electric mountain bike

Bottom bracket alignment, pump accuracy, cable housing, and gravel frame geometry – VeloNews.com

Bottom bracket alignment, pump accuracy, cable housing, and gravel frame geometry – VeloNews.com 2020-09-01Leave a comment

electrical bike Backside bracket alignment, pump accuracy, cable housing, and gravel body geometry – VeloNews.com

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Have a query for Lennard? Please electronic mail him at veloqna@comcast.net to be included in Technical FAQ.

Expensive Lennard,
How can I decide if the underside bracket bores of my new carbon street body are in alignment with one another? I’ve measured the bores utilizing dial calipers in a number of locations on either side, they usually have been inside spec and spherical. However, the brand-new SRAM backside bracket appears to have extra drag, even after a 1000 miles or so, than my earlier cracked body from the identical firm that got here with the identical kind of SRAM backside bracket. With the cranksets eliminated, all the underside bracket bearings appear tremendous on each bikes. Maybe the store that put in a brand new backside bracket within the new body, didn’t press it in precisely flush with the body? I’ve redone the lateral preload adjustment and eliminated and reinstalled the crankset a number of instances. I’m utilizing a SRAM RED 22 crankset which got here from my earlier, 3-year-old body.

I’ve constructed wheels, bikes, and so forth. since I began racing in Nineteen Seventies whereas getting my BSME. Maybe I should purchase the Park PF30 device and take away the underside bracket and reinstall it myself. Can the PF30 backside bracket be reused?
— Jeff


Expensive Jeff,
It actually sounds as if the bearings weren’t aligned parallel with one another, and I’ve no manner of realizing if that’s as a result of they weren’t pressed in straight or as a result of the body received’t enable them to be. I don’t know the best way to verify if the bores are parallel with out gear that solely a machinist would have.

I might attempt to press that BB in once more; sure, you may reuse it so long as the bearings really feel easy to show in your hand, and a regular headset press will do the job. The Park BB30 removal tool is comparatively cheap.

If that doesn’t work, I’d set up certainly one of these Wheels Manufacturing bottom brackets as an alternative. Because it threads collectively on itself, it retains the whole lot in alignment.
― Lennard

Expensive Lennard,
As a lighter rider, I’ve been a decrease stress/bigger tire disciple for a few years now. I lastly got here to appreciate that whereas we’re using and speaking, we predict we’re speaking stress however are actually about speaking about completely different pumps.

All three of my ground pumps learn completely different pressures, and I’m certain different folks’s pumps are wildly inaccurate too, so I exploit a Schwalbe Digital Gauge, which I’m inclined to consider greater than varied pump stress gauges, however I’m wondering if all that does is give me a fourth studying. Which one ought to I consider? How can I reliably learn my pumps’ gauges?

Ought to I break up the distinction or common them, can I add a fudge issue, or can I calibrate the gauges?
Would the discrepancy be linear; that’s, if the pump reads 10 over at 100 psi will or not it’s 5 over at 50 psi?
— Doug

Expensive Doug,
I run into this continually. I consider {that a} pump gauge, since it’s really measuring the stress within the hose, a great distance from the valve, goes to be inherently inaccurate. I’ve plenty of completely different digital gauges, they usually all appear to learn inside 1psi of one another. That’s lots adequate for me. I like to recommend you consider your digital gauge and never any of your pumps.

I don’t know if the discrepancy is linear or not, and I believe it relies on the gauge. Some gauges appear to have an preliminary offset, like if the spring contained in the gauge is bent, through which case the discrepancy actually wouldn’t be linear.

I don’t know if there’s a normal to calibrate towards that’s simply obtainable. Don’t overthink it. Simply use your digital gauge.
― Lennard

Campagnolo cable housing.
A Klein Rascal about to be restored for using.

