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Discussion Starter · #1 ·
My next build will be a really big frame for a heavy rider with some specific oddities that make a good fit for a bigger head tube diameter and a bigger steerer diameter.

Partly for proportions (aesthetics), but partly for the beefiness, I'd like to do a 1.5" steerer rigid fork. I'm a hobby builder, and I sold my milling machine a couple years ago. I'd like to buy a pre-machined head tube and steerer or race ring/seat. Anything out there? Suggestions?

Richard
 

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rocwandrer said:
My next build will be a really big frame for a heavy rider with some specific oddities that make a good fit for a bigger head tube diameter and a bigger steerer diameter.

Partly for proportions (aesthetics), but partly for the beefiness, I'd like to do a 1.5" steerer rigid fork. I'm a hobby builder, and I sold my milling machine a couple years ago. I'd like to buy a pre-machined head tube and steerer or race ring/seat. Anything out there? Suggestions?

Richard
I want to do this some day as well.... I think I'll end up getting one made for me from one of the local machinist hobbyists. You could get them to do two feet worth of head and steerer tube, and be set for a while.
 

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Can't you just figure it?

-1.5" ID, then figure what you want the wall thickness to be (.9mm, 1, 1.1, etc), OD will be the dependent variable. (I listed ID and wall thickness as SAE and metric, respectfully, so convert as necessary)

Find the stock that has a minimum of meterial to meet the above criteria, turn it down to meet your criteria, and you're in business. :)
 

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Discussion Starter · #6 ·
What has a 1.5" ID? I don't get what you are saying swift....?



I have that the 1.5" standard uses a 38.1 mm steerer, a 39.8 mm crown race seat, and a 49.6 mm ID head tube. Can someone at least tell me if that is accurate?


Does anyone make a race ring for the 1.5 size?

If it is 49.6mm (1.9528 inches) ID head tube, there isn't anything in structural 4130 that I can find that is close enough. 2.375" schedule 80 would still need ~6 thou taken off the inside, and would be heavy as hell without some machining on the outside...
 

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49.6mm ID is about 1.95". Seems a little big but I'm not familiar with the 1.5 standard so I won't speak to this.

Assuming the 1.5" standard does, in fact mean, 1.5" ID headtube:

I didn't see anything with exactly 1.5" ID but there are several "options" in the 1 5/8" OD stock sizes that I see listed on the aircraftspruce site.

http://www.aircraftspruce.com/catalog/mepages/4130tubing_un1.php

In particular, the 0.65 wall tubing seems to be pretty darn close with a listed ID of 1.495". The wall is 0.65", so it would require a fair amount of machining on the O.D. to lighten it up for your application. If it were me, I'd leave the ID as it comes and just ream it to size following your build. The 0.83 and 0.95 would also be likely candidates but would require more material be removed. I think your choice may be influenced by your joining method and how much distortion you anticipate.

If, in fact, the 1.5" standard refers to 1.5" steer tube then the above applies except you'll be shopping a larger ID for the headtube. In this case, the 2" OD stock size lists a couple options that could be used.

Good luck!
 

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swift said:
49.6mm ID is about 1.95". Seems a little big but I'm not familiar with the 1.5 standard so I won't speak to this.

Assuming the 1.5" standard does, in fact mean, 1.5" ID headtube:

I didn't see anything with exactly 1.5" ID but there are several "options" in the 1 5/8" OD stock sizes that I see listed on the aircraftspruce site.

http://www.aircraftspruce.com/catalog/mepages/4130tubing_un1.php

In particular, the 0.65 wall tubing seems to be pretty darn close with a listed ID of 1.495". The wall is 0.65", so it would require a fair amount of machining on the O.D. to lighten it up for your application. If it were me, I'd leave the ID as it comes and just ream it to size following your build. The 0.83 and 0.95 would also be likely candidates but would require more material be removed. I think your choice may be influenced by your joining method and how much distortion you anticipate.

If, in fact, the 1.5" standard refers to 1.5" steer tube then the above applies except you'll be shopping a larger ID for the headtube. In this case, the 2" OD stock size lists a couple options that could be used.

Good luck!
He said he would rather get something pre machined as he doesn't have a lathe. :p

I think the best way would be to get a local machinist to crank out one / a few for you.
 

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I was holding off since my lathe is currently disassembled, but the replacement part I have been waiting for just arrived :thumbsup:

If you want the tube linked to above cut to finished size for your design, bored to a .005" DOC final reaming size (49.35mm) and a crown race made, let me know. Wouldn't be a problem for me. I can get the tubing Will Call from McMaster and ship flat-rate USPS box to you.
 

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Discussion Starter · #15 ·
Arrak Thumrs said:
I was holding off since my lathe is currently disassembled, but the replacement part I have been waiting for just arrived :thumbsup:

If you want the tube linked to above cut to finished size for your design, bored to a .005" DOC final reaming size (49.85mm) and a crown race made, let me know. Wouldn't be a problem for me. I can get the tubing Will Call from McMaster and ship flat-rate USPS box to you.
The offer sounds good. I think I need to eat something, get some sleep and come back. Most of the stuff posted here isn't making any sense to me....

