Fitting Truvativ cranks to Specialized frames

[Johan Bornman]

Like Dangle himself said, if you can't explain it, rather stay out of it.

Anyone else?  I don't understand why 2 x 10-speed has changed the chainline of mountain bikes - if indeed it has. For the chainline to change, you either change the cassette position on the hub or, the crank axle length.

 

With 2 x 10, the way I understand it, the 10 sprockets are just squeezed into the same place occupied by the old 9. The two chainrings simply take up a space between where the 1st and 3rd chainring on a triple crank would have been. The perfect chainline on such a bike would thus be the line from the centre of the two chainrings to the line that runs through the middle of the 10 sprockets at the back i.e., between 5 and 6.

 

 

 

 

[borys]

HI

HOPE MAKES A SHIM SO YOU CAN USE A GXP ON SHIMANO BB

YOU CAN ORDER FROM CHAINREACTIONCYCLES.

 

IT WORKS WITH THE SM 91 ADAPTOR THAT IS IN THE FRAME. EASIEST SOLUTION.

 

I WAS NOT SATISFIED (BUT THEN I AM FULL OF SH****t)

 

HERE IS MY SOLUTION

 

YOU WILL NEED

 

2 X 6509 BEARINGS

2 X SPRINGWASHERS

2 X SHIMANO TOP HAT DUST SEALS

1 X HOPE SHIM ( BECAUSE TRUVATIV SPINDLE IS TAPERED)

1 X 8MM SPACER

 

PROCEDURE

 

REMOVE THE SM 91 CUPS FROM THE FRAME

 

INSERT THE SPRINGWASHERS IN THE GROOVES INSIDE THE BB SHELL

 

PUSH THE BEARINGS INTO THE SHELL UNTILL THEY MAKE CONTACT WITH      THE WASHERS 

 

INSERT THE SHIMANO DUST SEALS IN THE OPENINGS IN THE BEARINGS

 

PUT THE 8MM SPACER ON THE DRIVE SIDE

 

PUT THE HOPE SHIM IN THE OPENING ON THE NON-DRIVE SIDE

 

TIGHTEN UP THE CRANK AND YOU'RE DONE

 

THE BEARINGS YOU CAN GET FROM ANY BEARING SHOP EVEN CERAMIC IF YOU WANT.

THEY HAVE THE SAME OUTSIDE DIAMETER AS BB30 BEARING (42MM)

SAME INSIDE DIAMETER AS SHIMANO STD BEARING (25MM). THAT IS WHY YOU NEED THE DUST SEALS, THEY REDUCE THE OPENINGS TO 24MM. PULL THEM OFF ANY SHIMANO BB IF YOU CAN NOT FIND THEM NEW LOCALLY.

THE HOPE SHIM YOU NEED BECAUSE OF THE TAPERED SPINDLE THAT TRUVATIV USE.

 

THESE BEARING ARE WIDER, BUT THEY STILL FIT FLUSH WITH THE BB SHELL, NEEDLESS TO SAY THEY WILL BE MUCH STRONGER AND LAST MUCH LONGER THAN SMALLER ONES, AND MUCH SMOOTHER.

 

GOOD LUCK

[_im_from_earth]

Manic: I have some kits coming in from Enduro in my next shipment which will allow this conversion Should solve your problem as well as many others.

 

As a matter of interest, what is wrong with the Specialized cranks? I've always thought them so be super sexy!!

 

[udxcob]

I have truvativ stylo cranks on my stuntjumper hardtail with external bb and it fitted perfectly without the spacers, runs like a dream

[_im_from_earth]

 

[quote name='Johan Bornman]

Like Dangle himself said' date=' if you can't explain it, rather stay out of it.

Anyone else?  I don't understand why 2 x 10-speed has changed the chainline of mountain bikes - if indeed it has. For the chainline to change, you either change the cassette position on the hub or, the crank axle length.

 

With 2 x 10, the way I understand it, the 10 sprockets are just squeezed into the same place occupied by the old 9. The two chainrings simply take up a space between where the 1st and 3rd chainring on a triple crank would have been. The perfect chainline on such a bike would thus be the line from the centre of the two chainrings to the line that runs through the middle of the 10 sprockets at the back i.e., between 5 and 6.

 

 

 

 

[/quote']

 

Johan: having ridden an XX group for nearly 12 months with many setup configurations I think I can offer a little insight as to the reasoning behind a few changes.

 

Current setup:

 

Crank: SRAM XX, 156mm Q-Factor, 175mm 28, 39T [only running 39T i.e. single ring setup]

Cassette: 11- 34

Frame: Morewood Zula

 

First off, there is only 2mm of clearance on either chainstay with the 156mm Q-Factor crankset. I have not found another dual sus frame which can run the 156mm crankset!

 

The narrower Q-Factor has two main benefits:

 

Anatomical: [although I don't personally buy into this] it is claimed by many top professional that the narrow Q-Factor increases power output by improving the line in which the power is applied by the rider. Decreasing the distance between the riders feet improves hip alignment and hence increases performance and comfort.

 

Chainline: having the narrower Q-Factor reduces the chainline by 9mm bringing both chainrings in towards the bottom bracket by the same amount. What this achieves is the ability to run the entire range of gears on the cassette on both chairings. Losing the ability to do this renders the 10 x 2 groupset useless!

