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by Brucey
29 Mar 2024, 9:09pm
Forum: Bikes & Bits – Technical section
Topic: Vitus escarpe 2018 27.5 inch seat stay/chain stay
Replies: 4
Views: 172

Re: Vitus escarpe 2018 27.5 inch seat stay/chain stay

where are you exactly? Someone may be able to recommend a good value welder near you
by Brucey
29 Mar 2024, 8:43pm
Forum: Bikes & Bits – Technical section
Topic: issue with new inner ring on ultegra hollowtech
Replies: 11
Views: 562

Re: issue with new inner ring on ultegra hollowtech

it should be possible to machin e the cranks in situ, using a fairly simple wooden fixture. BTW real dremel tools use a 1/8" tool shanks but a lot of similar-looking tools use 3mm ones instead. This apparently small difference can be significant.
by Brucey
29 Mar 2024, 8:05pm
Forum: Bikes & Bits – Technical section
Topic: Going from dual to triple crankset
Replies: 26
Views: 1752

Re: Going from dual to triple crankset

I would probably look to convert the extant double to a (very) non-standard 26-36-46 triple. The usual pitch of triple (and double) chainrings, is ~8mm. If you reduce this to about 6mm it'lll probably fit and work OK, but you won't be able to run some of the small-small cross-chained combinations any more. You probably will need to re-machine the extant crank; it may be possible to do this in-situ using a variant of the SG method in combination with a wooden fixture. You will also have to modify a front mech so that it moves a bit less far than normal; not difficult, in many cases using a simple am extension.. This is undoubtedly a lot of work, but the end result could be a 26,36,46T triple that fits and works better than anything you can buy.
by Brucey
29 Mar 2024, 5:39pm
Forum: Bikes & Bits – Technical section
Topic: Connecting Batteries in Paralell
Replies: 3
Views: 196

Re: Connecting Batteries in Paralell

discharging batteries in parallel presents no great difficulty provided the batteries are 'the same'. However, even if they are identical when new, they are unlikely to stay that way.
by Brucey
29 Mar 2024, 4:03pm
Forum: Bikes & Bits – Technical section
Topic: Tyre pressures for different width tyres using Silca
Replies: 18
Views: 967

Re: Tyre pressures for different width tyres using Silca

Nearholmer wrote: 29 Mar 2024, 3:27pm Brucey,

I don’t think it represents the bike as mass-less, and I don’t think it represents a bike with suspension, only compliance, because if it did the model would need dash-pots, as well as springs, between axles and frame-mass, unless I’m missing a trick here......
my point was (in part) that tyres are a form of suspension. also, early on the mass of the bike is considered to be 'small' by comparison with the mass of the rider. Thereafter, the mass of the bike is considered to be zero.
by Brucey
29 Mar 2024, 3:37pm
Forum: Bikes & Bits – Technical section
Topic: Tips for fitting tyres to WH-6800 rims?
Replies: 11
Views: 442

Re: Tips for fitting tyres to WH-6800 rims?

FWIW rims with a shallow-looking well are often problematic. Not only may the well depth be less than normal, but unless the bead is under some tension all the time, it won't stay in the deepest part of the rim well, where it needs to be.
by Brucey
29 Mar 2024, 2:52pm
Forum: Bikes & Bits – Technical section
Topic: Tyre pressures for different width tyres using Silca
Replies: 18
Views: 967

Re: Tyre pressures for different width tyres using Silca

Miles_Turner wrote: 28 Mar 2024, 12:07pm Apologies for arriving late. Although the published text of my paper is indeed paywalled (I'm sorry to say), for those interested there is a nearly identical preprint text here: https://www.researchgate.net/publicatio ... _vibration
That is very interesting and tallies quite well with what I know of the real world. However in the real world I also note the following (which may or may not be important);

1) real bicycles are not massless (unfortunately)

2) real bicycles (and riders) exhibit very different stiffnesses at the front and rear wheels. A fork of a different stiffness is often one of the few options available to the rider.

