Advice on 650b Lemond Poprad Disc

[MCCX]

Hello all,

I'm looking for any advice or experience anyone might have on 650b with a Lemond Poprad Disc.  The bb drop is 74mm, which is lower than ideal, but would this still be okay if I go with 650b x 38 or x 42 tires and 170mm cranks?

Does anyone have experience fitting Hetres on a Poprad?

Anything else I should consider?  (I don't have a 650b disc wheelset or Hetres in hand, but I'm aware I'll need 130 spaced rear hubs for the Poprad.)

Many thanks,

Mark

[Nick Payne]

I converted a Litespeed with (according to Litespeed, I never measured
it) 76mm BB drop to 650B and rode it for a couple of years using
Michelin Megamium 650Bx32mm tyres. It was possible to scrape a pedal
when cornering fast if I pedalled through the corner, but I just
automatically learned not to pedal through fast corners, and never had
another pedal strike after the first one.

If you can fit Hetres, then you've got a wheel that is pretty much the
same outside diameter as a 700c wheel with a 23mm tyre, and I road raced
my Litespeed for several years on 23mm tyres without any problems.

Nick

[Sean Bham]

I realize I'm bumping up an ancient thread and for that I apologize...

I'm kicking around the idea of building up a 650b disc 'do almost anything and everything' build and the disc Poprad frame is very attractive due to it's geometry, tubing, quality, price, etc.

I'm hoping someone out there has some first hand knowledge and experience with this frame and/or configuration and can shed some light on the potential tire clearance between the chainstays.

I've searched high and low and haven't been able to find a clear and definitive answer.....

The chainstays aren't dimpled at all from the factory and the prevailing opinion seems to be that 700x35 tires fit without modification. I've found one reference online, without pics unfortunately, of a frame having the chainstays dimpled enough to allow 700x42 tires to fit; which gives me hope.

I'll likely be putting a torch to the frame in order to add a few things like proper fender mounts, 3rd bottle mounts, re-space the rear end to 135, etc and will almost certainly massage the chainstays to maximize clearance as well as build a low trail steel disc fork.

I would like, at a minimum, to be able to fit BSPs w/fenders and BG 650bx43 RocknRoads w/o fenders. My hope is that either SBHs or a RTPs could be made to fit as well.....

Anyone have any insights or a 55cm disc Poprad frame?

Thanks!

[Chris Cullum]

I think I've mentioned this before but the Poprad is not one of the best choices in disc cross bikes to convert to 650B because it is notable for its low BB. It has 7.2cm drop whereas most cross bikes have drop in the 6cm range.

On Jan 7, 2017 13:00, "Sean Bham" <wheeler...@gmail.com> wrote:

I realize I'm bumping up an ancient thread and for that I apologize...

I'm kicking around the idea of building up a 650b disc 'do almost anything and everything' build and the disc Poprad frame is very attractive due to it's geometry, tubing, quality, price, etc.

I'm hoping someone out there has some first hand knowledge and experience with this frame and/or configuration and can shed some light on the potential tire clearance between the chainstays.

The chainstays aren't dimpled at all from the factory and the prevailing opinion seems to be that 700x35 tires fit without modification. I've found one reference online, without pics unfortunately, of a frame having the chainstays dimpled enough to allow 700x42 tires to fit; which gives me hope.

I'll likely be putting a torch to the frame in order to add a few things like proper fender mounts, 3rd bottle mounts, re-space the rear end to 135, etc and will almost certainly massage the chainstays to maximize clearance as well as build a low trail steel disc fork.

I would like, at a minimum, to be able to fit BSPs w/fenders and BG 650bx43 RocknRoads w/o fenders. My hope is that either SBHs or a RTPs could be made to fit as well.....

Anyone have any insights or a 55cm disc Poprad frame?

Thanks!

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[Sean Bham]

The Poprad doesn't sport a traditional CX geometry, it's far more roadish with a BB drop of 74mm.

Lower than average to be sure, but nothing outside the range of normal, and right in my sweet spot for the type of riding I do; I'm a fan of low BBs

The BDB Pelican has 70mm of drop, I'm fairly certain the Jeff Lyons L'avecaise runs +/- 75mm of drop, Richard Sachs frames run 80mm of drop, etc....

On Saturday, January 7, 2017 at 1:07:54 PM UTC-8, Chris Cullum wrote:

I think I've mentioned this before but the Poprad is not one of the best choices in disc cross bikes to convert to 650B because it is notable for its low BB. It has 7.2cm drop whereas most cross bikes have drop in the 6cm range.

On Jan 7, 2017 13:00, "Sean Bham" <wheeler...@gmail.com> wrote:

I realize I'm bumping up an ancient thread and for that I apologize...

I'm kicking around the idea of building up a 650b disc 'do almost anything and everything' build and the disc Poprad frame is very attractive due to it's geometry, tubing, quality, price, etc.

I'm hoping someone out there has some first hand knowledge and experience with this frame and/or configuration and can shed some light on the potential tire clearance between the chainstays.

The chainstays aren't dimpled at all from the factory and the prevailing opinion seems to be that 700x35 tires fit without modification. I've found one reference online, without pics unfortunately, of a frame having the chainstays dimpled enough to allow 700x42 tires to fit; which gives me hope.

I'll likely be putting a torch to the frame in order to add a few things like proper fender mounts, 3rd bottle mounts, re-space the rear end to 135, etc and will almost certainly massage the chainstays to maximize clearance as well as build a low trail steel disc fork.

I would like, at a minimum, to be able to fit BSPs w/fenders and BG 650bx43 RocknRoads w/o fenders. My hope is that either SBHs or a RTPs could be made to fit as well.....

Anyone have any insights or a 55cm disc Poprad frame?

Thanks!

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[Michael Mann]

I have a disc poprad. I've only run 700c wheels on it, though I could try some 650b wheels to check. I can run maybe 38s w/o fenders, I'd be pushing it with 32s and fenders. Be aware of 2 things: this bike was built for cyclocross and has accordingly higher bb drop. Also rear spacing is 130 (not 135) and it has NO chainstay bridge. I mount fender to the hole in bottom of B.B

But I love the bike for what it does.

Mike

Sent from my iPhone

[Sean Bham]

Mike-

I'd be immensely appreciative if you could mount a 650b rear wheel in your frame and take some measurements and pics to determine the maximum potential clearance between the chainstays.

Thanks!

[Michael Mann]

Mounted a rear 650b wheel. Pacenti rim with Compass Loup Loup tire on my 2007 Lemond Poprad. Sidewall says 38, calipers measure 35. I measure 7-8mm clearance to chainstay either side so theoretically should take 45s ok w/o fenders.

from my iPhone

Mike

[Sean Bham]

Exactly what I was looking for.

Thank you very much Mike, your effort is very much appreciated!

[Andrew]

When it gets this tight I've found that it's hard getting my calipers near enough to the gap to measure properly. I roll a few drill bits over the tyre and down through the gap, and see which one catches. Easily at hand, accurate, and most of us would have at least a few in the the 2-8mm range that is most of interest if it already looks tight enough to ask the question.

[Jeff Bertolet]

A Poprad disc came through the shop this week. He was running a tire that was 700c and measured 40mm wide, not much clearance. I measured 42mm clearance for 700C wheels and ~45 where I estimated a 650B sidewall would hit. Maybe I will get a chance to tests a proper 650 wheel tomorrow. This was before the rear triangle was respaced to 135 and with no dimpling.

[Bill M.]

I use Allen wrenches, they're always close by when working on a bike.

Bill