Advice req: Chainset suitable for shortening?



C

Call me Bob

Guest
I've been experimenting lately with adjustable crank shorteners on my
recumbent, trying to find a shorter crank length that suits me and my
one wonky knee. I've settled on a length of 125mm and now want to buy
a new chainset that I can have re-drilled and threaded by Highpath
Engineering.

I'm having difficulty finding a suitable chainset and am wondering if
anyone has a suggestion for cranks that will be up to this kind of
modification.

I'm currently using a 39/53 double. With shortened cranks and the 406
wheels on my Taifun this works well as a high gear ratio (11t
sprocket), so the new chainset will need to be a road model in order
to retain this kind of top end. However, the set up doesn't provide a
low enough gear for me to be comfortable on some ascents and I'd like
to move to a triple chainset. I think a 30/42/52 "racing triple" would
work very well, but I can't find one that looks strong enough in the
arms at the required 125mm length to support the new pedal position.

Highpath have said they need a minimum width of 25mm at the point of
the new thread. I'd just about settled on a Campag Centaur, but the
width is borderline - it's just 25mm but the arm is beveled so it's
thinner than that on the front face. Of course, this is for use on a
recumbent, so the pedals wont ever be stood upon and honked uphill as
on an upright bike. Perhaps it would be okay, but buying the chainset
and then having it rethreaded isn't cheap, and I'd rather not have to
start over again in 6 months time because it's cracked due to lack of
material.

Shimano cranks are out because most of their range nowadays is hollow
and so unsuitable for re-drilling. I think the Tiagra is still solid,
but it's rather clunky and comes with low quality rings and I was
hoping to find something a bit nicer as this is my favourite bike.

Anyone have suggestions on something that might be suitable? Comments
or advice much appreciated.

"Bob"
--

Email address is spam trapped, to reply directly remove the beverage.
 
Call me Bob wrote:
>
> Anyone have suggestions on something that might be suitable? Comments
> or advice much appreciated.
>


St John Street Cycles do a 125mm Altus crankset or a 140mm Thorn
crankset off the shelf.
http://www.sjscycles.com/store/cat363.htm

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
Call me Bob <[email protected]> wrote:
>
> Shimano cranks are out because most of their range nowadays is hollow
> and so unsuitable for re-drilling. I think the Tiagra is still solid,
> but it's rather clunky and comes with low quality rings and I was
> hoping to find something a bit nicer as this is my favourite bike.
>
> Anyone have suggestions on something that might be suitable? Comments
> or advice much appreciated.
>


St Johns Street Cycles (http://www.sjscycles.com/store/vIndex.htm) cut and
drill their cranksets down to 110mm and have several double drilled for sale
at 110 / 140mm. I bet they'd be able to sort you out with some 125mm ones
for a price.

Tom

--
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http://toomanybikes.com/address.jpg
 
On Sat, 27 May 2006 17:41:16 +0100, Tony Raven <[email protected]>
wrote:

>St John Street Cycles do a 125mm Altus crankset or a 140mm Thorn
>crankset off the shelf.
>http://www.sjscycles.com/store/cat363.htm


Thanks for the suggestion. The 140 would be too long, the 125 was
interesting, but I think I've settled on a TA Vega triple.

The arms are more or less the same width all the way along their
length which should make them a good candidate for shortening. Plus of
course, it's TA :)

"Bob"
--

Email address is spam trapped, to reply directly remove the beverage.
 
Call me Bob wrote:

> Plus of
> course, it's TA :)
>


At the speed you will be spinning them no-one will ever know


--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci
 
On Sun, 28 May 2006 16:24:09 +0100, Tony Raven <[email protected]>
wrote:

>> Plus of
>> course, it's TA :)
>>

>
>At the speed you will be spinning them no-one will ever know


Ah, but one person will know.



"Bob"
--

Email address is spam trapped, to reply directly remove the beverage.
 
In article <[email protected]>, Call me Bob
([email protected]) wrote:
> I've been experimenting lately with adjustable crank shorteners on my
> recumbent, trying to find a shorter crank length that suits me and my
> one wonky knee. I've settled on a length of 125mm and now want to buy
> a new chainset that I can have re-drilled and threaded by Highpath
> Engineering.
>
> I'm having difficulty finding a suitable chainset and am wondering if
> anyone has a suggestion for cranks that will be up to this kind of
> modification.


IIRC various of my racing chums who have gone to short cranks have used
cut-down Tiagras.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
God was my co-pilot, but we crashed in the mountains and I had to eat
Him.