49.6 only allows about 0.025" wall on a 2" OD tube. That seems very thin. I guess if the bore a that diameter only extends 1" into the tube on each end then I could silver on ring gussets out of a couple pieces of 2.25" x0.120"

49.85 must be a typo and you meant 49.5 mm?
 

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rocwandrer said:
49.85 must be a typo and you meant 49.5 mm?
Whoops :eek: I meant 49.35mm ID only for the depth of the headset cups. That was so you could finish to size with the Park reamer/facer tool. You're right, though, the result could be a little thin. Tell me this instead: what would you like to spec, regardless of material available? I can work that out---even if it means I have to bore the full ID and then turn down the full OD. Please specify:

Given an ID of 49.60mm:
*Headtube OD (mm)
*Headtube total length (mm)
*Quantity

Given a 38.10mm OD:
*Steerer wall thickness (mm)
*Steerer total length (mm)
*Quantity

I would expect HT stock to be McMaster-Carr #6920T111:
*4140/4142 steel
*38.1mm ID
*63.5mm OD
*Available in 12", 36" & 6' lengths.

Steerer might be something like McMaster-Carr #89955K68:
*4130 steel
*38.1mm OD
*33.9mm ID (2.1mm wall thickness)
*Available in 6' length
 

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Discussion Starter · #18 ·
Arrak Thumrs said:
Whoops :eek: I meant 49.35mm ID only for the depth of the headset cups. That was so you could finish to size with the Park reamer/facer tool. You're right, though, the result could be a little thin. Tell me this instead: what would you like to spec, regardless of material available? I can work that out---even if it means I have to bore the full ID and then turn down the full OD. Please specify:

Given an ID of 49.60mm:
*Headtube OD (mm)
*Headtube total length (mm)
*Quantity

Given a 38.10mm OD:
*Steerer wall thickness (mm)
*Steerer total length (mm)
*Quantity

I would expect HT stock to be McMaster-Carr #6920T111:
*4140/4142 steel
*38.1mm ID
*63.5mm OD
*Available in 12", 36" & 6' lengths.

Steerer might be something like McMaster-Carr #89955K68:
*4130 steel
*38.1mm OD
*33.9mm ID (2.1mm wall thickness)
*Available in 6' length
Arrak, before I waste any of your time I'll talk quantity. I'm a hobby builder. I suspect price depends on quantity and the quantity I would want would depend a bit on price :D I wonder if anyone else out there wants in on this? If there was hope of a slow trickle of demand, I might consider financing a run in order to get mine at a volume price. I'd only need two 5" length and three 8" length 1.5 head tubes for many years, and more likely (depending on price) only want to buy a single 5" one for now.

Head tube:

0.05" wall for a plain tube. I'll throw out another possibility... Assuming starting with the stock you specify and only boring and facing operations, I would do this: headset cup bore ~0.5" in either end, wall thickness in the center (between the headset "lands") bored out to about a 0.045" wall, leaving the OD as delivered.

I'm hopeful the second option might actually be less money than boring all the way through and turning down the entire outside. If I could just find some leftover (they don't make it at the mill anymore) 2.125" x 0.095" 4130 stock and a 1.5 standard reamer.... I bought some a long time ago for a totally different project and had some scrap, but I can't find it now.

The way I plan to use this and my desired thickness should mean I will not need to clean it up after joining. I am betting there is not a 1.5 standard facing/reaming tool in a bike shop in the state, and I have confidence that I can make a pre-faced and reamed tube work well. Therefore, it would be ideal if it were already faced (a quick kiss with the lathe is fine, just saying not saw cut), and reamed to the proper press fit for the headset.

Steerer tube:

Some quick math shows I'm looking at about 80 grams to be saved with a custom machined steerer. In my mind, that isn't worth custom machining. FYI, aircraftspruce.com has that stock at $5.25/ft, minimum order 1ft.

Race ring:

nothing special needed here, but I will need it for this project to happen.

Richard
 

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Richard,
I need to follow up on a possible option tomorrow for some tubing which may fit the spec far better than anything so far. I'm not sure of the material alloy on hand, minimum order quantity or price.

As for the machining, I wasn't looking to make any money off this. I know what it is like to have a task which requires a machine I don't have access to and a minimal job no shop wants to even bother quoting. As long as you don't take advantage of the offer, I was going to charge you materials + shipping only.

Look for a post tomorrow in regard to the headtube stock. Send me a private message through MTBR so we can email off-list on the specific details.
 

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So I found what you need. The only problem is I do not have a business license, and Parker Steel doesn't accept retail orders. 55mm OD, 3.0mm wall, 49mm ID. They list a 42CrMo stock, but it would have to be special ordered. CR1018 steel equivalent in stock. I have no idea on price. Sounds like a minimum order would be about 3ft.

http://www.metricmetal.com/

What do you want to do, rocwanderer? Should I get that material quoted through a retail supplier?
 
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