Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Fatter tires: minimum clearance

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Fatter tires: minimum clearance

Old 08-20-22, 07:58 AM
  #1  
tiger1964 
Senior Member
Thread Starter
 
tiger1964's Avatar
 
Join Date: Apr 2011
Location: Maryland, USA
Posts: 1,746

Bikes: Drysdale/Gitane/Zeus/Masi/Falcon/Palo Alto/Raleigh

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 641 Post(s)
Liked 278 Times in 199 Posts
Fatter tires: minimum clearance

As I mentioned, I think, in another topic, I was getting some new Continental GP5000 tires. I ended up getting 700x28mm cream sidewall, to put on the 1961 Gitane which has huge amounts of clearance; then the 25mm ones already on the Gitane with almost no miles on them got transferred to my 1980 Palo Alto with already had 25ís but worn out and blackwall. Anyway, while doing all this, just for fun, I stuck the Gitaneís rear wheel on the Palo Alto. OK, it fit but the clearance at the chainstays was only about 4mm per side. Whatís the normal minimum clearance desired here? My 1st thought was ó if it clears, then it clears. My 2nd thought was, if I broke a spoke while riding and the wheel got out of true, it might bind against the chainstay and strand me.

This new stratagem of wider tires is something Iíve been approaching in baby steps; I do not think I have any 23mm tires left. And I am contemplating perhaps doing a 650B conversion on a yet different bike so knowing minimum clearance is germane there too.
__________________
Larry:1958 Drysdale, 1961 Gitane Gran Sport, 1974 Zeus track, 1988 Masi Gran Corsa, 1974 Falcon, 1980 Palo Alto, 197x Raleigh Gran Sport. Susan: 1976 Windsor Profesional.

tiger1964 is offline  
Old 08-20-22, 08:09 AM
  #2  
ehcoplex
Senior Member
 
Join Date: Jun 2021
Posts: 947

Bikes: '38 Schwinn New World, '72 Peugeot PX-10, ‘7? Valgan, ’79 Holdsworth Pro, ’80 Peugeot TH-8 tandem, '87 Trek 400T, ’97 Cannondale T900, '98 Peugeot Appalaches, ‘7? Raleigh Sports, ‘7? Raleigh Superbe, ‘6? Herc

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 389 Post(s)
Liked 648 Times in 327 Posts
Originally Posted by tiger1964 View Post
As I mentioned, I think, in another topic, I was getting some new Continental GP5000 tires. I ended up getting 700x28mm cream sidewall, to put on the 1961 Gitane which has huge amounts of clearance; then the 25mm ones already on the Gitane with almost no miles on them got transferred to my 1980 Palo Alto with already had 25ís but worn out and blackwall. Anyway, while doing all this, just for fun, I stuck the Gitaneís rear wheel on the Palo Alto. OK, it fit but the clearance at the chainstays was only about 4mm per side. Whatís the normal minimum clearance desired here? My 1st thought was ó if it clears, then it clears. My 2nd thought was, if I broke a spoke while riding and the wheel got out of true, it might bind against the chainstay and strand me.

This new stratagem of wider tires is something Iíve been approaching in baby steps; I do not think I have any 23mm tires left. And I am contemplating perhaps doing a 650B conversion on a yet different bike so knowing minimum clearance is germane there too.
It depends on how true your wheels are (and stay...)! I've shoe-horned 38c tires on my Cannondale T900, with about 2, maybe 3mm clearance/side at the chain stays. Some would be uncomfortable with things that tight..
ehcoplex is offline  
Old 08-20-22, 08:22 AM
  #3  
gugie 
Bike Butcher of Portland
 
gugie's Avatar
 
Join Date: Jul 2014
Location: Portland, OR
Posts: 10,807

Bikes: It's complicated.

