JeffOYB

So... Im trying to squeeze 2.4-inch Conti Trail Kings into my 1990 Bridge mb1. I have already dremeled the sideknobs down halfway. They almost work. They ride on the straights without a buzz, but when I put the twisty G-forces on em they buzz. Now, this frame already has hollow dimples. Ha! It would be silly to mess with a frame just to fit a tire that I dont even know if I like, but our local trails are rooty... Im curious if wider lower-psi tires might help things for me. I run 2.25 no sweat. Is there any quick easy dirty sure-fire DIY way to squish the dimples a bit more to get a wee bit more clearance? I have no cosmetic or longterm rust concern. I have bashed this bike for decades. I just might wanna squish me some steel. Ive never done this trick. How do I squish the inside without squishing the outside? Do I need a big vise and a hollow shape to fit the outside, and, um... Then theres the notion that a soft tire on an old wheel is just gonna flex a LOT from side to side on singletrack due to the forces, G- and otherwise. Ive dremeled the side knobs twice now and the buzz gets less but... I know --> maybe file the dropouts back a couple mm?

maddog34

so you want to ruin your trusty Bridgestone for an 1/8" of extra tread that you won't feel at all? And you've already removed most of that extra width from a tire you might not like?

wow.

Heat the tube with a welding torch until red hot (the burning paint fumes can be deadly) in the area you wish to ruin, then hit it repeatedly with the ball end of a ball peen hammer while the outside of the tube is supported by a form-fitted 2x4 board.... oh wait... there's no ROOM to swing the hammer at the area you want to ruin.... you'll need a radiused tip punch and Excellent Fabricating skills... skills that would have already told you to NOT ruin your trusty Bridgestone.................. and then you'll need to reset the O.L.D. and dropout/frame alignment since all the pounding for that extra clearance you might not need will screw up those factors on your Trusty Bridgestone...

Better to GET THE CORRECT TIRE AND QUIT RUINING THINGS FOR NO REASON...find a type with softer rubber compound and MORE COMPLIANT SIDEWALLS, to better grip and conform over roots. No, i won't list any tires for you...

i'd think what you really want is a decent XC MTB bike with lockout suspension. Can't afford it? quit ruining tires and start saving cash.

Signed: A. Riderinanareawithroots,rocks,mud,dust,limbs,slipperyleaves,andvinemaplethatripsbarsoutofyourhands... . and fabrication skills.
and that's just One ride, in the fall, in Coastal Oregon hills.

dedhed

https://www.bikeforums.net/classic-v...hey-works.html

​​​​​​https://www.bikeforums.net/framebuil...hainstays.html

JeffOYB

...filing dropouts a bit rearward doesnt seem very extreme.

But yeah its silly to spend any time wrecking a frame to gain tire width...

FBinNY 

Let's be real.

You're not going to get improving with 2.4" tires vs. 2.25. Especially since tires don't run true to nominal width.

However, if you still want to, consider seeking tires whose actual width is closer to the max without needing frame modification. Or since your current tires only rub slightly when leaning, you might protect the critical places on the stay as with muffler tape or similar.

It is possible to deepen the inside crimp, it'll want more than you expect to pull the shoulders in.

FWIW the difference between knowledge and wisdom, is the knowing difference between what you can do and what you should do.(or shouldn't)

smd4

I think I love this post.

veganbikes

I will take your bike off your hands and trade it for a something else. That is a nice heavily sought after bike. In the end it is just a bike but to destroy it for some tires that aren't needed is just really crazy.

Get a bike that works for your desired tire choice and use this for slightly less wide tires or sell it to someone who will take care of it and cherish it.

Trakhak

But . . . he has no choice. He already bought the tires.

maddog34

they are indeed, popular... https://portland.craigslist.org/clk/...651657089.html

there's another one in some town i'm not familiar with yet...... $675, "modified" to single front, has some tasty parts added... wearing 1.25" gravel slicks... my kind of ride! very similar to my DB Ascent.
https://seattle.craigslist.org/see/b...647006047.html

wheelreason

Breathing dremeled tire bits will give you recycled tire ball field cancer...

grumpus

G-clamp, 1/4" ball bearing, block of wood is the classic method for eking out just a little bit more clearance. We used a fly press to dimple stays, but that was loose stays, you'll not have clearance to use a press in a built frame without special tooling. Bear in mind you'll be slightly reducing the lateral rigidity, so you may not benefit a great deal as that's a problem you already have.

icemilkcoffee 

Your frame doesn't have horizontal sliding dropouts though. It has fixed dropouts. Once you turn that into a slotted dropout you will introduce a new problem- the hub can slip in the dropout.

If it's a Huffy frame then hack away. But a Bridgestone MB1? This bike has serious collector value today. Don't wreck it.

unterhausen

I don't care much about how collectible Bridgestones might be, but since it has the typical dimpled chainstays of its era, you may well cause that frame to fail.

JeffOYB

I wont wreck it chasing after a tire. I will try to find a wheel with a wider rim to change the orientation of the knobs. ...But giving some backward space for a wheel in the vertical dropout doesnt make it more likely to slip than in any dropout with room to the rear. ... Also when my bikes are done they are trash. my last ride-to-fail frame just sagged in the middle of a CX race with frame break in several locations. my bikes and cars go to scrapyard when i am done with them.

FBinNY 

Keep in mind that modern QRs are designed around vertical dropouts and generally lack the holding power of QRs made when horizontal dropouts were the norm.

Also note that it will be extremely hard to make room to move the wheel back and still have a proper purchase for the axle and QR unit. If not properly supported with 2 arcs on opposite sides of thd axle it will be impossible to secure the wheel.

You came here for advice, and atypically for BF got near unanimous advice to live with the existing limitations rather than risk all in pursuit of very marginal improvement.

Take the advice you sought.

smd4

Sure. They all do. But you’re not riding your bike into the ground here. You’re actively shortening it’s life for virtually no reason.

I don’t care what you do to your bike; doesn’t mean I have to think you’re smart for doing it.