Dotek 155mm Triples "Available"

[Mark Stonich]

I just made my first Dotek 155mm triple conversion. This one has a 58mm bolt circle, for 20, 22 or
24t rings. But I can also do 74mm for 24, 26, 28, 30 or 32t rings.
http://bikesmithdesign.com/cranks/Dotek58.jpg and http://bikesmithdesign.com/cranks/Dotek58Back.jpg

If there is interest, I could run off a few more. I figure around $60 + S&H, but I haven't
finalized a price yet, as my usual supplier has quit selling the arms, and I don't have a
J&B account.

For those who don't know, the Doteks are sold in the US as BMX equipment. However, they have an area
cast into the arms that can be tapped for a 3rd ring for other markets.

I use a CNC'd drilling guide which accurately centers the holes on the tapered hole, using a
modified BB spindle.

 

[Scott]

[email protected] (Mark Stonich) wrote in message
news:<[email protected]>...
> I just made my first Dotek 155mm triple conversion. This one has a 58mm bolt circle, for 20, 22 or
> 24t rings. But I can also do 74mm for 24, 26, 28, 30 or 32t rings.
> http://bikesmithdesign.com/cranks/Dotek58.jpg and
> http://bikesmithdesign.com/cranks/Dotek58Back.jpg
>
> If there is interest, I could run off a few more. I figure around $60 + S&H, but I haven't
> finalized a price yet, as my usual supplier has quit selling the arms, and I don't have a J&B
> account.
>
> For those who don't know, the Doteks are sold in the US as BMX equipment. However, they have an
> area cast into the arms that can be tapped for a 3rd ring for other markets.
>
> I use a CNC'd drilling guide which accurately centers the holes on the tapered hole, using a
> modified BB spindle.

Mark: Great job! Next time I need some short cranks I'll look you up. That's a *really* good price.

Scott

 

[Mark Stonich]

There have been quite a few questions (On and off this list and others) regarding the 155mm Dotek
triple chainring conversion. Sorry it has taken me so long to get all the answers.

Price will be $60 + S&H, at least on the 1st batch. Due to a lack of foresight on my part, it
takes 2-3 times longer to fixture them for drilling to 58mm than for 74mm. I may make a price
adjustment later.

How to get them; If your still interested, Email me at [email protected] and have "155mm" or
"Dotek" in the subject header. Include your mailing address. I have a PayPal account, but don't send
any money there yet, as I don't expect to have any more cranks to modify till at least Thursday. BTW
I'll be away Tues. and Wed.

I don't know what S&H will be yet, till I find boxes, and send the 1st ones out.

BCD; 110mm Sorry the 130mm 105 rings won't fit. However I have heard of 175mm 105s successfully
retapped to 152mm. (I now have the setup to do it, but haven't tried it yet)

BB spindle; Square taper. On an EZ-1 with the stock Shimano C201 derailleur, it works fine with the
stock 118mm spindle and also with a Shimano 110mm. At least with this derailleur, I wasn't at the
limits either way, with either spindle. (Buy a 113mm to be safe?)

Weight; Left arm is 15g less than 170mm Shimano 105. (My scale maxes out trying to weigh right arms)

Q factor; Seems slightly higher than average, whatever "average" is. I'd try a short spindle.

Spin? Yes JJ, everyone I've talked to says they spin much faster with shorties, without feeling like
they are making an effort to do so.

Gearing; Some people don't gear down at all when going to shorter cranks. I'd recommend ?5%. The leg
applies more pressure when it is working more extended. This makes up for some, if not all of the
reduced leverage.

Seat Adjustment; If your new cranks are 15mm shorter, move your seat back 15mm. Retrofit. I can
modify your existing Doteks, if you send them in a box good enough to ship back.

Chainrings spacers and bolts; If there is interest I could supply these at normal retail prices. I'd
give a slight discount on complete cranksets. With Salsa rings I used 4.2mm spacers. With 9 speed
chain you might need a thinner 3rd ring or thinner spacers. I used 16mm bolts, but 13mm would work,
probably 11.5mm would too.

About the Doteks, These aren't fancy cranks. Not much better than the arms on an EZ-1. The dies were
hand carved, and the arms aren't perfectly symmetrical around the spindle, so one of the new holes
looks a bit "Off"

 

[Windy City Ride]

Mark:

Do you have a lead on 150mm Dotek's?

-Windy City Keith

 

[Mark Stonich]

[email protected] (Windy City Rider) wrote in message
news:<[email protected]>...
> Mark: Do you have a lead on 150mm Dotek's?

No. However if you don't need 3 rings there are other, more expensive, options in 150mm.

 

[Dave Larrington]

Mark Stonich wrote:

>> Mark: Do you have a lead on 150mm Dotek's?
>
> No. However if you don't need 3 rings there are other, more expensive, options in 150mm.

Or if you *do* need three rings...

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================