Expensive Lennard,
At age 67, I’m most likely about your age, however my ardour for bikes remains to be sturdy. I just lately acquired a 1992 Klein Rascal body/fork/mission-control headset and I’m within the means of constructing it up. My query is that this:

I actually like older Campy-style cabling, the stainless coils form. I’ve used it earlier than and would really like your recommendation as to the standard of any such cable housing. Though I’ve some classic XT thumb shifters, I’m planning to simply use the friction mode, at the least for now, so I received’t want the rigidity of listed shifting cables and housing.
— Pete

Expensive Pete,
Wow, you’ve saved that little Rascal in good situation all of those years! When you imply the unlined little piece of coil product of stainless-steel spherical wire (versus flat wire) that Campagnolo used to provide for the final little stretch from the chainstay cable cease to the rear derailleur, I might not suggest it for lengthy cable runs, as a result of it has no liner and can consequently create extra friction.

The flat coil within the photograph of your white bike appears to be like like normal lined brake cable housing with a transparent cowl. That could possibly be used with frictional shifters. And also you clearly do perceive that listed shifting won’t work with coil housing as a result of the compression of the housing ends in extra cable pull per shift required than the listed lever pulls on every click on.
― Lennard

Expensive Lennard,
Why are prime tube lengths on gravel bikes the size that they’re?

Some gravel bikes are touted as having new revised geometry, in contrast with street bike geometry. From what I can inform they’ve merely prolonged the highest tube by 1cm (dimension 56). Huge deal, one whopping cm! What occurs to dealing with when the highest tube will get longer, and the stem will get correspondingly shorter? Does a 1cm enhance in prime tube size make a tangible distinction?

Professional street riders use lengthy stems. Would they be higher off in the event that they make prime tubes longer and stems shorter? Would Caleb Ewan’s rear wheel skitter around much less throughout sprints? Would riders catapult over their handlebars much less usually? Would there be riots within the streets proclaiming the hazards of disc brakes… I imply lengthy prime tubes?

Again to gravel bikes and longer prime tubes. I’ve brief legs. My gravel bike has a 130mm stem. Having completed numerous mountain bike racing up to now, I really feel manner too far over the entrance wheel when the street will get tough or unfastened. Specialised got here out with the brand new Diverge EVO. I’m going to get a dimension medium (60cm prime tube) and put a drop bar on it with a 90mm or 100mm stem. I’m considering this may end in a greater dealing with gravel bike? Any ideas?

When you inform me that lengthy stems decelerate dealing with, then how do mountain bikes, which have to make a lot tighter turns, get away with such lengthy prime tubes?
— John

Expensive John,
A number of the identical rationale is at work with trendy gravel bikes as with trendy mountain bikes. On mountain bikes, as prime tubes have gotten longer and stems shorter, handlebars have change into longer. Rather a lot longer. Sure, on the mountain bikes of the Nineteen Eighties and early Nineties with 560mm lengthy handlebars, the lengthy stem, generally so long as 150mm, slowed down the dealing with by requiring extra hand motion to rotate the steering tube by means of a given variety of levels. Quick ahead to at the moment, the place the handlebar is 800mm lengthy and the stem is maybe 40mm lengthy. That lengthy bar is having the same impact to the lengthy stems of yesteryear, once more requiring extra hand motion to rotate the steering tube by means of a given variety of levels.

The primary technology of gravel bikes tended to have the identical handlebar, in addition to the identical prime tube and stem size as street bikes. Now, the handlebars are flared out and wider, and the stem has change into correspondingly shorter to extend the steering quickness misplaced with the rise in bar width. The highest tube size needed to enhance to pair with the shorter stem. And, in the same method to what has occurred with the march of time to mountain bikes, the longer prime tube has moved the entrance wheel additional ahead relative to the ft, arms, and butt, one thing you’ll undoubtedly respect.
― Lennard

Lennard Zinn, our longtime technical author, joined VeloNews in 1987. He’s additionally a {custom} body builder (www.zinncycles.com) and purveyor of non-custom big bikes (bikeclydesdale.com), a former U.S. nationwide crew rider, co-author of “The Haywire Heart,” and writer of many bicycle books together with “Zinn and the Art of Road Bike Maintenance,” “DVD, in addition to “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado Faculty.

Comply with @lennardzinn on Twitter.

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