650b clearance on Rambouillet?

[Wyatt]

I've seen a few 650b Rambouillet conversions on here over the years, but I can't quite remember the largest tire I've seen cleared by the frame. Has anyone tried 650x47?

I like the idea of making it my two-wheelset, do-almost-anything frame, but I'd like to make sure there could be a sufficiently dramatic difference to make it worth it, say 700x32 on one end and 650x47 on the other. Seems like it would be tight but possible? Would love for someone to talk me out of splurging on this if I'm going to end up with a more marginal difference in range. 

[Fullylugged]

The spec is a max tire size of 700 x 37 (without fender). So going to 650B will increase that, but I don't know by how much. Another point of possible interest is the rear dropouts are spaced at 132.5 so you can use a 130 road or a 135 mountain hub easily.

tailwinds

Bruce

[David B]

My understanding is that one run of the Ram had more clearance. My Redwood, no frills Ram made as Romulus/Redwood fits 47mm 650b tires.
https://www.instagram.com/p/B710F-BFJwP/?igshid=1w4rdy2q7lm3s

[Wyatt]

Love the metallic sage color of that old Redwood, David. Honestly, everything about the simplicity of that comfy cork grip setup is pushing me try out a 1x flatbar revision of my Ram at some point. The proportions on your frame look identical to mine (if there is a difference aside from paint I can't see it) so I'm inclined to say it would clear 650x47, as well. If anyone else with a Ram has done it, though, would love to hear. Seems like the chainstays are the closest call?

[Reid Echols]

Following with interest, as I’ve thought of doing the same on my Ram. This recent photo would suggest it is indeed possible:

https://www.instagram.com/p/B89GYbSlVxe/?igshid=10xp9jnzm2p44

Reid in Austin

[christian poppell]

Hi Wyatt,

I've got a 62cm Orange Rambouillet mocked up with Compass Switch Back Hill EL tires. The tightest location is at the chainstays with about 3mm clearance each side. I can provide photos if you would like. The wide 650b tires are possible but the frame is lacking clearance for any significant wheel wobble or minor amounts of mud.

Christian

Berkeley, CA

[Adam Leibow]

my friend has a 650b rambo (62cm) with compass/RH SBH 42mm wide tires AND fenders. 

On Monday, February 24, 2020 at 3:21:41 AM UTC-8, Wyatt wrote:

[Kieran J]

Here are some pics of my 68cm Ram wearing 584x47 Byways:

https://www.instagram.com/p/Bu-oMfegnvb/?utm_source=ig_web_button_share_sheet

KJ

On Monday, February 24, 2020 at 3:21:41 AM UTC-8, Wyatt wrote:

[Wyatt]

All of these pictures seem to be terrible news for my bank account and great news for this ridiculous two-wheelset project. Those clearances look tight but I think I'm going to have to try it. Have had this bike in close to the same set up since I bought it back in 2005. Looking forward to doing a full overhaul.

Will be a minute before I can get it all done, but will report back once I have. Thanks for the help, y'all.

[Arthur Lewy]

Greetings Wyatt

I will echo comments above. With DiaCompe 750s I easily fit 584x42s on my green Ramb. The chainstays are the biggest limitation: there was 3 mm clearance on each side. My wheels were true and over 3 years I had no problems, although it was a source of worry.

All of this said, I will share my experience with the conversion. Going to 650 B on the Ramb, for me led to a series of compromises, like shortening my cranks. Using long centerpulls was a hassle: they are less efficient and due to my own limited skills, they are hard to adjust. My beloved Mark’s rack did not play well with the centerpull cable. I took off the rack but then lost capability to use my Shopsack.....

This summer I drove back to Seattle from Brooklyn with my beloved lab Princess Buttercup. We drove through Canada to stop by Lakes Huron and Superior. From the first day she ran in, fetched balls, dove for rocks and it seemed she would swim to Wisconsin. It reminded me of what Mother Superior said to fraulein Maria about doing what you were born to do.

A few weeks ago I slapped the 700c wheels back on the Ramb along with the Silver brakes, the Mark’s rack, basket, and Shopsack. In the absence of Ruffy Tuffys, I put on Vitoria Corsa Courses. There’s gobs of tire room and the Ramb just sings again in a way it didn’t do with the supposedly cushier 650Bs. It is such a joy.

I am sure that wide tires are great. At this point I would only do
them on a bike really designed for them.

Just my 2 cents. Good luck figuring things out.

Art Lewy
Seattle

[Wyatt]

This is an interesting dissenting opinion Art! 