Mentioned: 1198 Post(s)
Tagged: 0 Thread(s)
Quoted: 4189 Post(s)
Liked 3,923 Times in 1,708 Posts
Originally Posted by tiger1964 View Post
My 1st thought was — if it clears, then it clears. My 2nd thought was, if I broke a spoke while riding and the wheel got out of true, it might bind against the chainstay and strand me.
Pretty much dead on. Since spoke quality has improved a lot over my lifetime, I haven't broken a spoke in years, but I always carry a spoke wrench with me. BITD if I broke a spoke I could true it enough to limp to a bike shop. I always carry a couple of spare spokes when I'm touring, along with a way to remove a cassette, since drive side rear spokes are almost always the ones that break.

So, yeah, that can definitely happen, so carry a spoke wrench.
__________________
If someone tells you that you have enough bicycles and you don't need any more, stop talking to them. You don't need that kind of negativity in your life.

Last edited by gugie; 08-20-22 at 08:27 AM.
gugie is offline  
Old 08-20-22, 09:03 AM
  #4  
Rooney 
Full Member
 
Join Date: Apr 2018
Location: Pennsylvania
Posts: 258

Bikes: '73 Cinelli Speciale Corsa; '80 Trek 710; '90 Cannondale ST1000; '92 Trek 520; 2022 Cannondale Topstone 2L

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 116 Post(s)
Liked 199 Times in 91 Posts
I wanna say 6mm per side is the generally "safe" rule, that's about the max we would do at the shop I was working in. Working on friend's bikes, I've definitely done some shoe-horning of tires into frames, but I've always been very upfront about the drawbacks and usually recommend going to the next size down when looking for new tires. I've become a little more tempered in my shoe-horning if for no other reason than it's easier to get the wheel in and out with more clearance.
Rooney is offline  
Old 08-20-22, 09:06 AM
  #5  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 11,021

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 115 Post(s)
Tagged: 0 Thread(s)
Quoted: 3705 Post(s)
Liked 2,546 Times in 1,666 Posts
I'd say it's about risk management. And consequences. What is your rear wheel? Rim? Number of spokes? How much do you value your chainstay paint? (I'm assuming steel; this being C & V; carbon fiber changes this one a lot.) Do you carry a spoke wrench and know how to use it? DO you have an acceptable back-up plan? (The call of shame - NBD or martial no-no?)

Two broken spoke scenarios I witnessed. Both on bikes with "plenty" of clearance. First, myself in 1979 on my brand new Peter Mooney. Saturday morning. Santa Cruz Cycling Club ride. Town line sprint. A strong but inexperienced rider put his rear wheel where my front belonged. Eventually I had to return my wheel to under my weight or I was going down at 30 mph+ (and the next half dozen behind me). To stay up, I leaned my wheel into his rear and pushed off. Worked, but - his quick release cut out 8 consecutive spokes! I rode the bike to a standstill with a wild once per revolution throb.

My 28c clincher was rubbing solidly against the fork under the crown and had polished the bare steel. Outside that and a few missing spokes, no damage at all. Wheel went thousands more miles. The fellow on my wheel was a complete stranger but upon my bike handling saving his skin, he turned around in gratitude, got his truck and drove me home. (Robert Wright, gifted bike mechanic and author of a very good and equally simple book on how to build bicycle wheels.) Oh, I was riding the wide Weinmann rims with 36 spokes. I doubt a stiffer side-to-side semi performance rim has ever been made. And TG! Saved my butt.

Other scenario - rider in a small group broke a high-tech, non-steel spoke on a CF bike and rim. No spoke wrench and he had so few spokes to work with I"m not sure it would have helped. The tire had already done a little CF damage to the chainstay. They were debating options. Not my ride; they were complete strangers and I had nothing on me that could help so I rode on. I don't know what he chose to do but already., his bike had suffered more than mine for a far less consequential mishap.

With aluminum rims (I've never owned CF), enough spokes (32, 36), a spoke wrench and a modicum of skill with it, you can often juggle the spoke tensions of the remaining spokes to ride home. If your fork and frame are steel and some hard to see paint scrape is OK, you have little to fear of a spoke breaking, even with very close clearances. (But at speed, you may kill the tire with sidewall wear, especially if you are riding a thin walled performance tire. The medium priced Paselas would not take kindly to that sidewall wear at all.

