
Maybe I’ll just have to use some fiberglass!

ourmaninthenorth – Member
So, you have a frame made from Ti, a material that people always eulogise over for its suppleness and give – and you want to make it stiffer..?

Crazy person.

Probably, but stiffness in certain areas is a good thing, I’m told it’s how you have children
😉

bent_udder – Member
A higher resale value, I suppose.

Out of interest, how do you know it’s BB flex? Genuine question – are you getting tyre rub, noticeable flex or something else?

The front mech rubs on the chain under load, fine if your pottering along though, a touch annoying, but not the end of the world.

Cheers.

The front mech rubs on the chain under load, fine if your pottering along though, a touch annoying, but not the end of the world.

Cheers.

HT2 would fix that.

STW does strange things to my head, I mean I immediately wanted to say thanks to Brant, as I’m on-line. But my head said not to as I hadn’t thanked everybody else personally (as I was at work earlier) for fear of perceived arse licking, but sod it…

Thanks Brant 🙂

Now, are we sure Brant is right? 😉

(off to eat dinner, back later)

get a gripshifter for the front mech – incremental shifting lets you keep the cage out of the way

I had the same rubbing with OEM Bontrager square tapers, LX HT2 fixed it.

scaredypants, I’ve noticed that with other peoples bikes running gripshift, but don’t want to go there, thanks for the info (personally)

TheChunk, thanks (personally) for the conformation.

Cheers all.

square taper Ti BB

That’s where the flex is coming from.

stiffening foam LOL111

It’s a known method as linked above, not just for bike frames. if you prevent the sides of the tube getting closer together as they do when they flex, ie support the tube internally, you stiffen it. a bit like an i-beam principle. simple concept. but no, i’ve not tried it )

Thanks again, if you can help with this that would be great.

Cheers.