 

Having said the above and having ridden both the 156 and 165 Q-Factor cranskets I can't honestly say that I find either point to stand much ground. The 165mm Q-Factor cransket has a 4.5mm wider stance on either side and I actually find this MORE comfortable than the 156mm. as far as chainline is concerned, the 156mm is certainly better than the 165mm, this is exacerbated by the fact that I am only running a single ring upfront [39t]. That said, with the true dual-ring setup of the XX on the 165mm Q-Factor crankset you are still able to easily run the entire range of 20 gear combinations with minimal chain-rub or miss-alignment. On my current "project" for example I will be running the regular 165mm Q-Factor crankset with a 37T E13 chainring simply run inboard of the crank spider as apposed to bolted on the outside. This solves both the chainline issues as well as the wider stance which I prefer.

 

 

 

[WorcesterWheelers]

Manic: I have some kits coming in from Enduro in my next shipment which will allow this conversion Should solve your problem as well as many others.

As a matter of interest' date=' what is wrong with the Specialized cranks? I've always thought them so be super sexy!!
[/quote']

Thanks, please contact me as soon as you have the kits, I'll definately take a few.

 

As for the Specialized Cranks, two problems:

1. Stock - No stock

2. Price - VERY price

 

But yes definately super sexy.

 

 

[Wyatt Earp]

 

Chainline: having the narrower Q-Factor reduces the chainline by 9mm bringing both chainrings in towards the bottom bracket by the same amount. What this achieves is the ability to run the entire range of gears on the cassette on both chairings. Losing the ability to do this renders the 10 x 2 groupset useless!

 

 

 

 

 

 

Being a "TECHNICAL GURU" I thought he would be capable of figuring this out all by himself, but alas there are some things that you simply can't learn off the web or a screen

 

Quite flippin ironic.

 

I have only seen 155, 164 and 166 Q-factors, where did you get a 165 ?

 

I agree with Worcester that the stock situation as well as the cost situation is a tricky one on the Spesh cranks.Dangle2010-06-17 02:17:24

[Johan Bornman]

Being a "TECHNICAL GURU" I thought he would be capable of figuring this out all by himself' date=' but alas there are some things that you simply can't learn off the web or a screen
Quite flippin ironic.
I have only seen 155, 164 and 166 Q-factors, where did you get a 165 ?
I agree with Worcester that the stock situation as well as the cost situation is a tricky one on the Spesh cranks.[/quote']

 

I thought you were out of here but alas, not.

 

It is not a given that if you reduce or increase the Q-factor that the effective BB length changes. In fact, Q-Factor is a very poor indicator of BB length since the crank's' curve can add or subtract to the BB length.

 

Why do you sneer when I ask a question? Do you do that to all people who ask questions or do you reserve your bad manners just for me?

 

 

[Johan Bornman]

 

 

Thanks for the explanation. I found it useful.

 

2mm clearance is very little! But enough is enough. Are those chainstays particularly long in order to get away with such a low QF or have you applied some tricks to the chainstay tube profile?

 

 

I have more questions. However, I want to do some measurements first.

 

 

[AndreZA]

I like a wider q-factor. I'm much more comfortable on my MTB then on my road bike. And as I understand it, if they shorten the BB axle to get a better chainline for double and want to keep the original q-factor as on triple, then they will have to either increase the outward bend of the crank arms (will also solve the problem with stay clearance) or increase the length of the pedal axles.

 

 

 

Please don't kill me, this is just how I understand it.

[Wyatt Earp]

 

Why do you sneer when I ask a question? Do you do that to all people who ask questions or do you reserve your bad manners just for me?

 

?

 

?

 

Dunno Johan, you seem to sneer often.

[udxcob]

Touchy bunch of bike mechanics these

[_im_from_earth]

 

Touchy bunch of bike mechanics these

 

Thats what happens when you get your Q-Factor caught in your Chainline

 

[AndreZA]

Looks like Sram is addressing the problem.

 

 

 

http://www.cyclingnews.com/features/photos/first-ride-sram-x0-family/125627

 

 

 

 

 

 

[Wyatt Earp]

Looks like Sram is addressing the problem.

 

 

 

http://www.cyclingnews.com/features/photos/first-ride-sram-x0-family/125627

 

 

 

 

 

 

Yip, now we wait.

[LazyTrailRider]

Being a "TECHNICAL GURU" I thought he would be capable of figuring this out all by himself' date=' but alas there are some things that you simply can't learn off the web or a screen
Quite flippin ironic.
I have only seen 155, 164 and 166 Q-factors, where did you get a 165 ?
I agree with Worcester that the stock situation as well as the cost situation is a tricky one on the Spesh cranks.[/quote']

 

I thought you were out of here but alas, not.

 

It is not a given that if you reduce or increase the Q-factor that the effective BB length changes. In fact, Q-Factor is a very poor indicator of BB length since the crank's' curve can add or subtract to the BB length.

 

Why do you sneer when I ask a question? Do you do that to all people who ask questions or do you reserve your bad manners just for me?

 

 

 

I agree that Johan's question was valid, the curve affects the outcome directly.