Look at what you've got, decide what is acceptable and what isn't and go from there.
79pmooney is offline  
Likes For 79pmooney:
Old 08-20-22, 12:26 PM
  #6  
droppedandlost 
small ring
 
droppedandlost's Avatar
 
Join Date: Jul 2012
Location: PNW
Posts: 907
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 378 Post(s)
Liked 643 Times in 290 Posts
Originally Posted by tiger1964 View Post
if it clears, then it clears.
as long as the wheels are good
__________________
droppedandlost is offline  
Likes For droppedandlost:
Old 08-20-22, 12:49 PM
  #7  
tiger1964 
Senior Member
Thread Starter
 
tiger1964's Avatar
 
Join Date: Apr 2011
Location: Maryland, USA
Posts: 1,746

Bikes: Drysdale/Gitane/Zeus/Masi/Falcon/Palo Alto/Raleigh

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 641 Post(s)
Liked 278 Times in 199 Posts
Originally Posted by gugie View Post
Pretty much dead on. Since spoke quality has improved a lot over my lifetime, I haven't broken a spoke in years, but I always carry a spoke wrench with me. BITD if I broke a spoke I could true it enough to limp to a bike shop. I always carry a couple of spare spokes when I'm touring, along with a way to remove a cassette, since drive side rear spokes are almost always the ones that break. So, yeah, that can definitely happen, so carry a spoke wrench.
Thanks, and I normally only carry a tube, tire irons and a simple multi-tool -- but most rides are short. I've taken longer rides with an old friend who totes along everything short of a shop stand and brazing torch so I can borrow his stuff. Time to find a lightweight spoke wrench. Good advice!

Originally Posted by Rooney View Post
I wanna say 6mm per side is the generally "safe" rule, that's about the max we would do at the shop I was working in.
So I'm under the "catch limit" and need to throw this one back? Well, honestly, I have no issues with the 25's but am trying to embrace new concepts like fatter tires...

Originally Posted by 79pmooney View Post
I'd say it's about risk management. And consequences. What is your rear wheel? Rim? Number of spokes? How much do you value your chainstay paint? (I'm assuming steel; this being C & V; carbon fiber changes this one a lot.) Do you carry a spoke wrench and know how to use it? DO you have an acceptable back-up plan? (The call of shame - NBD or martial no-no?) Two broken spoke scenarios I witnessed. Both on bikes with "plenty" of clearance. First, myself in 1979 on my brand new Peter Mooney. Saturday morning. Santa Cruz Cycling Club ride. Town line sprint. A strong but inexperienced rider put his rear wheel where my front belonged. Eventually I had to return my wheel to under my weight or I was going down at 30 mph+ (and the next half dozen behind me). To stay up, I leaned my wheel into his rear and pushed off. Worked, but - his quick release cut out 8 consecutive spokes! I rode the bike to a standstill with a wild once per revolution throb. My 28c clincher was rubbing solidly against the fork under the crown and had polished the bare steel. Outside that and a few missing spokes, no damage at all. Wheel went thousands more miles. The fellow on my wheel was a complete stranger but upon my bike handling saving his skin, he turned around in gratitude, got his truck and drove me home. (Robert Wright, gifted bike mechanic and author of a very good and equally simple book on how to build bicycle wheels.) Oh, I was riding the wide Weinmann rims with 36 spokes. I doubt a stiffer side-to-side semi performance rim has ever been made. And TG! Saved my butt. Other scenario - rider in a small group broke a high-tech, non-steel spoke on a CF bike and rim. No spoke wrench and he had so few spokes to work with I"m not sure it would have helped. The tire had already done a little CF damage to the chainstay. They were debating options. Not my ride; they were complete strangers and I had nothing on me that could help so I rode on. I don't know what he chose to do but already., his bike had suffered more than mine for a far less consequential mishap. With aluminum rims (I've never owned CF), enough spokes (32, 36), a spoke wrench and a modicum of skill with it, you can often juggle the spoke tensions of the remaining spokes to ride home. If your fork and frame are steel and some hard to see paint scrape is OK, you have little to fear of a spoke breaking, even with very close clearances. (But at speed, you may kill the tire with sidewall wear, especially if you are riding a thin walled performance tire. The medium priced Paselas would not take kindly to that sidewall wear at all. Look at what you've got, decide what is acceptable and what isn't and go from there.
That's a comprehensive answer! This is Ukai rims, unsure of date or width. 36H as are all my bikes. All of my bikes are steel and most, like this one, freshly powder coated and I'd rather not damage the finish but I have matching touch-up paint. The 8broken-spokes event of yours sounds outside of what I might encounter, although anything can happen (If I get hit be a car, the state of true of the rear wheel might not be my #1 concern). Anyway, it sounds like "it depends, and maybe you'll get lucky and never have to worry about it -- or not!"

