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Discussion Starter · #1 ·
Hey frame builders,
I have absolutely no experience with frame building at all- can I pick your brain? I have a potential project in mind and want to toss it in the ring to see if you think it is feasible.

Take a look at the attached pic. I would like to convert this frame into a single speed 650b with a carbon belt drive. It is made from reynolds 853 chromoly tubing. My questions are:

Is it possible to replace these dropouts with horizontal dropouts? Is it as simple as cutting the existing dropouts and replacing with new ones or are there more issues I will run into? Are horizontal dropouts a good solution to get a little more room for the 650b wheel size, or am I completely messing up the whole deal?

Any experience retro fitting a carbon belt drive to an existing frame? I was thinking horizontal dropouts will give me a little exrta room for the larger wheel, plus a way to tension the carbon belt, plus I know I need a split in the frame, and obviously a way to close the frame back together after installing the belt.

Or is this just all crazy talk??? :eek:ut:

Any information would be greatly appreciated. By the way, I won't be doing any of this work myself, I'm just giving due dilligence. if I decide to do it, I will definitely go to an experienced frame builder. Thanks!
 

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Just get a new frame

Once you deal with shipping, parts, labor, stripping old paint, re-painting, and re-shipping, you'll have spent almost as much as you would on a custom frame, without the extra goodies like custom geometry and a setup that's dialed in for the belt drive and the 650b wheels.

If you sell the frame you've got, you might even come out ahead getting a new custom setup.

Also, FWIW, the belt sprockets require a LOT of chainstay clearance. IMO they won't retrofit to any existing frame without a total chainstay replacement. There may be exceptions to that, but I have yet to see a frame I thought it would work on.

Good luck!

-Walt
 

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Discussion Starter · #3 ·
Thanks for the info, Walt. I've been toying around with the idea of a new custom frame from Lynskey, but I don't know if I can justify the cost for this single speed because it was originally supposed to be a pub crawler/ hood cruiser. Looks like it's back to the drawing board!
 

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Hank at henryjames.com sells horizontal drops that have longer tabs specifically for replacing vertical dropouts on existing frames. you could go that far pretty easily, if you drop the belt drive. i think building a whole frame is probably a lot easier way to learn though....
 

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Discussion Starter · #5 ·
Thanks rocwandrer- I'll check into those. One possible solution is I have old 29er ss frame that already has horizontal dropouts I could use for experimenting. I might put some 650b wheels on it just to see how it rides, and then just take it from there.
 

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Chazz, check out the 650b/bastard wheel forum for 29-650b conversions.
Where are you located?
putting on some sliding style dropouts could keep this bike a 26", but also allow room for the 650b wheels.
Alas, Walt is a smart guy, you may end up spending as much as a custom steel build once all is said and done.
 

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Have you done that?

J -

I've looked at putting sliders (the Paragons, anyway) on a lot of frames, and it never works, because the existing chainstays are way too close together to mate up with the (super outboard and far forward) attachment points for the sliders.

I'd love to hear about a workable option, because I get questions about that all the time. Is there a sliding dropout that is easily retrofittable?

-Walt

Cracked Headtube said:
Chazz, check out the 650b/bastard wheel forum for 29-650b conversions.
Where are you located?
putting on some sliding style dropouts could keep this bike a 26", but also allow room for the 650b wheels.
Alas, Walt is a smart guy, you may end up spending as much as a custom steel build once all is said and done.
 

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From what I've seen of Paragon, they will fab parts up based on demand, pretty quick. Perhaps a "conversion slider" should be drawn up.
If you know Eric Baar, contact him. He was the original designer of the slider that is now copied by Paragon. I saw on his FLICkR page he machined some new, lighter sliders.
 

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Meh.

This was discussed in another thread recently - Paragon doesn't generally want to do new stuff unless there's proven demand.

Honestly, conversion projects are always a cheapskate kinda thing - so unless there's something out there that already works, it's not worth my time. I've fielded a lot of questions about dropout replacements like this, but never had anyone pull the trigger once they hear what it'll cost.