I hope to avoid too much trouble with brakes, as I'm already running Tektro r556s with seemingly all of the clearance in the world, but I am afraid I'll hear your bit about Mother Superior's advice echoing in my ears if/when this project goes sideways. I guess the dream is that the two-wheelset plan would allow for the best of both worlds, but we'll see.

[Steven Frederick]

This touches on why I've never seriously considered a 650b conversion of my early, orange Rambly.  It's just such a fine bike with 700c.  I have 650b bikes too; variety is good.  Steve

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[Jeremy Till]

I follow the Instagram user linked by Reid and while it's a cool bike, i'm not entirely certain it is a Rambouillet. For one thing, it looks like it uses the Homer/Roadeo head lugs, not the Rambouillet ones. It also seems to have shorter chainstays than other Rambouillets I've seen (including my own). Roadeo in Rambouillet drag? One of those "unauthorized" Rambouillet frames that was available from a Japanese retailer for a while? Who knows.  

Art's experience reinforces my own feelings about sticking with 700c wheels on my Rambouillet: it seems like there would be a lot of compromises involved in the conversion (low BB and excessive brake reach would be the hardest for me), which makes it hard to justify when the bike rides so well with 700c wheels. Mine has Ruffy Tuffys (700x27) and I've done mellow gravel and all-day rides on it, always perfectly comfortable. However, I have the benefit of having a small stable of bikes, all of which have wider tires than the Ram. If were my only bike or my only road-ish bike I might feel differently.  

-Jeremy Till

Sacramento, CA

[Wyatt]

You're right, those head tube lugs on the green "shivatakosuke" instagram are completely different than the ones on my bike. I'd be surprised if it was a rebadged Roadeo, as I was under the impression the clearances were tighter on that design? I also had no clue there were "unauthorized" Rambouillet frames floating around. Sounds like a weird story, does anyone know the details?

Have definitely gotten thousands of miles on my Ram with 700x28, including a few short, lightly loaded tours, but I also find it is the bike I ride the least these days. I think maybe it's just that I want a project, too? But those concerns do make sense.

[Toshi Takeuchi]

I had a blue 54 Ram that I converted to 650b.  I was able to use the Tektro long reach brakes on the front and back with Synergy rims and 42mm Hetre tires with fenders.  On the rear, I had to use thinline V-brake style pads to prevent rubbing of the brake pad on the tire.

When I switched to A32 rims, I had to increase the reach and went to the Diacompe 750 centerpulls in the rear.  With the caveat that my centerpull setup technique may not be so great, I didn't get as effective braking with the Diacompe compared to the Tektro sidepulls.

The 650b Ram was one of my favorite bikes ever with a great plush 650 ride and low center of gravity (I use 170 cranks).  I only scratched asphalt with my crank once in thousands of miles with no harm done.  (I think 650bx42mm was more or less equivalent to 700cx25mm tires in terms of BB height).

Ultimately I resolved my less than perfect braking and better dynamo/light setup etc. by purchasing my custom 650b Rando machine, which I love.

--Based upon my experience, I recommend the 650b conversion and use of wider rims if a choice is available.  The other alternative to increase reach is to file the slot for the brake mount to drop it a mm or two.

Toshi

[David B]

This is why I seem to swap my Redwood from 650b to 700c on an annual basis! I think I'm sticking with my 650b setup for a bit - IMO if you're after fenders AND 47mm tires, then this sort of hits the limit of Tektro R559s as a 55m fender width (at a bare minimum for 47mm) doesn't seem to play well with the quick release of the R559s. Dia Compe 750s don't seem to help either as the narrowness limits where the fender can fit vertically. I settled on Mafac Raids, which I cleaned up and upgraded pads to v-brake style and everything works great - setup with 58mm Velo Orange fenders - and with the straddle cable released on the Raids I can remove wheels without deflating tires.

All of this is not for everyone. Had I not picked up an 80s Specialized Sequoia that is virtually identical in dimensions, I likely would've gone back to 700c on the Redwood.

[Bruce Herbitter]

I’ve converted all my 700c bikes to 650B.  38 mm seems the sweet spot for tire size. I can run Grand Bois or Pari Motos or Gravel Kings and play with pressure to suit the route.  The MaFac Pro centerpulls are really strong brakes and I like them. Tektros with good pads are okay, just not as good.  Just for fun, I tried 584 wheels with the pads all the way down and they work, and you can get fat tires, but the handling suffers so I went back to 650B.   My 52 cm Ram has 2 wheel sets and one runs the stock 32 mm tires and the other Pasela 38s.  I like the 32s better.

Sent from my iPad

On Feb 26, 2020, at 10:11 AM, David B <daba...@gmail.com> wrote:



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