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85 Trek 420 - adding Canti stubs?

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85 Trek 420 - adding Canti stubs?

Old 09-07-11, 09:43 AM
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85 Trek 420 - adding Canti stubs?

I was able to purchase a rough shape 1985 Trek 420 with the thought of making it my next everyday bike. The paint is very doing but the frame is straight with no rust. It also has so many cool details that some later Treks just dont have (this is my first Trek). I realize it is a low end frame but it seems pretty nice, quality build wise. I am lucky to have a wonderful frame builder close by to help add a few things on it to 'update' it.

Has anyone added canti stubs to this frame? The frame builder said that it has a 'fastback' arrangement on the rear triangle which may make the spacing difficult. I am also looking to cold set it to 130mm, add shifter braze-ons and a brake bridge for the cantis.

After this is all done I'll have it stripped and powder coated. The existing paint is beyond anything worth keeping. Believe me. Now, I just need to find the head age and maybe some decals?

GG
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Old 09-07-11, 11:21 AM
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You may just need to use a zero offset canti boss aligned directly over the stay for sufficient width rather than the more typical mitered boss that is attached inboard of the stay. https://www.cycle-frames.com/bicycle-...-BRAKE-BOSSES/ . Probably a good idea to get your hands on the brakes you will be using and test fit to see what is needed for width spacing. The brakes will likely have more leverage if the bosses are spaced a bit too close together rather than too far apart.

Bit of info I saw on the 420 was that it had a decent butted CrMo frame but used a hi-tensile steel fork. It might be a good opportuninty to upgrade the fork to a stronger & lighter CrMo fork (and get one that already has canti bosses) rather than throwing $ at the hi-tensile fork.

Rather than brazing shifter bosses to the frame, you might just want to set it up for bar-ends or brifters so add cable stops rather than shifter bosses.
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Old 09-07-11, 11:40 AM
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+1 on the above. I modified a 613 frame for cantis and found that w/ fenders, 32mm was the max tire size. I was running 700c wheels. Also you need to know what brake pads you will be using and that they have enough clearance to let the tire out when the brake is open.
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Old 09-07-11, 11:57 AM
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Originally Posted by guygadois View Post
I was able to purchase a rough shape 1985 Trek 420 with the thought of making it my next everyday bike. The paint is very doing but the frame is straight with no rust. It also has so many cool details that some later Treks just dont have (this is my first Trek). I realize it is a low end frame but it seems pretty nice, quality build wise. I am lucky to have a wonderful frame builder close by to help add a few things on it to 'update' it.

Has anyone added canti stubs to this frame? The frame builder said that it has a 'fastback' arrangement on the rear triangle which may make the spacing difficult. I am also looking to cold set it to 130mm, add shifter braze-ons and a brake bridge for the cantis.

After this is all done I'll have it stripped and powder coated. The existing paint is beyond anything worth keeping. Believe me. Now, I just need to find the head age and maybe some decals?

GG

I had a Mangalloy framed 84 420 that was a great bike- I'm sure conventional logic is that the True Temper frame is "better," but I REALLY liked that bike regardless of where it sat in the food chain.

I had the Z series brakes on that bike- and they were as fine as any other brakes. The only "upgrade" I'd consider dumping money into on that bike would be getting rid of the Helicomatic.
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Old 09-07-11, 12:06 PM
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Originally Posted by GrayJay View Post
You may just need to use a zero offset canti boss aligned directly over the stay for sufficient width rather than the more typical mitered boss that is attached inboard of the stay. https://www.cycle-frames.com/bicycle-...-BRAKE-BOSSES/ . Probably a good idea to get your hands on the brakes you will be using and test fit to see what is needed for width spacing. The brakes will likely have more leverage if the bosses are spaced a bit too close together rather than too far apart.

Bit of info I saw on the 420 was that it had a decent butted CrMo frame but used a hi-tensile steel fork. It might be a good opportuninty to upgrade the fork to a stronger & lighter CrMo fork (and get one that already has canti bosses) rather than throwing $ at the hi-tensile fork.

Rather than brazing shifter bosses to the frame, you might just want to set it up for bar-ends or brifters so add cable stops rather than shifter bosses.
+2 on all of this, but if you are going to need to buy equipment or hire a pro frame builder to do this, from a $ standpoint you may be better off finding another frame you like. Not as cool as what you want to do, but I have yet to have a rehab project, bikes or otherwise, that ended up being as cost-effective as I originally thought. YMMV.
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Old 09-07-11, 12:44 PM
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Would this fork do well? https://www.ebay.com/itm/Surly-cross-...-/140584548449

I am in the bike for almost nothing. Adding the cantis, shifter stubs and brake bridge is about $100 and a new powder coat is about $100. So, I didn't think a $200 price tag is too much. Now, the new fork is $81 but saves me $40 in torch fees ($40 per pair is quoted price). I am not sure I could find a newly painted and ready to roll frame and fork for $240. Am I crazy?
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Old 09-07-11, 01:21 PM
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Sounds like an entirely reasonable expenditure. You likely could get a new chinese aluminum CX frame for a bit less so you might want to weigh against that. If you want to slash the project budget, rattlecan the paint yourself rather than powdercoat. THe surley fork looks like a good upgrade option for the project.
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Old 09-07-11, 04:20 PM
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I was talking my plan over with an LBS and they recommended avoiding a 700 fork as it may throw off the geometry of the bike. They recommended just using a pair of Tektro long reach brakes and that should do it.

Thoughts?

GG
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Old 09-07-11, 04:23 PM
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Have you considered 650b? Since you are having canti bosses installed it's just a thought? As for the Surly fork, would you have it threaded, or would you go threadless? Be sure and post pics of the build

Cheers,
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Old 09-07-11, 04:41 PM
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Oh, and the rear brake is butted if I remember correctly but I think the Tektros now come with a butted version?
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Old 09-07-11, 05:57 PM
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Originally Posted by guygadois View Post
I was talking my plan over with an LBS and they recommended avoiding a 700 fork as it may throw off the geometry of the bike. They recommended just using a pair of Tektro long reach brakes and that should do it.

Thoughts?

GG
Measure the axel to crown distance of your current fork and compair with the 400mm spec of the surley fork. An cyclocross fork should have more clearance for tires+mud at the crown than a road fork so hopefully the 700C cyclocross measurement will be fairly close length to the original 27" wheel road fork. If the CX fork is shorter, it will steepen your frame angles by 1 degree per 20mm difference in length. I would guess that up to a 20mm difference in fork length should have fairly minimal impact on the handeling and still ride OK.
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Old 09-07-11, 06:30 PM
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Originally Posted by GrayJay View Post
Measure the axel to crown distance of your current fork and compair with the 400mm spec of the surley fork. An cyclocross fork should have more clearance for tires+mud at the crown than a road fork so hopefully the 700C cyclocross measurement will be fairly close length to the original 27" wheel road fork. If the CX fork is shorter, it will steepen your frame angles by 1 degree per 20mm difference in length. I would guess that up to a 20mm difference in fork length should have fairly minimal impact on the handeling and still ride OK.
Interesting. The trek fork has a axel to crown distance of 370mm while the surly is 400mm. So does this mean the tire will be 30mm higher minus the 700mm to 27 inch wheel difference. Is that going to be a problem?

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Last edited by guygadois; 09-08-11 at 12:20 AM.
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