_Walt

Cracked Headtube said:
From what I've seen of Paragon, they will fab parts up based on demand, pretty quick. Perhaps a "conversion slider" should be drawn up.
If you know Eric Baar, contact him. He was the original designer of the slider that is now copied by Paragon. I saw on his FLICkR page he machined some new, lighter sliders.
 

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Walt said:
I'd love to hear about a workable option, because I get questions about that all the time. Is there a sliding dropout that is easily retrofittable?
If you pull the stay bridges it shouldn't be that hard, but then it would almost be easier just to replace the whole rear end. I've never converted a 135 to the 145ish for the Paragon sliders, but I've converted a bunch of 126 touring frames to 135 back in the day.
 

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Discussion Starter · #12 · (Edited)
Money is not necessarily the driving factor behind the potential conversion, although it is true that I didn't want to spend the equivalent of a new custom frame since this won't be a racing bike. I just like experimenting with different setups and was curious if anyone thought it could work. In the end, it is probably better just to go with the custom option, especially for belt drive compatibility as you guys have stated.
The ss conversion dropouts that rocwandrer mentioned are something I may look into some more. Hans Schneider helped design those and he is not very far from me in Huntsville, TX. I may contact him and see what he thinks. I'll just have to put some more thought into all this. Thanks for all the help!
 

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More than 10mm

Hey MM -

It's more like 10-15mm on each side, depending on the chainstay/seatstay configuration. Remember that the tabs sit way outboard AND way forward compared to a "normal" dropout.

If it was just 5mm on each side, I'd do it all the time and just replace a bridge to re-space. But 25mm is too much, IMO.

-Walt

themanmonkey said:
If you pull the stay bridges it shouldn't be that hard, but then it would almost be easier just to replace the whole rear end. I've never converted a 135 to the 145ish for the Paragon sliders, but I've converted a bunch of 126 touring frames to 135 back in the day.
 

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Ah, right I wasn't thinking about how much more forward in the stays they would need to be. Once you hack of the 2+" at the end off the stays you're getting a lot more deflection of the stays. I have seen a couple people do conversions that they mount the dropouts on the outside of the stays, but it really doesn't look too hot.

I've seen some nice slotted dropouts with slotted disc-brake mounts which look like it would work well for SS conversions. Of course I'm still a big fan of the good old forward facing dropouts for fixed and single-speed use without a disc-brake.
 

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Discussion Starter · #15 ·
Hey Walt

Sorry I'm not trying to flog a dead frame mod project here, but I was curious about your thoughts on the spacing required in the rear for the belt drive to work. Gates website says their system is designed for use with a standard 9 splined Shimano hub. If it were installed on a standard hub, do you feel there still would not be adequate space in the rear to make it work? I haven't seen a belt drive system in person so i only have the pictures to go on. Tanks!
 

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The hub isn't the problem.

The drive cog/chainring/whatever won't clear the chainstay on most frames. It's HUGE (46+ "teeth" and >1cm thick). That's the issue, not the hub or rear cog/ring/whatever.

-Walt

chazz michael michaels said:
Sorry I'm not trying to flog a dead frame mod project here, but I was curious about your thoughts on the spacing required in the rear for the belt drive to work. Gates website says their system is designed for use with a standard 9 splined Shimano hub. If it were installed on a standard hub, do you feel there still would not be adequate space in the rear to make it work? I haven't seen a belt drive system in person so i only have the pictures to go on. Tanks!
 

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Discussion Starter · #19 ·
Smokebikes said:
".....me in Huntsville, TX"

Are you in the TDC or SHSU? :p I spent 3 years in Huntsville (SHSU) lots of fun at the Jolly Fox back in the early 80's. :thumbsup:
Awesome! I'm actually in the Houston area (I know, I know, boooooo hiss hiss) but I love it up that way. They are starting to work on trying to connect the trails in Huntsville with the Double lake trails now- would be an awesome quasi-epic trail (at least for this area) if they could make it work!
 
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