Originally Posted by droppedandlost View Post
as long as the wheels are good
Wow -- have feeler gauges handy????
__________________
Larry:1958 Drysdale, 1961 Gitane Gran Sport, 1974 Zeus track, 1988 Masi Gran Corsa, 1974 Falcon, 1980 Palo Alto, 197x Raleigh Gran Sport. Susan: 1976 Windsor Profesional.

tiger1964 is offline  
Old 08-20-22, 01:55 PM
  #8  
Bad Lag
Senior Member
 
Join Date: Jul 2013
Location: So Cal, for now
Posts: 1,884

Bikes: 1975 Bob Jackson - Nuovo Record, Brooks Pro, Clips & Straps

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 798 Post(s)
Liked 390 Times in 240 Posts
You need some clearance. Frames and wheels deflect, as in when cornering.
Bad Lag is offline  
Old 08-20-22, 02:47 PM
  #9  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,080

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 95 Post(s)
Tagged: 0 Thread(s)
Quoted: 3644 Post(s)
Liked 2,092 Times in 1,327 Posts
My Bianchi 650B conversion has spent long periods of time with close to zero clearance at the chainstays. The Col de la Vie tires I started with measured about 36.5mm wide, giving about 1-2mm of clearance per side. Then, I switched to Pacenti Pari-Motos, which started at a full 38mm and grew to 40mm! After dimpling my chainstays I'm back to about 2mm clearance per side. With my true wheels and spoke wrench in the bag, I'm completely comfortable with that much.
__________________
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Likes For ThermionicScott:
Old 08-20-22, 07:10 PM
  #10  
Classtime 
Senior Member
 
Classtime's Avatar
 
Join Date: Jan 2015
Location: Los Angeles
Posts: 3,706

Bikes: 82 Medici, 2011 Richard Sachs, 2011 Milwaukee Road

Mentioned: 42 Post(s)
Tagged: 0 Thread(s)
Quoted: 1445 Post(s)
Liked 1,025 Times in 626 Posts
4mms is HUGE.
__________________
I don't do: disks, tubeless, e-shifting, or bead head nymphs.
Classtime is offline  
Likes For Classtime:
Old 08-21-22, 03:57 PM
  #11  
top506
Death fork? Naaaah!!
 
top506's Avatar
 
Join Date: Nov 2005
Location: The other Maine, north of RT 2
Posts: 5,184

Bikes: Seriously downsizing.

Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 520 Post(s)
Liked 422 Times in 206 Posts
Having spent a while stuffing 28/32mm tires into older sport bikes ('just put in the biggest tires that'll fit!'), I've found the tight spot to be the rear brake bridge of caliper, not the stays.

Top
__________________
You know it's going to be a good day when the stem and seatpost come right out.

(looking for a picture and not seeing it? Thank the Photobucket fiasco.PM me and I'll link it up.)
top506 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.