Cannondale SI Cranks - SRM - Do they fit 'standard' frames?

Discuss light weight issues concerning road bikes & parts.
matad
Posts: 2
Joined: Wed Dec 22, 2010 11:54 pm

by matad

Hi All,

I'm interested in buying an SRM crankset and looking at a cannondale SI model, i need to know whether is it possible to mount the cannondale cranks onto a standard road frame with an english bottom bracket?

There seem to be conflicting views! Does anyone know how this can be done.... or not!

If so, i guess the final part to the question is 'how'?

Thanks for all your help!

by Weenie


jeffr
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by jeffr

There is a hack involving using a long mountain spindle and cups from something like a thm.

I would not suggest it.

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itsacarr
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by itsacarr

As far as I know BB30 is NOT compatible with threaded standard bottom brackets however there are adapters for BB30 bottom brackets to work with threaded cranksets. If you're going to shell out the money for an SRM I would make sure it has proper compatibility and not a work around. As far as I know there is not "hack" for a bb30 crank to work in a threaded shell but I could be mistaken.

jeffr
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by jeffr

There are threads on here and pictures online of BB30 in BSA. You only have to search. It just uses outboard bearings with a 30mm ID and a long axle. You end up with a very wide q-factor. starnut posted it I believe.

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STARNUT
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by STARNUT

someone needs to sticky this thread or one of the other ones as this is the 2nd time I've posted this in as many weeks



So here's the deal; it's not just plug and play with off the shelf parts. At a minimum the process requires a modified spindle and machined spacer to take up slack.

Image

In the above photo you can see the stock cannondale spindle on the top and the modified one below. The bearing surfaces have to be moved and the coller needs to be machined off for the thing to work. Additionally, you will need a spacer has been machined to fill the gap on the excess spindle length. The above spindles are longer than a standard BB30 104 or 103 mm from cannondale or anyone else. They were orginally designed for the Rush 2x9s which were wider for a year.

Knowing that the arms are built around a 104 spindle the stance width does increase a little with the above spindles. Also, the road spiders for the SISLs are machined with a drivetrain offset for the 104 spindle also. Because of that, the chainline on some bikes (particularly those with short chain stays) is not ideal and is spaced a little far to the DS and can become an issue.

What we're currently working on it a few things. First, we're working on machining a custom spider to correct the offset so the drivetrain works. There is obviously no work around for the SRM. Second, we're working on a carbon spider with the offset also and a spider with the BB30 offset (should be light :twisted: ). Third, I'm looking at making a new spindle from the ground up to fix the stance width. The deal is the Cannondale spindle is about 3-4 mm longer than we need. I'm trying to find a way to make one that is the cirrect length and make sure it's going to be as light as the cannodnale one and be made at a price where it is feasible to sale at retail. If I can fix it but the cost is $100 a spindle, it's not likely a viable option for retail and I wouldn't be able to sell enough to make it worth my time.

On top of all this...... I've started my own shop and we own BB30.com as well. So........ you'll have to forgive me if it seems a bit slow coming to market with this. Also, it looks like a lot of the industry is moving to BB30 anyway that or they are moving to standard where the comversion or BB30 woulnd't work anyway..... so.......

Starnut
"Don't pedal harder, pedal faster!"
Q-FACTOR IS A RED HERRING

BB30.COM

matad
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Joined: Wed Dec 22, 2010 11:54 pm

by matad

Wow.... thanks for the informative and speedy response....

Looks like its a no go for me... I'm a rider not an engineer!!!

But thanks so much for the responses, hope you all have a wonderful Christmas

Cheers

Matt

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jwilliams
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by jwilliams

Zipp vuma quad bb30 work on both bb30 and non bb30 by use of a thread cup with bb30 sized cups. I have them on a non bb30 2010 time rxr. I bring this up as it could be a simple plug and play option.
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bricky21
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by bricky21

Yes, but it still doesn't make it possible to effectively use a BB30 crank in a BSA BB.

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jwilliams
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by jwilliams

Brick was that directed at me. I am running the zipp vuma quad bb30 on my time that I took a fsa mega bb off and Easton ec90 cranks.
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2011 C59 Di2 AX SRT 24's, THM Calvica, Fibula
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jeffr
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by jeffr

The point is that you can't take just any bb30 crank and use the zipp cups for bsa. Their crank is specifically designed to work in this way using some spacers. It won't work with cannondale si cranks.

bricky21
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by bricky21

jwilliams, yes, that was directed at you, but not in a hostile way. The point is that the vuma quad is BB30 compatible, and not a true BB30 crank.

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jwilliams
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by jwilliams

Great I was not aware of that, sounds like the zip then is not a true bb30 as it's not plug and play with other bb30. Good point! Guys.
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2011 C59 Di2 AX SRT 24's, THM Calvica, Fibula
2010 RXR VIP @ Red RXR Sold
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maxvain
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Joined: Wed Jan 05, 2011 9:06 pm

by maxvain

Hi, Starnut thank you for the info. I have a buddy with Canoondale Si SRM Crankset that has been unused for about 2 years, because he owns standard BB frames now. Is there someone that can service the Crankset or is there a product we can buy to use the Cannondale Si SRM Crankset with standard BB frames. I went to BB30.com but it not operational as yet.

Also I see that this guy Pritchett made a homemade device
http://fairwheelbikes.com/forum/viewtop ... 314#p94314

What would you suggest... My buddy is pretty eager to use his Cannondale Si SRM Crankset on his standard BB frames. Any advice or instruction would be helpful and greatly appreciated.

My buddy had access to machine shop and good metal working equipment, but may need some instruction, from someone who has the experience of converting such a crank.

Thanks in advance, and I always enjoy reading your threads and post.

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STARNUT
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by STARNUT

Pritch didn't make that.... he bought it from me.

Starnut
"Don't pedal harder, pedal faster!"
Q-FACTOR IS A RED HERRING

BB30.COM

maxvain
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Joined: Wed Jan 05, 2011 9:06 pm

by maxvain

ah okkk, well then that's great. That is of course if your services are still available. I will inform my friend. What are the particulars? Cost? Do we have to send Crank to you? Or do you send out a product to us to mount? Lastly, does it makes sense converting or is my buddy better off selling it on ebay and re-purchasing a quarq etc.

Thanks again

by Weenie


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