3) engineers will soon tell you that any vehicle with suspension is liable to be faster over rough ground for a constant power, In reality however, the power is far from constant, because it is the human machine here. Anyone who has ridden full suspension knows that it doesn't suit everyone, and even those who like it are forced to pedal differently very often. So 'bobbing' (or other losses associated with a 'pulsy' torque delivery) are a real possibility with any suspension system, including fat tyres. Also there might be a substantial difference in the effects of stiffness changes between the saddle and pedals vs elsewhere. Even once you have come to grips with the likely physiological changes relating to power output, there is the no less important matter of 'what is going on between the ears?' to consider also.
by Brucey
29 Mar 2024, 9:52am
Forum: Bikes & Bits – Technical section
Topic: Dynamo carbon fork mounting options
Replies: 16
Views: 668

Re: Dynamo carbon fork mounting options

IIRC most CF forks have no hole at the base of the steerer.
by Brucey
28 Mar 2024, 8:36pm
Forum: Bikes & Bits – Technical section
Topic: Tips for fitting tyres to WH-6800 rims?
Replies: 11
Views: 442

Re: Tips for fitting tyres to WH-6800 rims?

it is certainly best if you finish at the valve as previously suggested. Some rim/tyre combinations have been so bad they have made my thumbs sore, but I have seldom failed.
by Brucey
28 Mar 2024, 8:09pm
Forum: Bikes & Bits – Technical section
Topic: Dynamo carbon fork mounting options
Replies: 16
Views: 668

Re: Dynamo carbon fork mounting options

it should be possible to create a wire bracket that mounts with an M5 bolt on the back of the fork crown.

My suggestion is that you make a four-legged bracket as per my previous post, but you make it so that two legs go under the fork crown, and two go over it. I think it would be best done with the two sides having one leg of each sort. Again, an additional modified 'V'-brake washer could be used, this time to secure the ends of the bracket legs. If the legs are fitted with a few of those protector 'o' rings as seen on many mtb top tube cable runs (or similar), it ought to be possible to make the bracket so that it is partially supported by the fork crown but the fork is not marred by it.
by Brucey
28 Mar 2024, 6:38pm
Forum: Bikes & Bits – Technical section
Topic: Vitus escarpe 2018 27.5 inch seat stay/chain stay
Replies: 4
Views: 172

Re: Vitus escarpe 2018 27.5 inch seat stay/chain stay

I would wager that it can be repaired, and in fact if you can't buy replacement parts, you have little choice. However, more details of this allegedly 'unrepairable' part would be useful.
by Brucey
28 Mar 2024, 6:07pm
Forum: Bikes & Bits – Technical section
Topic: Tiagra ST-4703 Shifter Not Working
Replies: 20
Views: 727

Re: Tiagra ST-4703 Shifter Not Working

when I rode with my chum, it soon became clear that he changed gear at least ten times more often than I did. I guess that is what many years of riding a SA 5s hub does for you. To give you some idea, I worked out that you could nigh-on replicate the gear ratios using a derailleur system, but even I was surprised by the result.

If you started with a 7s 13-28T freewheel and simply omitted 3rd and 5th, you would be pretty close. Because the middle gear is
arguably doing the work of three, gear changes on a flattish road with a SA 5s hub can be few and far between.
by Brucey
28 Mar 2024, 1:29pm
Forum: Bikes & Bits – Technical section
Topic: Tiagra ST-4703 Shifter Not Working
Replies: 20
Views: 727

Re: Tiagra ST-4703 Shifter Not Working

Cyclothesist wrote: 28 Mar 2024, 11:05am.... The only trouble I've had is fishing broken gear cable strands out when I've been tardy in replacing them.
Maybe I've been lucky?
things can wear out or break depending on the exact model but by far the most common faults are dried grease and broken cables. Very often shifters don't survive an episode of broken cables, because they get damaged when the broken bits are removed. Needless to say you don't have the same problem if the cable is largely outside the shifter. One of my chums had repeated problems with broken cables inside STIs on his commuting machine. Riding with him, I soon established the reason; he was wont to do many more gear changes than most people,and his gear cables wouldn't last 9 months without fatiguing and breaking. Using him as a guinea pig, I was able to establish that the life expectancy of cables inside STI shifters is typically about 150000 shifts. By routinely changing the cables at about 125000 shifts my chum's problem was almost completely cured.
by Brucey
28 Mar 2024, 11:18am
Forum: Bikes & Bits – Technical section
Topic: M2.5 bolt
Replies: 30
Views: 1127

Re: M2.5 bolt

FWIW a drop of loctite on these screws never hurts.
by Brucey
28 Mar 2024, 10:23am
Forum: Bikes & Bits – Technical section
Topic: Noisy freehub - quieten with grease?
Replies: 35
Views: 1596

Re: Noisy freehub - quieten with grease?

that is pretty much what I'd do anyway tbh